Chronic low level lead exposure precociously induces rat glial development in vitro and in vivo.

Lead has been demonstrated to induce precocious glial differentiation both in vitro and in vivo. Lead-treated rat glioma (C6) and cerebellar astrocytes exhibited cytoplasmic extensions and the presence of glial endfeet after a 3-day exposure to 10(-6) to 10(-4) M PbCl2. In similar experiments no effect was noted in neuroblastoma (Neuro-2a) or on neurite outgrowth from chick spinal cord explants. This prodifferentiative effect on glia was also seen in the cerebella of postnatal rats in which the developmental expression of glial-specific glutamine synthetase activity was significantly increased up to postnatal day 12 after chronic exposure to lead from time of birth via their dam's drinking water (400 mg PbCl2/l).