Chronic lead exposure in immature animals: Neurochemical correlates

Abstract

Although, clinically, lead poisoning is thought to cause several serious behavioral problems, a causal relationship between lead ingestion and behavioral dysfunction has not been shown. Neurochemical and behavioral effects of chronic postnatal lead ingestion by animals have been studied, but the literature on experimental animals is still meager. It is expected that research resolving the uncertainties about effects of lead in the areas of environmental, developmental, and child health will be forthcoming in the near future. Contradictory reports exist in the literature regarding the effect of inorganic lead ingestion on the levels and turnover rate of brain catecholamines. These inconsistent observations could probably be due to differences in the timing and ways the inorganic lead was administered to the animals, and the duration of lead exposure when the test was performed. However, there is enough evidence to suggest a general trend of elevated activity of catecholaminergic function in these experimental animals. The effects of lead exposure on the cholinergic function have been reported in a more consistent manner in the literature. Both neurochemical and electrophysiological (78) data in these animals have indicated the inhibitory function of lead on cholinergic activity. Most interestingly, available pharmacological studies have supported this concept ofmore » a neurochemical hyperfunction of the catecholaminergic system and simultaneous hypofunction of the cholinergic system following lead exposure.« less