Effect of intratesticular administration of TRH or anti-TRH antiserum on function of rat testis

The effect of intratesticular administration of thyrotropin-releasing hormo ne (TRH) and anti-TRH antiserum on steroidogenesis was studied in immature and adult rats. In 9-day-old animals local administration of the neuropepti de resulted in an increase in basal testosterone secretion in vitro. Simila r treatment of 15-day-old rats suppressed hCG-stimulated testosterone secre tion with no change in basal testosterone production, In both immature grou ps the treatment did not affect serum testosterone concentration, By contra st, in adults TRH decreased serum testosterone level, but did not influence basal and hCG-stimulated testosterone secretion. Both in immature and adul t rats, the changes in steroidogenesis were evident 1 hour posttreatment, F ive days after the administration of anti-TRH antiserum into the remaining testis of immature rats subjected to hemicastration just prior to the antis erum treatment, the alterations in steroidogenesis were opposite to those d etected after treatment with TRH. In 9-day-old rats the antiserum suppresse d steroidogenesis, while in 15-day-old animals it stimulated testosterone s ecretion. The results suggest that testicular TRH might exert a local actio n on testicular steroidogenesis, and the effect is age-dependent. (C) 2000 Elsevier Science Inc. All rights reserved.