The effects of antimalarial drugs on cholinesterase activity in malarial infected rodents

Abstract

The alteration in serum and whole blood choolinesterase in Plasmodium berghei infected,chloroquine-treated or untreated mice were followed for 6 days. Choroquine, the 4-aminoquinoline, had been known for its effective with rapid onset and inexpensive antimalarial drug. The in vitro anticholinesterase activity of chloroquine was reported by many investigators. In this study, attempts have been made to study the time course of alteration in serum cholinesterase during P. berghei infection, and observe the effect of minimum effective dose of chloroquine on serum cholinesterase activityy. Serum cholinesterase activity of malarial infected mich was markedly increased whereas chloroquine did not have any effect on this enzyme. The same result was obtained in the whole blood cholinesterase measurement. Low dose of methyl parathion that enough to produce detectable lowering of cholinesterase activity but did not exhibit cholinergic overactivity such as salivation or lacrimation, did not have any effect on the progression of malarial infection. The median lethal dose (LD(,50) of methyl parathion in malarial-infected group was higher than the control, non-infected group. However, paraoxon, the active metabolite of parathion had the lower LD(,50) value in P. berghei infected group than the uninfected group. The results from this study suggested that the increased serum cholinesterase during P. berghei infection may alter the toxic effects of the anticholinesterase agents.