Antinociceptive Effect of Aqueous Extract of Origanum vulgare L. in Male Rats: Possible Involvement of the GABAergic System

Document Type: Research article

Authors

1 1- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2- Kerman Neuroscience Research Center, Kerman University of Medical Sciences, Kerman, Iran.

2 1- Kerman Neuroscience Research Center, Kerman University of Medical Sciences, Kerman, Iran. 2- Ardabil University of Medical Sciences, Ardabil, Iran.

3 Kerman Neuroscience Research Center, Kerman University of Medical Sciences, Kerman, Iran.

4 Ardabil University of Medical Sciences, Ardabil, Iran.

Abstract

The objective of the present investigation was to assess the possible involvement of
GABAergic 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) were
cannulated into the left ventricle. Five to seven days after the recovery from surgery, ORG extract
was 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 separately
injected 20 min before the injection of ORG. The experimental groups were compared with
intact (control) group (n = 7). The response latency of rats to thermal stimulation was recorded
using Tail-Flick test. Injection of ORG extract resulted in a significant and dose-dependent
increase in the response latency. There was also a significant increase in the response latency
after co-administration of ORG extract with baclofen when compared with control group.
However, following co-administration of ORG extract/bicuculline, a significant decrease in
the response latency was observed compared to control group. In conclusion, the results of
the present study suggest that aqueous extract of Origanum vulgare L. ssp. viridis possesses
antinociceptive activity in a dose-dependent manner and ORG-induced antinociception might
be mediated, at least in part, by both GABA receptors.

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