Calcitonin gene-related peptide (CGRP) modulates cholinergic neurotransmission in the small intestine of man, pig and guinea-pig via presynaptic CGRP receptors.
The effect of calcitonin gene-related peptide (CGRP) on the cholinergically mediated twitch contraction in longitudinal muscle strips of the small intestine (duodenum, jejunum, ileum) of guinea-pig, pig and man was investigated. Independently of the anatomical region, CGRP inhibited the twitch response in the different specimens of all three species by about 40% with similar IC50 values (1.5-2.4 nmol/l). Only in the guinea-pig small intestine CGRP induced a contraction of the smooth muscle which was sensitive to scopolamine and tetrodotoxin. The electrically evoked [3H]acetylcholine release from jejunal longitudinal muscle strips with myenteric plexus attached of the guinea-pig, which were incubated with [3H]choline, was concentration-dependently inhibited by CGRP. A direct relaxant effect of CGRP on smooth muscle tone of carbachol precontracted preparations was only observed in specimens of the guinea-pig. In conclusion, presynaptic inhibitory CGRP receptors on cholinergic neurones modulate the release of acetylcholine in different parts of the small intestine.
Schwörer
H
H
Department of Medicine, University of Göttingen, Germany.
Schmidt
W E
WE
Katsoulis
S
S
Creutzfeldt
W
W
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007421:Intestine, Small / Q000294:innervation*; D007583:Jejunum / Q000294:innervation; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013552:Swine
D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface; D015740:Calcitonin Gene-Related Peptide; D000109:Acetylcholine