Functional and neurochemical evidence that neurotensin-induced release of acetylcholine from Auerbach's plexus of guinea-pig ileum is presynaptically controlled via alpha 2-adrenoceptors.
The effect of neurotensin (NT) on [3H]acetylcholine release and contraction from isolated longitudinal muscle strip of guinea-pig ileum was examined. Neurotensin dose-dependently enhanced the release of [3H]-acetylcholine. This effect of neurotensin was inhibited by stimulation of alpha 2-adrenoceptors: noradrenaline, clonidine, xylazine or dexmedetomidine (alpha 2-adrenoceptor agonists) inhibited neurotensin-induced release of acetycholine (ACh) as well as the contractions, while CH-38083 or yohimbine (alpha 2-adrenoceptor antagonist) prevented this inhibitory effect. Our findings suggest that neurotensin may play a neuromodulatory role in the regulation of cholinergic neuronal activity in the gut and this modulatory effect is continuously controlled by the tonic activity of the sympathetic nervous system: endogenous noradrenaline release is capable of reducing the release of ACh and the consequent contraction of the gut enhanced by neurotensin.
Rakovska
A D
AD
Institute of Physiology, Bulgarian Academy of Sciences, Sofia.
D000109:Acetylcholine / Q000378:metabolism*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001599:Berberine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D009496:Neurotensin / Q000008:administration & dosage / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D001599:Berberine; C048886:7,8-(methylenedioxy)-14-hydroxyberbane; D009496:Neurotensin; D000109:Acetylcholine; D009638:Norepinephrine