Gonadotropin: Wikis

  

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Gonadotropins are protein hormones secreted by gonadotrope cells of the pituitary gland of vertebrates.[1]

Gonadotropin is sometimes abbreviated Gn. The British spelling is gonadotrophin.

Contents

Types

The two principal gonadotropins in vertebrates are luteinizing hormone (LH) and follicle-stimulating hormone (FSH), although primates produce a third gonadotropin called chorionic gonadotropin (CG). LH and FSH are heterodimers consisting of two peptide chains, an alpha chain and a beta chain, linked by Hydrogen bonds and van der Waals forces. LH and FSH share nearly identical alpha chains (about 100 amino acids long), whereas the beta chain provides specificity for receptor interactions. These subunits are heavily modified by glycosylation.

Another human gonadotropin is human chorionic gonadotropin (hCG), produced by the placenta during pregnancy.

Human Menopausal Gonadotropin (hMG) is a mixture of FSH, LH and hCG, extracted and purified from the urine of postmenopausal women.[2] It is used to treat anovulation in women by stimulating follicular development, as well as hypo- or normagonadotropic hypogonadism in men and, in combination with hCG, it can stimulate spermatogenesis.[2]

Mechanism

Gonadotropin receptors are embedded in the surface of the target cell membranes and coupled to the G-protein system. Signals triggered by binding to the receptor are relayed within the cells by the cyclic AMP second messenger system.

Gonadotropins are released under the control of gonadotropin-releasing hormone (GnRH) from the arcuate nucleus and preoptic area of the hypothalamus. The gonadstestes and ovaries — are the primary target organs for LH and FSH. The gonadotropins affect multiple cell types and elicit multiple responses from the target organs. As a simplified generalization, LH stimulates the Leydig cells of the testes and the theca cells of the ovaries to produce testosterone (and indirectly estradiol), whereas FSH stimulates the spermatogenic tissue of the testes and the granulosa cells of ovarian follicles.

Diseases

Gonadotropin deficiency due to pituitary disease results in hypogonadism, which can lead to infertility. Treatment includes administered gonadotropins, which, therefore, work as fertility medication. Such can either be produced by extraction and purification from urine or be produced by recombinant DNA.

Failure or loss of the gonads usually results in elevated levels of LH and FSH in the blood.

Manny Ramirez controversy

Major League Baseball player Manny Ramirez was suspended for 50 games on May 6, 2009, for allegedly failing a drug test which identified gonadotropin. [1]

References

  1. ^ Parhar, Ishwar S. (2002). Gonadotropin-releasing Hormone: Molecules and Receptors. Amsterdam: Academic Press. ISBN 0444509798.  
  2. ^ a b fertility.com - Human Menopausal Gonadotropin (hMG) Retrieved on August 31, 2009

External links


Simple English

Gonadotropins (or Gonadotrophins) are hormones. The two main hormones of the group are Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH). Gonadotropins are hormones that tell the testicles to make sperm or the uterus to release an egg.









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