AJP - Regu Fuel your research with LabChart
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Regul Integr Comp Physiol 293: R1037-R1045, 2007. First published June 6, 2007; doi:10.1152/ajpregu.00125.2007
0363-6119/07 $8.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
293/3/R1037    most recent
00125.2007v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Wang, C.
Right arrow Articles by Kotz, C. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wang, C.
Right arrow Articles by Kotz, C. M.

APPETITE, OBESITY, DIGESTION, AND METABOLISM

Brain-derived neurotrophic factor in the ventromedial nucleus of the hypothalamus reduces energy intake

ChuanFeng Wang,1,3 Eric Bomberg,1 Allen Levine,1,2,3,4 Charles Billington,1,2 and Catherine M. Kotz1,2,3,4

1Veterans Affairs Medical Center and 2Minnesota Obesity Center, Minneapolis, Minnesota; and 3Department of Food Science and Nutrition and 4Graduate Program in Neuroscience, University of Minnesota, Saint Paul, Minnesota

Submitted 20 February 2007 ; accepted in final form 6 June 2007


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Recent studies show that brain-derived neurotrophic factor (BDNF) decreases feeding and body weight after peripheral and ventricular administration. BDNF mRNA and protein, and its receptor TrkB, are widely distributed in the hypothalamus and other brain regions. However, there are few reports on specific brain sites of actions for BDNF. We evaluated the effect of BDNF, given into the ventromedial nucleus of the hypothalamus (VMH), on normal and deprivation- and neuropeptide Y (NPY)-induced feeding behavior and body weight. BDNF injected unilaterally or bilaterally into the VMH of food-deprived and nondeprived rats significantly decreased feeding and body weight gain within the 0- to 24-h and the 24- to 48-h postinjection intervals. Doses effectively producing inhibition of feeding behavior did not establish a conditioned taste aversion. BDNF-induced feeding inhibition was attenuated by pretreatment of the TrkB-Fc fusion protein that blocks binding between BDNF and its receptor TrkB. VMH-injected BDNF significantly decreased VMH NPY-induced feeding at 1, 2, and 4 h after injection. In summary, BDNF in the VMH significantly decreases food intake and body weight gain, by TrkB receptor-mediated actions. Furthermore, the anorectic effects of BDNF in this site appear to be mediated by NPY. These data suggest that the VMH is an important site of action for BDNF in its effects on energy metabolism.

food intake; body weight

THE VENTROMEDIAL NUCLEUS OF THE HYPOTHALAMUS (VMH) is a brain area important to the regulation of energy metabolism. Early studies indicated that VMH lesions resulted in hyperphagia and obesity (28, 38, 66), whereas electrical stimulation of the VMH immediately suppressed feeding and induced lipolysis (65). Glucose-sensing neurons (7, 27, 55, 74, 75) and receptors for neuropeptides important to energy metabolism have been identified in the VMH, including leptin (13, 17, 20, 22, 51), melanocortin (26), neuropeptide Y (NPY) (43), corticotrophin-releasing hormone (49), CCK (12), insulin (33), and orexin (44) receptors. Many biological agents given into the VMH have been demonstrated to affect feeding. Food intake is inhibited by administration of histamine (4, 47), glucagon-like peptide 1 (70), serotonin agonists (25), urocortin (58), CCK (79), leptin (51), and insulin (78), whereas thyroid hormone (3,5,3'-triiodothyronine) (40), GABA or GABA agonists (32, 34, 35), norepinephrine (73), orexin (74), and NPY induce feeding after administration into the VMH (5, 9, 24, 31, 43, 56, 76).

Anatomically, the VMH receives inputs from regions important to the regulation of energy metabolism, including the hypothalamic arcuate nucleus (ARC) (2, 14, 23), lateral hypothalamus (18, 67, 80), amygdala (45, 50), and lateral septum. The VMH also projects to ARC (77), paraventricular nucleus (PVN) (42, 52), lateral hypothalamus (72, 80), dorsomedial nucleus of the hypothalamus (46, 80), amygdala (6, 68), lateral septum (68), ventral tegmental area (68), nucleus accumbens (6), and nucleus of the solitary tract (6). These behavioral and neuroanatomic data provide evidence for the importance of the VMH in regulation of energy metabolism.

Brain-derived neurotrophic factor (BDNF) has recently been reported to affect energy metabolism. Intracerebroventricular (ICV) BDNF decreased feeding and body weight gain in animals (62). BDNF+/– heterozygous animals displayed hyperphagia and obesity (36), and exogenous BDNF reversed the phenotype. Human patients with BDNF receptor (TrkB) defects exhibit hyperphagia and obesity (91). Low levels of plasma BDNF have been found in obese patients with Type 2 diabetes and metabolic syndrome (21). This evidence indicates that BDNF is important in the regulation of energy metabolism, but information on sites of BDNF action in the central nervous system is limited. Low BDNF expression was observed in the hypothalamus of BDNF+/– heterozygous animals, including the PVN and VMH (36). Bariohay et al. (3) reported significant decreases in feeding and body weight gain during chronic infusion of BDNF in the dorsal ventral complex, and our previous work (85, 86) indicates that the PVN is an important site of BDNF action.

BDNF in the VMH may also play an important role in the regulation of energy metabolism. Both mRNA and protein for BDNF and its receptor TrkB have been identified in the VMH (8, 36, 87, 90). Low levels of BDNF in the VMH are accompanied by hyperphagia and obesity (36), and animals lacking the orphan nuclear steroidogenic factor-1 receptor develop BDNF deficiency and VMH abnormalities and also display hyperphagia and obesity (11, 48, 82, 92). Recent studies indicate that expression of BDNF in the VMH is regulated by leptin (39) and melanocortins (89), two key mediators of energy metabolism. On the basis of these data, we set out to determine whether the VMH is an important site of BDNF action.

We first tested the effect of a single injection of BDNF in the VMH on normal feeding and deprivation-induced feeding. We then determined whether these effects could be reversed by preadministration of the TrkB-Fc fusion protein, which functionally blocks binding between BDNF and the TrkB receptor. We also performed a conditional taste aversion (CTA) study to determine whether BDNF into this brain area results in feelings of malaise, which could potentially explain reductions in feeding. Finally, we tested the interaction between BDNF and NPY by measuring the effect of BDNF on NPY-induced feeding. Our study demonstrated that 1) a single injection of BDNF in the VMH significantly reduces feeding and body weight gain in normal and food-deprived animals for up to 48 h; 2) pretreatment with TrkB-Fc significantly blocks BDNF-induced anorexia; 3) BDNF, at doses that effectively inhibit feeding (0.1–1 µg), does not result in a conditioned taste aversion; and 4) BDNF significantly blocks NPY-induced feeding.


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Animals

Male Sprague-Dawley rats (Harlan, Madison, WI) weighing 280–320 g were housed individually in cages with a 12:12-h light-dark photocycle (lights on at 7:00 AM) in a room at 21–22°C. Teklad lab Chow and water were allowed ad libitum, except where noted. All experimental study protocols were approved by the Veterans Affairs Medical Center Institutional Animal Care and Use Committee before commencement of procedures.

