PRENATAL AND POSTNATAL LEAD-EXPOSURE INDUCES 70 KDA HEAT-SHOCK-PROTEIN IN YOUNG-RAT BRAIN PRIOR TO CHANGES IN ASTROCYTE CYTOSKELETON

In previous studies we found that chronic postnatal (PN) lead exposure [1g% (w/v)] induced astroglial hypertrophy in rat hippocampus. Since astrocytic responses change upon the stage during which exposure occur s, astroglial reactions in cerebral cortex and hippocampus of young an imals were studied and compared when exposure began during development . Lead-treatment started 90 days prior to mating, and was maintained d uring gestation and after birth up to PN160. Alterations observed from PN21 to PN140 were assessed by antibodies to the 70kDa heat shock pro teins (hsp), glial fibrillary acidic protein (GFAP) and vimentin (VIM) using immunohistochemistry, transmission electron microscopy (TEM) an d computer assisted image analysis. The induction of hsp was seen from PN21 to PN45 in non-pyramidal neurons and astrocytes, and at the same time, astroglial swelling was noticed. After PN45 the resolution of t his edema coincided with an increase of gliofilaments and GFAP and VIM immunoreaction (PN60-PN90). Recovery of VIM expression persisted afte r PN120 in the hilus; meanwhile, lipofuscin-like bodies appeared in ne urons and astrocytes. Lead exposure during rapid brain growth induced hsp after weaning in neurons and astrocytes prior to astrocyte cytoske letal changes. Astroglial and neuronal alterations could modify comple x neuron-glia interactions, disturbing brain function in consequence. (C) 1997 Intox Press, Inc.