TRANSFORMING GROWTH-FACTOR-BETA-1 AND GROWTH-FACTOR-BETA-2 PROMOTE NEURITE SPROUTING AND ELONGATION OF CULTURED RAT HIPPOCAMPAL-NEURONS

Transforming growth factor-beta (TGF-beta) is known as a potent regula tor of cell proliferation and differentiation. In the present study, w e investigated the effects of TGF-beta 1 and -beta 2 on the survival, neurite sprouting and process elongation of primary cultured hippocamp al neurons obtained from rat embryos. Addition of TGF-beta 1 little af fected the total number of surviving neurons, but clearly increased th e number of neurons bearing processes, indicating that TGF-beta 1 prom otes neurite sprouting rather than neuronal survival. Furthermore, TGF -beta 1 significantly promoted the elongation of axon-like processes, but did not affect the process branching and the number of dendrite-li ke processes. TGF-beta 2 also promoted the neurite sprouting and stimu lated the elongation of axons without affecting the branching. The eff ects of TGF-beta 2 were very similar to those of TGF-beta 1 in terms o f both effective concentrations (0.1-1 ng/ml) and maximal effects. It is possible that TGF-beta 1 and -beta 2 play roles in the formation of neuritic networks in the central nervous system.