Accumulation of Luteinizing Hormone, Oestradiol and Androstenedione by Sheep Ovarian Follicles in Vivo

McNatty, Kenneth P.; Dobson, Carolyn; Gibb, M.; Kieboom, L. E.; Thurley, D.C.

doi:10.1677/joe.0.0910099

Cited by 20 publications

(12 citation statements)

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“…The LH concentration in the fluid of preovulatory bovine follicles started to rise when the LH concentration in the peripheral blood had already reached its maximum, as was reported by McNatty, Dobson, Gibb, Kieboom & Thurley (1981a) for ovine follicles after administration of LH-releasing hormone to ewes under anaesthesia at 10 days after oestrus. The effects of LH, however, were already evident concurrently with the LH plasma rise, as shown by the rapid decrease of the androstenedione concentration in the follicular fluid.…”

Section: Discussionsupporting

confidence: 65%

Steroid and pituitary hormone concentrations in the fluid of preovulatory bovine follicles relative to the peak of LH in the peripheral blood

Dieleman¹,

Bevers²,

Poortman³

et al. 1983

Reproduction

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Summary. Preovulatory bovine follices (n = 73) were collected at different times after the onset of oestrus until shortly before ovulation, which occurred at 24 \m=+-\1 \ m=. \ 4h after the peak concentration of LH in the peripheral blood. Non-atretic antral follicles (n = 9) of 15\p=n-\19mm were also collected from cows during the luteal phase of the oestrous cycle. Follicular fluid concentrations of dehydroepiandrosterone, androstenedione and oestrone, and of LH, FSH and prolactin were compared in 2-h periods relative to the LH plasma peak. Before the LH surge the concentrations of the steroids were much higher than in non-atretic luteal-phase follicles of similar size. From 0 to 6 h after the LH peak the steroid concentrations decreased sharply to remain low until ovulation; only that of androstenedione increased again after 14 h to remain constant. The ratio between the concentrations of androstenedione and dehydroepiandrosterone remained constant until 14 h after the LH peak; at 14 h it increased about 4-fold and remained high until ovulation. The ratio between the oestrone and androstenedione concentration increased gradually to a 10-fold higher value until at 14 h an abrupt decrease was observed. These changes indicate that after the LH peak androgen production is directly inhibited and, at a slower rate, the aromatizing activity. Androstenedione appeared to be the major aromatase substrate.Before the plasma LH peak the follicular fluid concentration of FSH was higher than in luteal-phase follicles; the concentrations of LH and prolactin were not different from those in luteal-phase follicles. About 4 h after the LH plasma peak the LH concentration in follicular fluid reached a maximum, which was one seventh of that in peripheral blood; it remained elevated until 20 h. The FSH concentration was higher after the LH plasma peak than before; just before ovulation it was still 2-fold higher. The concentration of prolactin fluctuated throughout the preovulatory development from the onset of oestrus until ovulation. It is suggested that oestradiol biosynthesis in bovine preovulatory follicles is terminated by an inhibitory action of the preovulatory LH peak on androgen production.

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Section: Discussionsupporting

confidence: 65%

Steroid and pituitary hormone concentrations in the fluid of preovulatory bovine follicles relative to the peak of LH in the peripheral blood

Dieleman¹,

Bevers²,

Poortman³

et al. 1983

Reproduction

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“…The method of collecting ovarian venous blood under sodium thiopentone anesthesia was as described elsewhere [3]. After the blood samples were recovered, the ovaries were collected into minimum essential medium (Gibco, Grand Island, NY) + Hepes buffer (20 mmol/L; Sigma Chemical Co., St Louis, MO) + 1.0% (w/v) BSA (> 97% pure; Immuno-Chemical Products Ltd., Auckland, New Zealand) + 3-isobutyl-1-methylxanthine (0.2 mmol/L; IBMX; Sigma) (MEM buffer).…”

Section: Methodsmentioning

confidence: 99%

Plasma Gonadotropin Concentrations and Ovarian Characteristics in Inverdale Ewes that are Heterozygous for a Major Gene (FecX1) on the X Chromosome that Influences Ovulation Rate

Shackell

Hudson²,

Heath³

et al. 1993

Biology of Reproduction

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Ewes heterozygous (I+) for the Inverdale prolificacy gene (FecX1) located on the X chromosome have ovulation rates approximately 1.0 times higher than noncarriers (++). The aims of this study were to examine, in I+ and ++ ewes, the peripheral plasma concentrations and/or ovarian secretion rates of FSH, LH, inhibin, estradiol, and progesterone during anestrus and the estrous cycle and after ovariectomy. Also examined were aspects of ovarian morphology and functions of granulosa cells in vitro. No FecX1-specific differences were noted for the ovarian hormones or for FSH or LH. However, I+ animals contained significantly more ovarian antral follicles (p < 0.05) and their granulosa cells had a higher mean LH responsiveness in vitro with respect to cAMP synthesis at smaller follicular diameters relative to ++ ewes (I+ = > 2.5 mm; ++ = > 4.5 mm). Moreover, nonatretic follicles in I+ animals compared to the ++ genotype contained fewer granulosa cells and smaller CL. Although the I+ animals had a higher ovulation rate than the controls (p < 0.05), the total weight of CL was not different between the genotypes. These findings suggest that the FecX1 gene affects ovarian function without altering ovarian hormone secretion. The findings also suggest that there are no FecX1-specific differences in the mean concentrations of gonadotropins, although further studies on temporal changes in gonadotropin secretion are warranted.

