Enhancement of neurotrophic activity in cholinergic cells by hippocampal extract prepared from colchicine-lesioned rats.

The effect of hippocampal extract on neurotrophic activity for cultured cholinergic cells was determined. Extract prepared from lesioned hippocampus caused by intrahippocampal infusion of colchicine promoted neuron survival of chick ciliary ganglion cells. The maximal level of survival-promoting activity was reached at 12 days postlesion. The biochemical differentiation of NG108-15 cells was assessed by measuring the activity of choline acetyltransferase (ChAT). After 3 days in culture, hippocampal extract was found to stimulate ChAT activity in a concentration-dependent manner. Hippocampal extract prepared after colchicine lesions elicited a large increase in ChAT-enhancing activity. The effect of hippocampal extract was additive to that of dibutyryl cyclic AMP (db-cAMP). The neurite outgrowth from NG108-15 cells was also potentiated when cells were cultured with hippocampal extract plus db-cAMP. The results suggest that one or several factors in colchicine-lesioned hippocampus promote neurotrophic activity, and the enhancing effect of hippocampal extract on cellular differentiation may act, at least in part, through a mechanism distinct from that for db-cAMP.