Analgesic activity and effect of Maerua angolensis stem bark extract and fractions on morphine dependence in mice
Hosea Iliya, Eric Boakye-Gyasi, Kofi Annan, Edmund Ekuadzi, Eric Woode
Pain is associated with most pathological conditions in humans that affects thinking, sleeping, emotion and performance of daily chores, thereby making it an important therapeutic priority for control of pains. In conditions like advanced cancer, the only viable therapeutic option is management of the pain with analgesics, but potent and safe analgesics is limited. Opioids such as morphine are suitable for moderate to severe pain but their frequent use causes physical dependence and tolerance. Since Maerua angolensis is a medicinal plant used traditionally in the treatment of pain, the study examined the analgesic effect of the petroleum ether/ethyl acetate extract and fractions prepared from the stem bark of this plant in the mouse tail-flick test using Hargreaves thermal hyperalgesia model. The effect of the extract and fractions on morphine dependence was also assessed in mice. Dependence was induced using subcutaneous injections of morphine at doses of 50, 50 and 75 mg/kg three times daily for 3 days. On day 4, morphine was injected 2 hours prior to the intraperitoneal injection of naloxone. The number of jumps during the 30 minutes period after naloxone injection was taken as a measure of the withdrawal syndrome. The extract and fractions from Maerua angolensis (3 – 30 mg/kg, orally) significantly (P < 0.0001) and dose-dependently attenuated nociception in the tail-flick test and produced dose-dependent inhibition of the number of jumps comparable to muscimol and baclofen acting on Gamma-Amino Butyric Acid system. Additionally, the inhibition of jumping caused by the extract and fractions was reversed by intraperitoneal treatment of mice with bicuculline (Gamma-Amino Butyric Acid A receptor antagonist) and aminophylline (a non-selective adenosine receptor antagonist) suggesting stimulation of Gamma-Amino Butyric Acid and adenosine transmission. The antinociceptive effect and the suppression of withdrawal syndrome of morphine dependence established in this study contribute to the analgesic knowledge of this species.
How to cite this article:
Hosea Iliya, Eric Boakye-Gyasi, Kofi Annan, Edmund Ekuadzi, Eric Woode. Analgesic activity and effect of Maerua angolensis stem bark extract and fractions on morphine dependence in mice. Pharma Innovation 2015;4(2):62-68.