Reproductive HormonesReproductive Hormones

HormonesA hormone is a chemical released into the blood and transported to affect cells in other parts of the body.Hormones regulate many things in the body, such as:

•Growth and development.•Male and female development.•How the body uses energy.•Levels of salts and sugars in the blood.•The amount (volume) of fluid in the body.

•Certain hormones play key Certain hormones play key roles in reproduction. roles in reproduction. They cause different sexual They cause different sexual characteristics in males and characteristics in males and females and control fertility or females and control fertility or the ability to have offspring.the ability to have offspring.•There are several There are several reproductive hormones but the reproductive hormones but the major ones are major ones are EstrogenEstrogen , , ProgesteroneProgesterone and and TestosteroneTestosterone..•these hormones are these hormones are associated with pubertyassociated with puberty

• Puberty is the process of physical changes by which a child's body becomes an adult body capable of reproduction.

• Puberty is initiated by hormone signals from the brain via the pituitary gland to the ovaries of the females and testes of the males. In response, these organs produce a variety of hormones that stimulate the growth, function, or transformation of brain, bones, muscle, skin, breasts, and reproductive organs.

Source: Ovary, Placenta and Testis. (Estrogens are hormones found in females and in low levels in males.)

Types: 17-β Estradiol, Estrone and Estriol.

Function:

1. Growth and development of fallopian tubes, uterus, vagina, external genitalia. In females, estrogens control the development of secondary sex characteristics

2. These hormones control different stages of the menstrual cycle in females.

3. In males and females estrogen promotes normal bone development and density.

4. Estrogen inhibits LH release.

Normal range: EstradiolMen: 30-200 pmol/l.Female: 100-1500 pmol/l

• During the extensive studies of sex hormones in the 1920s, American biochemist, Edward Doisy, discovered how to isolate and purify estrogens..

The Structure of Estrogen

Compounds that have this basic 4-ring structure of carbon atoms are called “steroids.” The side chains of H and OH distinguish the different kinds of steroids.

Five years later, German biochemist, Adolf Butenandt, isolated progesterone, another important sex hormone, from the urine of pregnant women.

Progesterone prepares the uterus for pregnancy. A sudden fall in progesterone is one of several events that triggers labor.

C21H30O2

Progesterone• Source: Corpus luteum, Adrenal Cortex,

Placenta.• Normal level : 6-60 nmol/l• Function:1. Stimulation & growth of mammary

glands.2. Plays role in conception and

maintenance of pregnancy.3. Inhibition of FSH & LH. (Contraception)

How estrogens and progesterone achieve their

effectsSteroids like estrogens and progesterone are small, hydrophobic molecules that are transported in the

blood bound to a serum globulin. In "target" cells, i.e., cells that change their gene

expression in response to the hormone, they bind to receptor proteins located in the cytoplasm and/or

nucleus. The hormone-receptor complex enters the nucleus and binds to specific sequences of DNA, called the

estrogen (or progesterone) response elements

How estrogens and progesterone achieve

their effects

Response elements are located in the promoters of genes.

The hormone-receptor complex acts as a transcription factor which

turns on (sometimes off) transcription of those genes.

Gene expression in the cell produces the response.

Menopause occurs in older women when the ovaries stop producing estrogen, resulting in a stopping of menstrual cycles and loss of fertility.

Postmenopausal women receive estrogen therapy to help prevent bone loss and control symptoms of menopause.

In this therapy, women are given the estrogen their ovaries no longer produce.

• Hormone replacement therapy does more than relieve symptoms of menopause.

• It has been shown that bone fractures decrease by 50 – 70% and bone density increases by ~5%.

• Also cardiovascular disease is less prevalent in women who receive this therapy.

• The most serious drawback of hormone replacement therapy are blood clots.

• These can be dangerous if they occur in the circulatory system because they can block blood flow.

Hypothalamus

Adenohypophysis

Testes or Ovaries

Target tissues

Control ofSex Hormones

IndirectLoop

ShortLoop

DirectLoop

GnRH

LH, FSH

Testosterone or Estrogen &Progesterone

neural inputs

Testosterone, like estrogen, is also a steroid hormone. It is found in males and in smaller amounts in females.

In males, testosterone controls the development of secondary sex characteristics such as facial hair and increased muscle mass.

Testosterone in males is produced by the testicles.

Compare and contrast the characteristics of these male animals to the females you observed earlier.

• Testosterone was purified by Ernst Laqueur at the University of Amsterdam in 1934 from bull reproductive organs.

• Testosterone was then isolated in 1935 by Karoly David, E. Dingemanse, J. Freud and Ernst Laqueur.

• Butenandt, who was also involved in estrogen research, studied testosterone and chemically synthesized it and worked out its chemical structure.

C19H28O2 

Testesterone (leydig cell)

• Plasma Testesterone• Men: 10-35 nmol/L• FSH : 2-15 IU/L• LH : 1.2-13 IU/L

Testesterone• Fetal : Differentiation of wolffian ducts

into epididymis, vas deferens and seminal vesicles.

• Descent of testis. (cryptorcidism) Post-natal: • Development of 2ndry sexual characters.• Anabolic effect : increase in muscle mass,

stimulation of erythropoiesis• Erectile function & initiation of libido.

Disorder1. Infertility in males: Causes: Hypogonadism and Dis. affecting

Sperm synthesis & transport. Diagnosis: Measurement of sex hormones,

gonadotropins and sperm analysis.2. Gynecomastia

3. Prostrate Hypertrophy and Cancer: Due to DHT hypersecretion for

mainly to patient above 60 yrs.Treatment- Fenasteride :analogs that inhibits enz(5 alpha reductase) required for conversion of DHT from cholesterol.or structure analogs that inhibts FSH and LH secretion.

• If prostate cancer is present, an increase of growth in cancerous tumors will occur.

• It can also cause an absence of sperm, an excess of red blood cells, and sleep apnea (when breathing completely stops during sleep).

•These steroids are man made derivatives of testosterone.•Users of anabolic steroids include athletes and body builders, who use it to stimulate the body to build muscle tissue and strengthen bones and speed muscle recovery following exercise or injury. •Use of anabolic steroids is illegal and extremely harmful.Can you guess why they are harmful?

• Shrinking of the reproductive organs, reduced sperm count, infertility. Why do you think this happens?*

• Cancer, jaundice, liver tumors and high blood pressure are the more serious risks.

• Aggression, acne, irritability, paranoia and delusions can also occur.