Attenuating effect of hydroalcoholic extract of Acorus calamus in vincristine-induced painful neuropathy in rats

The present study was designed to investigate the attenuating potential of hydroalcoholic extract of Acorus calamus in vincristine-induced neuropathic pain in rats. Vincristine (50 mu g/kg, i.p. for 10 consecutive days) was administered to induce neuropathic pain in rats. Hot plate, plantar, Randall-Selitto and von Frey hair tests were performed to assess the degree of thermal and mechanical hyperalgesia and mechanical allodynia, respectively, at different time intervals, viz., 0, 1, 3, 6, 9, 12, 15, 18 and 21 days. Tissue myeloperoxidase, superoxide anion and total calcium levels were determined after day 21to assess biochemical alterations. Histopathological evaluations were also performed. Hydroalcoholic extract of Acorus calamus (HAE-AC, 100 and 200 mg/kg, p.o.) and pregabalin (10 mg/kg, p.o.) were administered for 14 consecutive days. Vincristine significantly induced peripheral neuropathic pain, manifested in thermal and mechanical hyperalgesia and mechanical allodynia, along with rises in the levels of superoxide anion, total calcium and myeloperoxidase activity. Moreover, significant histological changes were also observed. HAE-AC attenuated vincristine-induced development of painful behavioural, biochemical and histological changes in a dose-dependent manner comparable to that of pregabalin, serving as positive control. Acorus calamus prevented vincristine-induced neuropathic pain, which may be attributed to its anti-oxidative, anti-inflammatory, neuroprotective and calcium inhibitory actions, among others.