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“…Also, the exogenous ovine FSH regimen was effective when administered for 24 h but not when administered for only 6 h. These findings suggest that during the 6 h treatment regimen the dose of ovine FSH may have been too low and/or that the granulosa cells were not exposed to the additional FSH for a sufficient period of time. The latter is a possibility because of the time required for proteins to traverse to the granulosa cells from the peripheral circulation (Cran, Moor & Hay, 1976 Dobson, Gibb, Kieboom & Thurley, 1981;Dieleman, Bevers, Poortman & van Toi, 1983).…”

Section: Methodsmentioning

confidence: 99%

FSH influences follicle viability, oestradiol biosynthesis and ovulation rate in Romney ewes

McNatty¹,

Hudson²,

Gibb³

et al. 1985

Reproduction

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Summary. Injection of steroid-free bovine follicular fluid (bFF; 2 \m=x\5 ml s.c. 12h apart) into anoestrous ewes lowered plasma FSH concentrations by 70% and after 24 h had significantly (P < 0\m=.\01) reduced the number of non-atretic follicles (\ m=ge\ 1 mm diam.) without influencing the total number of follicles (\ m=ge\ 1 mm diam.) compared to untreated controls. Hourly injections of FSH (10 \g=m\g i.v. NIH-FSH-S12) for 24 h did not influence the number of non-atretic follicles but did negate the inhibitory effects of bFF on follicular viability. Hourly injections of FSH (50 \ g=m\ gi.v., NIH-FSH-S12) + bFF treatment for 24 h significantly increased the total number of non-atretic follicles, and particularly the number of medium to large non-atretic follicles (\ m=ge\ 3 mm diam.) compared to the untreated controls (both P < 0\m=.\01). The 10\g=m\g FSH regimen (without bFF) significantly increased aromatase activity in granulosa cells from large ( \ m=ge\ 5 mm diam.; P < 0\m=.\01) but not medium (3\ p=n-\ 4\ m=. \ 5 mm diam.) or small (1\ p=n-\ 2\ m=. \ 5 mm diam.) follicles compared to controls. The 10 \g=m\g FSH + bFF regimen had no effect on granulosa-cell aromatase activity compared to the controls. However, the 50 \g=m\g FSH plus bFF regimen increased the aromatase activity of granulosa cells from large, medium and small non-atretic follicles 2\m=.\6-,8\m=.\3-and \m=ge\11-fold respectively compared to that in the control cells. Ewes (N = 11) that ovulated 2 follicles had significantly higher plasma FSH concentrations from 48 to 24 h and 24 to 0 h before the onset of a cloprostenol-induced follicular phase (both P < 0\m=.\01) than in the ewes (N = 12) that subsequently ovulated one follicle. Hourly FSH treatment (1\m=.\6 \ g =m\ g i.v., NIAMDD-FSH-S15) for 24 h but not for any 6 h intervals between 48 and 24 h or 24 and 0 h before a cloprostenol-induced luteolysis also resulted in significant increases (P < 0\m=.\05) in the number of ewes with 2 ovulations.We conclude that (1) the number of non-atretic antral follicles in sheep ovaries is influenced by plasma FSH concentrations; (2) the level of follicular oestradiol biosynthesis can be enhanced by FSH treatment; and (3) sustained elevations of plasma FSH concentrations for 24 h but not 6 h within 48 h of the onset of luteolysis significantly enhances the ovulation rate in Romney ewes.

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Accumulation of Luteinizing Hormone, Oestradiol and Androstenedione by Sheep Ovarian Follicles in Vivo

Cited by 20 publications

References 0 publications

Steroid and pituitary hormone concentrations in the fluid of preovulatory bovine follicles relative to the peak of LH in the peripheral blood

Steroid and pituitary hormone concentrations in the fluid of preovulatory bovine follicles relative to the peak of LH in the peripheral blood

Plasma Gonadotropin Concentrations and Ovarian Characteristics in Inverdale Ewes that are Heterozygous for a Major Gene (FecX1) on the X Chromosome that Influences Ovulation Rate

FSH influences follicle viability, oestradiol biosynthesis and ovulation rate in Romney ewes

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