Interaction of growth hormone with testosterone in stimulating the renal sexual segment of Anolis carolinensis

Growth hormone and prolactin, alone and in combination with testosterone, were injected into “physiologically” hypophysectomized male Anolis carolinensis to determine possible interactions of these hormones in controlling renal sexual segment function. Testosterone stimulated moderate sexual segment growth. Prolactin alone had no effect and did not enhance androgenic stimulation. Growth hormone alone did not cause hypertrophy of the sexual segment, but did enhance the stimulatory effect of testosterone. To eliminate a possible influence of endogenous hypophysial hormones, growth hormone in combination with testosterone was injected into surgically hypophysectomized animals. Growth hormone plus testosterone stimulated greater sexual segment hypertrophy than did testosterone alone. Inasmuch as growth hormone alone had no effect, it possibly acts directly on the sexual segment rather than by stimulating testicular androgenic secretions which in turn affect the sexual segment. The possibility that growth hormone has a cyclic pattern of secretion in reptiles is discussed.