Abstract
Vasoactive intestinal polypeptide (VIP)-like immunoreactive cell bodies and fibers and VIP binding sites exist in the brainstem nuclei that regulate autonomic function. Therefore, we investigated the effects of microinjection of VIP in the dorsal vagal complex (DVC), nucleus raphe obscurus (nROb) and nucleus ambiguus of α-chloralose-anesthetized rats while recording intragastric pressure, pyloric and greater curvature smooth muscle contractile activity, blood pressure and heart rate. Microinjection of VIP into the DVC increased intragastric pressure (1–100 pmol) and pyloric smooth muscle contractile activity (100 pmol), as well as arterial blood pressure (1–100 pmol). Whereas VIP microinjected into the nROb (10–100 pmol) decreased intragastric pressure and inhibited pyloric smooth muscle contractile activity. Mean arterial blood pressure increased in response to VIP in the nROb at the highest dose of 100 pmol only. No changes in gastric motor and cardiovascular function were noted after microinjection of VIP (1–100 pmol) into the region of the nucleus ambiguus. The gastric motor effects of VIP in the DVC (10 pmol) and nROb (50 pmol) were completely abolished by bilateral cervical vagotomy. These data show that VIP may produce opposite vagally mediated gastric motor responses upon its microinjection into the DVC and nROb.
Footnotes
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Send reprint requests to: Zbigniew K. Krowicki, M.D., Ph.D., Dept. of Pharmacology, LSUMC, 1901 Perdido Street, New Orleans, LA 70112.
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↵1 This work was supported by Public Health Service grant DK-42714 to P.J.H. and partially by the LSU Neuroscience Center incentive grant to Z.K.K. Preliminary reports of this study were presented at the Second International Congress of the Polish Neuroscience Society in Krakow, Poland (Acta Neurobiol. Exp.55: Suppl., 57, 1995) and at the 25th Society for Neuroscience Annual Meeting in San Diego, CA (Soc. Neurosci. Abstr.21: 1016, 1995).
- Abbreviations:
- DMV
- dorsal motor nucleus of the vagus
- DVC
- dorsal vagal complex
- nAmb
- nucleus ambiguus
- nROb
- nucleus raphe obscurus
- nTS
- nucleus of the solitary tract
- VIP
- vasoactive intestinal polypeptide
- MAP
- mean arterial pressure
- MMI
- minute motility index
- PACAP
- pituitary adenylate cyclase-activating polypeptide
- GTP
- guanosine 5′-triphosphate
- Received June 18, 1996.
- Accepted March 6, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
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