Testosterone is a hormone belonging to the category degliandrogeni (typically male sex hormones, but also important in women). Testosterone is produced mainly in the Leydig cells of the testes under the influence of luteinizing hormone (LH) released from the anterior pituitary.
Testosterone is secreted with a circadian rhythm: in the early hours of the morning to reach the peak blood, which then falls during the rest of the day.
In the human body testosterone is synthesized from cholesterol:
Cholesterol -> Pregnenolone -> DHEA -> androstenedione -> testosterone
Of all the testosterone produced by the human body only a small proportion circulates in the blood in a free form. Within the bloodstream, as happens with many other hormones, testosterone is tied in large part (about 98% in men, 99% women) to specific plasma proteins (Sex Hormone Binding Protein 45% and 53% albumin ) that inactivate temporarily. According to the metabolic demands a small amount of these bonds can break and free testosterone to migrate into the cells and regulate gene transcription.
In case there is an excess of free testosterone the body has the ability to neutralize transforming it into estradiol (typically female hormone) through a reaction of aromatization which occurs especially at the level of adipose tissue and the central nervous system. Estradiol works, in turn, an inhibitor of testosterone production by reducing the secretion of hypothalamic GnRH (gonadotropin-releasing hormone LH eFSH). This reduces the amount of LH hormone product and consequently the synthesis of testosterone in the testes.
From this brief introduction, already emerged two key concentti:
Traditional laboratory tests detect only the share of total testosterone, without giving us information on the share of free testosterone. To obtain this information specific tests are needed and much more expensive. It follows that the usual blood tests can give only an estimate of the body's metabolism of androgens.
An abuse of testosterone, its precursors or derivatives, may in a sense have effects contrary to those expected. Excess testosterone would in fact be transformed into estradiol, a female hormone that typically increases the storage of fat in specific body regions (see gynecomastia).
SHARES OF CLINICAL TESTOSTERONE
PRENATAL LIFE: development of the external genitalia
Prepubertal: influence on behavior
At puberty:
> The development and maturation of the external genitalia
> Acquisition of secondary sexual characteristics (appearance of beard, mustache, hair, recession time, lowering of the voice)
> Linear growth pubertal growth spurt (interaction with GH and IGF-1)
> Psyche: the more aggressive attitudes and the development of the libido> increase in muscle mass
IN ADULT:
testosterone promotes hair growth, maintenance of secondary sex characteristics or appearance of baldness
> psyche: the maintenance of behavioral attitudes and libido
> stimulation of spermatogenesis
> hematopoiesis: increased production of erythropoietin (EPO)
The males produce about 50 times more testosterone than females.
This difference depends on the increased production of testosterone, both the low activity of the enzyme aromatasiresponsabile the conversion of testosterone to estrogen. This enzyme is present in high amounts in the adipose tissue, which results in a lower amount of testosterone in overweight and obese individuals.
The difference in hemoglobin concentration in men and women is due to higher values of testosterone in the male. This powerful anabolic hormone stimulates erythropoiesis fact, that is the formation of new red blood cells.
A significant reduction in blood levels of testosterone also occurs with aging and in the course of specific diseases such as hypothyroidism, liver cirrhosis and kidney failure.
DID YOU KNOW that smoking induces vasoconstriction by narrowing the small arteries of the testis and reducing their functionality. If you smoke tends to produce less testosterone and menospermatozoi than a nonsmoker. Even alcoholics have free testosterone levels significantly lower than occasional drinkers.
A small amount of testosterone is converted to estradiol by the enzyme aromatase, particularly concentrated in adipose tissue. In humans, the estradiol, which is a typically female hormone interacts with specific receptors contributing to the maturation of various tissues, particularly the bone. At puberty, the secretion of testosterone by reflection also increases the production of estrogen, which determine the welding of the discs intercartilaginei resulting in growth arrest.
Testosterone and hirsutism >>
TESTOSTERONE AND EXERCISE
A YEAR SHORT AND INTENSE ACCOMPANIED BY AN INCREASE OF ABOUT 35% OF TESTOSTERONE IN THE CLUB
A YEAR LONG IT GOES TO A SIGNIFICANT REDUCTION OF TESTOSTERONE *
* However, athletes in endurance sports such as marathon runners have testosterone levels similar to normal subjects; that this decrease is lower the more the subject is trained
EXCESS Androgen
The use of testosterone and / or anabolic-androgenic steroids (SSA) derived from it results in an increase in protein synthesis and lean muscle mass (when taken during a workout combined with proper nutrition). The intake of these hormones can cause an increase in strength and tolerance to acid latticodiminuendo so recovery time. This phenomenon is directly related to increased production of creatine phosphate in the muscle.
Androgens are often taken in high doses together with masking substances such as diuretics to dilute the concentration of banned substances in the urine.
