Demonstration of follicle-stimulating hormone receptor in cauda epididymis of rat

Combined evaluation of prolactin-induced peptide (PIP) and extracellular signal-regulated kinase (ERK) as new sperm biomarkers of FSH treatment efficacy in normogonadotropic idiopathic infertile men

PURPOSE

Nearly, 40% of the causes of male infertility remain idiopathic. The only suggested treatment in idiopathic oligo- and/or asthenozoospermia in normogonadotropic patients is the FSH. In the current clinical practice, efficacy is exclusively assessable through semen analysis after 3 months of treatment. No molecular markers of treatment efficacy are appliable in clinical practice. The aim of the present work is to evaluate the combination of extracellular signal regulated kinase (ERK) 1 and 2 and prolactin inducible peptide (PIP) as potential markers of idiopathic infertility and FSH treatment efficacy.

METHODS

Western blot and confocal microscopy were performed to analyze the modulation of PIP and ERK1/2 in idiopathic infertile patients (IIP) sperm cells. Taking advantage of mass spectrometry analysis, we identified these proteins unequivocally in sperm cells.

RESULTS

 We demonstrated a significant decrease of both PIP protein and of ERK1/2 levels in spermatozoa obtained from IIP in comparison to healthy fertile patients (HFP). Conversely, we reported a significant increase of these markers comparing infertile patients before and after 3 months of FSH treatment. Importantly, this correlated with an increase in total number of sperm and sperm motility after FSH treatment. Finally, we identified of PIP and ERK2 proteins in sperm samples by proteomic analysis.

CONCLUSIONS

The combined evaluation of ERK1/2 and PIP proteins might represent a useful molecular marker to tailor FSH treatment in the management of male normogonadotropic idiopathic infertility.

Regulation of glucocorticoid metabolism in the boar testis and caput epididymidis by the gonadotrophin-cAMP signalling pathway

In target tissues, cortisol is metabolised by two 11β-hydroxysteroid dehydrogenase (11βHSD) isoenzymes, namely 11βHSD1 and 11βHSD2, both of which are co-expressed in the boar testis and reproductive tract. The present study has assessed whether cortisol-cortisone metabolism in boar testis and caput epididymidis can be regulated via the gonadotrophin-cAMP signalling pathway. 11βHSD activities were measured by using a radiometric conversion assay in static tissue culture. In both testis and caput epididymidis, the net reduction of cortisone but not the net oxidation of cortisol, was significantly decreased by luteinising hormone (by 53 ± 20% and 45 ± 9%, respectively, P < 0.05), forskolin (by 60 ± 7% and 57 ± 9%, respectively, P < 0.01) and 8-bromo-cAMP (by 54 ± 4% and 64 ± 1%, respectively, P < 0.01). This suppression of 11-ketosteroid reductase activity in the boar testis by forskolin could be attenuated by the protein kinase A (PKA) inhibitor, H89. Hence, within the boar testis and the caput epididymidis, the local actions of glucocorticoids are modulated by gonadotrophin-cAMP-PKA signalling via their selective effects on the reductase activity of 11βHSD.

A switch in Sertoli cell responsiveness to FSH may be responsible for robust onset of germ cell differentiation during prepubartal testicular maturation in rats

FSH and Testosterone (T) regulate spermatogenesis via testicular Sertoli cells (Sc), which bear receptors for these hormones. Despite sufficient circulating levels of FSH and T postnatally, predominant appearance of spermatogonia B and spermatocytes is not discernible until 11 and 18 days of postnatal age, respectively, in rat testes. In an attempt to explore the underlying causes, we cultured Sc from neonatal (5- and 9-day-old) and prepubertal (12- and 19-day-old) rat testes and compared the status of FSH receptor (FSH-R) and androgen receptor (AR) signaling. Protein and mRNA levels of FSH-R and AR remained uniform in cultured Sc from all age groups. Androgen binding ability of AR was similar, and T-induced nuclear localization of AR was discernible in Sc from all age groups. Binding of FSH to FSH-R, subsequent production of cAMP, and mRNA of stem cell factor (SCF) and glial cell line-derived neurotrophic factor (GDNF), known to be essential for the robust differentiation of repopulating spermatogonia, were significantly augmented in prepubertal Sc compared with those in neonatal Sc. However, treatment of neonatal Sc with cholera toxin or forskolin, which stimulate cAMP production bypassing FSH-R, demonstrated a concomitant rise in SCF and GDNF mRNA expression, which was similar to the FSH-mediated rise observed in prepubertal Sc. These observations suggested that, during prepubertal Sc maturation, the ability of FSH-R to respond to FSH is significantly augmented and is associated with the robust differentiation of repopulating spermatogonia, and such a switch in Sc from FSH-resistant to FSH-responsive mode during prepubertal development may underlie the initiation of robust spermatogenesis.

