Testosterone|Male sex hormone

This article discusses different aspects of testosterone -the male sex hormone. Here, learn about the site of secretion, average values, action, functions, and more…

Keywords: Testosterone| C 19 steroid| Leydig cells |testis |ovary estrogen| Luteinizing hormone | World Anti Doping Agency

Table of contents

1.	Introduction
2.	Site of secretion
3.	Biosynthesis
4.	Normal values and daily secretion
5.	Mechanism of action
6.	Functions
7.	Clinical

In males, testosterone is the primary sex hormone. In 1935, Ernst Laquer isolated, and Adolf Butenandt and Leopold Ruzicka synthesized testosterone.

Site of secretion:

Testis secretes testosterone from Leydig cells present in the seminiferous tubules. The testis also secretes estrogen in small amounts.

In females, ovaries secrete testosterone in lesser amounts.

Testosterone is synthesized by zona reticularis of the adrenal cortex.

Chemically testosterone is a C 19 steroid with one hydroxyl group in the seventeenth 17th position.

Biosynthesis of testosterone

Testosterone is secreted from cholesterol like other steroid hormones. Steps of synthesis:

The anterior pituitary gland’s Luteinizing hormone (LH) controls testosterone secretion.

The Luteinizing hormone stimulates the Leydig cells via c AMP. The mechanism is as follows.

c AMP coupled to Gs triggers many reactions causing the formation of testosterone.

c AMP

Average plasma concentration depends on age and sex, in

Adult male-300-1000 ng[i]/dl of blood. It decreases with advancing age. Testosterone is used in older men to fulfill the deficiency. and

Adult females have 30 to 70 ng/dl of blood.

Daily secretion of testosterone varies in males and females.

In adult males average is 7 mg per day, and in females, it is 300 micrograms per day.

The physiologically active form of testosterone circulates in the free state, only 1-2%.

97-98 % of testosterone circulates bound to plasma proteins.

About 65% binds with GBG -gonadal steroid binding globulin and 33 % with albumin, rest to other plasma proteins.

Mechanism of action:

Cells of target organs have specific receptors for testosterone. Testosterone combines with these receptors, and inside the cell, it is converted into dihydrotestosterone by 5-‘alpha reductase’.

Dihydrotestosterone is active and enters the nucleus, which binds to nuclear chromatin and stimulates mRNA .Stimulated m-RNA stimulates protein synthesis.

Metabolism and excretion:

The liver inactivates dihydrotestosterone into androsterone and dehydroepi androsterone., conjugate it with glucuronic and sulphuric acids as 17-ketosteroid .17-ketosteroids are excreted in the urine.

Functions:

In males, testosterone is responsible for :

Loss of virility and fertility due to loss of testis has been known since antiquity.

1. Development of male reproductive tissues-testes, prostate.

2. Development of secondary sexual features-increase in bone mass, muscle mass, and increased hairs.

In both sexes, testosterone is responsible for

1. Good mental health and well-being.

2. Prevention of osteoporosis.

Detail of functions:

1. Maintenance of Spermatogenesis.

2. Promotes and maintains the motility of the sperms.

3. Promotes and maintains the fertilizing capacity of the sperm.

4. Causes development of accessory sex organs and secondary sexual features at puberty -penis and scrotal enlargement.

5. Testosterone plays a crucial role in adolescent growth spurts and increases libido.

6. Testosterone has an anabolic effect-increases muscle mass, and increases muscular strength.

7. Testosterone has virilizing and anabolic effects.

8. Testosterone regulates acute hypothalamic-pituitary-adrenal axis responses when there is a dopaminergic challenge.

9. Testosterone regulates thromboxane A2 receptors on the megakaryocytes and platelets, regulating platelet aggregation.

10. Masculinization of the male child’s brain occurs at 4 to 7 months by transforming testosterone into estrogen, which crosses the blood-brain barrier and enters the male brain.

Female brains are not affected as female fetuses have alpha-fetoprotein, which binds the estrogen so that the estrogen can not pass the blood-brain barrier.

