Histological Study On Hippocampus Following Low Lead Exposure During Prenatal And Postnatal Brain Development In Rats.

Abstract

Background: Neuropsychological studies in children who are exposed to lead have confirmed its detrimental effects on behavioral and cognitive development. However there is inconsistency in information on the crucial period of brain development as far as lead neurotoxicity is concerned. Aims: To assess the cellular damage in hippocampus of rat pups exposed to lead during different periods of early brain development. Methods: Four groups of rat pups were investigated. (a) control group (n=6) (mothers of these rats were given normal drinking water throughout gestation), (b) Gestation lead exposed group (n=6) (exposed to 0.2% lead acetate in the drinking water through the mother throughout gestation [gestation day 01 to day 21]), (c) Lactation lead exposed group (n=6) (exposed to 0.2% lead acetate in the drinking water through the mother throughout lactation [postnatal day 01 to day 29]), (d) Gestation and lactation lead exposed group (n=6) (exposed to 0.2% lead acetate throughout gestation and lactation). On postnatal day 30, rat pups of all the groups were sacrificed. Numbers of surviving neurons in the CA3 and dentate gyrusregions of hippocampus were counted following cresyl violet staining. The significance of differences among the groups were assessed using one way analysis of variance (ANOVA) test followed by Bonferroni multiple comparison test.P values < 0.05 were considered as significant. Results: Hippocampal histological data indicate that lead exposure caused significant damage to neurons of CA3 and dentate gyrus in all lead exposed groups and the extent of damage to neurons of CA3 and dentate gyrus of Lactation group was comparable to Gestation and lactation group. Conclusion: Postnatal period of brain development seems to be more vulnerable to lead neurotoxicity as it had shown significant hippocampal damage even though period of exposure was less compared to Gestation and lactation group.