IN VITRO AND IN VIVO EFFECTS OF A NERVE GROWTH-STIMULATING AGENT ISOLATED FROM SNAKE VENOM

Abstract

A nerve growth-promoting agent was discovered in snake venoms, and its in vitro and in vivo effects were investigated. In both sets of experiments the nerve fiber outgrowth from sensory and sympathetic ganglia was found to be far beyond the normal range. Furthermore, the experiments in vivo gave evidence of a remarkable increase in cell size and cell numbers in sympathetic ganglia and of an acceleration of their differentiative processes. The nerve fibers produced in excess entered into the adjacent viscera. The snake venoms duplicate the effects of a "protein fraction" of mouse sarcomas in vitro and the effect of living sarcomas in vivo. The purest fraction of snake venom so far obtained was about 1000 times as effective as the purest tumor fraction. Failures to obtain positive effects after in vivo injection of some mouse tumor fractions was attributed to the relative weakness of the tumor fraction rather than to the presence of 2 different agents in the tumor.