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.

Metabolic and behavioral effects of high-dose, exogenous testosterone in healthy men.

Abstract: In addition to their use as replacement therapy for hypogonadal males, androgens, particularly testosterone (T), are being explored as potential hormonal male contraceptive agents, alone or in combination with other compounds. Androgens have regulatory effects on a variety of physiological systems in addition to gonadotropin secretion and spermatogenesis. Therefore, as hormonal contraceptive regiments that alter serum T levels are explored, it is important to evaluate their effects on these aspects of normal male physiology. The effects of exogenous T on suppression of spermatogenesis in 19 healthy men were recently compared, using a T dosage of 200 mg im/week for 20 weeks. Before treatment, the men were evaluated during a 3-month pretreatment period, and after treatment, they were followed for 4-6 months or until their sperm counts normalized. Because of the lack of information regarding the effects of exogenous T on nonreproductive physiology, we examined the effects of high-dose T on plasma lipids, calcium metabolism, and sexual behavior in our subjects. Mean serum T and estradiol levels increased significantly during the treatment period. Plasma high-density lipoprotein (HDL) cholesterol levels decreased significantly within the first month and remained suppressed during the duration of T administration. At the end of the treatment period, mean plasma HDL cholesterol had decreased by 13 +/- 2% (P < 0.05); plasma levels of HDL2, HDL3, and apoprotein AI also decreased significantly; mean levels of low density lipoprotein cholesterol and triglycerides were unchanged. After 1 month of the recovery period, plasma HDL levels had returned to the baseline range. Serum calcium levels decreased slightly during treatment; this decrease was statistically significant. Urinary calcium excretion did not change. Mean levels of serum intact PTH increased by 84 +/- 17% (P < 0.05) during T administration; in contrast, 25-hydroxyvitamin D levels decreased by 16 +/- 4% (P < 0.05), and 1,25-dihydroxyvitamin D levels did not change significantly. All markers of calcium metabolism returned to baseline during the posttreatment period. Little change was found in self-reported sexual and aggressive behaviors during the study. There was a trend toward increased arousal and spontaneous erections during T administration, but this did not reach statistical significance. Frequency of sexual intercourse, masturbation, and kissing and fondling did not change, nor was the subjects' satisfaction in their relationships affected by T administration. Mean body weight increased by 4.0 +/- 0.5 kg. Approximately half the men noted mild acne. Body weight and acne symptoms returned to baseline during the recovery period.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of combined androgen blockade on bone turnover and bone mineral densities in men treated for prostate carcinoma: longitudinal evaluation and response to intermittent cyclic etidronate therapy.

Abstract: BACKGROUND Androgen receptor blocking agents have become an established form of therapy for men with disseminated prostate carcinoma. The purpose of this study was to evaluate markers of bone turnover and to measure bone mineral densities (BMD) in men with disseminated prostate carcinoma treated with combined androgen blockade prior to and after 6 months of intermittent cyclic etidronate therapy. METHODS Twelve consecutive men with disseminated prostate carcinoma were evaluated at 0, 6, and 12 months after treatment with a long acting gonadotropin-releasing hormone agonist (goserelin acetate) and an androgen antagonist (flutamide). During the 6-12 month period, patients were treated with adjuvant intermittent cyclic etidronate therapy and calcium supplementation. Lumbar spine BMD was measured by spinal quantitative computed tomography (QCT) and femoral neck BMD by dual energy X-ray absorptiometry (DXA). RESULTS Combined androgen blockade resulted in all men achieving serum free testosterone concentrations of <2.2 pmol/L (normal range, 38-114 pmol/L). The mean serum prostate specific antigen activities decreased from 130.8 ± 46 to 6.9 ± 4.4 ng/mL (P < 0.05). Although serum calcium, parathyroid hormone, and 25-hydroxyvitamin D measurements remained unchanged, serum bone Gla-protein concentrations and urinary deoxypyridinolene excretion rates increased significantly (P < 0.01, respectively). Mean lumbar spine QCT decreased by 6.6 ± 1.5% from 76.5 mg/cm3 (95% confidence interval [95% CI], 57-96 mg/cm3) to 73.9 mg/cm3 (95% CI, 55-93 mg/cm3) (P < 0.001) and mean femoral neck DXA decreased by 6.5 ± 1.3% from 0.94 g/cm2 (95% CI, 0.81-1.07 g/cm2) to 0.91 g/cm2 (95% CI, 0.79-1.04 g/cm2) (P < 0.001). After treatment with adjuvant intermittent cyclic etidronate, mean lumbar spine QCT increased by 7.8 ± 3.7% to a final value of 75 mg/cm3 (95% CI, 48.7-101 mg/cm3) (P = 0.001 compared with the initial 6 months without intermittent cyclic etidronate therapy). Significant increases in BMD also were observed in the femoral neck and Ward's triangle. CONCLUSIONS Androgen receptor blocking agents have an established role in the treatment of disseminated prostate carcinoma. However, combined androgen blockade in elderly men with disseminated prostate carcinoma results in high bone turnover with significant cancellous bone loss. The results of this study show that adjuvant therapy with intermittent cyclic etidronate may prevent these changes and decrease the risk of spinal fractures. Cancer 1998;83:1561-1566. © 1998 American Cancer Society.

