Androgens are steroids that have masculinizing effects or anabolic effects associated with proteins building in muscle and bones of both males as well females. Testosterone are the most important androgen present in humans which is synthesized by testes in males, by the ovary of the females and by the adrenal gland in both genders. Other androgens secreted by the testes in small amounts are dihydrotestosterone, androstenedione, and dehydroepiandrosterone. In adult males, testosterone secretion is controlled by gonadotropin-releasing hormone from the hypothalamus, which stimulates the anterior pituitary gland to secrete Follicle Stimulating Hormones and Luteinizing Hormone. Testosterone or its active metabolite Dihydrotestosterone, regulates testosterone production by inhibits production of these specific hormones through a negative feedback.
The structure of androgens are designed synthetically to modify solubility and susceptibility to enzymatic breakdown which prolongs the half-life of the hormone and to separate anabolic and androgenic effects.
Modifications in the structure of testosterone can be done to maximize the anabolic effect and minimize the androgenic effect.
Anabolic steroids bind to a specific nuclear receptor in a target cell. Although testosterone itself is the active ligand in muscle and liver but in other tissues, it must be metabolized to active derivatives, such as Dihydrotestosterone. Testosterone is converted by 5Î±-reductase to DHT after diffusing into the cells of the prostate, seminal vesicles, epididymis, and skin that binds to the receptor. Testosterone is biotransformed to estradiol by cytochrome P450 aromatase in the brain, liver, and adipose tissue. The synthesis of specific RNAs and proteins is stimulated by the formation of hormone-receptor complex binds to DNA. Testosterone derivatives that cannot be converted to DHT have less effect on the reproductive system than they do on the skeletal musculature.
There is a gain in muscle mass and strength when anabolic steroids are administered to healthy women and children due to the anabolic effect. There is a downregulation of receptors in the skeletal muscle when androgen receptor population is saturated with testosterone in the adult men during puberty. The mycotrophic effect could be through anticatabolic mechanism rather than a direct anabolic effect from the administration of anabolic steroids to men. The upregulation may occur with the administration of androgens by converting muscles that normally have a minor or no response to muscles with enhanced response to androgen.
The behavioural effects of androgens/anabolic steroids include sexual behaviour, cognitive abilities, aggression and mood. Androgens are important in the human male sexual behaviour and they can also enhance female sexual desire and arousal as well. Testosterone also plays an important role in cognitive functioning like attention and alertness, memory and spatial skills. Major mood syndromes can arise with use of anabolic steroid such as mania or hypomania. Anabolic steroids also increase aggression, especially when used in high doses.
The administration of these drugs for clinical purposes can be of therapeutically effective and reasonably safe, with the physician making objective decisions based on the benefit/ risk ratio in relation to the condition of a patient.
Androgenic steroids are used for males in which androgen secretion is inadequate. Androgen therapy is indicated in hypogonadism which can be caused by testicular dysfunction i.e. primary hypogonadism or due to failure of the hypothalamus or pituitary i.e. secondary hypogonadism.
Anabolic steroids can be used to treat senile osteoporosis associated with human immunodeficiency virus or cancer. They can also be used in severe burns and to speed up recovery from surgery or chronic debilitating diseases.
Danazol is a mild androgen which is commonly used in the treatment of fibrocystic breast disease and ectopic growth of the endometrium. Although it has no effect on the aromatase but it inhibits release of FSH and LH.
Anabolic steroids are used to increase lean body mass, strengthen the muscle, and to improve endurance in athletes and bodybuilders. DHEA is a precursor of testosterone and estrogen, is used as the anti-aging hormone and also to improve performance.
Testosterone and its C17-esters (for example, testosterone cypionate or enanthate) are administered intramuscularly and are rapidly absorbed. Testosterone is therapeutically ineffective after oral administration because of inactivation by first-pass metabolism. Testosterone derivatives such as Fluoxymesterone and Oxandrolone are hormones that are effective when administered orally. Topical gels, buccal tablets and transdermal patches of testosterone are also available.
Anabolic steroids are metabolized to relatively or completely inactive compounds that are excreted primarily in the urine. The hormone becomes more lipid-soluble by addition of esterified lipid, which results in increase in its duration of action.
Anabolic steroid such as fluoxymesterone have a longer half-life in the body than that of the naturally occurring androgens.
Androgens can cause masculinization, deepening of the voice, male pattern baldness, with acne, growth of facial hair, excessive muscle development and menstrual irregularities. Testosterone is contraindicated in pregnant women because it may cause virilization of the female fetus.
Excessive androgens may leads to impotence, decreased spermatogenesis, priapism, and gynecomastia. Changes that occur in females, may also occur in males as well. Growth of the prostate can also be stimulated by Androgens.
Androgens may leads to growth disturbances and sexual maturation.
Androgens increase serum Low-Density Lipoproteins and lower serum High-Density Lipoproteins levels. Therefore, significantly increase the risk for premature coronary heart disease. Androgens can also cause edema because of fluid retention.
Use of anabolic steroids such as DHEA or nandrolone by athletes, stunts the growth of long bones and interrupts development. The high doses taken by these young athletes may result in hepatic abnormalities, increased aggression, and reduction of testicular size, major mood disorders, and the other common adverse effects in males.
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