AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 4 453-R458, Copyright © 1985 by American Physiological Society
Level of satiety: GABA and pentose shunt activities in three brain sites associated with feeding
T. R. Kasser, R. B. Harris and R. J. Martin
The hypothesis addressed was that metabolic activity within specific brain
areas may be altered to depict peripheral metabolic status. Sixty-three
female Sprague-Dawley rats (225 g) received 150, 100, or 50% of normal
intake by gastric intubation for 7 days. The incentive for spontaneous
feeding would be inhibited in 150% fed rats (anoretic), stimulated in 50%
fed rats (hungry), and maintained in 100% fed rats (control). Glucose flux
through the gamma-aminobutyric acid shunt of the ventrolateral hypothalamus
was 32% lower in hungry rats and 35% higher in anoretic rats relative to
control values. Glucose flux through the pentose shunt of the ventromedial
hypothalamus was 111% lower in hungry rats and 152% higher in anoretic rats
relative to control values. Pentose shunt activity in the area postrema
nucleus of the solitary tract (AP NTS) was 116% lower in hungry rats and
60% higher in anoretic rats relative to control values; however, hungry and
anoretic rats had AP NTS pentose shunt activities that were not different
from control values but were different from each other. The data
demonstrate that within selective brain sites, specific pathways for
glucose oxidation are affected by energy intake and may be used by the rat
to assess and respond to changes in peripheral energy status.