Cannulation and Verification of Placement

Rats were anesthetized with intramuscular xylazine (3.5 mg/kg) and ketamine (20 mg/kg) and were fitted with 28-gauge stainless steel guide cannulae placed just above the VMH either unilaterally or bilaterally. Stereotaxic coordinates were determined from the rat brain atlas of Paxinos and Watson (61) and are as follows: 0.6 mm lateral and 2.5 mm posterior to bregma and 8.5 mm below the skull surface. The injector extended 1 mm further than the end of the guide cannula. The animals were given at least 1 wk to recover after surgery before experimental trials. After terminal experiments, the rats were decapitated and whole brain tissues were removed and soaked in 10% formalin solution for at least 48 h. The brain tissues were sectioned by cryostat at a thickness of 50 µm, mounted on gelatin-coated slides, stained with 0.1% thionin, and treated with ethanol (from 30% to 100%) and clearing agent (Electron Microscopy Sciences, Hatfield, PA). After the slides had dried, injection placement was determined microscopically at x10, using the brain atlas of Paxinos and Watson (61) as a reference. Placements of the unilateral injection sites for study of BDNF effects on normal and deprivation-induced feeding and bilateral injection sites for study of BDNF effects on normal feeding are summarized in Fig. 1, and photomicrographs of representative histologies with bilateral cannulation are shown in Fig. 2. A cannula was deemed correct if the histological examination indicated that the injection was within a 0.25 mm diameter from the targeted site. This rationale is based on diffusion coefficients for the injection volume delivered (57) and work showing effectiveness within this range (85, 86). Data from animals with misplaced cannulae were excluded from data analyses. Histological examination of brain tissue to verify injection site was not possible in some studies because rats were undergoing additional studies. In this situation, we used feeding response to injected NPY as a behavioral assay to determine correct cannula placement, as verified in previous studies (5, 9, 24, 31, 43, 56, 76). According to this assay, cannula placement is deemed correct if the animal consumes more than 2 g of chow within 2 h after 100 pmol NPY. Animals not responding to NPY are excluded from the study.


Figure 1
View larger version (46K):
[in this window]
[in a new window]

  		Fig. 1. Location of placed injections in the ventromedial nucleus of hypothalamus (VMH). A: placement from 18 rats in the study of effects of unilateral brain-derived neurotrophic factor (BDNF) on normal and deprivation-induced feedings. Two rats without correct placement were excluded from the statistical analysis. B: placement from 17 rats in the study of effects of bilateral BDNF on normal feeding. Three rats without correct placement were excluded from the statistical analysis. [From Paxinos and Watson (61)].

 

Figure 2
View larger version (114K):
[in this window]
[in a new window]

  		Fig. 2. Photographs of correct injection placements in the VMH. The right injection placement is in the rostral VMH site (A), and the left injection placement is located in the more caudal part of the VMH (B).

 
Drugs

BDNF was kindly provided by Regeneron Pharmaceuticals (Tarrytown, NY) and stored at –70°C in 10 mg/ml of 150 mM NaCl, 10 mM NaHPO3 buffer, and 0.004% Tween 20 until use. Just before use, BDNF was diluted with artificial cerebrospinal fluid (aCSF). NPY was purchased from Phoenix Pharmaceuticals (Mountain View, CA) and was diluted with aCSF just before use. TrkB-Fc fusion protein was purchased from R&D System (Minneapolis, MN), dissolved in PBS (pH 7.4) as stock, and diluted to a final concentration of 1.0 µg/µl in a mixture of PBS and aCSF (1:1 vol/vol) containing 0.1% BSA.

Injections

Volume of 0.5 µl was injected slowly over 2 min for TrkB-Fc and over 30 s for vehicle and other compounds, with injector left in place for an additional 15 s to ensure extrusion from the tip and to minimize distribution of drug upward on the cannula tract. In total, animals received <10 injections. Injection sites were examined by light microscopy for tissue damage in the present studies, and none was found.

Experiments

Effect of BDNF on normal feeding. Food was allowed ad libitum before and during the experimental period. Eighteen rats were injected unilaterally with aCSF and 0.1, 0.3, or 0.5 µg of BDNF just before the dark phase (7:00 PM). Food intake was measured at 1, 2, 4, 24, and 48 h after injection. Body weight was measured at 0 h and at 24 and 48 h after injection. Each animal received each treatment once with at least 72 h between treatments to allow for clearance of BDNF from the central nervous system and for normal feeding patterns to be reestablished. Treatments were given in a randomly selected Latin square design to avoid a treatment-order confound. Sixteen rats had correct cannula placement (verified by histology) and therefore were included in the final statistical analyses. Another set of 17 rats with bilateral cannulae were injected with 0.1, 0.3, 0.5, 1.0, and 3.0 µg of BDNF on each side at 2:00 PM. Food intake and body weight change were measured at 24 and 48 h after injection. After 3 rats were excluded because of incorrect cannula placement (verified by histology), 14 rats were included in the final statistical analyses.

Effect of BDNF on deprivation-induced feeding. Eighteen rats were injected unilaterally with aCSF or BDNF (0.1, 0.3, or 0.5 µg) after 18 h of food deprivation and were given food immediately after injection. Food intake was measured at 1, 2, 4, 24, and 48 h after injection. Body weight was measured at 0 h and at 24 and 48 h after injection. Each animal received each treatment once with at least 72–96 h between treatments. Sixteen rats had correct cannula placement (verified by histology) and were included in the statistical analyses. Another set of 20 rats was bilaterally injected with 0.1, 0.3, 0.5, or 1.0 µg BDNF on each side. Each animal received each treatment once with at least 72–96 h between treatments. Correct placement was determined by response to NPY. All rats were deemed to have correct placement and were included in the statistical analyses.

Effect of TrkB-Fc fusion protein on BDNF-suppressed feeding. TrkB-Fc is a fusion protein that consists of an extracellular domain of the TrkB receptor and an Fc domain of IgG. TrkB-Fc binds to BDNF with high affinity and thus functionally blocks BDNF binding to its receptor. Twenty-four rats were injected bilaterally with one of the following combined treatments on each side: 1) aCSF + aCSF, 2) aCSF + 0.5 µg BDNF, 3) 0.5 µg TrkB-Fc + 0.5 µg BDNF, or 4) 0.5 µg TrkB-Fc + aCSF. The second injection was given 10–15 min after the first injection. Food intake and body weight were measured at 0, 24, and 48 h after the second injection. Each animal received each treatment once with at least 72 h between treatments. The dose of TrkB-Fc was chosen based on effective dose ranges from published in vivo studies (30, 41, 64, 69) and pilot studies in our laboratory. After 3 rats were excluded because they did not respond to NPY, 21 rats were included in the statistical analysis.

The effect of VMH-injected BDNF on preference for saccharin solution. In a separate group of animals, the two-bottle preference test was used to determine whether BDNF results in aversive consequences after administration into the VMH. The procedures for the experiment have been previously described (84). In brief, drinking water was allowed only between 10:30 and 11:00 AM for 30 bilaterally VMH-cannulated rats each day for 7 days. During water access, two bottles of water were presented. The rats were then randomly divided into five groups (with an even distribution of body weight) and given 15 ml of 0.1% saccharin; this was immediately followed by injection on each side with either aCSF or BDNF (0.1, 0.3, 0.5, or 1.0 µg). This conditioned stimulation was repeated once after 2 days, and the animals were then given the choice of water or saccharin in the absence of drug administration 2 days later. To avoid the possible confound of bottle placement, initial position and order of presentation of the saccharin bottle were counterbalanced across subjects, and the two-bottle test was repeated 2 days later in which the two bottle positions were reversed. Intake of water and saccharin during 24 h was measured, and the mean of the two tests was calculated. One rat was excluded because it did not respond to VMH NPY; thus 29 rats were included in the statistical analyses.

