Inhibin and related peptides: Mechanisms of action and regulation of secretion

Franchimont, P; Hazee-Hagelstein, M. T.; Jaspar, Jean-Marie; Charlet-Renard, Chantal; Demoulin, A

doi:10.1016/0022-4731(89)90163-5

Cited by 28 publications

(14 citation statements)

References 30 publications

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“…Supporting the present results, many follicles developed and plasma levels of E 2 increased significantly after the passive im munoneu tralization of endogenous inhibin by anti-inhibin serum in mares [16]. It is a well-known fact that the physiological roles of inhibin are as 1) a main inhibitor of FSH secretion, 2) a chemical signal of the number of growing follicles in the ovary and thus 3) a key hormone in determining speciesspecific ovulation rates [4,13,21]. The significant increase in the number of follicles detected in the present study clearly demonstrates that active immunization will act on follicle development as a factor limiting the number of growing follicles through FSH secretion.…”

Section: Discussionsupporting

confidence: 86%

“…In a previous study, active immunization of thoroughbred and standardbred mares against recombinant inhibin α-subunit twice with a 21 day interval increased the ovulation rate in mares [3]. Factors that influence the rate of multiple ovulations are breed, season, reproductive status and genetic predisposition, which might explain the higher incidence of multiple ovulations in Thoroughbred and warm-blooded mares, the intermediate incidence in standardbred mares and the lowest incidence in quarter horses and pony mares [4]. This is may be one of the reasons why mares in this study showed no increase in the ovulation rate after immunization despite the increase in the number of preovulatory follicles.…”

Section: Discussionmentioning

confidence: 89%

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Effect of Active Immunization of Pony Mares against Recombinant Porcine Inhibin .ALPHA. Subunit on Ovarian Follicular Development and Plasma Steroids and Gonadotropins

Derar

Maeda

Hoque

et al. 2004

The Journal of Veterinary Medical Science

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ABSTRACT. Two pony mares were immunized against recombinant porcine inhibin α subunit three times with 39 day intervals. Clinical findings and endocrinological changes before immunization were taken as the control. The first significant rise in the anti-inhibin titre (P<0.05) in the circulation was found 27 days after the first injection. Maximum binding activity was reached by the 12th day after the second booster dose. The number of small, medium and large sized follicles had increased significantly compared to before immunization (11.75 ± 4.30, 2.75 ± 0.69 and 2.51 ± 0.63 vs 6.50 ± 1.43, 1.83 ± 0.44 and 1.33 ± 0.38, respectively), but the ovulation rate remained unchanged after immunization. The average plasma concentration of FSH and estradiol-17β during the estrous cycle increased significantly (P<0.05) after immunization. These results suggest that immunization against inhibin is a useful tool to increase the number of ovarian follicles during the estrous cycle of pony mares. Moreover, the present study supported the concept that inhibin plays a major role in the control of follicular growth through its inhibitory effect on FSH secretion synergistically with steroid hormones. KEY WORDS: follicular development, FSH, immunization, inhibin, mare.J. Vet. Med. Sci. 66(1): [31][32][33][34][35] 2004 The physiological mechanisms responsible for limiting one follicular development and ovulation from multiple follicles during the normal follicular phase in the mare is not yet fully understood. Attempts at inducing multiple ovulation or promoting fertility in the mare with various treatments such as equine chorionic gonadotropin (eCG), equine pituitary extract and PGF 2 α have met with limited success [2,6,10,12,17,20]. Currently, crude pituitary extracts are the most reliable method for inducing multiple ovulations in the mare and this method usually results in one to four ovulations per cycle [5], but pituitary extracts are not readily available and the regimens required are relatively intensive.Inhibin is a large glycosylated protein consisting of two subunits linked by disulfide bridges, and specifically inhibits FSH secretion and suppresses the expression of GnRH receptors in the pituitary gland [1,7,15,22]. On the other hand, the production of inhibin is stimulated by FSH thereby forming a tight feedback circuit [18,19]. It is argued that ovarian inhibin may be the most important hormone for determining the species-specific number of ovulations in both single and multiple ovulatory species.In cattle, active immunization against inhibin enhanced ovarian follicular development and the number of oocytes collected by transvaginal follicular aspiration [8,9]. Furthermore, passive immunization of mares against inhibin during the follicular phase of the estrous cycle results in a marked increase in plasma concentrations of FSH induced by immunoneutralization of endogenous inhibin, and stimulates the rapid growth of a large number of follicles. As a result, multiple ovulations can be induced in mares [16].This study...

