Involvement of Acetylcholinesterase and Nitric Oxide on the Behavioural Changes Induced by Harugana madagascariensis Extract in Mice Infected with and without Plasmodium berghei Malaria Parasite

Abstract

We evaluated the role of acetylcholinesterase (AChE) and nitric oxide (NO) in the behavioural effects of Harugana madagascariensis extract in mice, infected with and without Plasmodium berghei in novelty–induced behavioural models. This is also to examine the possible mechanism through which the plant reverses the behavioural effects during malaria infection. The novelty –induced rearing (NIR), grooming (NIG), locomotion (LC) and exploratory (EXP) behaviours were observed in non-infected and malaria infected mice using the suppressive; the curative and the prophylaxis modes of malaria treatment(s). In independent experiments, the ability of the Harungana stem bark extract treatments in changing the activity of AChE and NO in the brain cells of infected mice were evaluated. The result showed that the extract decreased the various behaviours in both infected and non-infected mice. The reserved observable novelty-induced behaviours in curative test were not significant (p > 0.05), but were significant in suppressive test. Likewise, the prophylactic treatment showed a significant (p < 0.05) reversal and increase in behavioural patterns after extract administration in infected mice. It is likely that the reduction in AChE and increase in NO activities by the extract contributed significantly to the behavioural effects exhibited. The significant reversal from depressive state in the prophylactic treatment especially could suggest the mechanism through which the constituents of this plant are best employed in traditional medicine for malaria. It is also possible that NO production and reduction in AChE activities are important for the behavioural changes.