17 beta-estradiol activates rapid signaling pathways involved in rat pachytene spermatocytes apoptosis through GPR30 and ER alpha.

Aim of the present study was to investigate whether estrogens were able to directly activate rapid signaling pathways controlling spermatogenesis in rat pachytene spermatocytes (PS). Classically, estrogens act by binding to estrogen receptors (ERs) alpha and beta. Recently, it has been demonstrated that rapid estrogen action can also be activated through the G-protein-coupled receptor (GPR)-30.

Protective effects of estrogens and caloric restriction during aging on various rat testis parameters.

Aim: To investigate the effects of 17beta-estradiol (E2), Peganum harmala extract (PHE) and caloric restriction (CR) on various testis parameters during aging.

Methods: Twelve month-old male rats were treated for 6 months with either E2 or PHE, or submitted to CR (40%).

Results: Our results show that estrogens and CR are able to protect the male gonad by preventing the decrease of testosterone and E2 levels as well as the decrease of aromatase and estrogen receptor gene expressions.

Estrogens: a new player in spermatogenesis.

The mammalian testis serves two main functions: production of spermatozoa and synthesis of steroids; among them, estrogens are the end products obtained from the irreversible transformation of androgens by aromatase. The aromatase is encoded by a single gene (cyp19) in humans which contains 18 exons, 9 of them being translated. In rat the aromatase activity is mainly located in Sertoli cells of immature animals and then in Leydig cells of adults.

Age-related decrease in aromatase and estrogen receptor (ERalpha and ERbeta) expression in rat testes: protective effect of low caloric diets.

Aim: To examine the effects on rat aging of caloric restriction (CR1) and undernutrition (CR2) on the body and on testicular weights, on two enzymatic antioxidants (superoxide dismutase and catalase), on lipid peroxidation and on the expression of testicular aromatase and estrogen receptors (ER).

Methods: CR was initiated in 1-month-old rats and carried on until the age of 18 months.

Results: In control and CR2 rats an age-related decrease of the aromatase and of ER (alpha and beta) gene expression was observed; in parallel a diminution of testicular weights, and of the total number and motility of epididymal spermatozoa was recorded.

Three promoters PII, PI.f, and PI.tr direct the expression of aromatase (cyp19) gene in male rat germ cells.

Aromatase is the key enzyme responsible for the irreversible transformation of androgens into estrogens. It is encoded by the cyp19 gene and is expressed in the mammalian testis under the control of the proximal promoter PII. Since both somatic and germ cells contain a biologically active aromatase, we looked for the existence of other promoters that may direct the expression of aromatase in adult rat germ cells.

Effects of maternal undernutrition during lactation on aromatase, estrogen, and androgen receptors expression in rat testis at weaning.

The goal of this study was to evaluate the effects of maternal malnutrition during lactation on serum levels of testosterone and estradiol, testicular testosterone concentration, aromatase, testicular androgen (AR) and estrogen alpha (ERalpha) receptors expression in the pups at weaning. From parturition until weaning, Wistar rats were separated into three groups: (C) control group, with free access to a standard laboratory diet containing 23% protein; protein-energy restricted (PER) group, with free access to an isoenergy and protein-restricted diet containing 8% protein; and energy-restricted (ER) group, receiving standard laboratory diet in restricted quantities, which were calculated according to the mean ingestion of the PER group. All pups were killed at weaning, corresponding to 21 days post partum.

beta-Nerve growth factor participates in an auto/paracrine pathway of regulation of the meiotic differentiation of rat spermatocytes.

NGF appears to be involved in spermatogenesis. However, mice lacking NGF or TrkA genes do not survive more than a few days whereas p75(NTR) knockout mice are viable and fertile. Therefore, we addressed the effect of betaNGF on spermatogenesis by using the systems of rat germ cell culture we established previously.

Aromatase and estrogen receptors in male reproduction.

Aromatase is a terminal enzyme which transforms irreversibly androgens into estrogens and it is present in the endoplasmic reticulum of numerous tissues. We have demonstrated that mature rat germ cells express a functional aromatase with a production of estrogens equivalent to that of Leydig cells. In humans in addition to Leydig cells, we have shown the presence of aromatase in ejaculated spermatozoa and in immature germ cells.

The promoter(s) of the aromatase gene in male testicular cells.

Aromatase is the terminal enzyme responsible for estrogen biosynthesis in mammals; it is present in various testicular cells including germ cells. The aromatase gene (Cyp19) is unique in humans and its expression is regulated in a tissue and more precisely, in a cell-specific manner via the alternative use of various promoters located in the first exon. Nevertheless, there is little information concerning the regulation of the testicular aromatase especially in germ cells.