Acceleration of gastrointestinal transit by momordin Ic in mice: possible involvement of 5-hydroxytryptamine, 5-HT(2) receptors and prostaglandins.
Possible involvement of 5-hydroxytryptamine (5-HT), 5-HT receptors and prostaglandins in the acceleration of gastrointestinal transit by momordin Ic was investigated in mice. Accelerative effect of momordin Ic (25 mg/kg, p.o.) on gastrointestinal transit was attenuated by pretreatment with a bolus of DL-p-chlorophenylalanine methyl ester (an inhibitor of 5-HT synthesizing enzyme), but not repeated pretreatment with DL-p-chlorophenylalanine methyl ester. Furthermore, cyproheptadine (a nonselective 5-HT(2) receptor antagonist), ritanserin (a 5-HT(2A/2B/2C) receptor antagonist) and clozapine (a 5-HT(2A/2C) receptor antagonist) also attenuated the effect of momordin Ic, but methiothepin (a 5-HT(1) receptor antagonist), MDL 72222 (3-tropanyl-3,5-dichlorobenzoate) and metoclopramide (5-HT(3) receptor antagonists), tropisetron (a 5-HT(3/4) receptor antagonist), ketanserin and haloperidol (5-HT(2A) receptor antagonists) did not. These results suggested a possible involvement of endogenous 5-HT and 5-HT(2B/2C) over 5-HT(2A) receptors. Attenuation by pretreatment with indomethacin (an inhibitor of prostaglandins synthesis) suggested involvement of prostaglandins. It is postulated that momordin Ic accelerates gastrointestinal transit partially by stimulating synthesis of 5-HT to act through 5-HT(2), possibly 5-HT(2C) and/or 5-HT(2B) receptors, which, in turn, increases synthesis of prostaglandins.
Li
Y
Y
Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina, Japan.
Matsuda
H
H
Yamahara
J
J
Yoshikawa
M
M
D000818:Animals; D010134:Fenclonine / Q000031:analogs & derivatives / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007213:Indomethacin / Q000494:pharmacology; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051379:Mice; D009828:Oleanolic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D011453:Prostaglandins / Q000502:physiology*; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D014326:Tropanes / Q000494:pharmacology
D011453:Prostaglandins; D011985:Receptors, Serotonin; D014326:Tropanes; C408362:momordin I (Oleanolic Acid); C020261:4-chlorophenylalanine methyl ester; D012701:Serotonin; D009828:Oleanolic Acid; D007650:Ketanserin; C042253:bemesetron; D010134:Fenclonine; D007213:Indomethacin