Dehydroepiandrosterone, adrenal production

Overall, other adrenal androgens also show a progressive decrease in urinary excretion in both men and women. Thus, the mean 17-ketosteroid urine levels of elderly people are about 50% of those in young adults. This is primarily secondary to decreased dehydroepiandrosterone (DHEA) and androsterone production. In men, about one-third of the daily 17-ketosteroids are of testicular origen, the remainder being mainly from the adrenals. Androstenedione is a prehormone for testosterone. 

The liver is the most important area for (he production of cholesterol and bile acids. The ovaries are the most important sources of estrogen and progesterone (progesterone is produced in the corpus luteum of the ovary). The testes are the major site of androgen production, testosterone especially. The adrenal cortex produces the mineralocorticoids and glucocorticoids, and the androgens dehydroepiandrosterone and androstenedione. 

Fig. 1 Human steroidogenic pathway from cholesterol to adrenal or gonadal steroid products. CYP cytochrome P450 enzyme, ftSfthydroxysteroid dehydrogenase, DHEA dehydroepiandrosterone, Oft hydroxy, arom aromatase...

DHEA (dehydroepiandrosterone) is another nonprescription antidepressant that has gone through cycles of popularity (Figure 6.2). DHEA, a steroid, is made from cholesterol in the adrenal gland and is part of the biochemical pathway in which hormones such as estrogen and testosterone are end-products. While its properties as a peripheral hormone are well characterized, less is known about DHEA s function in the brain. Media interest in DHEA arose when it was shown to prevent or slow memory loss in older populations. Further research showed that DHEA could influence neuronal function in the hippocampus, a region important for memory formation. However, several clinical studies showed mixed results when DHEA was used in... 

Dehydroepiandrosterone (DHEA, (18)) is a major secretory product of the adrenal cortex [188] which ameliorates several metabolic abnormalities found in obese, insulin-resistant rodents. The first metabolic alteration was noted in mice carrying the viable yellow (genetic obesity) mutation [ 189] where a 0.2% dietary addition or oral administration (150-500 mg/kg, three times per week, 28 weeks) of DHEA reduced weight gain with no alteration in food consumption. Decreased accumulation of carcass triacylglycerol and decreased... 

Testosterone and oestradiol are known as the sex steroid hormones. Testosterone is the principal androgen and is synthesized by the testes in the male. Oestradiol. which is secreted by the ovaries, varies w idely in concentration in plasma throughout the female menstrual cycle. Steroids with oestradiol-like action arecalledoestrogens. Progesterone is a product ofthe ovary and is secreted when a corpus lutcum forms after ovulation. Normal female plasma also contains testosterone, about half of which comes from the ovary and half from peripheral conversion of androstenedione and dehydroepiandrosterone (DHA) sulphate which are secreted by the adrenal cortex. Some oestradiol is present in low concentration in normal male plasma. 

ABSTRACT This article describes physiological properties of two classes of natural products, namely cholesterol oxides and dehydroepiandrosterone (DHEA). The cholesterol oxides, also called oxysterols, are autoxidation products of cholesterol. Dehydroepiandrosterone and its sulfate DHEAS are formed mainly in the adrenals. The biological activities of these compounds are utilized to construct the two following hypotheses. 

DHEA is dehydroepiandrosterone. It is a plant derivative of a hormone from the Mexican wild yam. It is naturally produced by the adrenals and is one of the most abundant hormones in humans. It begins at age 7 and peaks around 30 years of age. As a supplement, it promises to enhance metabolic functions, increase energy, control stress, maintain proper mineral levels, balance the production of hormones, fight aging, improve memory, build body muscle, and reduce fat. It supposedly reduces the risk of cancer, heart disease, atherosclerosis, Alzheimer s disease, and schizophrenia. Many scientists claim this supplement is useless. 

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