Neurotoxic effects of differential doses of lead on rat brain followed by recovery

Long-term exposure to lead has been shown to produce behavioral disturbances in human and animal models. These disturbances are shown to be associated with alterations in cholinergic and dopaminergic neurotransmission in the CNS. The present experiment was designed to study the effect of lead exposure on neurotransmitters like dopamine, serotonin, and norepinephrine and the activity of acetycholinesterase along with alterations seen in memory and locomotor functions. Lead was administrated orally at doses of 10, 50, and 200 mg/kg for a period of 12 weeks, and a dose of 50 mg/kg was also given for a period of 8 weeks on alternate days; data were collected at the end of exposure and also after recovery of 8 weeks. The most significant change noticed was the decrease in activity of the acetylcholinesterase, which did not improve following withdrawal of lead exposure. The alterations seen in various neurotransmitters remain unchanged at the end of recovery of 8 weeks. Lead exposure affected the locomotor and cognitive functions; however, following the recovery period, a significant improvement was seen in locomotor as well as cognitive behavior. The short-term memory remained unchanged following both lead exposure and after recovery. J. Trace Elem. Exp. Med. 15:131–140, 2002. © 2002 Wiley-Liss, Inc.