Berthold conducted an experiment with six chickens to link the effects of castration with the internal secretion of the testes. Two chickens were used as a control group, two were castrated but had their testes transplanted back into their bodies at a distant location, and the remaining two were castrated and left to develop with no testes. Berthold found that the two castrated chickens never developed adult male chicken characteristics.
However, the interesting part of this experiment was that the two chickens with the transplanted testes developed into mature adult male chickens. Chemical structure of testosterone. He claimed that daily injections of testicular blood, seminal fluid and testicular extract from guinea pigs and dogs had made him feel 30 years younger. He told the audience that with the use of these injections he was able to lift heavier weights than before, work for hours after dinner, and run up and down steps.
In the decades following these experiments, numerous research teams explored the isolation of sex hormones. However, the testes proved to contain a more powerful androgenic factor. Dingemanse, J. Freud and Ernst Laqueur who first isolated the hormonal secretion in ; it was synthesized later that year by Leopold Ruzicka and A.
The study of testosterone and its possible effects and uses has continued without interruption from the time of its discovery. Some experiments sought to discover if an imbalance of sex hormones led to homosexuality. Other studies have been conducted to see if an excess of testosterone leads to highly aggressive or criminal behavior. In recent years, testosterone has been used as a treatment for erectile dysfunction and to treat men with extremely low natural testosterone levels. Prev Next.
Endocrine Abstracts 10 S2. Author affiliations. Volume 10 Next Prev. Summary Abstracts. Article tools. My recent searches. My recently viewed abstracts. These tissues are composed of groups of cells interstitial tissue between the seminiferous tubules.
Under the influence of LH, the interstitial tissues secrete the steroid hormone testosterone. Even though testosterone may be secreted by the adrenal cortex, the amount of secretion is usually insignificant [ 4 ]. Testosterone is also produced in ovary in females [ 5 ].
Testosterone, in the presence of normal amounts of growth hormone, promotes growth of the bony skeleton. This is in addition to promoting male characteristics, male behaviors and the maintenance of the spermatic tubules [ 4 , 6 , 9 ]. The secretion of androgen markedly increases at puberty accounting for rapid growth at that stage of life [ 4 , 7 ]. Illustration is shown in Figure 1.
Testosterone is the primary male sex hormone and anabolic steroid [ 6 ]. It is the main anabolic steroid hormone produced by the body but serving two main effects on the body: Anabolic effects, which promote muscle building. Androgenic effects, which are responsible for male traits, such as facial hair and a deeper voice, among others. Some athletes take testosterone to boost their performance because of its anabolic effects [ 6 ].
In women, the ovaries produce the hormone [ 8 ]. It also helps build muscles and bone masses [ 7 , 8 , 11 ]. However, therapy is not usually recommended, unless testosterone level falls quite below the normal range for a given age. This is because there are some natural remedies which can help [ 9 ]. Testosterone levels can decrease naturally due to age or other health conditions. When men reach above 40 years of age, some symptoms of low testosterone become commonly seen.
The commonest symptom to appear is erectile dysfunction. Irrespective of age, low testosterone levels have often been observed in people with obesity [ 8 ]. Hypogonadism, also called low testosterone, is the most common problem related to testosterone, in men.
As discussed earlier Section 2. Therefore, men with low levels of testosterone might notice a reduction in these traits whereas women with too much testosterone might notice an increase in these traits [ 8 ].
The molecular formula is C 19 H 28 O 2 [ 10 ]. The molecular weight is In medical treatment, the therapeutic testosterone is a synthetic form of endogenous androgenic steroid testosterone [ 12 ]. Generally speaking, in vivo, testosterone is converted into dihydrotestosterone DHT in the target tissues irreversibly by the enzyme 5-alpha reductase. The testosterone or DHT ligand-androgen receptor complexes then act as transcription factor complexes.
In this way, it stimulates the expression of various responsive genes. In comparison, DHT binds with higher affinity to androgen receptors than testosterone, thus activating gene expression more efficiently. Testosterone, in addition, is irreversibly converted to estradiol by the enzyme complex aromatase. This occurs particularly in the liver and adipose tissue. Both testosterone and DHT promote the development and maintenance of male sex traits related to the internal and external genitalia, skeletal muscle and hair follicles.
On the other hand, estradiol promotes epiphyseal maturation and bone mineralization. However, because of rapid metabolism by the liver, therapeutic testosterone is generally administered as an ester derivative Figure 2 [ 11 ].
Chemical structure of testosterone [ 5 ]. In males, testosterone is the predominant sex hormone [ 6 , 9 ]. It plays a number of important roles. These roles include; Development of penis and testes. Appearance of facial and pubic hair at puberty. It starts at puberty but later in life, it may play a role in balding. Therefore, males in adolescent stages of life, who have too little testosterone may not experience normal masculinization.
The genitals of such males may not enlarge, as well as their facial and body hair may be scanty. The voice may also not deepen as normally expected [ 5 ]. Notably, testosterone also helps in the maintenance of normal mood [ 7 ]. Scholars have argued that there may be other important functions of this hormone, testosterone, that have not yet been discovered [ 5 ]. To control the production of testosterone in men, signals have to be sent from the hypothalamus in the brain to the pituitary gland at the base of the brain.
In turn, the pituitary gland then relays signals to the testes to produce testosterone [ 4 ]. Notably, when the level of testosterone rise too high, the brain hypothalamus then sends signals to the pituitary to reduce the production [ 5 ]. For normal working of the ovaries in females, there must be proper balance between testosterone and estrogen.
It is a known fact that androgens also play an important role in normal brain functions, including mood, sex drive and cognitive functions, although these areas may still require more studies [ 1 , 2 , 3 , 4 , 5 ]. A range of symptoms can occur if testosterone production drastically drops below normal [ 7 ]. In past few years, scholars have focused on the effects of testosterone deficiency among men.
The rate of this drop is slower compared to the relatively rapid drop in estrogen in females that culminates in menopause [ 5 ]. Majority of men, more than a third, who are above 45 years of age, have reduced levels of testosterone [ 5 ].
The following symptoms of deficiency of testosterone in adult males occur: they are but not limited to; Reduced body and facial hair. Indeed some men who have testosterone deficiency have related symptoms or conditions.
These symptoms or conditions appear to improve when testosterone replacement is done [ 4 , 5 , 9 ]. Therefore, in a nutshell, men with low levels of testosterone might notice a reduction in body hair, muscle mass and strength, while women with too much testosterone might notice an increase in these traits [ 8 ].
Having too much naturally-occurring testosterone is not a common problem among men [ 5 ]. Too much testosterone is common only in male athletes who inject themselves with the hormone in order to make use of its anabolic effects. This is because anabolic steroids, testosterone or related hormones, increase muscle mass and athletic performance [ 5 ].
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