(-trō'fĭn, -trō'pĭn)
n.
A hormone that stimulates the growth and activity of the gonads, especially any of several pituitary hormones that stimulate the function of the ovaries and testes.
gonadotropin
Dictionary:
go·nad·o·tro·pin (gō-năd'ə-trō'pĭn, -trŏp'ĭn)  also go·nad·o·tro·phin
|
| Dental Dictionary: gonadotropin |
(gōnad′ōtrōp′in)
n
n
(gonadotropic hormone) a gonad-stimulating hormone derived either from the pituitary gland (for example, follicle-stimulating hormone [FSH] and luteinizing hormone [LH], which is also an interstitial cell-stimulating hormone [ICSH]) or from the chorion (for example, chorionic gonadotropin, which is found in the urine of pregnant women).
| Veterinary Dictionary: gonadotropin |
Any hormone having a stimulating effect on the gonads. Two such hormones are secreted by the anterior pituitary: follicle-stimulating hormone and luteinizing hormone, both of which are active, but with differing effects, in the two sexes.
- chorionic g. — a gonad-stimulating hormone produced by cytotrophoblastic cells of the placenta; used in treatment of underdevelopment of the gonads and to induce ovulation. See also pregnancy tests.
- g. release inhibiting factor — pituitary hormone which inhibits the release of luteinizing hormone or follicle-stimulating hormone.
| Wikipedia: Gonadotropin |
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 are luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Both hormones consist 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, whereas the beta chain provides specificity for receptor interactions.
A third 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 gonads — testes 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
- ^ Parhar, Ishwar S. (2002). Gonadotropin-releasing Hormone: Molecules and Receptors. Amsterdam: Academic Press. ISBN 0444509798.
- ^ a b fertility.com - Human Menopausal Gonadotropin (hMG) Retrieved on August 31, 2009
External links
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved. Read more |
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