Oestrogens

OESTROGENS

  • There are a number of sources of estrogens produced in the body
  • They are produced from the granulose cells of the follicle, the corpus luteum of primates, the placenta the adrenals and the testes.
  • Oestrogens influence the female sex characteristics such as an increase in the growth, protein synthesis and fluid secretions of oviduct, uterus, cervix and vagina.
  • They also affect mammary development.
  • They induce the expression of behavioural estrus in the female and libido in the male.
  • Oestrogens also have many effects on general body metabolism including fat distribution and content within the body, mineral metabolism, bone growth and protein synthesis in may tissues including the muscle.
  • They influence gonadotrophin secretion and at low concentrations have a negative feed back effect on the hypothalamus, while at high doses, in the absence of progesterone they have a positive feed back effect in females resulting in the preovulatory surge in gonadotrophin output.
  • The testes of both the boar and the stallion produce oestrogens in high quantities and pregnant mares produce a wide range of estrogens like equilin, hippulin and equilenin.
  • Equine male urine and testes contain enormous quantities of estrogens.
  • The natural estrogens include 17 beta - estradiol, estrone and estriol.
  • They have low oral activity.
  • Synthetic steroidal estrogens include simple esters such as estradiol benzoate or valerate.
  • The most common non-steroidal estrogens, which have a high affinity for the estradiol receptor, are the stilbenes.
  • They are orally active, highly potent and are not easily metabolized.
  • Some are genotoxic carcinogens and hence their use is prohibited.

Clinical uses

  • Misalliance in the bitch
  • Induction of oestrus and ovulation in anoestrus animals
  • Control of the time of ovulation
  • Control of life-span of the corpus luteum
  • Treatment of pyometra and mummified foetus
  • Obesity due to hypogonadism in bitches
  • Urinary incontinence in old and spayed bitches
  • Anal oedema in dogs
  • Regression of hypertrophied prostrate glands
  • Caponization of young and old cockerels

Side effects

  • This includes gastrointestinal upsets, feminization in male, sodium retention and oedema.
  • In chronic overdosage genital erythema, irritation, polydipsia and polyuria are noticed.
Last modified: Thursday, 26 April 2012, 5:14 AM