Plasma 5 alpha-dihydrotestosterone and testosterone in the bullfrog, Rana catesbeiana: stimulation by bullfrog LH.

Effects of purified bullfrog (Rana catesbeiana) LH and FSH on plasma levels of the androgens, testosterone (T), and 5α-dihydrotestosterone (DHT), were studied using adult male bullfrogs. Rana LH was considerably more potent than Rana FSH in stimulating increased plasma androgen levels in hypophysectomized and intact animals. Simultaneous injection of Rana FSH or ovine PRL with Rana LH, over a 10-day period, did not alter the LH-induced increase in plasma androgens. More DHT than T was present in plasma after LH injection. Castration abolished plasma DHT and greatly reduced plasma T. Results indicate that DHT is a major testicular steroid, and that testicular androgen secretion is stimulated primarily by LH in the bullfrog.