Flutamide as an androgen antagonist on epididymal function in the rat

Pigment epithelium derived factor (PEDF) expression in the male tract of Wistar rats

Pigment epithelium derived factor (PEDF) expression has been described in many organs as showing neurotrophic, anti-angiogenic, anti-apoptotic, anti-inflammatory, anti-oxidant and pro-cell survival properties. However, references to its activity in the male reproductive system are scarce. We aimed to characterize the expression of PEDF in the male reproductive tract of Wistar rats by using RT-PCR, western blot and immunostaining and also evaluate the effect of flutamide in PEDF expression. We found that PEDF is expressed in the epididymis, prostate and seminal vesicles in Wistar rats, but notably not in the testes. Under the effect of flutamide PEDF expression decreased, recovering by suppressing the antiandrogen. The epididymis is an essential organ in sperm maturation-storages. The role of PEDF in this physiological process has not been fully elucidated yet, but considering that in other systems PEDF has anti-apoptotic, anti-oxidants and pro-cell survival properties, its expression along the epididymis could play a role in the protection of spermatozoa while they are stored.

Interpreting histopathology in the epididymis

While most of this Special Issue is devoted to the testis (which is where most drug and chemically induced toxicity of the male reproductive tract is identified), being able to recognize and understand the potential effects of toxicants on the epididymis is immensely important and an area that is often overlooked. The epididymis is the organ where the post-testicular sperm differentiation occurs, through a complex and still not completely understood sperm maturation process, allowing them to fertilize the oocyte. Also in the epididymis, sperm are stored until ejaculation, while being protected from immunogenic reaction by a blood-epididymis barrier. From a toxicologic perspective the epididymis is inherently complicated as its structure and function can be altered both indirectly and directly. In this review we will discuss the factors that must be considered when attempting to distinguish between indirect and direct epididymal toxicity and highlight what is currently known about mechanisms of epididymal toxicants, using the rat as a reference model. We identify 2 distinguishable signature lesions - one representing androgen deprivation (secondary to Leydig cell toxicity in the testis) and another representing a direct acting toxicant. Other commonly observed alterations will also be shown and discussed. Finally, we point out that many of the key functions of the epididymis can be altered in the absence of a detectable change in tissue structure. Collectively, we hope this will provide pathologists with increased confidence in identification of epididymal toxicity and enable more informed guidance as mechanism of action is considered.

Identification of early response genes and pathway activated by androgens in the initial segment and caput regions of the regressed rat epididymis

To identify the initial response to androgens and estrogens in the orchidectomized, regressed epididymis, we determined the gene expression changes triggered by the administration of either of two metabolites of testosterone, 5alpha-dihydrotestosterone (DHT) or 17beta-estradiol (E2), in the regressed rat epididymis. Adult rats were orchidectomized and 8 d later implanted with either empty implants (control), DHT-filled-, or E2-filled-polydioxanone implants. Rats were euthanized 12 h, 1 d, and 7 d later, and RNA was extracted and probed on Rat230-2.0 Affymetrix arrays. Probe sets that respond to DHT or E2 were identified at early time points; although the expression of some was repressed, the expression of many others was either transiently or chronically elevated. Nerve growth factor receptor (Ngfr) and S100 calcium binding protein G (S100g) were two E2 up-regulated genes detected at 12 h. Among the genes that showed a dramatic early response to DHT were endothelin 1 (Edn1), bone morphogenetic protein 4 (Bmp4), and IGF binding protein 3 (Igfbp3), which were suppressed, and IGF-I (Igf1), which was induced. Genes that were up- or down-regulated by DHT were classified based on biological function. Using PathwayStudio 4.0, we identified genes that were linked and directly influenced either the expression or regulation of one another. Epidermal growth factor and IGF-I play an important role in the pathway due to their function in regulation and expression of many other genes. These results provide novel insights into the impact of androgen action on the expression of genes that are important for epididymal function.

The aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD) reduces disinhibitory behavior in intact adult male rats treated with a high dose of testosterone

Anabolic androgenic steroids and high testosterone doses have been reported to induce impulsive behavior in man and behavioral disinhibition in rats. The purpose of the present study was to investigate whether aromatization of testosterone to estradiol is of importance for the behavioral disinhibiting effect of a high testosterone dose in adult male rats. Testosterone administered via five testosterone-filled silastic capsules implanted subcutaneously (s.c.) to non-castrated, group-housed rats for six days induced behavioral disinhibition in a modified Vogel's drinking conflict model and yielded supraphysiological serum levels of testosterone and increased accessory sex organ weights. Moreover, concurrent administration of the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD; 60 mg/kg/day s.c.) decreased behavioral disinhibition in testosterone-treated rats (without affecting accessory sex organ weights) while behavior was not significantly affected in sham-treated animals. Since some reports indicate that ATD, in addition to inhibit aromatase, also may affect the binding of testosterone to the androgen receptor, the effect of the non-steroidal androgen receptor antagonist flutamide was investigated. Flutamide treatment did not affect disinhibited behavior in testosterone-treated rats. However, in sham-treated animals, flutamide (50mg/kg/day) produced behavioral disinhibition. These results suggest that estradiol is of importance in the mechanisms underlying behavioral disinhibition in non-castrated rats treated with a high testosterone dose. Speculatively, aromatization may be involved in pro-impulsive effects of high testosterone doses in humans.

Toxicant-induced acceleration of epididymal sperm transit: androgen-dependent proteins may be involved

Previously we established that a 4-d exposure to chloroethylmethanesulphonate (CEMS), a chemical that significantly reduces serum testosterone (T) levels, resulted in a significant decrease in cauda epididymal sperm reserves in adult male rats while homogenization-resistant testicular spermatid numbers were unaffected. This epididymis-specific alteration occurred whether or not circulating T levels were maintained using T-filled Silastic implants. To determine whether this epididymis-specific decrease in sperm number was the result of decreased epididymal transit time, the vas deferens was ligated at its midpoint just prior to the first of 4 d of exposure to CEMS with and without T implantation. If epididymal sperm transit was accelerated due to treatment, there would be fewer sperm in the caput/corpus and more sperm in the cauda/vas of the treated animals compared to control. The number of sperm in the caput/corpus decreased significantly (P < 0.05) while the number of sperm in the cauda/vas increased significantly in both the CEMS and CEMS + T animals. Daily sperm production was unaffected, but transit time through the caput/corpus epididymidis was decreased significantly in both treatment groups. To determine if testicular fluid played a role in the epididymis-specific decline in sperm numbers, the efferent ducts were ligated at the same time the vas deferens was ligated. Again, the number of sperm in the caput/corpus decreased significantly with treatment while there was a reciprocal increase in the number of cauda/vas sperm relative to controls. Finally, to determine whether an androgen-mediated process might be involved, the known antiandrogen hydroxyflutamide (HFLUT) was given to castrated, T-implanted animals in which the fertilizing ability of epididymidal sperm is maintained over 4 days. Once again, the number of sperm in the caput/corpus decreased significantly while there was a reciprocal increase in cauda/vas sperm. A quantitative evaluation of the protein profile in homogenates of the caput/corpus epididymidis revealed treatment-related diminutions in two proteins CC9 (M(r) = 42 kDa, pI = 4.2) and CC34 (M(r) = 35 kDa, pI = 5.5), and the level of each of these proteins in the caput/corpus was significantly correlated with the decrease in caput/corpus sperm number. Thus, both CEMS and HFLUT accelerate sperm transit through the proximal segment of the epididymis; and, while this effect is not dependent on the testis, it may involve a lesion in androgen-dependent epididymal function.

Effects of different doses of cyproterone acetate (CA) on preputial gland structure and activity in intact male mice

The preputial is an androgen-dependent structure which appears to be used in pheromonal signalling in rats and mice. The structure of representative glands from intact oil injected male laboratory TO strain mice was contrasted with tissue from intact counterparts treated with the anti-androgen cyproterone acetate (CA). Sixteen days of an i.m. application of a modest range of CA doses (0.5, 1.0 and 2.0 mg/day given as oily solutions) and a variety of control treatments were used to assess influences on the structure and function of the preputial. The glands of intact male mice treated with oil were well-developed and actively secreting with parenchymatous acini at different stages of maturation. Such glands are generally highly Sudanophilic, with the lipophilic stain concentrated in acini in frozen sections and many acini are compressed by their neighbours to assume irregular shapes. Wax and frozen preputial sections from intact subjects treated with 0.5 or 1.0 mg CA were, in contrast, less well-developed and had fewer and smaller lipid droplets. Treatment of counterparts with 2 mg CA reduced acinar number and diameter in both wax and frozen sections with a concomitant increase in the proportion of connective tissue. The data confirm that this anti-androgen antagonizes the androgen secreted by the testis and adrenal cortex in terms of its expression of function on the preputial gland. These data provide further evidence that cyproterone acetate's suppressive actions on murine aggression are primarily via its ability to depress the secretion of odour cues that facilitate attack.