Nelsonia Canescens Extract: Analgesic Properties in Male Rats

Bamidele Victor Owoyele¹, Ilaria Ceccarelli², Jessica Pinassi², Paolo Fiorenzani² and Anna Maria Aloisi^2
1Neuroscience and Inflammation Research Unit, Dept. of Physiology, University of Ilorin, P.M. B. 1515, Ilorin. Nigeria.
²Behavioral Neurophysiology Lab. Dept. Medicine, Surgery and Neuroscience, University of Siena, via Aldo Moro, 2, 53100 Siena, Italy

A B S T R A C T
Plants used for many years for the treatment of diseases throughout the world can be the basis of the development of modern drugs. The benefits derived from plants have been linked to different functions including pain treatment. The extract of the aerial part of Nelsonia canescens was evaluated for its analgesic activity and its effect on spontaneous behavior in male rats subjected to a persistent painful stimulation (formalin test 2.5%, 50 ml) mimic a recurrent pain very common in clinic. The formalin-treated animals were divided into four groups and fed with almond oil (vehicle) or 12.5, 25 and 50 mg/kg of the extract for seven days. On the 8^th day, a second formalin test was carried out (formalin test 1%, 50 ml) to mimic a recurrent pain condition and to quantify pain intensity. During both tests the behavior was monitored in all groups, analyzed and compared. The behavioral responses taken into account were licking, flexing and paw jerk as pain measures and rearing, self-grooming, locomotion and crouch time as measures of spontaneous behavior. The results showed that the extract, in its different concentrations, was able to decrease pain behavior with no significant changes in general activity. The most effective concentration was 25 mg/kg as it reduced pain behavior, jerking and flexing in particular, indicating an analgesic action. In conclusion, the extract of the aerial part of Nelsonia canescens has demonstrated analgesic activity in a model of recurrent pain. An estrogen-like action is proposed.
Keywords: Recurrent pain, behavior, analgesia, estrogens