Abstract:
The antinociceptive potential of Pleurotus ostreatus. (Jacquin: Fries) P. Kummer (Tricholomataceae) was investigated in rats (doses used: 125, 500, and 1000 mg/kg). Male rats and female rats in proestrous, estrous, and diestrous stages were orally administered 1000 mg/kg of freeze-dried P. ostreatus. and the reaction times on hot-plate and tail-flick tests were recorded. In the hot-plate test, the reaction time was significantly prolonged in male rats and diestrous female rats. Marked and significant prolongation in the reaction time at 1 h in males (28% mid and 32% high dose) and up to 2 h in diestrous females (57% mid and 79% high dose after 1 h) were observed on the hot-plate test. This effect was dose-dependent. In contrast, none of the rats showed increases in reaction time in the tail-flick test. In the formalin test, in rats administered a 1000 mg/kg dose of P. ostreatus., pain was significantly suppressed in both phases (females: licking time, 23%, 48%; licking frequency, 28%, 28%; males: licking time, 32%, 43%; licking frequency, no significant change). P. ostreatus. possessed antihistamine activity (histamine wheal test). Naloxone blocked the antinociceptive activity in the hot-plate test; however, metochlopramide did not abolish the activity. P. ostreatus. also showed mild antioxidant activity. Further, a 1000 mg/kgdose of P. ostreatus. did not induce sedation (hole-board test). This dose did not cause mortality or show signs of acute toxicity or stress. It is concluded that P. ostreatus. shows antinociception against neurogenic and continuous inflammatory pain possibly by opioid mechanisms, antioxidative and antihistamine activities.