Effect of BDNF on NPY-induced feeding. Food was allowed ad libitum before and during the experimental period. Ten VMH bilaterally cannulated rats were randomly assigned to one of six treatments: 1) aCSF + aCSF, 2) aCSF + NPY (100 pmol), 3) BDNF (0.1 µg) + NPY (100 pmol), 4) BDNF (0.3 µg) + NPY (100 pmol), 5) BDNF (0.5 µg) + NPY (100 pmol), or 6) BDNF (0.5 µg) + aCSF. The first injection was made bilaterally at 7:00 AM, and the second injection was made unilaterally 4 h later (11:00 AM) on the alternate side on each experimental day. The 4-h delay was used in an effort to match the delayed effect of BDNF on feeding behavior in food-deprived animals. Each animal received each treatment once with at least 72 h between treatment to allow for clearance of BDNF from the central nervous system and for normal feeding patterns to be reestablished. Food intake was measured at 1, 2, and 4 h after the second injection. All 10 rats responded to NPY and were included in the statistical analyses.

Statistical Analyses

For all feeding experiments, data were analyzed with the use of StatView 5.0 (Cary, NC) and are expressed as means ± SE. Repeated-measures ANOVA was used to analyze food intake and body weight change. Thus each rat served as its own control. When main effects were observed, post hoc analysis was performed using multiple-comparison contrasts. For the conditioned taste aversion experiment, data were analyzed by a one-factor ANOVA followed by Fisher's least-significant difference t-test to compare means.


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 GRANTS
 REFERENCES
 
Effect of BDNF on Normal Feeding

Unilateral injections of BDNF did not significantly affect feeding within the first 4 h postinjection (Fig. 3A), but 0.5 µg BDNF significantly decreased feeding in the 4- to 24-h postinjection interval by 21.6% (P = 0.0056; Fig. 3B), by 17.4% (P = 0.0084) in the 0- to 24-h interval, and by 13.2% (P = 0.0061; Fig. 3B) in the 0- to 48-h interval. BDNF at 0.1 and 0.5 µg significantly reduced body weight gain in the 0- to 24-h postinjection interval (P = 0.0449 and P = 0.0005, respectively) and in the 0- to 48-h postinjection interval, and the 0.5-µg BDNF dose significantly reduced body weight gain (P = 0.0170; Fig. 3C).


Figure 3
View larger version (27K):
[in this window]
[in a new window]

  		Fig. 3. Effects of unilateral VMH-injected BDNF on normal feeding and body weight change. Animals (n = 16) were injected with artificial cerebrospinal fluid (aCSF) and 0.1, 0.3, and 0.5 µg BDNF just before 7:00 PM. Food intake was measured at 1, 2, 4, 24, and 48 h after injection. A: food intake at 1, 2, and 4 h. B: food intake at 24 and 48 h. C: body weight change at 24 and 48 h. *P < 0.05 and #P < 0.01, compared with control (animals treated with aCSF).

 
Bilaterally injected BDNF dose-dependently inhibited normal feeding (Fig. 4A). At 24 h after injection, BDNF at the 1- and 3-µg doses significantly inhibited normal feeding by 10.3% (P = 0.024) and by 16.3% (P = 0.0005), respectively. In the 24- to 48-h interval, BDNF at 0.5, 1, and 3 µg significantly inhibited normal feeding by 9.5% (P = 0.0073), 7.5% (P = 0.0329), and 9.7% (P = 0.0066), respectively. In the 0- to 48-h postinjection interval, BDNF at 1 and 3 µg significantly inhibited normal feeding by 8.9% (P = 0.0112) and by 12.9% (P = 0.0003), respectively. In the 0- to 24-h postinjection interval, BDNF at 0.5, 1, and 3 µg significantly inhibited body weight gain by 53.9% (P = 0.0471), 60.1% (P = 0.0295), and 98.8% (P = 0.0004), respectively (Fig. 4B). In the 0- to 48-h interval, BDNF at 0.5, 1, and 3 µg inhibited body weight gain (P = 0.0412, P = 0.0074, and P = 0.0004, respectively; Fig. 4B).


Figure 4
View larger version (26K):
[in this window]
[in a new window]

  		Fig. 4. Effect of bilateral VMH-injected BDNF on normal feeding and body weight change. Animals (n = 14) were injected with aCSF and with 0.1, 0.3, 0.5, 1.0, and 3.0 µg BDNF at 2:00 PM. Food intake and body weight were measured at 24 and 48 h after injection. A: food intake at 24 and 48 h. B: body weight change at 24 and 48 h. *P < 0.05 and #P < 0.01, compared with control (animals treated with aCSF).

 
Effect of BDNF on Deprivation-Induced Feeding

Unilateral injections of BDNF did not significantly affect feeding within the first 4 h postinjection. In the 4- to 24-h postinjection interval, BDNF at 0.3 and 0.5 µg significantly decreased feeding by 12.3% (BDNF, 18.37 ± 0.69 g vs. aCSF, 21.29 ± 0.81 g; P = 0.0163) and by 15.8% (BDNF, 17.93 ± 0.85 g vs. aCSF, 21.29 ± 0.81 g; P = 0.0025), respectively. In the 0- to 24-h postinjection interval, BDNF at 0.1, 0.3, and 0.5 µg significantly reduced feeding by 7.8% (BDNF, 29.16 ± 0.96 g vs. aCSF, 31.61 ± 0.91 g; P = 0.0196), 8.1% (BDNF, 29.04 ± 0.81 g vs. aCSF, 31.61 ± 0.91 g; P = 0.0147), and 9.3% (BDNF, 28.66 ± 0.72 g vs. aCSF, 31.61 ± 0.91 g; P = 0.0056). In the 0- to 48-h postinjection interval, BDNF reduced feeding and body weight gain in a dose-dependent pattern, but these changes did not reach statistical significance (P > 0.05, data not shown).

Similar to the data from unilateral BDNF administration, bilaterally injected BDNF did not inhibit feeding at 4 h after injection (Fig. 5A). In the 4- to 24-h postinjection interval, BDNF at 0.3, 0.5, and 0.1 µg dose dependently inhibited deprivation-induced feeding by 13.4% (P = 0.0077), 18.1% (P = 0.0004), and 22.1% (P < 0.0001), respectively (Fig. 5B). BDNF at 0.1, 0.3, 0.5, and 1 µg in the 0- to 24-h postinjection interval significantly reduced feeding by 7.0% (P = 0.0234), 11.8% (P = 0.0002), 17.5% (P < 0.0001), and 17.0% (P < 0.0001), respectively. BDNF-induced reductions in feeding in the 24- to 48-h postinjection interval did not reach statistical significance. During the 0- to 48-h postinjection interval, BDNF at 0.3, 0.5, and 1 µg significantly decreased feeding by 6.8% (P = 0.0111), 13.3% (P < 0.0001), and 14.3% (P < 0.0001), respectively (Fig. 5B). In the 0- to 24-h postinjection interval, BDNF at 0.1, 0.3, 0.5, and 1 µg dramatically decreased body weight gain by 16.4% (P = 0.0551), 27.1% (P = 0.0019), 42.9% (P < 0.0001), and 45.4%, (P < 0.0001), respectively (Fig. 5C). In the 0- to 48-h postinjection interval, BDNF at 0.3, 0.5, and 1 µg significantly and dose dependently decreased body weight gain by 34.5% (P = 0.0028), 43.6% (P = 0.0002), and 58.5%, (P < 0.0001), respectively (Fig. 5C).


