EFFECTS OF CHRONIC LOW-LEVEL LEAD-EXPOSURE ON THE EXPRESSION OF GFAP AND VIMENTIN MESSENGER-RNA IN THE RAT-BRAIN HIPPOCAMPUS ANALYZED 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 deve lopment. Low level lead is known to affect astroglia. GFAP and Vimenti n 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 gestati on, lactation and post-weaning (EO-P100), a perinatal group exposed du ring gestation and postnatally until weaning (EO-P16), and a post-wean ing exposed group (P16-P100). All experimental animals were fed a diet containing 750ppm lead acetate. With respect to Vimentin mRNA no majo r differences could be detected among the treatment groups. Significan t differences in GFAP mRNA levels were detected in the post-weaning gr oup 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 C A1 region of the hippocampus. Permanent and perinatal groups showed no overt changes compared to controls. Our findings suggest that an irri tation of the mature astrocyte results in a change from the quiescent to the reactive state. The majority of astrocytes that have been expos ed during their development and differentiation fail to react even if the exposure is continued to adulthood This suggests an irreversible i nsult by low level lead exposure during this period of time. (C) 1994 Intox Press, Inc.