Low levels of Gαs and Ric8b in testicular sertoli cells may underlie restricted FSH action during infancy in primates.

FSH acts via testicular Sertoli cells (Sc) bearing FSH receptor (FSH-R) for regulating male fertility. Despite an adult-like FSH milieu in infant boys and monkeys, spermatogenesis is not initiated until the onset of puberty. We used infant and pubertal monkey Sc to reveal the molecular basis underlying developmental differences of FSH-R signaling in them. Unlike pubertal Sc, increasing doses of FSH failed to augment cAMP production by infant Sc. The expression of Gαs subunit and Ric8b, which collectively activate adenylyl cyclase (AC) for augmenting cAMP production and gene transcription, were significantly low in infant Sc. However, forskolin, which acts directly on AC bypassing FSH-R, augmented cAMP production and gene transcription uniformly in both infant and pubertal Sc. FSH-induced Gαs mRNA expression was higher in pubertal Sc. However, Gαi-2 expression was down-regulated by FSH in pubertal Sc, unlike infant Sc. FSH failed, but forskolin or 8-Bromoadenosine 3',5'-cyclic monophosphate treatment to infant Sc significantly augmented the expression of transferrin, androgen binding protein, inhibin-ß-B, stem cell factor, and glial-derived neurotropic factor, which are usually up-regulated by FSH in pubertal Sc during spermatogenic onset. This suggested that lack of FSH mediated down-regulation of Gαi-2 expression and limited expression of Gαs subunit as well as Ric8b may underlie limited FSH responsiveness of Sc during infancy. This study also divulged that intracellular signaling events downstream of FSH-R are in place and can be activated exogenously in infant Sc. Additionally, this information may help in the proper diagnosis and treatment of infertile individuals having abnormal G protein-coupled FSH-R.

A method for rapid generation of transgenic animals to evaluate testis genes during sexual maturation.

In certain forms of idiopathic infertility, there is failure of follicle stimulating hormone (FSH) and testosterone (T) to initiate spermatogenesis despite the presence of Sertoli cells and germ cells in the testis. In postnatal rats (up to 11 days of age) and infant monkeys (3-4 months old), robust division and differentiation of spermatogonial stem cells is not discerned, even though serum levels of FSH and T are similar to those found during adulthood. Lack of spermatogenesis together with normal hormone levels is a situation similar to that found in certain categories of male infertility. To investigate this intriguing situation, Sertoli cells were cultured from infant and pubertal rats and monkeys and differential gene expression by testicular Sertoli cells was evaluated by DNA microarray using the Agilent microarray system. To determine the role of candidate genes in regulation of spermatogenesis, transgenic animals over-expressing these genes must be generated. However, present techniques for generation of transgenic animals have limited utility for production of several transgenic animals within a short period of time. Therefore, we have developed a technique for making transgenic animals by the testicular route which is less labor intensive and less time consuming. This technique is also ethically superior since fewer mice are required than in existing alternative methods of transgenesis.