Hormonal Control of Testosterone Secretion by the Fetal Rat Testis in Organ Culture

Publisher Website
Google Scholar
Abstract
Testes isolated from fetal rats were maintained in organ culture for 72 h. Daily secretion of testosterone (T) into the medium was measured by radioimmunoassay. T secretion was stimulated by hCG (10-2000 mIU/ml); maximal stimulation was observed with a dose of 100-200 mIU/ml, whereas the 2000 mIU/ml dose resulted in a diminution of T secretion during Day 2 and Day 3 of incubation. Ultrastructural examination after 72 h of culture in the presence of higher doses of hCG (100-2000 mIU/ml) showed a reduction in Leydig cell lipid droplets and glycogen together with dilated profiles of smooth endoplasmic reticulum. Lower doses of hCG (10-50 mIU/ml) did not alter the appearance of Leydig cells. T secretion was also stimulated by isobutylmethylxanthine (0.25 mM), 8 bromo-cAMP (0.5 mM) and dibutyryl-cAMP (1 mM). Addition of progesterone (1 µg/ml), alone, increased T secretion significantly and also had an additive effect when added in combination with hCG (20 mIU/ml). Estradiol-17β (1 µg/ml), alone, did not affect T secretion, but when added (at a dose of 1-5 µg/ml) together with hCG (20 mIU/ml) significantly inhibited the stimulatory effect of hCG. Ovine prolactin (500 ng/ml), alone, did not affect T secretion but at a concentration of both 100 and 500 ng/ml significantly inhibited the stimulatory effect of hCG (20 mIU/ml) on Day 2 and Day 3 of incubation. Thus, the fetal rat testis in organ culture appears to respond to regulatory factors in a fashion remarkably similar to that observed in vivo in the postnatal animal and would appear to afford a convenient model for future studies on the hormonal control of testicular steroidogenesis.