Testosterone is secreted by the

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Aging men largely maintain their testicular androgen production. Cross-sectional studies have demonstrated that after the age of 40 yr a -2% annual decline is observed in morning total testosterone. In elderly males, the coordinate release of LH and testosterone became asynchronous despite normal serum levels of these hormones. The aim of this study was to test the reproductive hormone rhythm at night in middle-aged men. We studied seven healthy middle-aged ( +/- yr) and six healthy young ( +/- yr) men by determining their serum levels of LH and testosterone levels every 15 min from 1900-0700 h with simultaneous sleep recordings. The nocturnal rise in testosterone occurred earlier in young men (2235 +/- 0022 h) and at 2331 +/- 0057 h in middle-aged men (P < ). In young men, the mean testosterone level at night ( +/- ng/ml; +/- nmol/liter) and the integrated nocturnal secretion [area under the curve (AUC); +/- ng/; 210 +/- 31 nmol/] were significantly higher compared with the values ( +/- and +/- ng/; +/- and 108 +/- nmol/, respectively) observed in middle-aged men (P < and P < , respectively). The mean ( +/- mIU/ml; +/- IU/liter) and AUC ( +/- mIU/; +/- IU/) LH values in middle-aged men were significantly higher than the values observed in young men ( +/- and +/- mIU/; +/- and +/- IU/; P < and P < , respectively). Young men had significantly more testosterone pulses at night ( +/- /12 vs. +/- /12 h in middle-aged men; P < ) of shorter interpulse interval ( +/- vs. +/- min; P < ). LH pulse characteristics and sleep quality were similar in both groups. However, the first rapid eye movement (REM) sleep episode occurred earlier in middle-aged men (2303 +/- 0034 h) vs. young men (0010 +/- 0054 h; P < ). As a consequence, the testosterone rise antedated the first REM episode by 90 min in young men. The link between testosterone rise and REM sleep episode was not observed in middle-aged men. Linear regression analysis revealed that the LH AUC was significantly related to age (P < ). Analysis of covariance revealed that the two groups differed significantly in testosterone AUC (P < ). Comparison of LH and testosterone concentrations showed significant and positive cross-correlations between LH and testosterone only in young men, with the testosterone rise lagging 60 min after the rise in LH. Our findings suggest that in middle-aged men, less pulsatile testosterone and more LH are secreted at night than in young men, with disruption of the association between testosterone rhythm and REM sleep. The decline in nocturnal testosterone secretion appears to involve a combination of testicular and pituitary hypogonadism.

Though you may already be aware of potential side effects from testosterone abuse (note I said abuse and not use), here they are again: lowered HDL-cholesterol levels (good cholesterol), testicular atrophy, reductions in sperm count, prostate enlargement, liver damage (primarily with oral steroids that have been modified with a 17-alkyl substitution), menstrual irregularities, suppression of endogenous hormone levels (like LH and T), development of palpable breast tissue in men (also known as gynecomastia), clitoral enlargement, and acne.

Follicle Stimulating Hormone (FSH) - In women FSH is often used as a gauge of ovarian reserve. In general, under 6 is excellent, 6-9 is good, 9-10 fair, 10-13 diminished reserve, 13+ very hard to stimulate. In PCOS testing, the LH:FSH ratio may be used in the diagnosis. The ratio is usually close to 1:1, but if the LH is higher, it is one possible indication of PCOS. Basic hormone testing for males often only includes testosterone and FSH. However, in cases such as Klinefelters Syndrome doctors will usually look at both FSH and LH levels. In males FSH stimulates the Sertoli cells in the testes to produce androgen-binding proteins, testosterone, and a protein called inhibin. Inhibin, in turn, travels in the blood back to the pituitary gland whre it creates a "negative feedback loop" that decreases the output of FSH. Since FSH stimulates testosterone production, and testosterone can be converted to DHT and estradiol, an increase of any or all three can also create a "feedback loop" that decreases FSH secretion.

The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression". [77] [78] Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible. [77] The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game. [79] Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males. [80] [81] [82] [83] [84]

Testosterone is secreted by the

testosterone is secreted by the

Follicle Stimulating Hormone (FSH) - In women FSH is often used as a gauge of ovarian reserve. In general, under 6 is excellent, 6-9 is good, 9-10 fair, 10-13 diminished reserve, 13+ very hard to stimulate. In PCOS testing, the LH:FSH ratio may be used in the diagnosis. The ratio is usually close to 1:1, but if the LH is higher, it is one possible indication of PCOS. Basic hormone testing for males often only includes testosterone and FSH. However, in cases such as Klinefelters Syndrome doctors will usually look at both FSH and LH levels. In males FSH stimulates the Sertoli cells in the testes to produce androgen-binding proteins, testosterone, and a protein called inhibin. Inhibin, in turn, travels in the blood back to the pituitary gland whre it creates a "negative feedback loop" that decreases the output of FSH. Since FSH stimulates testosterone production, and testosterone can be converted to DHT and estradiol, an increase of any or all three can also create a "feedback loop" that decreases FSH secretion.

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