Pituitary response to GnRH and ovariectomy in Booroola-Awassi and Awassi ewe lambs

Braw–Tal, R.; Gootwine, E.

doi:10.1530/jrf.0.0870073

Cited by 8 publications

(6 citation statements)

References 18 publications

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“…On the other hand inhibin ßA subunit was not expressed in preantral follicles, partially expressed in small antral follicles Journal of Molecular Endocrinology (1994) 13, [253][254][255][256][257][258][259][260][261][262][263][264] and only fully expressed in large antral follicles (>2 mm). In the early prepubertal ovary, where antral follicles larger than 2 mm were rare or not found (Kennedy et al 1974;Braw-Tal & Gootwine, 1989;Braw-Tal et al 1993;present study), inhibin a subunit was expressed in all non-atretic antral follicles, while inhibin ßA subunit expression was limited mainly to the cumulus and periantral granulosa cells. Moreover, all follicles expressing inhibin ßA also expressed a subunit, but there were follicles which expressed a subunit where ßA mRNA was not found.…”

Section: Discussionmentioning

confidence: 63%

Expression of mRNA for follistatin and inhibin/activin subunits during follicular growth and atresia

Braw–Tal

1994

Journal of Molecular Endocrinology

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The aim of the present study was to investigate the sites and time of follistatin and inhibin alpha and beta A subunit gene expression during ovine follicular development and atresia. Prepubertal ovaries of 2-, 8- and 14-week-old ewe lambs (n = 9) were used. Regardless of age, the ovaries contained many follicles at different stages of development up to 2 mm in diameter, but large antral follicles were not found. Ovarian sections were hybridized with 35S-labelled antisense RNA probes transcribed from follistatin, inhibin alpha or inhibin beta A cDNA. Ovaries from mature gonadotrophin-stimulated ewes were used as controls. All three probes hybridized exclusively to granulosa cells, and not to other follicular or stromal cells. None of the probes hybridized to primordial follicles or primary follicles with less than two layers of granulosa cells. Follistatin mRNA was expressed strongly in the granulosa cells of all preantral follicles with two or more layers of cells, and in all non-atretic antral follicles. In addition, follistatin mRNA was found in some cells of the ovarian rete tubules. The inhibin alpha riboprobe hybridized to the granulosa cells of most preantral and all non-atretic antral follicles. In the preantral follicles, the strongest inhibin alpha expression was observed in the cells that were in close proximity to the oocyte. The inhibin beta A riboprobe hybridized exclusively to the granulosa cells of antral follicles. The labelling was observed either in the cumulus oophorus or in the cumulus oophorus and periantral granulosa cells of the non-atretic antral follicles. In adult ovaries, which were used as controls, the inhibin beta A riboprobe hybridized strongly to all granulosa cells of non-atretic large antral follicles. During follicular atresia, expression of all three mRNAs progressively decreased. In early atresia, inhibin beta A mRNA was observed only in the cells of the cumulus, whereas inhibin alpha and follistatin mRNAs were still present in the granulosa cells. As atresia progressed mRNA for inhibin alpha, and later also follistatin, disappeared. Our results suggest that there is a sequential appearance and disappearance of follistatin, inhibin alpha and inhibin beta A mRNAs during follicular development and atresia respectively. The marked expression of inhibin beta A in the cumulus cells implies a role of the oocyte in the differentiation of these cells.

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Section: Discussionmentioning

confidence: 63%

Expression of mRNA for follistatin and inhibin/activin subunits during follicular growth and atresia

Braw–Tal

1994

Journal of Molecular Endocrinology

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“…Other studies have been unable to show any F gene-specific differences in hypothalamic GnRH concen¬ trations (Gale et ai, 1987), GnRH-receptor binding in pituitary tissue (Fleming et ai, 1990) or in the GnRH secretory characteristics in hypophysial-portal blood (K. P. McNatty & I. J. Clarke, unpublished findings). Although a number of studies in gonad-intact Booroola ewe-lambs as well as in adult rams and ewes report differences between F gene carriers and controls in pituitary FSH and/or LH output to exogenous GnRH (McNatty et ai, 1987;Braw-Tal & Gootwine, 1989;Price et ai, 1991;C. A.…”

