Rates of protein synthesis in the regenerating hypoglossal nucleus: effects of testosterone treatment.

Rates of protein synthesis (ICPSleu) along the entire rostral to caudal extent of the hypoglossal nucleus were determined in adult, female rats with the quantitative autoradiographic L-[1-14C]leucine method two and five weeks after unilateral hypoglossal axotomy with and without chronic treatment with testosterone. Rates of protein synthesis were increased on the axotomized side, and the increases were greater in the rostral portion of the nucleus at both time points examined. The effects of axotomy on ICPSleu were less at five weeks post-axotomy than at two weeks. In spite of the fact that testosterone has been shown to accelerate both the rate of outgrowth of regenerating cranial motor nerves (Kujawa et al., J. Neurosci. 11:3898-3906, 1991) and the recovery of function (Kujawa et al., Exp. Neurol. 105:80-85, 1989) and to attenuate the loss of neurons (Yu et al., Exp. Neurol. 80:349-360, 1983) there were no effects of testosterone on 1CPSleu in the hypoglossal nucleus in either sham-operated or axotomized rats.