Alterations of central muscarinic functions during subchronic exposure to acrylonitrile in rats

Abstract

The effects of subchronic exposure to acrylonitrile (ACN) on central cholinergic functions are studied. Daily subcutaneous administration of ACN 1 (A1) and 25 (A25) mg/kg BW, 5 days/week for a period of 8 weeks induced significant decreases in motor behavioral activities as compared with the control groups. The parameters of motor activities affected include distance traveled, total ambulatory count, clockwise and counter-clockwise rotations. In control rats, atropine 10 mg/kg BW, administered intramuscularly (i.m.) caused significant increases in motor activities, while physostigmine 0.5 mg/kg BW, i.m.., caused significant decreases in some motor activity parameters. Subchronic treatment with low dose of ACN (A1) did not alter the effects of atropine and physostigmine on motor activities. On the other hand, subchronic exposure to a higher dose of ACN (A25) accentuated the effects of atropine, while those of physostigmine were not significantly altered. In this study the hypersensitivity of muscarinic receptor to atropine was revealed in ACN-treated rats. This motor activity test is simple and it could be used as a test model to detect the subtle change of central muscarinic receptors during chronic exposure to environmental cholinotoxic chemicals.