Testosterone is used in the treatment of

1. Hypogonadism in men
2. Breast cancer in women.
3. To increase muscular strength in athletes, it is ‘prohibited for all times’ by the World Anti Doping Agency”.
4. The older age group is sometimes used to fulfill the reduced testosterone level.

Clinical

Comparison of effects of low testosterone in males and females

Sr.no.	Effects of low testosterone in males	Effects of low testosterone in females
1.	Loss of libido	loss of libido
2.	Low muscle mass and strength Lack of body hair Slowed growth of secondary sexual characteristics Erectile dysfunction Infertility Delayed puberty	Infertility Menstrual disorders Amenorrhea
3.	Depression	Depression
4.	Cognitive disorders	Cognitive disorders
5.	Insomnia	Insomnia
6.	Lack of motivation	Lack of motivation

Effects of low testosterone in males include

• Loss of libido
• Low muscle mass and strength
• Lack of body hair
• Slowed growth of secondary sexual characteristics
• Erectile dysfunction
• Infertility
• Delayed puberty
• Depression
• Cognitive disorders
• Insomnia
• Lack of motivation

Effects of low testosterone in females include

• Loss of libido-sex drive
• Infertility
• Menstrual problems
• Depression
• Insomnia
• Lack of motivation

Comparison of low testosterone in males and females:

Sr.no.	Causes of low testosterone in males	Causes of low testosterone in females
1.	Testicular failure due to trauma, viral infection	Old age
2.	Pituitary tumor or disease	Ovarian failure
3.	Hypothalamic tumor or disease	Oral contraceptive -long-term use.
4.	Chronic diseases such as diabetes mellitus	Chronic diseases such as diabetes mellitus

Causes of low testosterone in males include

• Testicular failure due to trauma, viral infection
• Pituitary tumor or disease
• Hypothalamic tumor or disease
• Chronic diseases such as diabetes mellitus
• Some genetic diseases

Causes of low testosterone in females include

Old age

Ovarian failure

Oral contraceptive -long-term use.

Now, treatment of low testosterone is available for both males and females, known as ‘testosterone replacement therapy (TRT)’.-

Topical gel,

Patches

Testosterone injectable

Testosterone implant

Organ transplant in males -under trial.

Effects of high testosterone in males include

Excessive body hairs

Well-developed muscles and sexual organs.

Causes of high testosterone in males include

Adrenal hyperplasia

Tumors of the testis or adrenal cortex

Drugs.

Effects of high testosterone in females include

Hirsutism -Excessive body hair in male fashion.

Virilization -masculine appearance, deep voice, etc.

Causes of high testosterone in females include

Ovation tumor

adrenal gland tumor

polycystic ovarian syndrome

drugs- estrogen, clomiphene.

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Summary

The primary male sex hormone is testosterone, secreted mainly by the testis and, to some extent, by the zona reticularis of the adrenal cortex. In females, it is also secreted by the ovaries (though in little amount ) and zona reticularis.

In males, it is responsible for the development of male reproductive tissues-testes, prostate, and secondary sexual features-increase in bone mass, muscle mass, and increased hairs.

In both sexes

Testosterone is responsible for good mental health, well-being, and the prevention of osteoporosis.

FAQ :

Q. How to increase testosterone levels naturally?

A. Here are some natural methods to increase testosterone in both genders: lifestyle, change-Exercise, balanced diet at regular intervals, rest, no tension, or at least minimize stress in males, protect scrotum from trauma, infection, and exposure to high-temperature occupational hazards.

Q. How can you tell that a woman has a high testosterone level?

A. Effects of high testosterone in females include

Hirsutism -Excessive body hair in male fashion.

Virilization -masculine appearance, deep voice, may become bald.

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External link: https://en.m.wikipedia.org/wiki/testosterone

https://www.healthline.com/health/whatis-testosterone

[i] ng=nanogram was used in 1951 for the first time. It is one billionth of a gram.