[A new aspect of the regulation of reproduction: intragonadal cybernins].
The testes and ovaries secrete peptide compounds which act on the gonads themselves and can thus be defined as cybernines. Several factors have been identified. The granulosa cells secrete an ovocyte maturation inhibitor (OMI) into the follicular fluid which opposes ovocyte miosis activity before the pre-ovulatory LH peak. The follicular fluid also contains the inhibitor of FSH uptake by the receptors (FSH-RBI), which appears to be implicated in the maintenance of the follicle in the immature state or in its progression towards atresia. This FSH-RBI is also found in testicular extracts. The luteinization inhibitor (LI) prevents morphological transformation of the granulosa cells into luteal cells and the secretion of progesterone. Sertoli and granulosa cells secrete inhibin, which acts, by a feed-back mechanism, on FSH secretion and to a lesser degree on that of LH by the pituitary. Furthermore, it directly inhibits multiplication of spermatogonias and diminishes progesterone secretion by the granulosa cells, as shown by in vitro studies. The LH uptake inhibitor (LH-RBI) is found in the corpora lutea in increasing quantities with age of this ovarian structure, and prevents luteal and granulosa cell progesterone secretion. This cybernine is probably one of the luteolytic factors. Gonadocrinins secreted by Sertoli and granulosa cells stimulate gonadotrophins liberation from pituitary cells such as hypothalamic LH-RH. It could be the same or slight by different factors. They act on specific receptors in Leydig's cells, the internal theca and the corpora lutea, leading to a reduction in LH receptors and thus the formation of sex steroids. The chemical structure of the cybernines is unknown, as well as their physiological and biochemical interrelationships.
D000293:Adolescent; D000328:Adult; D000818:Animals; D002648:Child; D005260:Female; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors / Q000502:physiology; D006023:Glycoproteins / Q000502:physiology; D012739:Gonadal Steroid Hormones / Q000502:physiology; D006065:Gonadotropins, Pituitary / Q000378:metabolism; D006727:Hormone Antagonists / Q000502:physiology; D006801:Humans; D007265:Inhibins / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009479:Neuropeptides; D010053:Ovary / Q000502:physiology*; D010455:Peptides / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000502:physiology; D012098:Reproduction; D013737:Testis / Q000502:physiology*
D006023:Glycoproteins; D012739:Gonadal Steroid Hormones; D006065:Gonadotropins, Pituitary; D006727:Hormone Antagonists; D036341:Intercellular Signaling Peptides and Proteins; C011898:LH receptor binding inhibitor; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D010455:Peptides; D011956:Receptors, Cell Surface; C036580:cybernins; C014995:gonadotropin inhibitor; C018355:intraovarian peptides; D007265:Inhibins; D005640:Follicle Stimulating Hormone
Un aspect nouveau de la régulation de la reproduction: les cybernines intragonadiques.