Figure 5
View larger version (25K):
[in this window]
[in a new window]

  		Fig. 5. Effect of bilateral VMH-injected BDNF on deprivation-induced feeding and body weight change. Animals (n = 20) were deprived for 18 h and given food immediately after bilateral injection of aCSF and 0.1, 0.3, 0.5, and 1.0 µg BDNF. A: food intake in the first 4 h after injection. B: food intake in the 4- to 48-h interval after injection. C: body weight change at 24 and 48 h after injection. *P < 0.05 and #P < 0.01, compared with control (animals treated with aCSF).

 
Effect of TrkB-Fc Fusion Protein on BDNF-Induced Feeding Inhibition

In this experiment, the second injection (BDNF or aCSF) was made 10–15 min after the first injection (TrkB-Fc or aCSF). During the 0- to 24-h postinjection interval, BDNF at 0.5 µg significantly decreased feeding by 19.4% (P < 0.0001; Fig. 6A) and significantly decreased body weight gain (P < 0.0001; Fig. 6B). Preadministration of 0.5 µg of TrkB-Fc significantly attenuated BDNF-induced anorexia by 13.7% (P = 0.0011; Fig. 6A) and body weight decrease (P = 0.0426; Fig. 6B). During the 24- to 48-h postinjection interval, BDNF significantly decreased feeding by 6.2% (P = 0.0077; Fig. 6A) and significantly decreased body weight gain (P = 0.0028; Fig. 6B); preadministration of TrkB-Fc attenuated BDNF-induced anorexia by 4.7% and body weight loss, but this did not reach statistical significance (P = 0.2122 and P = 0.2147, respectively). During the 0- to 48-h postinjection interval, BDNF significantly decreased feeding by 14.3% (P < 0.0001; Fig. 6A) and decreased body weight gain (P < 0.0001; Fig. 6B), whereas pretreatment with TrkB-Fc significantly attenuated BDNF-induced feeding inhibition by 9% (P = 0.0073; Fig. 6A) and attenuated BDNF-induced body weight loss (P < 0.0191; Fig. 6B).


Figure 6
View larger version (22K):
[in this window]
[in a new window]

  		Fig. 6. Effect of TrkB-Fc on BDNF-induced feeding inhibition on normal feeding and body weight change. Animals (n = 21) were given combination of vehicle, 0.5 µg of BDNF, or 0.5 µg of TrkB-Fc. The first bilateral injection was followed by a second bilateral injection 10–15 min later. Food intake and body weight were measured at 24 and 48 h after administration. A: food intake at 24 and 48 h after injection. B: body weight change at 24 and 48 h after injection. The different letters indicate that the representative values are significantly different from each other, P < 0.05.

 
Effect of VMH-Injected BDNF on Preference for Saccharin Solution

In the conditioned taste aversion experiment, the percentage of fluid intake attributed to saccharin was 91.4 ± 1.8% for aCSF, 78.1 ± 8.2% for 0.1 µg BDNF, 86.8 ± 7.2% for 0.3 µg BDNF, 80.8 ± 6.1% for 0.5 µg BDNF, and 71.3 ± 8.9% for 1.0 µg BDNF. There was no main effect of BDNF on the intake of saccharin solution (P = 0.3013).

Effect of BDNF on NPY-Induced Feeding

Injection of NPY into the VMH significantly increased food intake at 1 h after injection (P = 0.0018; Fig. 7), and preadministration of BDNF (0.5 µg) significantly decreased NPY-induced feeding by 67.4% (P = 0.0139; Fig. 7). In the 1- to 2-h and 2- to 4-h postinjection intervals, there was no main effect on feeding (Fig. 7). However, in the 0- to 2-h post-NPY injection interval, NPY significantly induced feeding (P = 0.0066; Fig. 7), which was decreased 50.1% by 0.5 µg BDNF, but this did not reach statistical significance (P = 0.0645; Fig. 7). In the 0- to 4-h interval, NPY significantly increased feeding (P = 0.0131; Fig. 7), which was significantly inhibited by 0.5 µg BDNF (54.9%, P = 0.0091; Fig. 7).


Figure 7
View larger version (21K):
[in this window]
[in a new window]

  		Fig. 7. Effect of VMH-injected BDNF on neuropeptide Y (NPY)-induced feeding. Animals (n = 10) were given a bilateral injection followed by a second contralateral unilateral injection 4 h later. The different letters indicate that the representative values are significantly different from each other, P < 0.05.

 

   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
GRANTS
 REFERENCES
 
In the present study, a single injection of BDNF in the VMH significantly inhibited normal feeding, deprivation- and NPY-induced feeding, and body weight gain. The conditioned taste aversion experiment suggests that BDNF at doses effective in reducing feeding did not cause taste aversion, suggesting that BDNF effects on feeding are not the result of malaise.

Unilateral injections of BDNF did not affect normal feeding in the first 4 h after injection (Fig. 3A), but it decreased feeding and body weight gain at the 24- and 48-h postinjection intervals (Fig. 3, B and C). To determine whether bilateral injection of BDNF would effectively inhibit feeding, we injected BDNF bilaterally, using a wider range of doses. Bilateral injection of BDNF dose dependently inhibited normal feeding and body weight gain (Fig. 4, A and B), but in general the bilateral BDNF injections were no more effective than unilateral BDNF injections in reducing feeding or body weight gain.

We also tested unilateral and bilateral administration approaches in deprivation-induced feeding. With both unilateral and bilateral injection, BDNF did not significantly affect feeding in the first 4-h postinjection interval (see RESULTS and Fig. 5A). Both unilateral and bilateral BDNF decreased feeding at 24 h postinjection, and bilateral BDNF (same dose on each side) did not create further inhibition of feeding. At 48 h postinjection, unilateral BDNF did not significantly inhibit feeding and body weight gain (RESULTS), whereas bilateral BDNF at 0.1–1 µg dramatically decreased feeding and body weight gain (Fig. 5, B and C), suggesting that in this case the bilateral approach was more effective.

Several studies have reported inhibitory effects of BDNF on feeding after peripheral and central administration. Pelleymounter et al. (62) in the mid 1990s reported that chronic and continuous ICV BDNF decreased feeding and body weight gain, and Kernie et al. (36) reported that ICV BDNF reversed hyperphagia and obesity in BDNF heterozygous mice. Chronic, intermittent subcutaneous injections of BDNF reduced body weight (81), suggesting peripheral sites of action for BDNF, as a molecule of this size (13.6 kDa) cannot cross the blood-brain barrier (59, 60). In a recent study in which the dorsal vagal complex was specifically targeted, chronic administration of BDNF significantly decreased feeding and body weight gain at doses of 0.1 and 1.0 µg (3). Because these studies relied on a chronic infusion method, the time course of BDNF anorectic effects is unknown. In our previous study of BDNF in the PVN (86), a single BDNF injection significantly decreased feeding and body weight gain during normal, deprivation-induced, and NPY-induced feeding for up to 48 h after injection. Similarly, BDNF in the VMH also shows inhibitory effects on feeding and body weight gain during this time frame, implicating the VMH as an additional site of action for central BDNF.

