Assessment of the androgen environment within the human testis: minimally invasive method to obtain intratesticular fluid.

Previous studies of the rat have shown that testosterone concentrations within the interstitial and seminiferous tubularfluids of the testes are significantly higher than normal serum levels, and further, that although intratesticular testosterone concentration can be substantially reduced without an effect on spermatogenesis, the concentration that is minimally required to maintain spermatogenesis is also substantially higher than serum levels. The purpose of the present study was to adapt a minimally invasive technique to sample human intratesticular fluid to enable parallel observations in man. To this end, aspiration methods were first developed for the rat testis and then adapted to the human. The testosterone concentration in fluid obtained by unilateral aspiration of rat testes was approximately 50 ng/mL, similar to the known concentration in seminiferous tubular fluid. These aspiration methods were then adapted to obtain intratesticular fluid from human testes. Studies of 12 fertile human subjects demonstrated that percutaneous testicular aspiration could be performed safely and successfully using a 19-gauge needle. Nine additional human subjects had bilateral testicular aspiration and simultaneous measurement of peripheral blood testosterone levels. Testicular aspirations yielded 8 to 117 microL of fluid from each testicle. The mean concentration of testosterone in aspirates obtained from the 21 patients was 609 +/- 50 ng/mL. Dihydrotestosterone and 3alpha-androstanediol concentrations were quite low, below the limits of detection of our assay. The SHBG/ABP concentration in the aspirates was 8.5 +/- 1.1 nM. These results define testosterone as the major androgenic steroid in the human testis, as in the rat testis, and indicate that the testosterone concentration within the human testis is approximately 200-fold greater than that of SHBG/ABP, and more than 100-fold greater than the concentration of testosterone found in normal human serum.

Atrazine effects on testosterone levels and androgen-dependent reproductive organs in peripubertal male rats.

Previous studies have reported that atrazine, a widely used herbicide that selectively inhibits photosynthesis in broadleaf and grassy weeds, has adverse effects on reproductive function in the male, suggesting a direct effect of atrazine on the hypothalamicpituitary-testicular axis. As yet, however, no studies have critically examined the doses of atrazine that elicit such effects, and few have focused on the mechanism by which atrazine acts. Herein we report a dose-response study of the effects of atrazine ingestion on reproductive function in male Sprague-Dawley rats during a critical developmental period, the peripubertal period. Atrazine was administered by gavage to rats from day 22 to day 47 of age, at doses of 1-200 mg/kg body weight per day. Atrazine administration of up to 50 mg/kg per day had no effect on any of the measured variables. Serum testosterone concentration was reduced by atrazine at doses of 100 and 200 mg/kg per day, as were seminal vesicle and ventral prostate weights. Intratesticular testosterone concentration was reduced in parallel with serum testosterone, suggesting that the reductions in serum testosterone resulted from reduced testosterone production by Leydig cells or from changes in testosterone metabolism within the testis, or both. Serum luteinizing hormone (LH) concentration was reduced despite the reduced serum testosterone, suggesting an effect on the hypothalamus, the pituitary gland, or both. At the termination of the study, the average body weight of rats receiving atrazine at 100 mg/kg per day was found to be reduced by approximately 9%. This suggested the possibility that the effects of atrazine on the reproductive tract may not be direct, but rather, the noted deficits of the male reproductive tract resulted from reduced food intake by the treated rats. We tested this by feeding control (vehicle-gavaged) rats amounts of food equivalent to that consumed by the atrazine-fed rats, and then assessing reproductive tract endpoints. Even mild food restriction resulted in reductions in serum testosterone concentration, in the weights of androgen-dependent organs, and in serum LH concentration; the same deficits that were seen in atrazine-gavaged rats. Indeed, the effects of atrazine on the male reproductive tract seen in rats receiving atrazine at greater than 50 mg/kg per day could not be distinguished from the effects of reduced food consumption. These results suggest that caution must be exercised before concluding that atrazine (or any potentially toxic chemical) has direct, detrimental effects.