[Studies of gamma-oryzanol. (2) The antiulcerogenic action]

Investigations were performed in male Wistar rats to determine the effects of gamma-oryzanol on circadian rhythm of stress ulcer and on various kinds of experimental ulcers, and the modification of antiulcerogenic action of this drug when combined with the inhibitors or precursors of amine metabolism. Circadian rhythms were observed in stress ulceration with a peak at 2 : 00 p.m. and a reduction at 8 : 00 p.m. The inhibitory action of gamma-oryzanol was significant when stress was loaded for 6 hr from 2 : 00 a.m., 5 : 00 a.m., 11 : 00 a.m. or 2:00 p.m. An 8-day treatment with gamma-oryzanol, 100 mg/kg, s.c., showed a significant inhibition of fasting ulcer, while the 5-day pretreatment exerted slight effects on ulcers by pylorus-ligation or stress-atropine. A 10-day treatment with the same dose of gamma-oyzanol in acetic acid ulcers lowered the serum level of gastrin. Treatment with reserpine, alpha-MT or PCPA prior to stress loading abolished the anti-ulcer effect of gamma-oryzanol, 100 mg/kg, s.c. for 5 days in stress ulcer. Treatment with L-DOPA or 5-HTP revealed a tendency toward restoration of the anti-ulcer effect of gamma-oryzanol. It is suggested that the monoaminergic neuron system is involved in the anti-ulcer action of gamma-oryzanol.