Biphasic effect of aluminium on cholinergic enzyme of rat brain.

The cholinotoxic effect of aluminium has been widely reported. In vitro aluminium has a biphasic effect on acetylcholinesterase activity. The present study analyses its in vivo effect in brain regions. Rats were exposed to aluminium chloride by the oral route at a dose of 320 mg/kg body weight for shorter (4 and 14 days) and longer (60 days) duration. Acetylcholinesterase activity in olfactory bulb, striatum and hypothalamus brain regions increased after 4 and 14 days and decreased after 60 days of aluminium exposure. Aluminium level in the brain regions studied increased significantly. No significant change in body weight of rats exposed to aluminium was found. The biphasic change in acetylcholinesterase activity may be due to slow accumulation of aluminium in the brain regions and its effect on the enzyme.