5'-NUCLEOTIDASE ACTIVITY AND GALACTOLIPID ACCUMULATION IN TRIETHYLLEAD-EXPOSED GLIAL-CELL CULTURES

The developing nervous system is vulnerable to heavy metal exposure, w hich can cause alterations in neuronal and glial cells in the brain. T hus, heavy metals such as mercury and lead reduce myelin galactocerebr oside (GalC) synthesis, and increase the ratio of non-hydroxylated fat ty acids to hydroxylated fatty acids (GalC-N:GalC-OH) in the GalC mole cules in newborn rats. This study investigated the effect of lead on t he expression of myelin components by the myelin-forming oligodendrogl ial cells (OG) in vitro. Primary cultures of mixed glial cells From br ains of newborn rats were continuously exposed to triethyllead (TEL; 1 nM, 10nM, 50nM and 100nM) for 3 weeks, one week after seeding. The fir st morphological alteration observed was an increased proliferation of OG in cultures exposed to 10nM TEL. Biochemical analyses showed up-re gulation of the enzymes, 2'3'-cyclic nucleotide 3'-phosphodiesterase a nd 5'-nucleotidase. GalC synthesis was also stimulated, and the ratio GalC-N:GalC-OH was reduced. The results indicate that TEL stimulates t he differentiation and maturation of OG in cultures, which suggests th at the alterations induced by heavy metals in newborn rats are not due to interference with the OG maturation.