Testosterone has various effects on various organs. It causes, for example, the development of the male phenotype, is responsible for the growth and ensures sperm production. Testosterone, bound to a protein, is also transported via the blood to many other target organs which have receptors for this hormone. The transport protein is called sex hormone-binding globulin (SHBG). In the body, a part of the testosterone in the target cells is metabolized by the enzyme steroid 5α-reductase (SRD5) to the biologically still more active dihydrotestosterone (DHT). Through a negative biological feedback, testosterone inhibits the secretion of luteinizing hormone (LH) in the brain pituitary gland and the gonadoliberin in the hypothalamus, which is also called gonadotropin releasing hormone (GnRH).
Testosterone is transported via the androgen binding protein (ABP) of the Sertoli cells to the seminiferous tubules. Here it causes the maturation of the spermatids to sperm. In addition, testosterone in male individuals during puberty causes the development of the penis, hoof sack, the accessory sex glands, and the secondary sex traits and provides for adults to maintain these characteristics. Artificial testosterone intake in women can lead to masculinization and enlargement of the clitoris, which often no longer completely disappears after discontinuation.
Outside the sexual organs, the hormone promotes the growth of the body's hair and the beard but not the head of the head, see also hair loss) and has an anabolic, that is, muscle building effect. Furthermore, testosterone strengthens cartilage and bone remodeling, similar to thyroxine. A high testosterone level encourages the development or enhancement of sexual desire and generally drive, endurance and "loss of life" as well as dominant and aggressive behaviors. Finally, testosterone results in an increase in the red blood cells (erythrocytes) by the stimulation of the release of erythropoietin in the kidney and the activation of the bone marrow.
Testosterone is produced by specialized cells in the male testes and the female ovaries. They do this by receiving signals from your anterior pituitary gland Testosterone is a sex hormone that plays important roles in the body. In men, it’s thought to regulate sex drive, bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm. A small amount of circulating testosterone is converted to estradiol, a form of estrogen. Normal testosterone production varies widely in men, so it’s difficult to know what levels have medical significance. The hormone’s mechanisms of action are also unclear. The role of sex hormones in the prevention of cognitive decline is uncertain. there are studies to suggest that endogenous testosterone levels are associated with aggression in men with cognitive impairment
Testosterone was first used as a clinical drug as early as 1937, but with little understanding of its mechanisms. The hormone is now widely prescribed to men whose bodies naturally produce low levels. But the levels at which testosterone deficiency become medically relevant still aren’t well understood. The complex effects of testosterone, investigators found, depend partly on its conversion in the body to a type of estrogen. The insights will help guide the development of better ways to diagnose and treat men who don’t produce enough natural testosterone. Testosterone regulates hair growth by affecting the follicle and how it can produce the different types of hair, like facial, pubic and scalp hair. These follicle changes affect the growth phases of hair, producing different reactions.