EXCESS TESTOSTERONE
EFFECTS "POSITIVE"
HEALTH RISKS AND SYMPTOMS
Hypertrophy
MUSCLE
INCREASE
LEAN BODY MASS
ANTAGONISM OF THE catabolic
GLUCOCORTICOIDS
increased hematocrit
IN ADULT MALES: development of tumors, development of psychiatric syndromes, acute myocardial infarction, hypertension, renal or hepatic impairment, testicular atrophy, gynecomastia, high cholesterol.
THE MALE TEENAGERS:
severe acne on the face and body, premature epiphyseal closure delleossa long and then reduced height growth *.
IN FEMALE:
menstrual abnormalities, hypertrichosis, enlarged clitoris and breast atrophy, deepening of the voice.
* The same effect can be manifested by subjecting the teenager to a workout program too intense with the use of heavy loads
Testosterone and anabolic steroids
Testosterone is the male sex hormone par excellence. Is synthesized by the Leydig cells in the testes present in varying amounts depending on the age of the individual. Testosterone effects are evident in the age of puberty when increased secretion due to important physiological changes in the male. These changes include lowering the tone of the voice, increased sebum production, development of sexual organs and increased libido.
In adulthood, testosterone is involved in the maintenance of secondary sex characteristics, attitudes and behavior of libido.
In addition to all these properties, also known as androgenic effects, testosterone it combines other especially important for athletes. This hormone is in fact involved in the accumulation of muscle mass (increased protein synthesis) and in the production of erythropoietin (a substance that stimulates the synthesis of red blood cells).
To appreciate this fact simply compare men and donni. The first produces an average of 2.5 - 11 mg of testosterone per day while the female body generally does not exceed 0.25 mg share. These differences explain in part the increased athleticism of man (muscle mass and hemoglobin values exceeding).
Androgen EFFECTS OF TESTOSTERONE
development, maturation of the external genitalia (age of puberty)
maintenance of desire and sex drive (adulthood)
acquisition and maintenance of secondary sexual characteristics (appearance of beard, mustache, hair, recession time, lowering of the voice)
psyche: the more aggressive attitudes and development of libido
From the chemical point of view, for anabolic steroid drugs are those drugs that are derived from testosterone. With proper handling in the laboratory on the molecules as removing or adding methyl groups (nandrolone, methyltestosterone) add hydroxyl groups (oxandrolone), move the double bonds (methandrostenolone), add chlorine or fluorine atoms (fluoxymesterone, clortestosterone), one looks for in the general dimantenere positive anabolic effects with fewer adverse effects of androgens. Even small changes in the initial molecule of testosterone lead to major changes of the pharmacological effect.
The androgenità is in fact the main source of the side effects of steroids use anabolic steroids. Ognungo of these drugs, in varying degrees, is able to amplify the androgenic properties than testosterone. For this reason, a massive use of anabolic steroids is associated with hair loss, increased hair growth, prostatic hypertrophy, or priapism (erection spontaneous, prolonged and sometimes painful, is not linked to pleasure), testicular atrophy, acne and psychosis.
ANABOLIC EFFECTS OF TESTOSTERONE
pubertal growth spurt (interaction with GH and IGF-1)
increase in muscle mass, trophic bone and to a lesser extent in the liver, spleen and kidneys
hematopoiesis: increased synthesis of erythropoietin (EPO)
Metabolism of testosterone
After being produced in testicular Leydig cells, under the influence of pituitary hormone LH (luteinizing hormone), testosterone enters the bloodstream where it binds to specific plasma proteins. Thanks to this link testosterone can be transported to various tissues where it carries out its functions. In the blood of man 45% of the testosterone is bound by SHBG (sex hormon binding protein), while 53% binds to albumin (this protein has an affinity for testosterone 1000 times lower than SHBG but its blood concentration is 1000 times higher).
Only 2% of total testosterone in men and 1% in women is free to migrate into the cells and exert specific functions.
Laboratory tests detect only the traditional share of total testosterone, without giving us information on the share of free testosterone. To obtain this information specific tests are needed and much more expensive. It follows that the usual blood tests can give only an estimate of the body's metabolism of androgens.
The level of SHBG present in the organism varies from individual to individual and can be altered by numerous factors. An increased level of estrogen and thyroid hormones is associated with an increased concentration of SHBG and vice versa. Taking anabolic steroids with high androgenità is associated with a decrease in SHBG levels.
NOTE: anabolic steroids have different affinity for SHBG. For some this characteristic is less marked for the other. Some of them, such as Proviron ® are used for their strong tendency to bind with these proteins. This feature, apparently disadvantageous, can be especially useful if you are also taking other anabolic steroids. Given that most of the SHBG binding Proviron is committed to the free quota of the other hormones increases with all the positive consequences of the case.
Other anabolic steroids have rather low affinity for SHBG and just feature should their strong androgenic and anabolic power.
The binding of testosterone to SHBG protects it from rapid metabolism by ensuring a more stable blood concentration and keeping it intact until it reaches the target tissues. In the plasma membranes of cells sensitive to its action have been recently discovered specific receptors for SHBG. In light of these findings these carriers not only act as mere transporters but play a more complex role that has yet to be clarified.
