Gonadotropin requirements for dominant follicle selection in GnRH agonist-treated cows

Hampton, J H; Bader, J.F.; Lamberson, W. R.; Smith, Michael F.; Youngquist, R.S.; Garverick, H.A.

doi:10.1530/rep.1.00015

Cited by 23 publications

(15 citation statements)

References 28 publications

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“…Indeed, ovarian weight, follicular activity, and number of corpora lutea did not differ between animals receiving Fca alone and those receiving either the dually active chimera or the FcaCCGba combination. These observations are consistent with previous reports noting significant FSH-induced follicle development without coincident estrogen production in LH-deficient sheep (Picton et al 1990, Campbell et al 1998, cattle (Hampton et al 2004), and primates (Karnitis et al 1994, Zelinski-Wooten et al 1995.…”

Section: Discussionsupporting

confidence: 93%

Single-chain human gonadotropin analogs induce follicle development in sheep

Lemke

Adams

Jablonka‐Shariff

et al. 2007

Journal of Endocrinology

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The biopotency of single-chain analogs of human hFSH, human chorionic gonadotropin (hCG), and a dually active gonadotropin construct (FcCGba) was examined. Sheep (bwtZ61 . 4G1 . 1 kg; nZ6 ewes/treatment) received a single injection (5 IU/kg, i.v.) of the hFSH analog (Fca), the hCG analog (CGba), FcCGba, or Fca and CGba. Control animals received conditioned media. Ovulation was induced 3 days after analog administration using hCG (1000 IU, i.v.). Basal serum concentrations of estradiol (E 2 ) were maintained in control animals. Neither Fca nor CGba alone induced significant E 2 production during the pre-hCG period. Conversely, serum concentrations of E 2 were increased (P!0 . 05) 2 days after administration of FcCGba or FcaC CGba. Although P 4 concentrations were maintained at basal levels in control animals, significant increase was noted in all other treatment groups during the post-hCG period. Final ovarian weight was significantly increased (P!0 . 05) in animals receiving Fca, FcaC CGba, or FcCGba, but not CGba alone. Most of the ovarian enlargement was attributed to the formation of corpora lutea. Collectively, these observations demonstrate that the single-chain analogs of the human gonadotropins are active in sheep. The construct with singular FSH activity supports follicle development but not E 2 production. Conversely, the construct that incorporates b-domains from both CG and FSH has dual activity. The long-lived nature of the single-chain constructs suggests that these recombinant gonadotropins may be effective alternatives to pituitary-or placenta-derived gonadotropins in outof-season breeding and/or superovulation protocols.

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Section: Discussionsupporting

confidence: 93%

Single-chain human gonadotropin analogs induce follicle development in sheep

Lemke

Adams

Jablonka‐Shariff

et al. 2007

Journal of Endocrinology

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“…Our results concerning theca cells are consistent with those of a previous study that also tested the role of LH pulses in follicle growth [60]. Those researchers treated cows with a GnRH agonist until follicle growth greater than 5 mm in diameter was inhibited.…”

Section: Discussionsupporting

confidence: 91%

The Role of Luteinizing Hormone in Regulating Gene Expression During Selection of a Dominant Follicle in Cattle

