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Yohimbine stimulates colonic motility through a central action in conscious dogs
Author(s) -
FIORAMONTI J.,
BERLAN M.,
FARGEAS M. J.,
BUENO L.
Publication year - 1992
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/j.1365-2982.1992.tb00091.x
Subject(s) - yohimbine , motility , vagotomy , medicine , endocrinology , antagonist , biology , receptor , genetics
The effects of the α 2 ‐adrenoceptor antagonist yohimbine on colonic motility were examined before and after vagotomy in conscious dogs chronically fitted with strain gauge transducers on the proximal, transverse and distal colon, and a cannula placed in a lateral ventricle of the brain. They were compared to those of another α 2 ‐adrenoceptor antagonist, SKωF 86466, which poorly crosses the blood‐brain barrier. Intravenous administration of yohimbine (0.2 mg/kg) stimulated the motility of the proximal and transverse colon, the motility index being increased for the first hour by 59 and 55%, respectively, in comparison with controls. No significant increase in motility index was observed on the distal colon. After vagotomy the effects of intravenous yohimbine were limited to 1 to 3 high amplitude contractions. Intracerebroventricular administration of yohimbine (20 μg/kg) reproduced the effects of intravenous administration and was ineffective after vagotomy. Intracerebroventricular but not intravenous administration of SKωF 86466 stimulated the motility of the proximal and transverse colon; this effect was also abolished after vagotomy. It is concluded that yohimbine stimulates colonic motility through a blockade of central α 2 ‐adrenoceptor and that these effects are mediated by the vagus.