The free testosterone is able to interegire with specific cell receptors found mainly in the skin (increased sebum production, hair loss and hair growth), kidneys (increased synthesis of erythropoietin), bones (mineralization and, pubertal, stunting) in the central nervous system (increased aggression and libido), adipose tissue (increased lipid oxidation), testes (spermatogenesis) and nellaprostata (increased production of seminal fluid).
All steroid hormones and other substances of hydrophobic (lipophilic) readily cross the cell membrane and interact with specific receptors cytoplasmic or nuclear. Testosterone, as a member of this family, has specific receptors in the cytosol which binds as would a key with the corresponding lock. The hormone-receptor complex migrates to the nucleus where it regulates the transcription of specific genes responsible for the local action of testosterone (eg synthesis of contractile proteins, actin and myosin in muscles).
At the end of this first phase, the hormone-receptor complex is dissolved and return both free in the cytoplasm. At this point the testosterone can migrate out of the cell and reach another through the bloodstream.
The whole process (hormone-receptor binding, migration to the nucleus, regulation of transcription and back into the cytosol) is relatively slow and requires several hours to complete.
Testosterone, estrogen and flavoring
In humans, a fraction of testosterone is converted to estrogen, the female sex hormones for excellence. This conversion is performed by an enzyme chiamatoaromatasi localized mainly in adipose tissue but also present in the gonads, liver, muscles and at the level of the central nervous system.
Moderate amounts of estrogen improves blood lipid profile, but as soon as these values exceed the limits fisioligici appear different side effects. Problems such as gynecomastia, water retention and excessive accumulation of adipose tissue are common in people with high levels of estrogen.
In case there is an excess of free testosterone the body has the ability to neutralize transforming it into estradiol (typically female hormone) through a reaction of aromatization which occurs especially at the level of adipose tissue and the central nervous system. Estradiol works, in turn, an inhibitor of testosterone production by reducing the secretion of hypothalamic GnRH (gonadotropin-releasing hormone LH and FSH). This reduces the amount of LH hormone product and consequently also the synthesis of testosterone in the testes.
NOTE: bodybuilders, men and women often take drugs to lower estrogen. The Nolvadex or Clomid and tamoxifen citrate are structurally related to estrogen and block its action by preventing their binding to cellular receptors. Other drugs commonly used for the same purpose are the Arimidex and Cytraden that act by inhibiting the enzyme aromatase. The lowering of estrogen is suggested as a method to increase the muscularity of the lower part of the body and at the same time reducing the fat mass. By blocking these hormones also neutralizes their inhibitory effect on the secretion of testosterone by stimulating the body to produce larger quantities.
For all these reasons the use of an antiestrogen is particularly useful during the definition phase preagonistica and as a stimulant for the reactivation of the endogenous synthesis of testosterone after cycles particularly long and intense.
In recent years we have witnessed a sharp appreciation of the role of estrogen in muscle development. It seems that these hormones promote anabolism increasing the secretion of GH, IGF-1 and the number of receptors for testosterone, reducing the feeling of fatigue and improving the activity of certain enzymes involved in the metabolism delglucosio.
The anabolic properties of anabolic steroids aromatizable (which can convert to estrogen) are significantly higher than those of the products with low estrogenic activity.
It 'clear, therefore, that a bodybuilder should not completely restrict the production of estrogen, especially away from racing when you want to maximize muscle volume.
dihydrotestosterone
Estrogens are not the only hormones in which the testosterone may be converted. In particular there is an androgen metabolite, called dihydrotestosterone (DHT), which exerts an activity in some tissues definitely superior compared to testosterone.
The androgen hormone dihydrotestosterone is the most powerful body and its activity is 4-5 times higher than testosterone. It is produced by the action of the enzyme 5-alpha reductase inhibitors which makes simple the double bond existing between carbon 4 and carbon 5 (by adding a hydrogen atom to each carbon, see figure). This slight modification greatly increases the affinity of dihydrotestosterone to androgen receptors, enhancing, consequently the activity.
The enzyme 5-alpha reductase is highly concentrated in the skin, liver, central nervous system and prostate.
By virtue of its strong androgen dihydrotestosterone is responsible for most of the side effects associated with the use of anabolic steroids. In susceptible individuals this hormone promotes the appearance of acne, accelerates hair loss and prostatic causaipertrofia.
Despite these side effects dihydrotestosterone should not be seen as an absolute enemy. First, because it is not solely responsible for these effects since all steroids exert their anabolic and androgenic activity by interacting with medesimirecettori. Second dihydrotestosterone appears to stimulate the anabolic activity due to its strong interaction with the cells of the central nervous system.
By blocking the activity of the enzyme 5-alpha reductase inhibitors using a drug called finasteride (used to combat baldness) many bodybuilders notice a slowdown in progress, irrefutable sign that dihydrotestosterone is not intended as a mere side effect.