Serum and CNTF stimulate oligodendroglia and reduce fiber outgrowth from striatal cultures

Organotypic slice cultures of newborn rat striatal tissue displayed an exceptionally dense and fasciculated outgrowth of GABAergic fibers when grown in a chemically defined medium, compared to serum-containing medium. The enhanced fiber growth was not the result of an increased density of GABAergic neurons in the cultures, but coincided with a marked reduction of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-immunoreactive cells within and around the cultures. An inverse, causal relationship between the number of CNPase-positive cells, presumably of oligodendroglial lineage, and GABAergic fiber outgrowth was further evidenced by the observation that addition of ciliary neurotrophic factor (CNTF) to the chemically defined medium resulted in both an increase in CNPase-positive cells and a decrease in GABAergic fiber outgrowth. The observations suggest that CNTF and serum indirectly inhibit axonal growth by stimulating oligodendroglial cells.