Responsiveness of hypoglossal neurons to testosterone in pre-pubertal rats

We have shown previously that administration of testosterone propionate (TP) to adult rats accelerated regeneration of the hypoglossal nerve. This study was made to determine whether TP had a similar effect in pre-pubertal rats, in order to establish the ontogeny of the responsiveness of the hypoglossal neurons to androgenic stimulation. It was found that TP significantly shortened the time course of the regeneration of the hypoglossal nerve in the 4-weeks old but not in the 2- and 3-weeks old rats; and that males of 4-weeks of age responded to TP a few days earlier than females of the same age. The possible causes of the failure of the hypoglossal neurons of younger ages to respond to TP were discussed.