Role of endogenous 5-hydroxytryptamine in the regulation of gastric contractions by motilin in dogs.
It has been suggested that 5-hydroxytryptamine3 (5-HT3) receptors are involved in the control of phase III contractions in the stomach. We examined the effect of depletion of endogenous 5-HT by p-chlorophenylalanine (pCPA) on spontaneously and motilin-induced phase III contractions in conscious dogs, and the effect of 5,6-dihydroxytryptamine (5,6-DHT) in an isolated perfused dog stomach. Three-day treatment with pCPA significantly reduced plasma 5-HT concentration and 5-HT content in the stomach, and strongly suppressed the spontaneous and motilin-induced phase III contractions in the stomach. When spontaneous phase III contractions recovered in the stomach after a 3-day treatment, exogenous motilin induced typical phase III-like contractions, and the 5-HT content in the muscle layer was recovered to the normal pretreatment level. In the perfused stomach, 5,6-DHT decreased 5-HT content in the muscle layer alone and abolished motilin-induced contractions. In conclusion, endogenous 5-HT, probably in 5-HT neurons, plays an important role in the control of interdigestive phase III activity by motilin in the stomach.
Haga
N
N
Gastrointestinal Research Laboratories, Gunma University, Maebashi, Japan.
Mizumoto
A
A
Satoh
M
M
Mochiki
E
E
Mizusawa
F
F
Ohshima
K
K
Itoh
Z
Z
D015115:5,6-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D004285:Dogs; D010134:Fenclonine / Q000097:blood / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology*; D009037:Motilin / Q000494:pharmacology*; D012701:Serotonin / Q000097:blood / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013270:Stomach / Q000187:drug effects
D012702:Serotonin Antagonists; D012701:Serotonin; D009037:Motilin; D010134:Fenclonine; D015115:5,6-Dihydroxytryptamine