Testosterone

About: Testosterone is a research topic. Over the lifetime, 23258 publications have been published within this topic receiving 808079 citations. The topic is also known as: 4-androsten-17beta-ol-3-one & 4-Androsten-3-one-17b-ol.

The Pituitary-Testicular Axis in Men with Chronic Renal Failure

Abstract: We studied the effects of uremia on the pituitary-testicular axis in 35 men with creatinine clearances less than 4 ml per minute per 1.7m(2). We found significant elevation (p less than 0.001) of plasma luteinizing hormone and follicle-stimulating hormone (p less than 0.005) and subnormal levels of testosterone (p less than 0.005). Testicular histology revealed severe spermatogenic damage. Human chorionic gonadotropin produced a subnormal testosterone response. The initial response of plasma luteinizing hormone and follicle-stimulating hormone to luteinizing-hormone-releasing hormone was normal, but their subsequent decline was prolonged. The suppression of plasma luteinizing hormone levels by testosterone propionate was normal, but the nadir occurred late; the elevated plasma luteinizing hormone level was due to reduced metabolic clearnace and increased production. Chronic renal failure interferes with testicular steroid production and spermatogenesis.

Polymorphisms of the androgen receptor gene and the estrogen receptor beta gene are associated with androgen levels in women.

Abstract: To elucidate the possible role of genetic variation in androgen receptor (AR), estrogen receptor α (ERα), and ERβ on serum androgen levels in premenopausal women, the CAG repeat polymorphism of the AR gene, the TA repeat polymorphism of the ERα gene, and the CA repeat polymorphism of the ERβ gene were studied in a population-based cohort of 270 women. Total testosterone, free testosterone, dehydroepiandrosterone sulfate, androstenedione, 17-hydroxyprogesterone, 3α-androstanediol glucuronide, 17β-estradiol, LH, FSH, and sex steroid hormone-binding globulin (SHBG) were measured in serum samples obtained in the follicular phase of the menstrual cycle. Women with relatively few CAG repeats in the AR gene, resulting in higher transcriptional activity of the receptor, displayed higher levels of serum androgens, but lower levels of LH, than women with longer CAG repeat sequences. The CA repeat of the ERβ gene also was associated with androgen and SHBG levels; women with relatively short repeat regions hence disp...

Androgen action via testicular peritubular myoid cells is essential for male fertility

Abstract: Androgens are essential for normal spermatogenesis and male fertility, but how androgens exert this effect remains uncertain. Androgen receptors (ARs) are expressed in several testicular cell types, but continuing uncertainty exists over which cell type mediates androgen control of spermatogenesis. Androgen signaling via Sertoli cells (SCs) is essential for complete spermatogenesis, but the role for androgen signaling via peritubular myoid (PTM) cells is contentious. To address this controversy, we generated PTM-specific AR-knockout (PTM-ARKO) mice in which gross reproductive development was normal, but all PTM-ARKO males were azoospermic and infertile. Testis weight was reduced beyond puberty, and in adulthood there was an 86% reduction in germ cells, compared with wild-type littermates. These changes were not explained by any deficits in testosterone, luteinizing hormone, or follicle-stimulating hormone concentrations. SC function was impaired in PTM-ARKO males, indicated by reduced seminiferous tubule fluid production and reduced expression of some androgen-dependent SC genes. Androgen action via PTM cells is therefore essential for normal testis function, spermatogenesis, and fertility in males. This study also provides the first direct evidence for the importance of androgen-driven stromal-epithelial interactions underpinning the regulation of spermatogenesis; PTM-ARKO mice will enable identification of the new molecular pathways involved.—Welsh, M., Saunders, P. T. K., Atanassova, N., Sharpe, R. M., Smith, L. B. Androgen action via testicular peritubular myoid cells is essential for male fertility.

Androgen action in the masculinization programming window and development of male reproductive organs.

Abstract: We have shown previously that deficient androgen action within a masculinization programming window (MPW; e15.5-e18.5 in rats) is important in the origin of male reproductive disorders and in programming male reproductive organ size, but that androgen action postnatally may be important to achieve this size. To further investigate importance of the MPW, we used two rat models, in which foetal androgen production or action was impaired during the MPW by exposing in utero to either di(n-butyl) phthalate (DBP) or to flutamide. Reduced anogenital distance (AGD) was used as a monitor of androgen production/action during the MPW. Offspring were evaluated in early puberty (Pnd25) to establish if reproductive organ size was altered. The testes, penis, ventral prostate (VP) and seminal vesicles (SV) were weighed and penis length measured. Both DBP and flutamide exposure in the MPW significantly reduced penis, VP and SV size along with AGD at Pnd25; AGD and organ size were highly correlated. In DBP-, but not flutamide-, exposed animals, testis weight was also reduced and correlated with AGD. Intratesticular testosterone was also measured in control and DBP-exposed males during (e17.5) or after (e21.5) the MPW and related to AGD at e21.5. To evaluate the importance of postnatal androgen action in reproductive organ growth, the effect of combinations of prenatal and postnatal maternal treatments on AGD and penis size at Pnd25 was evaluated. In prenatally DBP-exposed animals, further postnatal exposure to either DBP or flutamide significantly reduced AGD and penis size in comparison with prenatal DBP exposure alone. In comparison, rats exposed postnatally to testosterone propionate after prenatal vehicle-exposure showed considerable increase in these parameters vs. controls. In conclusion, we show that the size of all male reproductive organs is programmed by androgen exposure in the MPW, but that growth towards this size is dependent on androgen action postnatally.