Besides the well-known function of thyroid hormones (THs) for regulating metabolism, it has recently been discovered that THs are also involved in testicular development in mammalian and non-mammalian species. THs, in combination with follicle stimulating hormone, lead to androgen synthesis in Danio rerio, which results in the onset of spermatogenesis in the testis, potentially relating the hyp...

The use of testosterone replacement therapy (TRT) for hypogonadism continues to rise, particularly in younger men who may wish to remain fertile. Concurrently, awareness of a more pervasive use of anabolic-androgenic steroids (AAS) within the general population has been appreciated. Both TRT and AAS can suppress the hypothalamic-pituitary-gonadal (HPG) axis resulting in diminution of spermatoge...

Received: Revised: Accepted: Published online: October 10, 2016 March 12, 2017 March 14, 2017 May 09, 2017 In teleosts, steroid synthesis is mainly controlled by hypothalamus-pituitary-gonadal (HPG) axis. A number of compounds released into aquatic environment that have potential to interfere with fish endocrine system. These endocrine disturbing chemicals (EDCs) can disturb piscine endocrine s...

In the prostate, testosterone action depends on conversion to bioactive metabolites dihydrotestosterone and 17beta-estradiol (E2) via the 5alpha-reductase and aromatase enzymes, respectively. Exogenous estrogen inhibits prostate growth by indirect effects caused by suppression of pituitary gonadotropins and testicular testosterone output, but direct effects are less well known. Direct effects o...

Genomic variant analysis is a complex process that allows to find and study genome mutations. For this purpose, analysis and tests from both biological and statistical points of view must be conducted. Biological data for this kind of analysis are typically stored according to the Variant Call Format (VCF), in gigabytes-sized files that cannot be efficiently processed using conventional softwar...

Exposure of female rodents to testosterone in the critical neonatal period produces defeminization/masculinization of the hypothalamo-pituitary-gonadal (HPG) axis, i.e. neonatal androgenization and postpones axis maturation. To address the hypothesis that HPG axis signaling is involved in the programming of thymic maturation/involution and sexual differentiation we studied the impact of neonata...

BACKGROUND Testicular microliths are calcifications found within the seminiferous tubules. In humans, testicular microlithiasis (TM) has an unknown etiology but may be significantly associated with testicular germ cell tumors. Factors inducing microlith development may also, therefore, act as susceptibility factors for malignant testicular conditions. Studies to identify the mechanisms of micro...

Ultradian pulsatile hormone secretion underlies the activity of most neuroendocrine systems, including the hypothalamic-pituitary adrenal (HPA) and gonadal (HPG) axes, and this pulsatile mode of signalling permits the encoding of information through both amplitude and frequency modulation. In the HPA axis, glucocorticoid pulse amplitude increases in anticipation of waking, and, in the HPG axis,...

OBJECTIVE A decline in hypothalamic-pituitary-gonadal (HPG) axis function is often seen in elderly men, and dysthymic disorder is common. Symptoms of both HPG axis hypofunction and dysthymic disorder include dysphoria, fatigue, and low libido. The authors compared total testosterone levels in three groups of elderly men. METHOD Total testosterone levels were measured in subjects who met DSM-I...

As for most vertebrates, reproduction in poultry is controlled by an integrated axis [the hypothalamo-pituitary-gonadal (HPG) axis]. External and internal cues are integrated at the level of the hypothalamus to initiate gonadal recruitment and control the subsequent reproductive cycle. Until recently, it was believed that the HPG was exclusively under stimulatory control from hypothalamic gonad...