title: Alterations in bone morphogenetic protein 15, growth differentiation factor 9, and gene expression in granulosa cells in preovulatory follicles of dairy cows given porcine LH.
abstract: In a previous work, using porcine LH (pLH) in lieu of GnRH for synchronizing ovulation in dairy cows improved pregnancy rates without increasing plasma progesterone concentrations after ovulation. The LH profile is known to remain elevated above basal concentrations (≥1 ng/mL) for up to 20 hours in pLH-treated cows compared to less than 6 hours in GnRH-treated cows. Because LH triggers a cascade of signaling networks in the preovulatory follicle to promote final maturation and support oocyte competence, we hypothesized that dissimilar LH profiles will differentially regulate the intrafollicular factors and expression of downstream genes associated with improved oocyte competence. Specific objectives were to determine differences in the abundance of oocyte-secreted factors in the preovulatory follicular fluid and target genes in granulosa cells associated with oocyte competence, in response to exogenous porcine LH or GnRH-induced endogenous bovine LH exposure, in dairy cows. Follicular contents were aspirated by a transvaginal ultrasound-guided procedure from the preovulatory follicle of cyclic, nonlactating Holstein cows 21 ± 1 hour after administration of either pLH (25-mg) or GnRH (100-μg). Mature forms of bone morphogenetic protein 15, growth differentiation factor 9, and transforming growth factorβ1 were approximately 2-fold more abundant in pLH-treated cows which were exposed to an extended, low LH profile, than in GnRH-treated cows that had a short, high LH profile. The relative abundance of messenger RNA for cyclooxygenase-2, LH receptor, and progesterone receptor in granulosa cells, was about two-, eight-, and two-fold higher, respectively, in cows subjected to pLH than GnRH treatment. We infer that the improved pregnancy rate after pLH-induced ovulation reported previously, occurred through greater activation of intrafollicular transforming growth factor-β1 superfamily members, as these proteins promote cumulus expansion and oocyte competence.
authors.affiliation: Livestock Research Branch, Alberta Agriculture and Forestry, Edmonton, AB, T6H 5T6, Canada; Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
authors.forename: Amir
authors.initials: A
authors.lastname: Behrouzi
authors.affiliation: Livestock Research Branch, Alberta Agriculture and Forestry, Edmonton, AB, T6H 5T6, Canada.
authors.forename: Marcos Germán
authors.initials: MG
authors.lastname: Colazo
authors.affiliation: Livestock Research Branch, Alberta Agriculture and Forestry, Edmonton, AB, T6H 5T6, Canada; Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada. Electronic address: divakar.ambrose@gov.ab.ca.
authors.forename: Divakar Justus
authors.initials: DJ
authors.lastname: Ambrose
mesh_terms: D000818:Animals; D055430:Bone Morphogenetic Protein 15 / Q000235:genetics / Q000378:metabolism*; D002417:Cattle / Q000502:physiology*; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry; D005786:Gene Expression Regulation / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D055429:Growth Differentiation Factor 9 / Q000235:genetics / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D013552:Swine
chemical_list: D055430:Bone Morphogenetic Protein 15; D055429:Growth Differentiation Factor 9; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone
keywords: Follicle; GnRH; Oocyte; Porcine LH; Pregnancy