Effects of chronic low level lead exposure on the expression of GFAP and vimentin mRNA in the rat brain hippocampus analysed by in situ hybridization.
In this study we used in situ hybridization to examine the effects of chronic low level lead toxicity during different periods of brain development. Low level lead is known to affect astroglia. GFAP and Vimentin were chosen as glialtypic markers for neurotoxicity. The effects of lead were investigated on male Wistar rats. Animals were divided into four groups: a control group, a permanent group exposed during gestation, lactation and post-weaning (E0-P100), a perinatal group exposed during gestation and postnatally until weaning (E0-P16), and a post-weaning exposed group (P16-P100). All experimental animals were fed a diet containing 750 ppm lead acetate. With respect to Vimentin mRNA no major differences could be detected among the treatment groups. Significant differences in GFAP mRNA levels were detected in the post-weaning group relative to controls. In this group we observed a strong increase of GFAP mRNA in the polymorphic zone of the dentate gyrus and in the CA1 region of the hippocampus. Permanent and perinatal groups showed no overt changes compared to controls. Our findings suggest that an irritation of the mature astrocyte results in a change from the quiescent to the reactive state. The majority of astrocytes that have been exposed during their development and differentiation fail to react even if the exposure is continued to adulthood. This suggests an irreversible insult by low level lead exposure during this period of time.
PubMed Abstracts
PubMed Abstracts