Differential mechanism of peptide YY and neuropeptide Y in inhibiting motility of guinea-pig colon.
The effect of peptide YY on contractility, acetylcholine release and noradrenaline release was examined in the isolated guinea-pig colon, and findings were compared with those for neuropeptide Y. Peptide YY and neuropeptide Y inhibited the twitch contractions mediated by the stimulation of cholinergic neurons. Peptide YY, neuropeptide Y, [Leu31,Pro34]neuropeptide Y and neuropeptide Y-(13-36) inhibited the electrically stimulated release of acetylcholine. Neuropeptide Y, but not peptide YY, inhibited the high K(+)-stimulated tetrodotoxin-resistant release of acetylcholine, while the inhibitory effect of neuropeptide Y disappeared after treatment with yohimbine. Neuropeptide Y, but not peptide YY or neuropeptide Y analogues, evoked the release of noradrenaline. After desensitization to the effects of neuropeptide Y, peptide YY inhibited electrically stimulated acetylcholine release. Thus, peptide YY inhibits acetylcholine release through stimulation of a receptor, distinct from the site of action of neuropeptide Y, located on cholinergic neurons as well as the neuropeptide Y Y1 and Y2 receptors in the guinea-pig colon. Neuropeptide Y inhibits acetylcholine release due to the noradrenaline release mediated by stimulation of a receptor distinct from neuropeptide Y Y1 and Y2 receptors, located on adrenergic neurons.
Sawa
T
T
Department of Internal Medicine II, Nagasaki University School of Medicine, Japan.
Mameya
S
S
Yoshimura
M
M
Itsuno
M
M
Makiyama
K
K
Niwa
M
M
Taniyama
K
K
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D005768:Gastrointestinal Hormones / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009478:Neuropeptide Y / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism; D019894:Peptide YY; D010455:Peptides / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D013618:Tachyphylaxis / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology
D005768:Gastrointestinal Hormones; D009478:Neuropeptide Y; D010455:Peptides; D019894:Peptide YY; D015016:Yohimbine; D000109:Acetylcholine; D011188:Potassium; D009638:Norepinephrine