Effect of Hydroalcoholic Leaves Extract of Rhus Coriaria on Pain in Male Rats

The drive toward the use of medicinal plants has been increasing in recent years. They have few side effects and a large variety of efficient components. This study was designed to investigate the analgesic effects of hydroalcoholic Rhus coriaria leaf extract (HRCLE) in a rat model. A total of 42 adult male rats were divided into seven groups: a control group (the animals did not receive any drug), three HRCLE groups, (receiving 80, 100, and 300 mg/kg, intraperitoneally [ip]), a morphine group (1 mg/kg, ip) an aspirin group (1 mg/kg, ip), and a group that received 300 mg/kg of HRCLE plus naloxone (1 mg/kg, ip). The analgesic effects of HRCLE were assessed via writhing, tail flick, and formalin tests, and the data obtained were compared with the control group using one-way analysis of variance and Tukey post hoc tests. HRCLE significantly inhibited the number of contractions induced by acetic acid in the writhing test at all doses, while anti-nociceptive activity was only shown at the 100 mg/kg dose (in the chronic phase) and at the 300 mg/kg dose (in the chronic-acute phase) in the formalin test. Interestingly, the greatest effect was observed at the 300 mg/kg HRCLE dose in the tail flick test. Simultaneous utilization of naloxone and HRCLE inhibited the anti-nociceptive effect of the extract in all tests. It is worth mentioning that aspirin and morphine revealed anti-nociceptive effects in all tests. Our findings suggest that the analgesic effect of HRCLE may be mediated via both peripheral and central mechanisms. The presence of flavonoids might be responsible for the anti-nociceptive activity of this plant.