The CTA experiment indicates that BDNF at effective feeding-inhibitory doses does not result in a CTA, suggesting that BDNF anorectic effects are not due to malaise or other aversive consequences of BDNF injection. Although it is possible that the temporal relationship between pairing of the novel solution exposure and potential BDNF injection-related malaise is not accurately matched, in our previous work (86) with BDNF in the PVN, matching the saccharin exposure with the delayed timing of the anorectic response did not result in a CTA. Although not absolute, these data provide strong support for the idea that BDNF anorectic effects are not via malaise or other aversive consequences of BDNF injections.

Leptin has been reported not only to activate nuclear groups in the ventromedial hypothalamus (10, 15, 16) but also to increase BDNF mRNA and protein in the VMH (39). ICV leptin rapidly reduces food intake within 0.5–1 h postinjection (71) (53), and VMH leptin also dramatically decreases feeding and body weight (29). Because leptin stimulates BDNF expression in the VMH, it is speculated that leptin decreases feeding by mediating VMH BDNF. However, as indicated above, the timing of BDNF inhibitory effects does not match that of leptin, suggesting that BDNF may not mediate leptin feeding inhibitory effects. BDNF has also been suggested as an important downstream effector of melanocortin-4 receptor signaling, and one study showed that melanocortin administration stimulates BDNF expression in the VMH (89). However, like leptin, the time course of melanocortin-induced anorexia (19, 88) does not match that of BDNF. Although these data do not exclude BDNF interaction with either leptin or melanocortins, the timing differences in behavioral responses suggest that BDNF likely does not mediate leptin- and melanocortin-induced feeding inhibition.

Several reports have indicated that the TrkB-Fc fusion protein is effective in blocking BDNF effects, such as BDNF-mediated N-methyl-D-aspartate-evoked responses (37), synaptic regulation (83), and noxious stimulation (63). To verify that BDNF decreases feeding and body weight gain via activation of TrkB, we used the TrkB-Fc fusion protein to block BDNF binding to its receptor. Although TrkB-Fc protein does not directly target the TrkB receptor, it contains the TrkB extracellular domain (BDNF binding site) and thus acts as a competitive inhibitor of TrkB receptor binding to BDNF and reduces BDNF-TrkB signaling. Therefore, this fusion protein can be used to test whether TrkB receptor binding is necessary for BDNF effects. On the basis of effective in vivo concentrations (1.6–2.5 µg/µl) and in vitro ED50 data available from the manufacturer indicating that relatively a large amount of the fusion protein is needed (ED50 reached when the ratio of TrkB-Fc to BDNF molecules was 6:1), we initially tested 1.5 µg of TrkB-Fc but found that this dose resulted in immediate hyperactivity, which endured for ~10–15 min. The dose was reduced to 0.5 µg, which did not cause hyperactivity. TrkB-Fc at 0.5 µg significantly blocked BDNF-induced feeding inhibition and body weight loss (Fig. 6, A and B), indicating that BDNF in the VMH reduces feeding and body weight gain via its receptor TrkB.

ARC NPY neurons project to other areas of the hypothalamus, including the PVN and VMH. NPY has been reported to increase feeding not only after administration into the PVN but also after VMH injection (5, 9, 24, 31, 43, 56, 76). We tested interactions between BDNF and NPY on feeding behavior. VMH NPY significantly increased feeding, and this effect was significantly reduced by BDNF (Fig. 7). This finding is similar to that for PVN BDNF and NPY coinjection studies and suggests that both VMH and PVN BDNF effects may be due to blockade of NPY orexigenic pathways.

In conclusion, BDNF in the VMH significantly decreases normal and deprivation- and NPY-induced feedings and body weight, at doses not producing a condition taste aversion, and the effect of BDNF is mediated by its receptor TrkB in the VMH. The delayed effect on feeding inhibition suggests that BDNF in the VMH may trigger activation and/or inhibition of neural circuit(s) or may be transported to other sites for the action (1, 54), for which further studies are needed. Together, these data implicate the VMH as an important site of BDNF action to influence energy metabolism.


   GRANTS
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 GRANTS
REFERENCES
 
This work was supported by the Department of Veterans Affairs and by the Minnesota Obesity Center (pilot and feasibility program no. 14).


   ACKNOWLEDGMENTS
 
We thank Regeneron Pharmaceuticals (Tarrytown, NY) for providing BDNF and Mark R. Margosian, Mary Mullett, and Martha Grace for technical support.


   FOOTNOTES
 

Address for reprint requests and other correspondence: CF. Wang, Veterans Affairs Medical Center, Research Service (151), One Veterans Dr., Minneapolis, MN 55417 (e-mail: cwang{at}umn.edu)

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.