Luo¹,

Gümen²,

Haughian³

et al. 2010

Biology of Reproduction

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At approximately 8.5 mm in diameter, the future dominant follicle is "selected" for continued growth in cattle. In the present study, cows were treated with a gonadotropin-releasing hormone receptor antagonist, acyline, just before follicle selection (near 7.8 mm) to investigate the role of LH in changing mRNA concentrations during selection of a dominant follicle. The ovaries containing the expected dominant follicle (EDF; first largest follicle) and expected largest subordinate follicle (ESF) were removed after 12 or 24 h of treatment. Real-time PCR was used to determine mRNA concentrations. ELISA was used to measure testosterone and 17beta-estradiol (E(2)) and radioimmunoassay to measure androstenedione (A(4)) in follicular fluid. Concentrations of E(2) were greater in EDF than in ESF of untreated cows near the time of follicle selection (12 h) or at 12 h after selection (24 h). Testosterone, E(2), and A(4) were all dramatically decreased by acyline treatment at both times. In theca cells, acyline treatment reduced CYP17A1 (P450 17alpha) in EDF and STAR (steroidogenic acute regulatory protein) in both EDF and ESF but did not alter CYP11A1 (P450scc). In granulosa cells (GCs), LHCGR (luteinizing hormone [LH] receptor) was much greater in EDF than in ESF at both time of selection (739% greater) and 12 h after selection (2837% greater) and was decreased by acyline in EDF (87% decrease). The mRNA for CYP19A1 (cytochrome P450 aromatase) and PAPPA (pregnancy-associated plasma protein-A) tended to be greater in EDF than in ESF at follicle selection, and both mRNAs were much greater at 12 h after selection, with acyline significantly decreasing PAPPA mRNA after 24 h of treatment. The mRNA for FSHR (follicle-stimulating hormone receptor) was not different in EDF versus ESF and was not altered by acyline. Thus, induction of LHCGR mRNA in GCs is an early event during the follicle selection process, and surprisingly, expression of LHCGR mRNA is dependent on circulating LH. Production of follicular A(4), testosterone, and E(2) are also acutely related to LH but due to changes in expression of STAR and CYP17A1 in TC.

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“…Suppression of LH secretion by P 4 treatment at the time of follicular deviation decreases follicular E 2 and free IGF1 concentrations and increases IGF-binding protein 2 (IGFBP2) concentration in the follicular fluid of the dominant follicle (Ginther et al 2001b). Pulsatile LH infusion into GNRH agonist-treated cows and during the follicular wave of cyclic cows demonstrated that the LH is required for mRNA expression of steroidogenic enzymes in both granulosa and theca cells, which is responsible for a dramatic increase in the follicular fluid concentration of E 2 and further follicular growth (Crowe et al 2001, Manikkam et al 2001, Hampton et al 2004. We postulated that enhanced LH pulses in the CL-absent cows permit accelerated F2 growth and thus stimulate E 2 production.…”

Section: Discussionmentioning

confidence: 99%

The absence of corpus luteum formation alters the endocrine profile and affects follicular development during the first follicular wave in cattle

Hayashi¹,

Matsui²,

Shimizu³

et al. 2008

Reproduction

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We previously established a bovine experimental model showing that the corpus luteum (CL) does not appear following aspiration of the preovulatory follicle before the onset of LH surge. Using this model, the present study aimed to determine the profile of follicular development and the endocrinological environment in the absence of CL with variable nadir circulating progesterone (P 4 ) concentrations during the oestrous cycle in cattle. Luteolysis was induced in heifers and cows and they were assigned either to have the dominant follicle aspirated (CL-absent) or ovulation induced (CL-present). Ultrasound scanning to observe the diameter of each follicle and blood collection was performed from the day of follicular aspiration or ovulation and continued for 6 days. The CL-absent cattle maintained nadir circulating P 4 throughout the experimental period and showed a similar diameter between the largest and second largest follicle, resulting in co-dominant follicles. Oestradiol (E 2 ) concentrations were greater in the CL-absent cows than in the CL-present cows at day K1, day 1 and day 2 from follicular deviation. The CL-absent cows had a higher basal concentration, area under the curve (AUC), pulse amplitude and pulse frequency of LH than the CL-present cows. After follicular deviation, the CL-absent cows showed a greater basal concentration, AUC and pulse amplitude of growth hormone (GH) than the CL-present cows. These results suggest that the absence of CL accompanying nadir circulating P 4 induces an enhancement of LH pulses, which involves the growth of the co-dominant follicles. Our results also suggest that circulating levels of P 4 and E 2 affect pulsatile GH secretion in cattle.

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Gonadotropin requirements for dominant follicle selection in GnRH agonist-treated cows

Cited by 23 publications

References 28 publications

Single-chain human gonadotropin analogs induce follicle development in sheep

Single-chain human gonadotropin analogs induce follicle development in sheep

The Role of Luteinizing Hormone in Regulating Gene Expression During Selection of a Dominant Follicle in Cattle

The absence of corpus luteum formation alters the endocrine profile and affects follicular development during the first follicular wave in cattle

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