Androgen
The androgens are male hormones and correspond to testosterone, androsterone and androstenedione. Androgens are cyclopentanoperhydrophenanthrene steroid hormones, whose main function is to stimulate the development of male sexual characteristics. Androgens, basically testosterone, are secreted by the testicles, but also by the ovaries in women (androstenedione) and by the adrenal cortex of the adrenal glands (mainly dihydroepiandrosterone). In man only 10% of androgens have an adrenal origin. All natural androgens are derived from androstane steroids (a tetracyclic hydrocarbon nucleus of 19 carbon atoms). It is also the precursor to all estrogens, the female sex hormones.
History
In 1935, Ernest Laqueur succeeded in isolating and chemically identifying testosterone, as well as contributing to the knowledge of the physiology, pharmacology, and clinic of male sex hormones.
Many analogues of testosterone, nandrolone and dihydrotestosterone, were produced in the mid-1950s in an attempt to obtain a purely anabolic drug, but none of them proved it. The modern era of doping in sport began.
Types of androgens
A subgroup of androgens, the adrenal androgens, harbor the 19 carbon steroids synthesized by the adrenal cortex in the inner layer (zona reticularis) of the adrenal gland, which functions as weak steroids or precursor steroids, including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione. Other androgens apart from testosterone are the following:
- Dehydroepiandrosterone (DHEA): steroid hormone produced by cholesterol in the adrenal cortex, which is the primary precursor of natural estrogens. DHEA is also called dehydroisoandrosterone or dehydroandrosterone.
- Androstenediona (andro): androgenic steroid, produced by testicles, adrenal cortex and ovaries. During the metabolic conversion process of the androstenediones in testosterone and other androgens, they also constitute the parent structure of the estrone. The use of androstenedion as an athletic or musculation supplement has been prohibited by the International Olympic Committee and other sports organizations.
- Androstendiol: steroid metabolite that is considered the main regulator of the secretion of gonadotrophine.
- Androsterone: a chemical that is created during the breakdown of androgens or derivatives of progesterone, which also has minor masculinizing effects, with a intensity seven times lower than testosterone. It is found in similar amounts in plasma and urine both of males and females. It is also produced by the adrenal cortex.
- Dihydrotestosterone (DHT): a metabolite of testosterone which, in fact, is a very powerful androgen because it links more strongly to androgen receptors.
Functions of androgens
Male Hormone Development
During mammalian development, the gonads can initially become both ovaries and testes. In humans, rudimentary gonads can be found in the intermediate mesoderm near the kidneys from the 4th week onwards. Developing. By the 6th week, epithelial sex cords develop in the developing testis and incorporate the germ cells as they move to the gonads. In males, certain genes on the Y chromosome, notably the SRY gene, control the development of the male phenotype, including the conversion of the potential primitive gonad to testis. In males, the sex cords completely invade the developing gonads. From the 8th week of human fetal development, Leydig cells appear in the male differentiated gonads. Epithelial cells derived from the mesoderm of the sexual cords of the developing testicles become Sertoli cells whose function is to facilitate sperm formation. Between the tubules there is a smaller population of non-epithelial cells, the Leydig cells responsible for the production of androgens. Leydig cells can be considered the producers of androgens, which function as paracrine hormones and are necessary for Sertoli cells to facilitate sperm production. Shortly after differentiation, Leydig cells begin to produce androgens, which are necessary for masculinization of the developing male fetus (including formation of the penis and scrotum). Under the influence of androgens, certain remnants of the mesonephros, the mesophrenic ducts, evolve into the epididymis, the vas deferens, and the seminal vesicles. This action of androgens is supported by a Sertoli cell hormone, AMH, which prevents the embryonic Müllerian ducts from developing into the fallopian tubes or other tissue of the female reproductive system in male embryos. AMHs and androgens work together to allow normal movement of the testicles into the scrotum.
Prior to the production of the pituitary hormone HL, which begins in the embryo from 11-12 weeks, human chorionic gonadotropin (hCG) enhances Leydig cell differentiation and androgen production. The action of androgens on target tissues usually involves the conversion of testosterone to 5α-dihydrotestosterone (DHT). they also influence the hormonal change of women
Spermatogenesis
During puberty, the production of androgens, LH and HFE increases; the sex cords hollow out to form the seminiferous tubules, and the germ cells begin to differentiate into sperm. Throughout adulthood, androgens and HFEs work together in the Sertoli cells of the testes to promote sperm production. Exogenous androgen supplements can be used as a male contraceptive. Elevated androgen levels caused by androgen supplementation can inhibit LH production and block endogenous androgen production from Leydig cells. Without the elevated local levels of androgens in the testis produced by the Leydig cells, the seminiferous tubules can degenerate and become infertile.
Inhibition of fat deposition
Men tend to have less fatty tissue than women. The latest results indicate that androgens inhibit the ability of certain adipose cells to store lipids by blocking a signal transduction pathway that normally facilitates adipocyte function.
Muscle mass
Men tend to have more skeletal muscle than women. Androgens potentiate the enlargement of skeletal muscle cells and probably act in a coordinated manner to enhance muscle function by acting on many cell types in skeletal muscle tissue.
Brain
Circulating androgen levels can influence human behavior as certain neurons are sensitive to steroid hormones. Certain levels of androgens are related to the regulation of human aggression and libido.