Cerebellar macroneurons in serum-free cultures: evidence for intrinsic neuronotrophic and neuronotoxic activities.

Cerebellar macroneurones survive and differentiate for at least 10 days in Eagle's minimum essential medium with insulin as the only supplement when cultured either as microexplants or in high-density dissociated cultures, while they do not survive if cultured in low density. The survival is related to the extracellular release of neuronotrophic factor(s). Using a quantitative bioassay of the neuronotrophic effect, it is possible to demonstrate that the effect is concentration dependent. The analysis of the dose-response curves suggests that the neuronotrophic activity is associated with a neuronotoxic activity. The two activities can be segregated using a simple physical method, allowing direct demonstration of the neuronotoxic activity.