Antinociceptive and anti-inflammatory effects of Rhodiola rosea L. extract in rats.

BACKGROUND Rhodiola rosea (golden root) is a unique phytoadaptagen with immunomodulatory, antioxidant, anti-inflammatory and antinociceptive activity. AIM The aim of this study was to evaluate the antinociceptive and anti-inflammatory effects of the alcohol/water extract of Rhodiola rosea roots in rats. MATERIALS AND METHODS Thirty male Wistar rats were used in the study. They were divided in 3 groups (n = 10), treated respectively with saline (controls), Rhodiola rosea extract 50 mg/kg bw and 100 mg/kg bw orally. The antinociceptive effect was evaluated using the hot-plate test, Randall-Sellito test and the formalin test. The hot-plate test evaluates the reaction time of rats which are dropped on a heated surface. The analgesy-meter test exerts a force increased at constant rate. In the formalin test we measured the total time spent in licking the injected paw during the early (0-10 min) and late phase (20-30 min) of test. To study anti-inflammatory effect the carrageenan-induced paw edema was used. The paw volume was measured plethysmometrically at 2, 3 and 4 hours. RESULTS In the hot-plate test Rhodiola rosea increased in both doses the latency reaction compared with that in the controls. In analgesy-meter test Rhodiola rosea in a dose of 50 mg/kg showed a significant increase of pressure reaction compared with the controls. In the formalin test Rhodiola rosea in a dose of 100 mg/kg significantly decreased the paw licking time during the first phase. In the plethysmometer test Rhodiola rosea extract significantly reduced carrageenan-induced paw edema when compared with the saline-induced edema. CONCLUSION The studied extract of Rhodiola rosea exhibited significant analgesic activity in all the pain models used--inhibition of thermal pain, mechanical hyperalgesia and formalin-induced pain behavior. Significant anti-inflammatory activity was observed from Rhodiola rosea extract in carrageenan induced paw edema in rats.