Effect of Luteinizing Hormone (LH) and LH-Releasing Hormone (LHRH) on Testosterone Production In Vivo, in Fetal Rabbit Testis in Late Gestation

Abstract

Plasma and testicular testosterone were measured by radioimmunoassay in the 29-day-old rabbit fetus receiving an injection of saline solution, LH or LHRH. 30 min following the injection of 5 μg LH into the umbilical vein, testosterone levels were significantly increased by 287% in the plasma and 293% in the testis, compared with controls receiving saline solution. The injection of 2 μg of LHRH under the same conditions significantly increased testicular testosterone by 256% and plasma testosterone by 746%. The results show that the fetal rabbit testis, at the end of gestation, is capable of responding to LH stimulation. The hypophyso-testicular axis is apparently functional at this stage of gestation, as shown by the response to LHRH.