   REFERENCES
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

  1. Altar CA, DiStefano PS. Neurotrophin trafficking by anterograde transport. Trends Neurosci 21: 433–437, 1998.[CrossRef][ISI][Medline]
  2. Bagnol D, Lu XY, Kaelin CB, Day HE, Ollmann M, Gantz I, Akil H, Barsh GS, Watson SJ. Anatomy of an endogenous antagonist: relationship between Agouti-related protein and proopiomelanocortin in brain. J Neurosci 19: RC26, 1999.[Abstract/Free Full Text]
  3. Bariohay B, Lebrun B, Moyse E, Jean A. Brain-derived neurotrophic factor plays a role as an anorexigenic factor in the dorsal vagal complex. Endocrinology 146: 5612–5620, 2005.[Abstract/Free Full Text]
  4. Berthoud HR, Jeanrenaud B. Acute hyperinsulinemia and its reversal by vagotomy after lesions of the ventromedial hypothalamus in anesthetized rats. Endocrinology 105: 146–151, 1979.[Abstract]
  5. Bouali SM, Fournier A, St-Pierre S, Jolicoeur FB. Effects of NPY and NPY2-36 on body temperature and food intake following administration into hypothalamic nuclei. Brain Res Bull 36: 131–135, 1995.[CrossRef][ISI][Medline]
  6. Canteras NS, Simerly RB, Swanson LW. Organization of projections from the ventromedial nucleus of the hypothalamus: a Phaseolus vulgaris-leucoagglutinin study in the rat. J Comp Neurol 348: 41–79, 1994.[CrossRef][ISI][Medline]
  7. Chen X, Ge YL, Jiang ZY, Liu CQ, Depoortere I, Peeters TL. Effects of ghrelin on hypothalamic glucose responding neurons in rats. Brain Res 1055: 131–136, 2005.[CrossRef][ISI][Medline]
  8. Conner JM, Lauterborn JC, Yan Q, Gall CM, Varon S. Distribution of brain-derived neurotrophic factor (BDNF) protein and mRNA in the normal adult rat CNS: evidence for anterograde axonal transport. J Neurosci 17: 2295–2313, 1997.[Abstract/Free Full Text]
  9. Currie PJ, Coscina DV. Stimulation of 5-HT(2A/2C) receptors within specific hypothalamic nuclei differentially antagonizes NPY-induced feeding. Neuroreport 8: 3759–3762, 1997.[ISI][Medline]
  10. Davidowa H, Plagemann A. Different responses of ventromedial hypothalamic neurons to leptin in normal and early postnatally overfed rats. Neurosci Lett 293: 21–24, 2000.[CrossRef][ISI][Medline]
  11. Davis AM, Seney ML, Stallings NR, Zhao L, Parker KL, Tobet SA. Loss of steroidogenic factor 1 alters cellular topography in the mouse ventromedial nucleus of the hypothalamus. J Neurobiol 60: 424–436, 2004.[CrossRef][ISI][Medline]
  12. Day NC, Hall MD, Clark CR, Hughes J. High concentrations of cholecystokinin receptor binding sites in the ventromedial hypothalamic nucleus. Neuropeptides 8: 1–18, 1986.[CrossRef][ISI][Medline]
  13. Dhillon H, Zigman JM, Ye C, Lee CE, McGovern RA, Tang V, Kenny CD, Christiansen LM, White RD, Edelstein EA, Coppari R, Balthasar N, Cowley MA, Chua S Jr, Elmquist JK, Lowell BB. Leptin directly activates SF1 neurons in the VMH, and this action by leptin is required for normal body-weight homeostasis. Neuron 49: 191–203, 2006.[CrossRef][ISI][Medline]
  14. Elias CF, Saper CB, Maratos-Flier E, Tritos NA, Lee C, Kelly J, Tatro JB, Hoffman GE, Ollmann MM, Barsh GS, Sakurai T, Yanagisawa M, Elmquist JK. Chemically defined projections linking the mediobasal hypothalamus and the lateral hypothalamic area. J Comp Neurol 402: 442–459, 1998.[CrossRef][ISI][Medline]
  15. Elmquist JK, Ahima RS, Elias CF, Flier JS, Saper CB. Leptin activates distinct projections from the dorsomedial and ventromedial hypothalamic nuclei. Proc Natl Acad Sci USA 95: 741–746, 1998.[Abstract/Free Full Text]
  16. Elmquist JK, Ahima RS, Maratosflier E, Flier JS, Safer CB. Leptin activates neurons in ventrobasal hypothalamus and brainstem. Endocrinology 138: 839–842, 1997.[Abstract/Free Full Text]
  17. Elmquist JK, Bjorbaek C, Ahima RS, Flier JS, Saper CB. Distributions of leptin receptor mRNA isoforms in the rat brain. J Comp Neurol 395: 535–547, 1998.[CrossRef][ISI][Medline]
  18. Fahrbach SE, Morrell JI, Pfaff DW. Studies of ventromedial hypothalamic afferents in the rat using three methods of HRP application. Exp Brain Res 77: 221–233, 1989.[CrossRef][ISI][Medline]
  19. Fan W, Boston BA, Kesterson RA, Hruby VJ, Cone RD. Role of melanocortinergic neurons in feeding and the agouti obesity syndrome. Nature 385: 165–168, 1997.[CrossRef][Medline]
  20. Funahashi H, Yada T, Muroya S, Takigawa M, Ryushi T, Horie S, Nakai Y, Shioda S. The effect of leptin on feeding-regulating neurons in the rat hypothalamus. Neurosci Lett 264: 117–120, 1999.[CrossRef][ISI][Medline]
  21. Geroldi D, Minoretti P, Emanuele E. Brain-derived neurotrophic factor and the metabolic syndrome: more than just a hypothesis. Med Hypotheses 67: 195–196, 2006.[CrossRef][ISI][Medline]
  22. Hakansson ML, Brown H, Ghilardi N, Skoda RC, Meister B. Leptin receptor immunoreactivity in chemically defined target neurons of the hypothalamus. J Neurosci 18: 559–572, 1998.[Abstract/Free Full Text]
  23. Haskell-Luevano C, Chen P, Li C, Chang K, Smith MS, Cameron JL, Cone RD. Characterization of the neuroanatomical distribution of agouti-related protein immunoreactivity in the rhesus monkey and the rat. Endocrinology 140: 1408–1415, 1999.[Abstract/Free Full Text]
  24. Heinrichs SC, Menzaghi F, Pich EM, Hauger RL, Koob GF. Corticotropin-releasing factor in the paraventricular nucleus modulates feeding induced by neuropeptide Y. Brain Res 611: 18–24, 1993.[CrossRef][ISI][Medline]
  25. Hikiji K, Inoue K, Iwasaki S, Ichihara K, Kiriike N. Local perfusion of mCPP into ventromedial hypothalamic nucleus, but not into lateral hypothalamic area and frontal cortex, inhibits food intake in rats. Psychopharmacology (Berl) 174: 190–196, 2004.[Medline]
  26. Huang XF, Han M, South T, Storlien L. Altered levels of POMC, AgRP and MC4-R mRNA expression in the hypothalamus and other parts of the limbic system of mice prone or resistant to chronic high-energy diet-induced obesity. Brain Res 992: 9–19, 2003.[CrossRef][ISI][Medline]
  27. Inokuchi A, Oomura Y, Shimizu N, Yamamoto T. Central action of glucagon in rat hypothalamus. Am J Physiol Regul Integr Comp Physiol 250: R120–R126, 1986.[Abstract/Free Full Text]
  28. Inoue S, Campfield LA, Bray GA. Comparison of metabolic alterations in hypothalamic and high fat diet-induced obesity. Am J Physiol Regul Integr Comp Physiol 233: R162–R168, 1977.[Abstract/Free Full Text]
  29. Jacob RJ, Dziura J, Medwick MB, Leone P, Caprio S, During M, Shulman GI, Sherwin RS. The effect of leptin is enhanced by microinjection into the ventromedial hypothalamus. Diabetes 46: 150–152, 1997.[Abstract]
  30. Jiang B, Akaneya Y, Ohshima M, Ichisaka S, Hata Y, Tsumoto T. Brain-derived neurotrophic factor induces long-lasting potentiation of synaptic transmission in visual cortex in vivo in young rats, but not in the adult. Eur J Neurosci 14: 1219–1228, 2001.[CrossRef][ISI][Medline]
