Anti-nociceptive effects of the hydroethanolic extract of Alysicarpus ovalifolius in rodents

Alysicarpus ovalifolius commonly known as gadagi in Northern Nigeria is claimed to possess tonic effects. Substances that show stimulant properties have demonstrated analgesic effects. This study therefore aimed at investigating the anti-nociceptive effects of the hydroethanolic extract of A. ovalifolius (HEAo) in mice and rats. The activities of the extract on acetic acid induced abdominal writhing, formalin induced pain and tail immersion test were carried out in mice. Effect on carrageenan induced pain was also determined in rats. The extract at the tested doses (100 – 400 mg/kg) significantly and dose dependently decreased the number of abdominal writhing in treated mice. Similarly, extract treated mice exhibited a decrease in the pain reaction in both phases of formalin induced algesia. Carrageenan caused hyperalgesia in rats which was ameliorated in rats treated with HEAo (400 mg/kg) when administered before and after exposure to carrageenan. Reaction time in the tail immersion test was increased in extract pre-treated mice. Results obtained from this study show that the hydro-ethanolic extract of A. ovalifolius may contain phytoconstituent probably acting on peripheral and centrally mediated pain receptors to produce anti-nociceptive actions. Key words: Anti-nociceptive effects, hydro-ethanolic extract, Alysicarpus ovalifolius, rodents.