Intratesticular factors and testosterone secretion. Effect of treatments that alter the level of testosterone within the testis.

Abstract

The authors recently have reported the presence of a nongonadotropic polypeptide factor in rat testicular interstitial fluid that can exert marked stimulatory effects on Leydig cell testosterone production. To assess the potential physiologic significance of this factor, its effective levels in rat interstitial fluid have been investigated in response to treatments that either markedly reduce interstitial fluid testosterone concentrations (anti-LH treatment; transient or chronic experimental cryptorchidism; destruction of Leydig cells with ethane dimethanesulphonate) or that significantly elevate testosterone levels in interstitial fluid by injection of hCG. The possible relationship between this factor and changes in testicular weight, serum LH and FSH, and interstitial fluid volume also were monitored. When testosterone levels in interstitial fluid were decreased by 75 to 99% either acutely (5-72 hours) or chronically (20-75 days), there was an accompanying increase (P less than 0.001) in the levels of the interstitial fluid factor(s), as determined by the ability of charcoal-stripped interstitial fluid from individual rats to enhance hCG-stimulated testosterone production by Percoll-purified Leydig cells in vitro. Anti-LH treatment increased the levels of the interstitial fluid factor(s) over the ensuing 5 to 48 hours. In abdominal testes from rats made unilaterally or bilaterally cryptorchid for 20 or 55 days, a decrease in interstitial fluid testosterone levels was associated with increased levels of the interstitial fluid factor(s). The same inverse relationship was found 72 hours after treatment with ethane dimethanesulphonate in which Leydig cells had disappeared from the testis.(ABSTRACT TRUNCATED AT 250 WORDS)