Induction of testis alcohol dehydrogenase in prepubertal rats

Unlike most mammalian species investigated the rat shows significant kidney alcohol dehydrogenase (ADH) activity in the testes which becomes demonstrable electrophoretically for the 1st time during puberty i.e. between the 35th-40th day after birth. This study was carried out to investigate the possibility of inducing the enzyme in the testes prior to the time of its normal appearance using infantile SIV-50 rats treated with various hormones and examining testis homogenates for the presence of ADH activity. Since testosterone was known to stimulate kidney ADH it was first tried in experiments on testis ADH. Testis ADH did not respond to this hormone. The effect of gonadotropins was then investigated. Follicle stimulating hormone (FSH) and human chorionic gonadotropin (HCG) both caused an increase in the weight of the testes of prepubertal rats but only HCG was active in stimulating testis ADH activity. Repeated injections of HCG from the 17th day after birth caused a marked rise in ADH activity by Day 24 even more than the normal increase at puberty by Day 55. In 24-day-old rats ADH activity was also provoked by dibutyryl cyclic AMP and by theophylline applied separately or in combination. A pretreatment with HCG inadequate to cause an increase in ADH stimulating the development of Leydig cells exerts its influence through the mediation of cAMP.