Insufficient androgen and FSH signaling may be responsible for the azoospermia of the infantile primate testes despite exposure to an adult-like hormonal milieu

BACKGROUND

In humans, as well as in other higher primates, the infantile testis is exposed to an adult-like hormonal milieu, but spermatogenesis is not initiated at this stage of primate development. In the present study, we examined the molecular basis of this intriguing infertile state of the primate testis.

METHODS

The integrity of androgen receptor (AR) and FSH receptor (FSHR) signaling pathways in primary cultures of Sertoli cells (Scs) harvested from azoospermic infant and spermatogenic pubertal monkey testes were investigated under identical in vitro hormonal conditions. In order to synchronously harvest Scs from early pubertal testis, the activation of testicular puberty was timed experimentally by prematurely initiating gonadotrophin secretion in juvenile animals with an intermittent infusion of gonadotrophin-releasing hormone.

RESULTS

While qRT-PCR demonstrated that AR and FSHR mRNA expression in Scs from infant and pubertal testes were comparable, androgen-binding and FSH-mediated cAMP production by infant Scs was extremely low. Compromised AR and FSHR signaling in infant Scs was further supported by the finding that testosterone (T) and FSH failed to augment the expression of the T responsive gene, claudin 11, and the FSH responsive genes, inhibin-βB, stem cell factor (SCF) and glial cell line-derived neurotrophic factor (GDNF) in Scs harvested at this stage of development.

CONCLUSION

These results indicate that compromised AR and FSHR signaling pathways in Scs underlie the inability of the infant primate testis to respond to an endogenous hormonal milieu that later in development, at the time puberty, stimulates the initiation of spermatogenesis. This finding may have relevance to some forms of idiopathic infertility in men.

The immunoexpression of FSH-R in the ductuli efferentes and the epididymis of men and rat: effect of FSH on the morphology and steroidogenic activity of rat epididymal epithelial cells in vitro

The Sertoli cells were regarded as the only target for FSH in male reproductive system. The expression of FSH receptor (FSH-R) was detected also in epithelial cells of the caput epididymis of rat and monkey. We showed in the immunohistochemistry study the expression of FSH-R in rat and human ductuli efferentes and the caput, corpus, and cauda epididymis, moreover, by Western blot analysis in the caput and cauda epididymis of rat. Additionally, we presented that the morphology of rat epididymal epithelial cells in vitro was affected by FSH, and FSH stimulation resulted in the increase of 17β-estradiol synthesis by rat caput epididymal cells in dose-depended manner. In conclusion, the identification of FSH receptors in human and rat epididymides supports our results that the epididymis is a target organ not only for LH but additionally for FSH. On the basis of the results we showed for the first time that morphology of epididymal epithelial cells and epididymal steroidogenesis can be regulated by FSH.

Effect of deprivation of endogenous follicle stimulating hormone on rat epididymis: a histological evaluation

The growth and function of the epididymis are regulated by testosterone produced by Leydig cells in the testes. In the present study it was observed that neutralization of endogenous follicle stimulating hormone (FSH) in immature rats using a highly specific antiserum to ovine FSH resulted in changes in the histology of the epididymis along with a decrease (50-60%) in its weight compared with the normal serum-treated controls. These changes were observed in both rat and monkey epididymis without any decrease in serum testosterone, on which epididymis is known to be dependent. A detailed study was therefore carried out on the effects of deprivation of FSH or testosterone on the histology of epididymis. The changes in epididymal histology following FSH deprivation included a decrease in the size of the tubule lumen in the rat as well as in the adult male bonnet monkey in which the antiserum against ovine FSH was raised. Intensive vacuolization and uneven surface of the luminal epithelium was also observed. In contrast, the effect of deprivation of testosterone support by way of administration of LH antiserum or fiutamide resulted in a decrease in the size of the lumen and degenerative changes. These results suggest that cauda epididymidis is a target for FSH action.