  31. Jolicoeur FB, Bouali SM, Fournier A, St-Pierre S. Mapping of hypothalamic sites involved in the effects of NPY on body temperature and food intake. Brain Res Bull 36: 125–129, 1995.[CrossRef][ISI][Medline]
  32. Kamatchi GL, Bhakthavatsalam P, Chandra D, Bapna JS. Inhibition of insulin hyperphagia by gamma aminobutyric acid antagonists in rats. Life Sci 34: 2297–2301, 1984.[CrossRef][ISI][Medline]
  33. Kang L, Routh VH, Kuzhikandathil EV, Gaspers LD, Levin BE. Physiological and molecular characteristics of rat hypothalamic ventromedial nucleus glucosensing neurons. Diabetes 53: 549–559, 2004.[Abstract/Free Full Text]
  34. Kelly J, Alheid GF, Newberg A, Grossman SP. GABA stimulation and blockade in the hypothalamus and midbrain: effects on feeding and locomotor activity. Pharmacol Biochem Behav 7: 537–541, 1977.[CrossRef][ISI][Medline]
  35. Kelly J, Rothstein J, Grossman SP. GABA and hypothalamic feeding systems. I. Topographic analysis of the effects of microinjections of muscimol. Physiol Behav 23: 1123–1134, 1979.[CrossRef][Medline]
  36. Kernie SG, Liebl DJ, Parada LF. BDNF regulates eating behavior and locomotor activity in mice. EMBO J 19: 1290–1300, 2000.[CrossRef][ISI][Medline]
  37. Kerr BJ, Bradbury EJ, Bennett DL, Trivedi PM, Dassan P, French J, Shelton DB, McMahon SB, Thompson SW. Brain-derived neurotrophic factor modulates nociceptive sensory inputs and NMDA-evoked responses in the rat spinal cord. J Neurosci 19: 5138–5148, 1999.[Abstract/Free Full Text]
  38. King BM. A re-examination of the ventromedial hypothalamic paradox. Neurosci Biobehav Rev 4: 151–160, 1980.[CrossRef][ISI][Medline]
  39. Komori T, Morikawa Y, Nanjo K, Senba E. Induction of brain-derived neurotrophic factor by leptin in the ventromedial hypothalamus. Neuroscience 139: 1107–1115, 2006.[CrossRef][ISI][Medline]
  40. Kong WM, Martin NM, Smith KL, Gardiner JV, Connoley IP, Stephens DA, Dhillo WS, Ghatei MA, Small CJ, Bloom SR. Triiodothyronine stimulates food intake via the hypothalamic ventromedial nucleus independent of changes in energy expenditure. Endocrinology 145: 5252–5258, 2004.[Abstract/Free Full Text]
  41. Liang FQ, Allen G, Earnest D. Role of brain-derived neurotrophic factor in the circadian regulation of the suprachiasmatic pacemaker by light. J Neurosci 20: 2978–2987, 2000.[Abstract/Free Full Text]
  42. Lin L, York DA. Amygdala enterostatin induces c-Fos expression in regions of hypothalamus that innervate the PVN. Brain Res 1020: 147–153, 2004.[CrossRef][ISI][Medline]
  43. Lopez-Valpuesta FJ, Nyce JW, Griffin-Biggs TA, Ice JC, Myers RD. Antisense to NPY-Y1 demonstrates that Y1 receptors in the hypothalamus underlie NPY hypothermia and feeding in rats. Proc Biol Sci 263: 881–886, 1996.[CrossRef][Medline]
  44. Lu XY, Bagnol D, Burke S, Akil H, Watson SJ. Differential distribution and regulation of OX1 and OX2 orexin/hypocretin receptor messenger RNA in the brain upon fasting. Horm Behav 37: 335–344, 2000.[CrossRef][Medline]
  45. Luiten PG, Ono T, Nishijo H, Fukuda M. Differential input from the amygdaloid body to the ventromedial hypothalamic nucleus in the rat. Neurosci Lett 35: 253–258, 1983.[CrossRef][ISI][Medline]
  46. Luiten PG, Room P. Interrelations between lateral, dorsomedial and ventromedial hypothalamic nuclei in the rat. An HRP study. Brain Res 190: 321–332, 1980.[CrossRef][ISI][Medline]
  47. Magrani J, de Castro e Silva E., Varjao B., Duarte G., Ramos A.C, Athanazio R, Barbetta M, Luz P, Fregoneze JB. Histaminergic H1 and H2 receptors located within the ventromedial hypothalamus regulate food and water intake in rats. Pharmacol Biochem Behav 79: 189–198, 2004.[CrossRef][ISI][Medline]
  48. Majdic G, Young M, Gomez-Sanchez E, Anderson P, Szczepaniak LS, Dobbins RL, McGarry JD, Parker KL. Knockout mice lacking steroidogenic factor 1 are a novel genetic model of hypothalamic obesity. Endocrinology 143: 607–614, 2002.[Abstract/Free Full Text]
  49. Makino S, Nishiyama M, Asaba K, Gold PW, Hashimoto K. Altered expression of type 2 CRH receptor mRNA in the VMH by glucocorticoids and starvation. Am J Physiol Regul Integr Comp Physiol 275: R1138–R1145, 1998.[Abstract/Free Full Text]
  50. Martinez-Marcos A, Lanuza E, Halpern M. Organization of the ophidian amygdala: chemosensory pathways to the hypothalamus. J Comp Neurol 412: 51–68, 1999.[CrossRef][ISI][Medline]
  51. Masaki T, Yoshimichi G, Chiba S, Yasuda T, Noguchi H, Kakuma T, Sakata T, Yoshimatsu H. Corticotropin-releasing hormone-mediated pathway of leptin to regulate feeding, adiposity, and uncoupling protein expression in mice. Endocrinology 144: 3547–3554, 2003.[Abstract/Free Full Text]
  52. McClellan KM, Parker KL, Tobet S. Development of the ventromedial nucleus of the hypothalamus. Front Neuroendocrinol 27: 193–209, 2006.[CrossRef][ISI][Medline]
  53. Mistry AM, Swick AG, Romsos DR. Leptin rapidly lowers food intake and elevates metabolic rates in lean and ob/ob mice. J Nutr 127: 2065–2072, 1997.[Abstract/Free Full Text]
  54. Mufson EJ, Kroin JS, Sendera TJ, Sobreviela T. Distribution and retrograde transport of trophic factors in the central nervous system: functional implications for the treatment of neurodegenerative diseases. Prog Neurobiol 57: 451–484, 1999.[CrossRef][ISI][Medline]
  55. Mukherjee K, Mathur R, Nayar U. Ventromedial hypothalamic mediation of sucrose feeding induced pain modulation. Pharmacol Biochem Behav 68: 43–48, 2001.[CrossRef][ISI][Medline]
  56. Myers RD, Wooten MH, Ames CD, Nyce JW. Anorexic action of a new potential neuropeptide Y antagonist [D-Tyr27,36, D-Thr32]-NPY (27-36) infused into the hypothalamus of the rat. Brain Res Bull 37: 237–245, 1995.[CrossRef][ISI][Medline]
  57. Nicholson C. Diffusion from an injected volume of a substance in brain tissue with arbitrary volume fraction and tortuosity. Brain Res 333: 325–329, 1985.[CrossRef][ISI][Medline]
  58. Ohata H, Suzuki K, Oki Y, Shibasaki T. Urocortin in the ventromedial hypothalamic nucleus acts as an inhibitor of feeding behavior in rats. Brain Res 861: 1–7, 2000.[CrossRef][ISI][Medline]
  59. Pardridge WM. Blood-brain barrier delivery. Drug Discov Today 12: 54–61, 2007.[CrossRef][ISI][Medline]
  60. Pardridge WM. Blood-brain barrier drug targeting: the future of brain drug development. Mol Interv 3: 90–105, 151, 2003.
  61. Paxinos G, Watson C. The Rat Brain in Stereotaxic Coordinates. San Diego, CA: Academic, 1998, p. xxvi.
  62. Pelleymounter MA, Cullen MJ, Wellman CL. Characteristics of BDNF-induced weight loss. Exp Neurol 131: 229–238, 1995.[CrossRef][ISI][Medline]
  63. Pezet S, Malcangio M, Lever IJ, Perkinton MS, Thompson SW, Williams RJ, McMahon SB. Noxious stimulation induces Trk receptor and downstream ERK phosphorylation in spinal dorsal horn. Mol Cell Neurosci 21: 684–695, 2002.[CrossRef][ISI][Medline]
