Analgesic effects of Harungana madagascariensis stem bark extract USING four experimental models of nociception

Abstract

The analgesic effects of Harungana madagascariensis stem-bark ethanolic extract (HME) in mice and rats were studied. The analgesic effects of the extract (HME,  20, 40, 80 mg/kg s.c.) were evaluated by mechanically induced pain through analgesiometer, tail immersion test, hot-plate, and acetic acid-induced analgesic test methods. HME, significantly and dose-dependently produced analgesic effects against thermally- and chemically-induced nociceptive pain in mice, without any  effect in mechanically-induced pain through analgesiometer. The opioid antagonist naloxone (2 mg/kg s.c) and acetylsalicylic (100 mg/kg s.c) blocked and potentiated the analgesic effect of Harungana extract respectively in various degrees. Our results also tend to suggest that HME possesses centrally- and  peripherally-mediated analgesic properties. Although the precise mechanisms of the analgesic actions of HME is established in this study, the findings of this  animal study  appear to suggest that HME possesses analgesic properties by enhancing Opioidergic neurotransmission and inhibiting COX pathways. These  findings, therefore, lend pharmacological credence to the suggested folkloric, ethnomedical uses of the plant as a natural supplementary remedy for the control of pain, as well as for the treatment or management of inflammatory-painful conditions.

Key words: Harungana madagascariensis stem bark extract, analgesic effects,