Secretion of Bioactive Inhibin by the Ovary of the Booroola Merino Ewe With or Without a Copy of the Fecundity (F) Gene.

Tsonis, C. G.; Baird, D. T.; Campbell, B. K.; Downing, J. A.; Scaramuzzi, R. J.

doi:10.1677/joe.0.119r005

Cited by 6 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The present results are, in part, at variance with those of Tsonis et al (1988) who, although reporting no gene differences in inhibin secretion during the luteal phase, noted a significant differ¬ ence at 48 h but not at 24 or 36 h after cloprostenol injection with a higher secretion rate in + /BB animals than in ++ animals. In our study no gene-specific differences in plasma inhibin were noted at any time during the follicular or luteal phase.…”

Section: Discussionsupporting

confidence: 60%

“…In our study no gene-specific differences in plasma inhibin were noted at any time during the follicular or luteal phase. In part, the discrepancy may be explained by the fact that, in the study by Tsonis et al (1988), only four B+ or BB animals and six ++ animals were examined and that these animals experienced their pre-ovulatory LH surges at markedly different times after cloprostenol injection (i.e. 48 h to > 72 h).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Concentrations of immunoreactive inhibin in ovarian and peripheral venous plasma and follicular fluid of Booroola ewes that are homozygous carriers or non-carriers of the FecB gene

McNatty¹,

Heath²,

Hudson³

et al. 1992

Reproduction

View full text Add to dashboard Cite

No gene-specific differences were found during either the luteal or follicular phases of the oestrous cycle in the venous secretion rates of ovaries or in concentrations of immunoreactive inhibin in peripheral plasma between Booroola ewes that were homozygous carriers (BB) or non-carriers (++) of the FecB gene. In three experiments in which concentrations of plasma inhibin and follicle-stimulating hormone (FSH) were compared, gene-specific differences were noted for FSH (P less than 0.05), but no significant correlations were noted between FSH and inhibin for either genotype. Granulosa cells and follicular fluid, but not theca interna, stroma or corpora lutea, were the major intra-ovarian sites of inhibin; no gene-specific differences were noted for inhibin concentrations in follicular fluid or in any of the intra-ovarian tissues. The mean concentrations of inhibin in follicular fluid remained constant irrespective of follicular diameter whereas the mean total contents of inhibin increased significantly with increasing diameter (P less than 0.05). Inhibin secretion rates were four times higher in ovaries with oestrogen-enriched follicles (i.e. greater than or equal to 50 ng oestradiol ml-1) than in ovaries with no such follicles (P less than 0.01). Moreover, inhibin concentrations were higher in follicular fluid of oestrogen-enriched follicles than in those with low oestrogen (i.e. less than 50 ng ml-1; P less than 0.05). Ovariectomy resulted in a significant reduction in concentrations of immunoreactive inhibin from plasma (P less than 0.01). The residual plasma inhibin in some Booroola ewes was not associated with genotype. It is concluded that, although antral follicles are a major source of inhibin in Booroola ewes, immunoreactive inhibin is not associated with the FecB gene and is not responsible for the gene-specific differences in concentrations of FSH in plasma.

show abstract

Section: Discussionsupporting

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Concentrations of immunoreactive inhibin in ovarian and peripheral venous plasma and follicular fluid of Booroola ewes that are homozygous carriers or non-carriers of the FecB gene

McNatty¹,

Heath²,

Hudson³

et al. 1992

Reproduction

View full text Add to dashboard Cite

show abstract

“…(Lincoln et al, 1990). Preliminary data suggest that Booroola Merino ewes ( + F or FF) carrying the high fecundity gene secrete the same amount of oestradiol and inhibin as those without the gene ( ++ ) (Tsonis et al, 1988c). The preovulatory follicles of the + F ewes are smaller and contain fewer granulosa cells than in ++ controls (Baird et al, 1982).…”

