Topic
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.
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TL;DR: In a significant proportion of men, there is good evidence of Leydig cell dysfunction after cytotoxic chemotherapy, and some of these men may benefit from testosterone replacement.
Abstract: PURPOSE: To evaluate testicular function in men after treatment with cytotoxic chemotherapy. PATIENTS AND METHODS: We measured testosterone, sex hormone–binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels in 209 men after treatment with mechlorethamine, vinblastine, procarbazine, and prednisone, hybrid chemotherapy, or high-dose chemotherapy and in 54 healthy age-matched controls. RESULTS: The mean age of the patients was 38 years (range, 19 to 68 years), and all patients had received chemotherapy between 1 and 22 years previously. Patients had significantly higher mean LH (7.9 v 4.1 IU/L; P < .0001) and FSH levels (18.8 v 3.1 IU/L; P < .0001) than controls. There was no significant difference in mean total testosterone level between the patients and controls, but there was a trend toward a lower mean testosterone/SHBG ratio in the patients (0.63 v 0.7; P = .08). Analysis of the hormonal parameters using a model that allowed for the effects of increasing age on...
154 citations
TL;DR: It is found that splenocytes from infected mice produced amounts of IL-6 higher than control as measured by ELISA, which could be involved in the immunoendocrine mechanism used by the parasite to maintain a highly permissive environment for its rapid growth.
154 citations
TL;DR: Depending on the doses, the combinations of testosterone and estradiol-17j3 resulted in 2 types of interaction: at low doses, these 2 steroids acted synergistically to decrease testicular content of spermatids and spermatozoa and testicular weights but had little or no effect on serum testosterone andEstradiol1713 or weights of sex accessory tissues; at higher doses, there was an apparent direct antagonism between these 2 compounds on all tissue components measured.
Abstract: The effects of subcutaneous sustained-release implants of testosterone and estradiol-173, given either alone or in combination to adult male rats, on the weights of testis and sex accessory tissues, the testicular content of spermatids and spermatozoa and the serum concentrations of testosterone, estradiol-17a and gonadotropins were investigated. Increasing amounts of testosterone, in the absence of added estradiol, caused a biphasic response (decline followed by a partial recovery) in testicular weight and in the number of spermatids and spermatozoa/testis. Serum testosterone initially remained unchanged and subsequently rose. lhis pattern was reflected by the weights of sex accessory tissues. Before serum testosterone rose, serum LH decreased to undetectable levels. Serum estradiol-17a levels were not affected by increasing doses of testosterone. Low doses of estradiol-17a (0.1 cm and 0.3 cm implants), in the absence of added testosterone, had no significant effect on serum estradiol-17a levels, on testicular weights or on the testicular content of spermatids and spermatozoa, but did cause a fall in serum LH and testosterone levels and in the weights of sex accessory tissues. Higher doses of estradiol-17i3 resulted in increased serum estradiol1713 levels and either a decrease or a sustained low level for all other measured parameters (weights of testes and sex accessory tissues and testicular content of spermatozoa and spermatids). Depending on the doses, the combinations of testosterone and estradiol-17j3 resulted in 2 types of interaction: 1) at low doses, these 2 steroids acted synergistically to decrease testicular content of spermatids and spermatozoa and testicular weights but had little or no effect on serum testosterone and estradiol-1713 or weights of sex accessory tissues; 2) at higher doses, there was an apparent direct antagonism between these 2 compounds on all tissue components measured.
153 citations
TL;DR: The findings indicate that the formation of behaviourally effective oestrogen in a specific brain target area is under hormonal control and suggest a role for this regulatory mechanism in the integration of courtship behaviour in the male dove.
Abstract: Oestradiol-17β (E2) formed from testosterone in the brain is thought to be involved in the hormonal control of male sexual behaviour in some mammal species1–3;. In the male dove, Streptopelia risoria, the aromatase system in the preoptic area (POA) is very active in converting testosterone to E2 (ref. 4), This oestrogenic metabolite has specific effects on male nest-orientated courtship patterns, which are mediated by an oestrogen-sensitive system in the preoptic-anterior hypothalamic area of the brain5. The preoptic aromatase system is likely to be important in the regulation of androgen action on male courtship behaviour, as no circulating oestrogen can be detected in the blood plasma of the male6. We report here that the level of aromatase activity in the POA depends on androgenic stimulation. Conversion of testosterone to E2 is markedly increased in castrated males injected intramuscularly (i.m.) with testosterone propionate (TP). Increased aromatase activity seems to be due to induction of the enzyme and is specific to the POA These findings indicate that the formation of behaviourally effective oestrogen in a specific brain target area is under hormonal control and suggest a role for this regulatory mechanism in the integration of courtship behaviour in the male dove.
153 citations
TL;DR: The data show that the POM volume is controlled by testosterone levels in adulthood and could thus be an interesting model for the study of the effects of steroids on the brain.
153 citations