The effect of increased levels of endogenous nerve growth factor on mouse sympathetic ganglia

Abstract

The present experiments showed that treatment of mice with a range of doses of testosterone propionate led to a significant increase in weight of the superior cervical ganglia (SCG). In all cases this was accompanied by an elevation of the level of nerve growth factor (NGF) in the submandibular glands (SMG) and, with the exception of animals treated with the lowest dose of testosterone, by an increase in weight of the SMG. Hypertrophy of the SCG was also found in mice treated with 5α-dihydrotestosterone which therefore excludes the possibility of the hypertrophy being due to a general metabolic effect of testosterone propionate. Treatment of mice with isoproterenol and of rats with testosterone propionate resulted in hypertrophy of the SMG but had no effect on the levels of NGF in the glands or on the weights of the SCG. These findings exclude the possibility that the hypertrophy of the SCG in testosterone-treated mice is a consequence of an increase in size of the SMG. It is concluded that the hypertrophy of the SCG in testosterone-treated mice results from the action of increased levels of endogenous NGF. The route of access of NGF responsible for the hypertrophy is discussed and a comparison is made of the effects produced by systemically administered NGF and increased levels of endogenous NGF.