Section: Second Fsh Peakmentioning

confidence: 99%

Inhibin and oestradiol in the control of FSH secretion in the sheep

Baird

Campbell²,

Mann³

et al. 2019

Proc

View full text Add to dashboard Cite

In the sheep both FSH and LH are necessary for development of large antral follicles. The secretion of FSH is controlled by the negative feedback effect of two ovarian hormones, oestradiol and inhibin, acting at the level of the anterior pituitary. Both are derived from the granulosa cells of large antral follicles which are present in sheep ovaries throughout the oestrous cycle. FSH stimulates growth and mitosis and so the fully differentiated granulosa cells of the large preovulatory follicles acquire receptors for LH, have maximal aromatase activity and produce large amounts of inhibin. The number of these large antral follicles (oestrogenic) which have the potential for ovulation corresponds to the ovulation rate specific for each particular breed of sheep. Over 90% of the oestradiol secreted by the ovaries is derived from these chosen follicles. In contrast, inhibin (and androstenedione) is also secreted by large antral follicles which have lost or not yet acquired maximal aromatase activity. The secretion of oestradiol by the preovulatory follicle(s) is dependent on the supply of androgen precursors produced by the theca which is stimulated by LH. When the concentration of progesterone falls at the end of the luteal phase the increased secretion of LH stimulates the progressive increase in secretion of oestradiol which occurs during the follicular phase. At this stage of the cycle there is a modest inconsistent rise in inhibin, the secretion of which is not stimulated by LH but is related to the increase in the number of large antral follicles. It is suggested that inhibin with its long half-life sets the overall level of negative feedback while oestradiol is responsible for the day-today fluctuations in the concentration of FSH which determines the number of ovulatory follicles. This dual control of FSH is adapted to monitor both the total number of large antral follicles in the ovaries (inhibin) and the number which are selected for ovulation (oestradiol).

show abstract

“…Recently Wang et al (16) concluded that the reduction of rat pituitary responsiveness to G n R H induced by inhibin might be partly related to a decrease in the number of GnRH receptors. Gene-specific differences in bioactive inhibin have been noted between FF/F + ewes and + + ewes at 36 to 48 h after prostaglandin treatment, but not at Day 14 of the oestrous cycle (14). It remains to be determined whether gene-specific differences exist in inhibin secretion at other times of the oestrous cycle in Booroola ewes.…”

Section: Discussionmentioning

confidence: 99%

Pituitary Binding Sites for Gonadotrophin‐Releasing Hormone in Booroola Merino Ewes which were Non‐Carriers or Homozygotes of the Fecundity Gene F

Fleming

Lun

Smith

et al. 1990

J Neuroendocrinology

View full text Add to dashboard Cite

Pituitary binding sites for gonadotrophin-releasing hormone (GnRH) were examined in Booroola ewes on Days 4 and 12 of the oestrous cycle and more than 12 months after ovariectomy. No significant differences were observed in the affinity of the binding sites for [lZ51]D Ala6, des Gly" GnRH ethylamide, in non-carriers ( + + ) or homozygotes of the fecundity gene (FF), in intact or ovariectomized animals (overall Ka=(1.8f0.1) x lo9 M-'; mean+SEM, n=67). In + + ewes, the number of GnRH binding sites on Day 4 of the oestrous cycle (0.199f0.025 fmol/mg pituitary, n=8) was significantly greater (P<0.05) than on Day 12 (0.107k0.012 fmol/mg pituitary, n=12). In contrast in FF ewes the number of binding sites on Days 4 and 12 were similar (Day 4: 0.119k0.030, n=8; Day 12: 0.092k0.014, n=10). On Day 4, but not Day 12, the binding site numbers were significantly higher in + + compared with FF pituitaries (P<0.05). Likewise on Day 4, but not Day 12, the plasma concentrations of follicle-stimulating hormone were significantly higher (P<0.005) in FF (1.60f0.15 nglml) than + + ewes (0.96f0.10 ng/ml). After ovariectomy, no gene-specific differences in binding site numbers were noted despite significantly higher plasma follicle-stimulating hormone concentrations in FF animals. No gene-specific differences in plasma luteinizing hormone concentrations were observed in these animals on Days 4 or 12, or after ovariectomy. Moreover, luteal phase plasma progesterone concentrations were also similar between + + and FF ewes.We conclude that the gene-specific differences in pituitary responsiveness to GnRH and in pituitary gonadotrophin output are unlikely to be due to differences in GnRH receptor binding affinities.

show abstract

Secretion of Bioactive Inhibin by the Ovary of the Booroola Merino Ewe With or Without a Copy of the Fecundity (F) Gene.

Cited by 6 publications

References 15 publications

Concentrations of immunoreactive inhibin in ovarian and peripheral venous plasma and follicular fluid of Booroola ewes that are homozygous carriers or non-carriers of the FecB gene

Concentrations of immunoreactive inhibin in ovarian and peripheral venous plasma and follicular fluid of Booroola ewes that are homozygous carriers or non-carriers of the FecB gene

Inhibin and oestradiol in the control of FSH secretion in the sheep

Pituitary Binding Sites for Gonadotrophin‐Releasing Hormone in Booroola Merino Ewes which were Non‐Carriers or Homozygotes of the Fecundity Gene F

Contact Info

Product

Resources

About