antinociceptive effect of aqueous extract of origanum vulgare l. in male rats: possible involvement of the gabaergic system

the objective of the present investigation was to assess the possible involvement ofgabaergic mechanism in analgesic effect of aqueous extract of origanum vulgare (org)in a rat model of acute pain test. sixty-three anaesthetized male wistar rats (200-250 g) werecannulated into the left ventricle. five to seven days after the recovery from surgery, org extractwas intraventricularly injected at dose of 3 μg/rat i.c.v. then, baclofen (10 mg/kg, ip), cgp35348(100 nmol/kg, i.c.v), muscimol (1 mg/kg ip) and bicuculline (5 mg/kg ip) were separatelyinjected 20 min before the injection of org. the experimental groups were compared withintact (control) group (n = 7). the response latency of rats to thermal stimulation was recordedusing tail-flick test. injection of org extract resulted in a significant and dose-dependentincrease in the response latency. there was also a significant increase in the response latencyafter co-administration of org extract with baclofen when compared with control group.however, following co-administration of org extract/bicuculline, a significant decrease inthe response latency was observed compared to control group. in conclusion, the results ofthe present study suggest that aqueous extract of origanum vulgare l. ssp. viridis possessesantinociceptive activity in a dose-dependent manner and org-induced antinociception mightbe mediated, at least in part, by both gaba receptors.