Endocrine Abstracts

Previously, we have described an inhibitory role of melatonin (Mel) in the expression of StAR and key steroidogenic enzymes, as well as in the regulation of testosterone production in testes of Syrian hamsters. The goal of the present work was to further investigate the signaling pathway involves in the testicular action of Mel. Thus, Leydig cells were purified from reproductively active hamsters killed by asphyxia with carbon dioxide, and incubated in the presence of Mel and ...

The Syrian hamster is a seasonal breeder that undergoes a testicular regression when exposed to a short day photoperiod (SD, 6 h light per day) for 16 weeks, and a subsequent gonadal reactivation after longer times of permanence in SD. In this study, we investigated the role of melatonin (Mel) and prolactin (PRL), key players in the recrudescence phase, on testicular cyclooxygenase 2 (COX2) expression and prostaglandins (PGs) production during the photoperiodic regression&#150...

Hypersecretion of hCG in transgenic mice produces profound alterations in the ovary, thus triggering failures in ovulation and affecting fertility. The objective of this study was to analyze the response of immature female mice overexpressing moderated (hCGβ+; 0.1 IU/ml) and elevated (hCGαβ+; 7 IU/ml) levels of hCG to an ovulation induction protocol (PMSG 7.5 IU i.p.; after 48 h, hCG 7.5 IU i.p). Wild-type (WT) females subjected to the same protocol were used as...

Male transgenic (TG) mice overexpressing both the hCGα- and hCGβ- subunits present elevated levels of circulating hCG, Leydig cell hyperplasia/hypertrophy, elevated androgen levels and infertility (Rulli et al. 2003). In addition, serum FSH is significantly reduced in prepuberal and adult TG males compared with wild-types (WT), and does not change after treatment with the antiandrogen flutamide. The aim of this study was to evaluate the regulation of the hypot...

Transforming growth factor β1 has a critical role in the regulation of testicular function. Transgenic male mice over expressing α and β subunits of hCG (hCG+) are infertile and testicular steroidogenesis is enhanced showing high levels of testosterone and progesterone (P4). The chronic hCG hyperstimulation leads to Leydig cell (LC) hypertrophy/hyperplasia in prepubertal mice.Aims: To analyze: i) the expression of the TGF-β...