Estrogen in Animals
Estrogen is an important hormone in animals, primarily involved in reproductive functions and various physiological processes.
It is mainly produced by the ovaries in females, with smaller amounts synthesized by the adrenal glands and testes in males.
Structure & Origin of Estrogen
Estrogen is derived from androgens by elimination of the C19 methyl group and aromatization of the A ring. Estrodiol 17 beta is the principal estrogenic hormone in the ovary and has the greatest biologic activity.
Within theca cells of the follicle, under the influence of LH, androstenodione is synthesized from cholesterol and converted to testosterone which is aromatized to estradiol 17 beta in the granulose cells under the influence of FSH. The precursor for estrogen is cholesterol.
Two cell, Two Hormone Theory
Functions of Estradiol (Estrogen)
- A long with progesterone induces sexual receptivity in the female (estrus).
- Estrogen is essential for maintenance of secondary sexual characteristics.
- Induce ductal development in the mammary gland.
- Necessary for normal development and function of the female reproductive tract. At puberty, increased levels play at role in the calcification of the epiphyseal cartilages and limit bone growth.
- Potential ability of oxytocin and prostaglandin to cause uterine contractions.
- Involved in attachment of the embryo to uterine wall.
- Exhibit anabolic effect.
- It enhances migration of leucocytes into the uterine lumen and thereby increase the bacteriocidal activity within the uterus.
- By negative and positive feed back mechanism control the levels of gonadotrophic hormones.
Clinical Uses of Estrogen
- Used in induction of heat.
- Treatment of misalliance.
- Used as an ecbolic in treatment of mummification and pyometra.
- Used in inducing milk production in cow.
- Anabotic effect used in beef cattle and poultry to fatten up the animals.
