Inhibines
L'inhibine est une hormone pepti- dique d'origine gonadique dont l'action inhibitrice sur la synthèse de la FSH a été suspectée dès 1932. Ce sont.
LInhibine B s6rique marqueur sensible de la production
duction d'inhibine par les cellules de Sertoli. L'inhibine exerce un effet de r6trocontr61e sur la s6cr6tion de FSH et module la spermatoge- n~se [5].
La cellule de Sertoli une cellule endocrine
de Leydig l'activine et l'inhibine. L'inhibine
Int6r6t du dosage de Iinhibine B et de IAMH dans le plasma s( minal
ni I'AMH ni I'inhibine B seule ou associ6e a la FSH
concentrations si riques en inhibine chez les patients souffrant de
Serum inhibin gonadal steroids and gonadotropins have been estimated in 51 patients with either a varicocele
Présentation PowerPoint
Fibrothécome ovarien sécrétant de l'inhibine A et de l'inhibine B Figure 3: Variation des taux plasmatiques d'inhibines et de gonadotrophines.
LInhibine
1 janv. 1980 des changements de l'anté-hypophyse observés après orchidectomie. Cette hormone a été dénommée Inhibine (INH) par Mc Cullagh (1932).
FLEX Monoclonal Mouse Anti-Human Inhibin ? Clone R1 Ready-to
Inhibin with activin a closely related dimeric glycoprotein hormone comprised of two ß-subunits
Complications obstétricales associées aux analytes anormaux des
inhibin inhibin-A
Is inhibin A a sign of Down syndrome?
Quantification of inhibin A is part of the prenatal quad screen that can be administered during pregnancy at a gestational age of 16–18 weeks. An elevated inhibin A (along with an increased beta-hCG, decreased AFP, and a decreased estriol) is suggestive of the presence of a fetus with Down syndrome.
Is Inhibins a reliable marker for ovarian cancer?
For medical purposes, measurement of inhibins in the circulation is a reliable marker for some types of ovarian cancer, and also a predictor for the conditions of spermatogenesis. Shlomo Melmed MB ChB, MACP, in Williams Textbook of Endocrinology, 2020
How do Inhibins block Activin signaling?
Inhibins compete for binding to type II activin receptors, preventing recruitment of type I receptors and thereby blocking activin signaling. Additional extracellular and intracellular proteins and mechanisms also serve to modulate the local activin signal.
Is inhibin B reciprocally elevated during the late luteal and early follicular phases?
Inhibin B is reciprocally elevated during the late luteal and early follicular phases of the menstrual cycle. Activin receptors are heteromeric complexes comprising type I (ActRI) and type II (ActRII) serine-threonine kinase receptors.
L'Inhibine.
M. R. BLANC
Station de
Physiologie
de laReproduction LN.R.A.,
37380Nouzilly,
Monnaie France.
Summary.
Inhibin : A review.
Inhibin
(INH), discovered in 1923, is a water-soluble factor secreted by the germinal epithelium responsible for the changes observed in the pars distalis after orchidectomy.More recent work
suggests that INH acts on FSH, and eventually on LH, secretion accor- ding to the dose (dualist theory : does an INH specific for LH exist or that it acts on bothFSH and LH
secretions but with different kinetics (unicist theory). Many tests have been proposed to identify INH, but only those taking into account the modifications of FSH and/or LH secretion(s) may be regarded as specific.One of
the most simple and sensitive in vivo tests uses the acutely castrated prepuberal rat. In vitro,INH decreases
the spontaneous secretion of FSH, probably through a decrease in the de novo synthesis, and it inhibits the LH and FSH response to LH-RH in systems using either hemipituitaries or isolated cultured pituitary cells. In vivo, LH plasma levels are inhibited first while those of FSH remain unaffected.Later,
FSH secretion is
decreased when LH has generally returned to basal levels.Various sources of
INH, male and female, have been used. Male sources include testis extracts, testicular lymph, rete testis fluid, epididymal extracts, seminal plasma or sperma- tozoa extracts, while female origins are ovarian extracts and follicular fluid. For the moment, it cannot be said if all these sources provide the same biochemical entity. TheSertoli and
granulosa cells are regarded as capable of synthesizing INH.INH is a
proteinaceous factor as shown by its sensitivity to proteolytic enzymes and heat. The range of molecular weights associated with INH activity is unexpectedly wide : from less than5 000 to more than 160 000.
Any measurements of the presence of INH must be carefully assessed : besides the sex steroids there are various compounds that may or do exist in the ovary and/or the testis and which can mimic the effect of INH, depending on the test used.Much can be said
regarding the physiology and the role of INH but very few facts exist. The INH excreted by the testis in the epididymis and present in the RTF presumably plays no role in the regulation of gonadotropin secretion. However INH could be related to the induction of spermatogenesis in the prepuberal animal, and it is probably implicated in the regulation of the secondary rise of FSH that takes place just after the preovulatory surges of LH and FSH.An effort must be made to
purifyINH and
adequate activity tests must be used in order to assess whether it is one biochemical entity having two activities (onFSH and
LH secre-
tion) or two entities which are each specific for a gonadotropin secretion.Introduction.
Si la régulation de la sécrétion de l'hormone folliculo-stimulante (FSH) par l'organe effecteur (ovaire ou testicule) est assurée par les stéroïdes sexuels (Mc Cann,quotesdbs_dbs24.pdfusesText_30[PDF] sertoli
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