Section: Discussionmentioning

confidence: 99%

GnRH-induced gonadotrophin secretion in ovariectomized Booroola ewes with hypothalamic--pituitary disconnection

McNatty¹,

Hudson

Shaw

et al. 1991

Reproduction

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To test whether the F gene-specific differences in the plasma concentrations of FSH and LH are due to differences in the pituitary responsiveness to exogenous GnRH, ovariectomized Booroola ewes with hypothalamic-pituitary disconnection (HPD-ovx) were treated with GnRH (250 ng i.v.) once every 2 h for up to 5 weeks. In Exp. 1, jugular venous blood was collected once weekly from 13 FF and 14 ++ HPD-ovx ewes for 6 weeks before GnRH treatment and every 2nd, 3rd or 6th day for 5 weeks during treatment. In Exp. 2, jugular venous blood was collected from another 8 FF and 7 ++ HPD-ovx ewes at 5- or 10-min intervals over 4 GnRH pulses (250 ng i.v. once every 2 h) on 3 separate occasions after the animals had been subjected to the GnRH pulse regimen for approximately 7 days beforehand. Also in Exp. 2, the animals were extensively sampled around a larger (10 micrograms) i.v. injection of GnRH and the pituitary FSH and LH contents assessed after the animals had been re-exposed to the once every 2 h GnRH (250 ng i.v.) pulse regimen for several days following the larger GnRH bolus. In Exp. 3 the distributions of mean plasma concentrations of FSH and LH in individual GnRH-treated HPD-ovx ewes were compared with those in ovariectomized and ovary-intact FF and ++ ewes. During the 6 weeks before GnRH treatment (Exp. 1), the plasma concentrations of FSH (approximately 1 ng/ml) and LH (less than or equal to 0.8 ng/ml) were not different between the genotypes. After GnRH treatment both the mean FSH and LH concentrations increased significantly (P less than 0.01) above basal values after 2 days with F gene-specific differences being noted for FSH but not LH (FSH; FF greater than ++; P less than 0.05). Thereafter, the mean FSH but not LH concentrations increased at a faster rate in FF than in ++ ewes with the overall mean FSH concentrations between the genotypes being significantly different (P less than 0.05). In Exp. 2 considerable between-animal variation in the pulsatile pattern of FSH but not LH concentrations was seen in ewes of both genotypes during GnRH treatment. The overall mean FSH concentrations were higher in FF than in ++ ewes (P less than 0.05) and the mean FSH response to each GnRH pulse was significantly higher in FF than in ++ ewes (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

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“…In ewe lambs, plasma FSH, but not LH concentrations, were significantly higher between 3 and 5 weeks of age in BB or B+ compared to ++ or non-Booroola controls (50)(51)(52). Neither LH nor FSH concentrations differed significantly between genotypes in ram lambs at these ages.…”

Section: Gonadotropin Concentrations In Peripheral Plasmamentioning

confidence: 75%

“…50-52 and 75 and Isaacs, K., and K. P. McNatty, unpublished data) and in the number and/or diameters of antral follicles (51,70,88). For example, differences have been observed in the plasma concentrations of FSH and inhibin (Refs.…”

Section: Is the Booroola Gene Expressed During Fetal Development?mentioning

confidence: 87%

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Physiology and Molecular Genetics of Mutations that Increase Ovulation Rate in Sheep

1992

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Pituitary response to GnRH and ovariectomy in Booroola-Awassi and Awassi ewe lambs

Cited by 8 publications

References 18 publications

Expression of mRNA for follistatin and inhibin/activin subunits during follicular growth and atresia

Expression of mRNA for follistatin and inhibin/activin subunits during follicular growth and atresia

GnRH-induced gonadotrophin secretion in ovariectomized Booroola ewes with hypothalamic--pituitary disconnection

Physiology and Molecular Genetics of Mutations that Increase Ovulation Rate in Sheep

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