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Gonadotropin-releasing hormone, estradiol, and inhibin regulation of follicle-stimulating hormone and luteinizing hormone surges: implications for follicle emergence and selection in heifers.
Biol Reprod 2013; 88(6):165BR

Abstract

Mechanisms regulating gonadotropin surges and gonadotropin requirements for follicle emergence and selection were studied in heifers. Experiment 1 evaluated whether follicular inhibins regulate the preovulatory luteinizing hormone (LH)/follicle-stimulating hormone (FSH) surges elicited by gonadotropin-releasing hormone (GnRH) injection (Hour = 0) and the subsequent periovulatory FSH surge. Treatments included control (n = 6), steroid-depleted bovine follicular fluid (bFF) at Hour -4 (n = 6), and bFF at Hour 6 (n = 6). Gonadotropins in blood were assessed hourly from Hours -6 to 36, and follicle growth tracked by ultrasound. Consistent with inhibin independence, bFF at Hour -4 did not impact the GnRH-induced preovulatory FSH surge, whereas treatment at Hour 6 delayed onset of the periovulatory FSH surge and impeded growth of a new follicular wave. Experiment 2 examined GnRH and estradiol (E2) regulation of the periovulatory FSH surge. Treatment groups were control (n = 8), GnRH-receptor antagonist (GnRHr-ant, n = 8), and E2 + GnRHr-ant (n = 4). GnRHr-ant (acyline) did not reduce the concentrations of FSH during the periovulatory surge and early follicle development (<7.0 mm) was unaffected, although subsequent growth of a dominant follicle (>8.0 mm) was prevented by GnRHr-ant. Addition of E2 delayed both the onset of the periovulatory FSH surge and emergence of a follicular wave. Failure to select a dominant follicle in the GnRHr-ant group was associated with reduced concentrations of LH but not FSH. Maximum diameter of F1 in controls (13.3 ± 0.5 mm) was greater than in both GnRHr-ant (7.7 ± 0.3 mm) and E2 + GnRHr-ant (6.7 ± 0.8 mm) groups. Results indicated that the periovulatory FSH surge stems from removal of negative stimuli (follicular E2 and inhibin), but is independent of GnRH stimulation. Emergence and early growth of follicles (until about 8 mm) requires the periovulatory FSH surge but not LH pulses. However, follicular deviation and late-stage growth of a single dominant follicle requires GnRH-dependent LH pulses.

Authors+Show Affiliations

Department of Dairy Science, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

23658431

Citation

Haughian, James M., et al. "Gonadotropin-releasing Hormone, Estradiol, and Inhibin Regulation of Follicle-stimulating Hormone and Luteinizing Hormone Surges: Implications for Follicle Emergence and Selection in Heifers." Biology of Reproduction, vol. 88, no. 6, 2013, p. 165.
Haughian JM, Ginther OJ, Diaz FJ, et al. Gonadotropin-releasing hormone, estradiol, and inhibin regulation of follicle-stimulating hormone and luteinizing hormone surges: implications for follicle emergence and selection in heifers. Biol Reprod. 2013;88(6):165.
Haughian, J. M., Ginther, O. J., Diaz, F. J., & Wiltbank, M. C. (2013). Gonadotropin-releasing hormone, estradiol, and inhibin regulation of follicle-stimulating hormone and luteinizing hormone surges: implications for follicle emergence and selection in heifers. Biology of Reproduction, 88(6), p. 165. doi:10.1095/biolreprod.112.107342.
Haughian JM, et al. Gonadotropin-releasing Hormone, Estradiol, and Inhibin Regulation of Follicle-stimulating Hormone and Luteinizing Hormone Surges: Implications for Follicle Emergence and Selection in Heifers. Biol Reprod. 2013;88(6):165. PubMed PMID: 23658431.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Gonadotropin-releasing hormone, estradiol, and inhibin regulation of follicle-stimulating hormone and luteinizing hormone surges: implications for follicle emergence and selection in heifers. AU - Haughian,James M, AU - Ginther,O J, AU - Diaz,Francisco J, AU - Wiltbank,Milo C, Y1 - 2013/06/27/ PY - 2013/5/10/entrez PY - 2013/5/10/pubmed PY - 2013/10/22/medline KW - FSH KW - GnRH KW - LH KW - estradiol KW - follicular development KW - inhibin SP - 165 EP - 165 JF - Biology of reproduction JO - Biol. Reprod. VL - 88 IS - 6 N2 - Mechanisms regulating gonadotropin surges and gonadotropin requirements for follicle emergence and selection were studied in heifers. Experiment 1 evaluated whether follicular inhibins regulate the preovulatory luteinizing hormone (LH)/follicle-stimulating hormone (FSH) surges elicited by gonadotropin-releasing hormone (GnRH) injection (Hour = 0) and the subsequent periovulatory FSH surge. Treatments included control (n = 6), steroid-depleted bovine follicular fluid (bFF) at Hour -4 (n = 6), and bFF at Hour 6 (n = 6). Gonadotropins in blood were assessed hourly from Hours -6 to 36, and follicle growth tracked by ultrasound. Consistent with inhibin independence, bFF at Hour -4 did not impact the GnRH-induced preovulatory FSH surge, whereas treatment at Hour 6 delayed onset of the periovulatory FSH surge and impeded growth of a new follicular wave. Experiment 2 examined GnRH and estradiol (E2) regulation of the periovulatory FSH surge. Treatment groups were control (n = 8), GnRH-receptor antagonist (GnRHr-ant, n = 8), and E2 + GnRHr-ant (n = 4). GnRHr-ant (acyline) did not reduce the concentrations of FSH during the periovulatory surge and early follicle development (<7.0 mm) was unaffected, although subsequent growth of a dominant follicle (>8.0 mm) was prevented by GnRHr-ant. Addition of E2 delayed both the onset of the periovulatory FSH surge and emergence of a follicular wave. Failure to select a dominant follicle in the GnRHr-ant group was associated with reduced concentrations of LH but not FSH. Maximum diameter of F1 in controls (13.3 ± 0.5 mm) was greater than in both GnRHr-ant (7.7 ± 0.3 mm) and E2 + GnRHr-ant (6.7 ± 0.8 mm) groups. Results indicated that the periovulatory FSH surge stems from removal of negative stimuli (follicular E2 and inhibin), but is independent of GnRH stimulation. Emergence and early growth of follicles (until about 8 mm) requires the periovulatory FSH surge but not LH pulses. However, follicular deviation and late-stage growth of a single dominant follicle requires GnRH-dependent LH pulses. SN - 1529-7268 UR - https://www.unboundmedicine.com/medline/citation/23658431/Gonadotropin_releasing_hormone_estradiol_and_inhibin_regulation_of_follicle_stimulating_hormone_and_luteinizing_hormone_surges:_implications_for_follicle_emergence_and_selection_in_heifers_ L2 - https://academic.oup.com/biolreprod/article-lookup/doi/10.1095/biolreprod.112.107342 DB - PRIME DP - Unbound Medicine ER -