Acetylcholinesterease Activity in Rat Brain Regions Following Acephate Exposure for 4, 14 and 60 Days

Author: S. Kumar

Source: Toxicological and Environmental Chemistry, Volume 84, Numbers 1-4, Numbers 1-4/December 2001 2003 , pp. 69-77(9)

Publisher: Taylor and Francis Ltd

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Abstract:

Effects of a short term (4 and 14 days) and sub-chronic (60 days) exposure to an organophosphorous pesticide acephate (O,S-dimethyl acetylphosphoramidothioic acid) on acetylcholinesterase inhibition were determined in: olfactory lobe, cerebellum, pons, medulla oblangata, spinal cord, hypothalmus, hippocampus, striatum, mid brain and cortex of the rat brain. Acephate treated rats had mild cholinergic toxic signs and the toxic signs persisted until tolerance to the pesticide developed. Chromodacryorrhea was also observed in the rats. Acetylcholinesterase (AChE) activity was inhibited in the brain regions studied. Enzyme activity was initially inhibited and remained at the 4-day level when measured in hippocampus, striatum, pons, medulla oblongata, spinal cord and cerebellum at 14 and 60 days except the midbrain, in which AChE was not inhibited at 4 days. Regional differences in inhibition of enzyme activity were apparent in the brain regions. Striatum and cortex were highly susceptible to inhibition of AChE after 4, 14 and 60 days of exposure. Inhibition of AChE enzyme activity in the olfactory lobe region was progressively less with increasing duration of treatment. Rats exposed to acephate repeatedly, developed tolerance to cholinergic hyperactivity. Variations in AChE activity observed in different brain regions in the present study may be attributed to the regional differences in tolerance development.

Keywords: Acephate; Acetylcholinesterase; Brain regions; Rat

Document Type: Research article

Publication date: 2003-12-01