An in-vivo method for estimating inhibin production by adult rat testes

Abstract

Summary. The concentrations of inhibin in samples of rat testicular venous and arterial blood and interstitial fluid were measured by an in-vitro bioassay using pituitary cells in culture in which the standard was an ovine testicular lymph preparation (assigned potency 1 unit/mg). Inhibin levels were undetectable ( < 2 U/ml) in both blood samples but reached a mean concentration of 120 \ m=+-\ 7 U/ml in testicular interstitial fluid. After unilateral efferent duct ligation the rate of inhibin accumulation in seminiferous tubules was determined by the difference in the inhibin content of the ligated and unligated testes. Additionally, the rate of seminiferous tubule fluid production was obtained from the difference in weight between the ligated and non-ligated testes. In the 24 h after efferent duct ligation there were linear increases in inhibin (18\m=.\5\ m=+-\1\m=.\0 U/h) and in seminiferous tubule fluid production (26 \ m=+-\ 1 \g=m\l/h), but there were no changes in serum FSH and LH levels.Experimental induction of bilateral cryptorchidism led to a decrease in the inhibin content of the testis after 10 days. The rate of inhibin accumulation after efferent duct ligation declined more rapidly than the inhibin content, being significantly depressed in cryptorchid testes after 3 days, suggesting that this measurement is a more sensitive index of inhibin production than the determination of testicular inhibin content.

Evidence for a major role of inhibin in the feedback control of FSH in the male rat

“…Glycerol doses of 25 µ , 100 µ and 400 µ lowered testicular inhibin activity by 24%, 68% and 90%, respectively. These findings suggest that inhibin is produced in the Sertoli cell and are in agreement with previous data obtained in vitro (Steinberger & Steinberger, 1976;LeGac & de Kretser, 1982) and in-vivo experiments (de Jong & Sharpe, 1977;Au et al, 1984Au et al, , 1986. Peripheral concentrations of immunoreactive inhibin were reduced by 10%, 25% and 57%, respectively, with increasing doses of glycerol.…”

Quantitative Cytological Studies of Spermatogenesis in Intact and Hypophysectomized Rats: Identification of Androgen-Dependent Stages*

“…This confirms the results of earlier studies that testosterone increases seminiferous tubule fluid production after efferent duct ligation (45,46). Despite this restoration of tubule diameter, seminiferous tubule length is not restored [1590 cm (Hi 0 ) vs. 2240 cm (Ti 0 )], suggesting that the maintenance of tubule length requires a pituitary factor.…”

Effect of Short Period Vasectomy on FSH, LH, Inhibin and Testosterone Secretions, and Sperm Motility in Adult Male Rats

“…The increase in plasma levels of inhibin may be similar to efferent duct ligation indicating that the inhibin secreted into the seminiferous tubule lumen is trapped [4]. However, the accumulated inhibin did not appear to influence FSH secretion significantly, probably because of the integrity of the blood-test barrier and the failure of the raised intratubular levels to affect an increase in the secretion of inhibin across the base of the Sertoli cells into testicular lymphatics [5]. Nevertheless, others have suggested that the passage of inhibin into the rete testis fluid and its subsequent absorption represents an important pathway by which inhibin reaches the circulation [27].…”

“…Bilateral vasectomy was created surgically (treated group) and intact rats were used as control (control group). On days 3,5,7,14,30, 60, and 90 after surgery, plasma concentrations of FSH, LH, inhibin, and testosterone were measured by radioimmunoassay, and sperm motility characteristics were measured by computer-assisted sperm analysis (CASA). The results show that weights of epididymides significantly increased in vasectomized rats as compared to control rats.…”