| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Pharmacology, Georgetown University Medical Center, Washington, District of Columbia, United States
2 Medicine, Georgetown University Medical Center, Washington, District of Columbia, United States
* To whom correspondence should be addressed. E-mail: gillisr{at}georgetown.edu.
Our primary purpose was to characterize vagal pathways controlling gastric motility by microinjecting L-glutamate into the dorsal motor nucleus of the vagus (DMV) in the rat. An intragastric balloon was used to monitor motility. In 39 out of 43 experiments, microinjection of L-glutamate into different areas of the DMV rostral to calamus scriptorius (CS) resulted in vagally-mediated excitatory effects on motility. We observed little evidence for inhibitory effects even with i.v. atropine or with activation of gastric muscle muscarinic receptors by i.v. bethanechol. Inhibition of nitric oxide synthase with L-NAME did not augment DMV-evoked excitatory effects on gastric motility. Microinjection of L-glutamate into the DMV caudal to CS produced vagally-mediated gastric inhibition that was resistant to L-NAME. L-glutamate microinjected into the medial subnucleus of the tractus solitarius (mNTS) also produced vagally-mediated inhibition of gastric motility. Motility responses evoked from the DMV were always blocked by ipsilateral vagotomy while responses evoked from the mNTS required bilateral vagotomy to be blocked. Microinjection of oxytocin into the DMV inhibited gastric motility, but the effect was never blocked by ipsilateral vagotomy, suggesting that the effect may have been due to diffusion of oxytocin to the mNTS. Microinjection of substance P and NMDA into the DMV also produced inhibitory effects attributable to excitation of nearby mNTS neurons. Our results do not support previous studies indicating parallel vagal excitatory and inhibitory pathways originating in the DMV rostral to CS. Our results do support previous findings of vagal inhibitory pathways originating in the DMV caudal to CS.
This article has been cited by other articles:
|
|
 |
|
  M. A. Herman, M. T. Cruz, N. Sahibzada, J. Verbalis, and R. A. Gillis GABA signaling in the nucleus tractus solitarius sets the level of activity in dorsal motor nucleus of the vagus cholinergic neurons in the vagovagal circuit Am J Physiol Gastrointest Liver Physiol, January 1, 2009; 296(1): G101 - G111. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. Herman, M. Niedringhaus, A. Alayan, J. G. Verbalis, N. Sahibzada, and R. A. Gillis Characterization of noradrenergic transmission at the dorsal motor nucleus of the vagus involved in reflex control of fundus tone Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2008; 294(3): R720 - R729. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Niedringhaus, P. G. Jackson, S. R. T. Evans, J. G. Verbalis, R. A. Gillis, and N. Sahibzada Dorsal motor nucleus of the vagus: a site for evoking simultaneous changes in crural diaphragm activity, lower esophageal sphincter pressure, and fundus tone Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2008; 294(1): R121 - R131. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
