Perturbation of fluid reabsorption in the efferent ducts of the rat by testosterone propionate, 17β‐oestradiol 3‐benzoate, flutamide and tamoxifen

Abstract

The regulation by oestradiol and testosterone of fluid reabsorption in the efferent ducts of the rat was investigated by determining the effects of administering the hormones and their antagonists. Untreated rats were compared to animals treated for 7 days with testosterone propionate (1 mg d(-1)), oestradiol benzoate (400 microg d(-1)), flutamide (10 mg d(-1)) or tamoxifen (1 mg d(-1)). Two procedures were used to measure perturbation of transepithelial fluid fluxes in vivo. The first procedure used cannulation of the proximal epididymal duct and micropuncture of the rete testis to compare the rate at which fluid enters and leaves the efferent ducts. Oestradiol administration increased (p < 0.001) the volume of fluid entering the epididymal duct from the efferent ducts (i.e. reduced reabsorption) while flutamide and tamoxifen decreased (p < 0.05) the amount of fluid entering the epididymal duct (i.e. increased fluid reabsorption). Testosterone did not have a statistically significant effect, although it produced a small increase in fluid reabsorption. There was some perturbation of the concentration of electrolytes and the osmotic pressure of the fluid leaving the efferent ducts, but as these were not large, it is suggested that the treatments had little effect on the basic mechanisms of osmotic water transport via solute-solvent coupling. The second procedure used to test the effect of the steroids involved microperfusing individual efferent ducts, and the results were consistent with those of the first study. Oestradiol decreased fluid reabsorption by the efferent ducts (p < 0.05), and testosterone (p < 0.05, lowest perfusion rate only), flutamide (p < 0.001) and tamoxifen (p < 0.01) increased reabsorption. The similar responses to flutamide and testosterone administration suggest that flutamide acted as an androgenic agonist by elevating systemic and luminal androgen. It is concluded that fluid reabsorption in the efferent ducts is perturbed by oestrogens and androgens. Although their actions have not been completely resolved, it is proposed that they are involved in a chronic regulation, with androgens stimulating and oestrogens suppressing fluid reabsorption by the ducts.

Effects of butyl paraben on the male reproductive system in mice

“…The reason of this discrepancy is not clear, but it is reported that low-dose administration of some estrogenic compounds increases the epididymal weights slightly but not significantly (Boockfor and Blake 1997;Biegel et al 1998;de Jager et al 1999;Lee 1998). Hansen et al (1997) reported that androgens promoted, and estrogens inhibited, luminal fluid resorption by epithelial cells of the efferent ducts in adult hormone-treated rats. Another report shows that estrogens regulate the resorption of luminal fluid in the head of the epididymis (Hess et al 1997).…”

Differential hormonal regulation of estrogen receptors ERα and ERβ and androgen receptor expression in rat efferent ductules

“…A high dosage of estradiol (400 mg) was used because this was found to be effective for inducing complete estrogenization in male rats without inducing significant regression of the efferent ductules (Hansen et al 1997, Tena-Sempere et al 2000. The dosage of 75 mg estradiol was equivalent to that shown to induce a response in reproductive organs, with minimal histological alterations .…”

“…The dosage of 75 mg estradiol was equivalent to that shown to induce a response in reproductive organs, with minimal histological alterations . The dose regimen of 1 mg testosterone was used to mimic physiological serum testosterone levels and that of 5 mg testosterone and DHT was based on previous studies showing that this concentration reproduces that which is normally found in the epididymis (Hansen et al 1997, Fan & Robaire 1998, Goyal et al 1998. DHT, the non-aromatizable metabolite of testosterone, was used to get around the problem of whether the potential effects of testosterone were direct or were dependent upon aromatization to estrogen or 5a-reduction to DHT.…”

Transport of IgG across the Blood-Luminal Barrier of the Male Reproductive Tract of the Rat and the Effect of Estradiol Administration on Reabsorption of Fluid and IgG by the Epididymal Ducts1

“…This study confirms that IgG enters the rete testis [9,10], and shows that most is reabsorbed mainly by the ductuli efferentes, although some is concentrated in the lumen as a consequence of fluid reabsorption by the ducts. The effect of administering estradiol on the concentration of specific IgG in the extratesticular ducts was examined, because the treatment is known to perturb fluid reabsorption in the ductuli efferentes [21][22][23] and so may affect the concentration of IgG in the duct system. Importantly, this work showed that the ductus epididymidis must recognize and compensate for a reduced function of the ductuli.…”