Reproductive Hormones Copyright PEER.tamu.edu

 A 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 roles in reproduction.  They cause different sexual characteristics in males and females and control fertility or the ability to have offspring.  There are several reproductive hormones but the two major ones are Estrogen and Testosterone.

 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.

 Growth accelerates in the first half of puberty and stops at the completion of puberty.  During puberty, major differences develop in many body structures and systems. The most obvious of these are referred to as secondary sex characteristics.  Estrogen and Testosterone are the hormones associated with puberty.

 Estrogens are hormones found in females and in low levels in males.  These hormones control different stages of the reproductive cycle in females.  In females, estrogens control the development of secondary sex characteristics.  In males and females estrogen promotes normal bone development.  In females, estrogen is produced by the ovaries.

How can you tell that these animals are females?

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

The Structure of Estrone 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.

 Compare the model to the drawing and the chemical formula. See if you can identify the corresponding parts.  In the model, the black atoms are carbon, the white atoms are hydrogen, and the red atoms are oxygen. C 18 H 22 O 2

 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. C 21 H 30 O 2

 Butenandt won the Nobel Prize in 1939* for demonstrating the structure of these steroids and showing that all sex hormones were steroids. C 18 H 24 O 2

 Towards the end of his career, Butenandt also came very close to isolating pheromones.  Hormones are released inside the body. Pheromones are released outside the body to affect another individual. In the following experiment, the type of pheromone observed is a chemical that attracts mates. Girls love me for my pheromones!

 Butenandt extracted an oily substance from the glands of 313,000 female silk moths, obtaining about 5.25 mg of the substance.  When a glass rod was dipped into the substance and brought to a male silk moth, an obvious attraction was observed.  Why was the male attracted to the rod?*

 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.  Blood clots occur when blood thickens around an injured area, such as a scab.  These can be dangerous if they occur in the circulatory system because they can block blood flow.

 Many people believe estrogen therapy causes breast cancer.  In recent lawsuits, millions of dollars have been won from drug companies for selling such estrogen.  Is this fair?  What if the patient and doctor both wanted the treatment for menopause and were informed of the side effects?

 What are hormones?  What are the two major reproductive hormones?  What are the functions of Estrogen?  What are some pros and cons of Estrogen Replacement Therapy?

 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. C 19 H 28 O 2

 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.

 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).

 A few men don’t have enough testosterone.  Men with primary hypogonadism or hormonal decline are eligible for treatment with testosterone.  Dangerous side effects are still possible.

 What is testosterone?  What are the functions of testosterone?  What are some of the side effects of anabolic steroid usage?  Why do you think some people take anabolic steroids even though they know about the side effects?