title: Glucocorticoid metabolism in equine follicles and oocytes.
abstract: The objective of this study was to determine whether (1) systemic and intrafollicular cortisol concentrations in horses are directly related and (2) supraphysiological levels of glucocorticoids affect in vitro maturation (IVM) rates of oocytes. Specifically, we studied the (1) changes in the intrafollicular cortisol and progesterone in context with granulosa cell gene expression during maturation of equine follicles (from 5-9 mm, 10-14 mm, 15-19 mm, 20-24 mm, and ≥25 mm in diameter) and (2) effects of cortisol supplementation on IVM rates and gene expression of equine cumulus-oocyte complexes (COCs). For these purposes, follicular fluid, granulosa cells, and COCs were collected from 12 mares (mean age 8.6 ± 0.5 yr) by transvaginal aspiration. Cortisol and progesterone concentrations in follicular fluid from follicles ≥25 mm were greater (P < 0.05) than in all other follicle classes and were positively correlated (r = 0.8; P < 0.001). Plasma concentrations of cortisol and progesterone did not differ before and after follicle aspiration (P > 0.05). In granulosa cells, gene expression of NR3C1, HSD11B1, HSD11B2, and CYP21A2 did not differ (P > 0.05) among different follicle classes. Maturation rates were similar (P > 0.05) among groups, regardless of the cortisol concentration in the IVM medium. In cumulus cells, messenger RNA expression of genes involved in glucocorticoid mechanism and apoptosis was either increased (NR3C1 and BCL2) or decreased (HSD11B2) by treatment (P < 0.01). In oocytes, gene expression of maturation markers (BMP15 and GDF9) was affected (P < 0.001) by cortisol treatment. This study demonstrates the involvement of glucocorticoids in follicle and oocyte maturation and cortisol modulation by HSD11B2 in equine COCs. Our data provide further information for understanding the normal ovarian endocrine physiology which might in turn also help improve equine assisted reproduction techniques.
authors.affiliation: Division of Obstetrics, Gynecology and Andrology, Department for Small Animals and Horses, University of Veterinary Medicine Vienna, 1210 Vienna, Austria. Electronic address: dragos.scarlet@vetmeduni.ac.at.
authors.forename: D
authors.initials: D
authors.lastname: Scarlet
authors.affiliation: Center for Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
authors.forename: N
authors.initials: N
authors.lastname: Ille
authors.affiliation: Vetcore Facility, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Ertl
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, IL 62901, USA.
authors.forename: B G
authors.initials: BG
authors.lastname: Alves
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, IL 62901, USA.
authors.forename: G D A
authors.initials: GDA
authors.lastname: Gastal
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, IL 62901, USA.
authors.forename: S O
authors.initials: SO
authors.lastname: Paiva
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, IL 62901, USA.
authors.forename: M O
authors.initials: MO
authors.lastname: Gastal
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, IL 62901, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Gastal
authors.affiliation: Center for Artificial Insemination and Embryo Transfer, Department for Small Animals and Horses, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Aurich
mesh_terms: D000818:Animals; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006736:Horses / Q000502:physiology*; D006854:Hydrocortisone / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D006080:Ovarian Follicle / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020858:Tissue and Organ Harvesting
chemical_list: D012333:RNA, Messenger; D011374:Progesterone; D006854:Hydrocortisone
keywords: Cortisol; Follicle; Horse; Oocyte; Ovary