Changes in neurotransmitter receptors and neurobehavioral variables in rats co-exposed to lead and ethanol

The influence of lead (10 mg/kg) and ethanol (10% v/v, in drinking water) a dministration, either alone or in combination for 8 weeks was investigated on the uptake of lead in tissues, dopamine, benzodiazepine and cholinergic (muscarinic) receptors, motor activity, number of fighting episodes and sev eral selected lead-sensitive biochemical indices in young rats. Lead or eth anol treatment did not elicit any appreciable influence on body weight gain , tissue weight, and food intake. However, a decreased amount of mean water intake was noticed in animals ingesting ethanol plus lead. Both lead and e thanol when administered individually exacerbate the decrease of blood delt a-aminolevulinic acid dehydratase (ALAD) activity while lead and ethanol ad ministered together exhibited a pronounced inhibition of ALAD activity. A s ignificant increase in hepatic GSH levels, hepatic and brain MDA levels was also observed in animals co-exposed to lead and ethanol compared to lead a lone treated rats. Simultaneous exposure to lead and ethanol also resulted in a significantly more pronounced decrease in binding of [H-3]fluintrazepa m in membranes prepared from the fronto-cortical region compared to the cor responding controls. The binding of [H-3]spiroperidol to striatal and [H-3] quinuclidinyl benzylate (QNB) to cerebellar membranes remained unaltered in all the exposed animals. Spontaneous locomotor activity and aggressive beh aviour increased significantly in the group treated with both lead and etha nol compared to the control group. The lead concentrations in blood, liver, kidney and brain were significantly higher in rats exposed simultaneously to lead and ethanol compared to lead alone exposed group. The results indic ate more pronounced neurotoxic and neurobehavioural changes in animals co-e xposed to lead and ethanol; however, the exact mechanism or site of its act ion is still not clear. (C) 1999 Elsevier Science Ireland Ltd. All rights r eserved.