Aromatase inhibitor and 17α-methyltestosterone cause sex-reversal from genetical females to phenotypic males and suppression of P450 aromatase gene expression in Japanese flounder (Paralichthys olivaceus)

Abstract: The sex of Japanese flounder (Paralichthys olivaceus) is easily altered by water temperature or sex steroid hormone treatment during the period of sex determination We have previously shown that rearing the genetically female larvae at high water temperature caused the suppression of P450 aromatase (P450arom) gene expression in the gonad and phenotypic sex-reversal of the individuals to males (Kitano et al 1999 J Mol Endocrinol 23:167-176) In the present study, we show that treatment of genetically female larvae with fadrozole (aromatase inhibitor) or 17alpha-methyltestosterone induces sex-reversal as well as suppression of P450arom gene expression The effect of fadrozole was counteracted by co-administration of estradiol-17beta Effective periods for fadrozole treatment to induce sex-reversal were similar to those for high water temperature treatment RT-PCR did not detect P450arom mRNA in gonad of the sex-reversed, phenotypic males These results indicate that sex-reversal of the genetically female larvae by aromatase inhibitor (or 17alpha-methyltestosterone) may be due to the suppression of P450arom gene expression and the resultant decrease in the amount of estrogen

Effects of endogenous testosterone and estradiol on sexual behavior in normal young men.

Abstract: The importance of androgens in establishing and maintaining sexual function in males of most species is well recognized. Estrogens also stimulate male sexual function in some species. In men, most studies of androgen effects on behavior have used hypogonadal men as an experimental model; much less is known about the role of endogenous testosterone (T) or estradiol (E2) in the regulation of behavior in healthy, eugonadal men. In a randomized, double-blind study, we used a GnRH antagonist, Nal-Glu, without T replacement, to induce acute, profound, reversible gonadal steroid deficiency in 9 normal men for 6 weeks (Nal-Glu alone). We also studied the effects of partial androgen replacement by administering Nal-Glu together with T enanthate, 50 mg im weekly, to 10 other men. A third group of 10 men received Nal-Glu plus T, 100 mg im weekly. We studied the role of endogenous E2 by administering Nal-Glu plus T, 100 mg im weekly, plus an aromatase inhibitor, testolactone (Teslac), 250 mg po qid, to 10 additional men (Nal - Glu + T + Teslac). Nine men received placebo injections and tablets. All subjects completed a behavioral questionnaire during the pretreatment period, at weeks 2, 4, and 6 of treatment, and at 3 weeks posttreatment. Men who received Nal-Glu alone became profoundly hypogonadal within 1 week after treatment began. Serum T levels did not change significantly in the controls and in the men who received full T replacement but decreased to approximately half the baseline level in men who received partial T replacement. E2 levels decreased profoundly in men who received Nal-Glu alone or Nal - Glu + T + Teslac and to a lesser degree in men who received partial T replacement. In men who received Nal-Glu alone, there were clinically and statistically significant decreases in the frequency of sexual desire, sexual fantasies, and intercourse at 4-6 weeks. These men also showed a strong trend (P = 0.55) towards decreased spontaneous erections after 4 and 6 weeks of treatment. A significant decrease in the frequency of masturbation was evident after 6 weeks. All measures returned to normal by posttreatment week 3. There was a trend toward increased aggression in the hypogonadal men, but this did not reach statistical significance. No changes in satisfaction or happiness with their partners were observed.(ABSTRACT TRUNCATED AT 400 WORDS)