Increase in hypothalamic pro-opiomelanocortin gene expression in response to prolonged low level lead exposure

Lead, an environmental pollutant, has been long recognized as a neurotoxic agent. Several reports have recently described behavioral disturbances caused by low level exposure. Lead-induced changes in neurotransmitter metabolism in the brain may help to elucidate the molecular basis for the observed behavioral alterations. In this study, the influence of low level lead exposure on the hypothalamic expression of rat opioid genes was examined. Determination of relative opioid mRNA levels revealed a dramatic increase of pro-opiomelanocortin (POMC) mRNA concentrations in response to lead. This increase was found to be specific, developmentally regulated, reversible and dependent on prolonged lead exposure. These findings may provide substantial evidence for the possible connections between early environmental inputs and the expression of neuropeptide genes in the brain.