title: The microenvironment of the ovarian follicle in the postpartum dairy cow: effects on reagent transfer from cumulus cells to oocytes in vitro.
abstract: This study's hypothesis was that the nutrient composition in follicular fluid (FF) of ovarian follicles in early lactating postpartum cows may influence reagent transfer from cumulus cells (CC) to the oocyte. To test this, concentrations of amino acids (AA), cholesterol, glucose, and nonesterified fatty acids were measured in FF from the largest antral follicles at Days 21 and 46 postpartum during which time, most animals were expected to have resumed ovulatory activity. From the range of concentrations measured, two media compositions (Lac and Half-Lac) were prepared to compare with medium 199 (M199). The AA and cholesterol concentrations in FF were on average, approximately 35% and greater than 1000% higher than in M199, respectively. The nonesterified fatty acids, but not glucose, concentrations also exceeded those in M199. The transfer of fluorescent dye from CC to oocytes in bovine cumulus-oocyte complexes incubated with and without phosphodiesterase inhibitors (dipyridamole and milrinone) and/or forskolin was assessed. Maximum dye accumulation in oocytes incubated in M199 occurred after 4 hours and was further increased (P < 0.001) by dipyridamole. The addition of dipyridamole to Lac, but not Half-Lac, media also increased dye accumulation. There were effects of media (P < 0.001), cholesterol (P < 0.001), and forskolin (P < 0.05) on dye accumulation but no effects of stearic or palmitic acid in either Lac or Half-Lac media. The addition of oleic acid in Half-Lac (P < 0.01), but not Lac, media inhibited dye accumulation. These results support the hypothesis that reagent transfer from CC to oocytes is compromised when the AA composition in FF is low, as sometimes occurs during early lactation.
authors: School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand.
authors: Norma L
authors: NL
authors: Hudson
authors: Reproductive Technologies Section, AgResearch Ruakura, Hamilton, New Zealand.
authors: Marty C
authors: MC
authors: Berg
authors: Reproductive Technologies Section, AgResearch Ruakura, Hamilton, New Zealand; The Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: Mark P
authors: MP
authors: Green
authors: Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
authors: Penny J
authors: PJ
authors: Back
authors: The Liggins Institute, University of Auckland, Auckland, New Zealand.
authors: Eric B
authors: EB
authors: Thorstensen
authors: Reproductive Technologies Section, AgResearch Ruakura, Hamilton, New Zealand.
authors: A Jim
authors: AJ
authors: Peterson
authors: School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand.
authors: Janet L
authors: JL
authors: Pitman
authors: School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand. Electronic address: kenneth.mcnatty@vuw.ac.nz.
authors: Kenneth P
authors: KP
authors: McNatty
mesh_terms: D000596:Amino Acids / Q000097:blood / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose; D002417:Cattle / Q000502:physiology*; D060833:Cellular Microenvironment; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007202:Indicators and Reagents / Q000378:metabolism; D006080:Ovarian Follicle / Q000166:cytology*; D049590:Postpartum Period
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007202:Indicators and Reagents; D004958:Estradiol; D002784:Cholesterol; D005947:Glucose
keywords: Bovine ovary; Cumulus cells; Follicular microenvironment; Oocytes; Reagent transfer