  64. Rattiner LM, Davis M, French CT, Ressler KJ. Brain-derived neurotrophic factor and tyrosine kinase receptor B involvement in amygdala-dependent fear conditioning. J Neurosci 24: 4796–4806, 2004.[Abstract/Free Full Text]
  65. Ruffin M, Nicolaidis S. Electrical stimulation of the ventromedial hypothalamus enhances both fat utilization and metabolic rate that precede and parallel the inhibition of feeding behavior. Brain Res 846: 23–29, 1999.[CrossRef][ISI][Medline]
  66. Sakaguchi T, Arase K, Bray GA. Sympathetic activity and food intake of rats with ventromedial hypothalamic lesions. Int J Obes 12: 285–291, 1988.[ISI][Medline]
  67. Saper CB, Swanson LW, Cowan WM. An autoradiographic study of the efferent connections of the lateral hypothalamic area in the rat. J Comp Neurol 183: 689–706, 1979.[CrossRef][ISI][Medline]
  68. Saper CB, Swanson LW, Cowan WM. The efferent connections of the ventromedial nucleus of the hypothalamus of the rat. J Comp Neurol 169: 409–442, 1976.[CrossRef][ISI][Medline]
  69. Scharfman HE, Mercurio TC, Goodman JH, Wilson MA, MacLusky NJ. Hippocampal excitability increases during the estrous cycle in the rat: a potential role for brain-derived neurotrophic factor. J Neurosci 23: 11641–11652, 2003.[Abstract/Free Full Text]
  70. Schick RR, Zimmermann JP, vorm Walde T, Schusdziarra V. Peptides that regulate food intake: glucagon-like peptide 1-(7–36) amide acts at lateral and medial hypothalamic sites to suppress feeding in rats. Am J Physiol Regul Integr Comp Physiol 284: R1427–R1435, 2003.[Abstract/Free Full Text]
  71. Schwartz MW, Seeley RJ, Campfield LA, Burn P, Baskin DG. Identification of targets of leptin action in rat hypothalamus. J Clin Invest 98: 1101–1106, 1996.[ISI][Medline]
  72. Sclafani A, Berner CN, Maul G. Multiple knife cuts between the medial and lateral hypothalamus in the rat: a reevaluation of hypothalamic feeding circuitry. J Comp Physiol Psychol 88: 201–207, 1975.[Medline]
  73. Shimazu T, Noma M, Saito M. Chronic infusion of norepinephrine into the ventromedial hypothalamus induces obesity in rats. Brain Res 369: 215–223, 1986.[CrossRef][ISI][Medline]
  74. Shiraishi T, Oomura Y, Sasaki K, Wayner MJ. Effects of leptin and orexin-A on food intake and feeding related hypothalamic neurons. Physiol Behav 71: 251–261., 2000.[CrossRef][Medline]
  75. Shiraishi T, Sasaki K, Niijima A, Oomura Y. Leptin effects on feeding-related hypothalamic and peripheral neuronal activities in normal and obese rats. Nutrition 15: 576–579, 1999.[CrossRef][ISI][Medline]
  76. Stanley BG, Chin AS, Leibowitz SF. Feeding and drinking elicited by central injection of neuropeptide Y: evidence for a hypothalamic site(s) of action. Brain Res Bull 14: 521–524, 1985.[CrossRef][ISI][Medline]
  77. Sternson SM, Shepherd GM, Friedman JM. Topographic mapping of VMH –> arcuate nucleus microcircuits and their reorganization by fasting. Nat Neurosci 8: 1356–1363, 2005.[CrossRef][ISI][Medline]
  78. Strubbe J, Mein C. Increased feeding in response to bilateral injection of insulin antibodies in the VMH. Physiol Behav 19: 309–313, 1977.[CrossRef][Medline]
  79. Takaki A, Nagai K, Takaki S, Yanaihara N, Nakagawa H. Satiety function of neurons containing a CCK-like substance in the dorsal parabrachial nucleus. Physiol Behav 48: 865–871, 1990.[CrossRef][Medline]
  80. Ter Horst GJ, Luiten PG. Phaseolus vulgaris leuco-agglutinin tracing of intrahypothalamic connections of the lateral, ventromedial, dorsomedial and paraventricular hypothalamic nuclei in the rat. Brain Res Bull 18: 191–203, 1987.[CrossRef][ISI][Medline]
  81. Tonra JR, Ono M, Liu X, Garcia K, Jackson C, Yancopoulos GD, Wiegand SJ, Wong V. Brain-derived neurotrophic factor improves blood glucose control and alleviates fasting hyperglycemia in C57BLKS-Lepr(db)/lepr(db) mice. Diabetes 48: 588–594, 1999.[Abstract]
  82. Tran PV, Lee MB, Marin O, Xu B, Jones KR, Reichardt LF, Rubenstein JR, Ingraham HA. Requirement of the orphan nuclear receptor SF-1 in terminal differentiation of ventromedial hypothalamic neurons. Mol Cell Neurosci 22: 441–453, 2003.[CrossRef][ISI][Medline]
  83. Vaynman SS, Ying Z, Yin D, Gomez-Pinilla F. Exercise differentially regulates synaptic proteins associated to the function of BDNF. Brain Res 1070: 124–130, 2006.[CrossRef][ISI][Medline]
  84. Wang C, Kotz CM. Urocortin in the lateral septal area modulates feeding induced by orexin A in the lateral hypothalamus. Am J Physiol Regul Integr Comp Physiol 283: R358–R367, 2002.[Abstract/Free Full Text]
  85. Wang CF, Bomberg E, Billington CJ, Levine AS, Kotz CM. Brain-derived neurotrophic factor in the hypothalamic paraventricular nucleus increases energy expenditure by elevating metabolic rate. Am J Physiol Regul Integr Comp Physiol. First published June 13, 2007; doi:10.1152/ajpregu.00516.2006.
  86. Wang CF, Bomberg E, Billington CJ, Levine AS, Kotz CM. Brain-derived neurotrophic factor in the hypothalamic paraventricular nucleus reduces energy intake. Am J Physiol Regul Integr Comp Physiol. First published June 20, 2007; doi:10.1152/ajpregu.00011.2007.
  87. Wetmore C, Ernfors P, Persson H, Olson L. Localization of brain-derived neurotrophic factor mRNA to neurons in the brain by in situ hybridization. Exp Neurol 109: 141–152, 1990.[CrossRef][ISI][Medline]
  88. Wirth MM, Olszewski PK, Yu C, Levine AS, Giraudo SQ. Paraventricular hypothalamic alpha-melanocyte-stimulating hormone and MTII reduce feeding without causing aversive effects. Peptides 22: 129–134, 2001.[CrossRef][ISI][Medline]
  89. Xu B, Goulding EH, Zang K, Cepoi D, Cone RD, Jones KR, Tecott LH, Reichardt LF. Brain-derived neurotrophic factor regulates energy balance downstream of melanocortin-4 receptor. Nat Neurosci 6: 736–742, 2003.[CrossRef][ISI][Medline]
  90. Yan Q, Radeke MJ, Matheson CR, Talvenheimo J, Welcher AA, Feinstein SC. Immunocytochemical localization of TrkB in the central nervous system of the adult rat. J Comp Neurol 378: 135–157., 1997.[CrossRef][ISI][Medline]
  91. Yeo GS, Connie Hung CC, Rochford J, Keogh J, Gray J, Sivaramakrishnan S, O'Rahilly S, Farooqi IS. A de novo mutation affecting human TrkB associated with severe obesity and developmental delay. Nat Neurosci 7: 1187–1189, 2004.[CrossRef][ISI][Medline]
  92. Zhao L, Bakke M, Hanley NA, Majdic G, Stallings NR, Jeyasuria P, Parker KL. Tissue-specific knockouts of steroidogenic factor 1. Mol Cell Endocrinol 215: 89–94, 2004.[CrossRef][ISI][Medline]



This article has been cited by other articles:


Home page
 NEJMHome page
J. C. Han, Q.-R. Liu, M. Jones, R. L. Levinn, C. M. Menzie, K. S. Jefferson-George, D. C. Adler-Wailes, E. L. Sanford, F. L. Lacbawan, G. R. Uhl, et al.
Brain-Derived Neurotrophic Factor and Obesity in the WAGR Syndrome
N. Engl. J. Med., August 28, 2008; 359(9): 918 - 927.
[Abstract] [Full Text] [PDF]