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 89%

Effect of Active Immunization of Pony Mares against Recombinant Porcine Inhibin .ALPHA. Subunit on Ovarian Follicular Development and Plasma Steroids and Gonadotropins

Derar

Maeda

Hoque

et al. 2004

The Journal of Veterinary Medical Science

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“…Under normal physiological conditions, these factors may act independently of or synergistically with testosterone and exert their positive effects on the NPY system. It may be recalled that, in addition to androgens, testes secrete proteinous substances, such as activin and inhibins, that are known to exert feedback actions on the brain and pituitary (Franchimont et al, 1989;Tilbrook and Clarke, 2001). Calogero et al (1998) suggested the combinatory participation of activin, inhibins, and testosterone in the regulation of hypothalamopituitarygonadal axis in rat by modulating hypothalamic GnRH release.…”

Section: Response Of the Npy-ir System To Castration And Testosteronementioning

confidence: 98%

Neuropeptide Y in the forebrain of the adult male cichlid fish Oreochromis mossambicus: Distribution, effects of castration and testosterone replacement

Sakharkar

Singru

Sarkar

et al. 2005

J of Comparative Neurology

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We studied the organization of the neuropeptide Y (NPY)-immunoreactive system in the forebrain of adult male cichlid fish Oreochromis mossambicus and its response to castration and testosterone replacement by using morphometric methods. Immunoreactivity for NPY was widely distributed in the forebrain, and the pattern generally resembled that in other teleosts. Whereas immunoreactivity was conspicuous in the ganglia of nervus terminalis (NT; or nucleus olfactoretinalis), a weak reaction was detected in some granule cells in the olfactory bulb and in the cells of area ventralis telencephali pars lateralis (Vl). Moderately to intensely immunoreactive cells were distinctly seen in the nucleus entopeduncularis (NE), nucleus preopticus (NPO), nucleus lateralis tuberis (NLT), paraventricular organ (PVO), and midbrain tegmentum (MT). NPY fibers were widely distributed in the forebrain. Castration for 10/15 days resulted in a drastic loss of immunoreactivity in the cells of NE (P<0.001) and a significant decrease (P<0.01) in their cell nuclear size. However, cell nuclei of the NT neurons showed a significant increase in size. A highly significant reduction in the NPY-immunoreactive fiber density (P<0.001) was observed in several areas of the forebrain. Although testosterone replacement reversed these changes, fibers in some areas showed supranormal responses. Immunoreactive cells in Vl, NPO, NLT, PVO, and MT and fiber density in some other areas did not respond to castration. We suggest that the NPY-immunoreactive elements that respond to castration and testosterone replacement may serve as the substrate for processing the positive feedback action of the steroid hormone.

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“…During the reproductive life of a human and many mammals, peripherally produced activins stimulate pituitary gonadotropin secretion [Ling et al, 1986] which regulate numerous gonadal functions, including the stimulation of inhibin ·-subunit production [Franchimont et al, 1989]. The inhibin ·-subunit then binds to a ß-subunit, these ·:ß dimers then enter the circulation and bind to activin receptors blocking their activity [Muttukrishna, 2001] effectively downregulating the HPG axis [Padmanabhan and West, 2001].…”

Section: Senescencementioning

confidence: 99%

Living and Dying for Sex

2004

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A mechanistic understanding of aging has yet to be described; this paper puts forth a new theory that has the potential to explain aging in all sexually reproductive life forms. The theory also puts forth a new definition of aging – any change in an organism over time. This definition includes not only the changes associated with the loss of function (i.e. senescence, the commonly accepted definition of aging), but also the changes associated with the gain of function (growth and development). Using this definition, the rate of aging would be synonymous with the rate of change. The rate of change/aging is most rapid during the fetal period when organisms develop from a single cell at conception to a multicellular organism at birth. Therefore, ‘fetal aging’ would be determined by factors regulating the rate of mitogenesis, differentiation, and cell death. We suggest that these factors also are responsible for regulating aging throughout life. Thus, whatever controls mitogenesis, differentiation and cell death must also control aging. Since life-extending modalities consistently affect reproduction, and reproductive hormones are known to regulate mitogenesis and differentiation, we propose that aging is primarily regulated by the hormones that control reproduction (hence, the Reproductive-Cell Cycle Theory of Aging). In mammals, reproduction is controlled by the hypothalamic-pituitary-gonadal (HPG) axis hormones. Longevity inducing interventions, including caloric restriction, decrease fertility by suppressing HPG axis hormones and HPG hormones are known to affect signaling through the well-documented longevity regulating GH/IGF-1/PI3K/Akt/Forkhead pathway. This is exemplified by genetic alterations in Caenorhabditis elegans where homologues of the HPG axis pathways, as well as the daf-2 and daf-9 pathways, all converge on daf-16, the homologue of human Forkhead that functions in the regulation of cell cycle events. In summary, we propose that the hormones that regulate reproduction act in an antagonistic pleiotrophic manner to control aging via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence.

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Inhibin and related peptides: Mechanisms of action and regulation of secretion

Cited by 28 publications

References 30 publications

Effect of Active Immunization of Pony Mares against Recombinant Porcine Inhibin .ALPHA. Subunit on Ovarian Follicular Development and Plasma Steroids and Gonadotropins

Effect of Active Immunization of Pony Mares against Recombinant Porcine Inhibin .ALPHA. Subunit on Ovarian Follicular Development and Plasma Steroids and Gonadotropins

Neuropeptide Y in the forebrain of the adult male cichlid fish Oreochromis mossambicus: Distribution, effects of castration and testosterone replacement

Living and Dying for Sex

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