title: Changes in intrafollicular concentrations of free IGF-1, activin A, inhibin A, VEGF, estradiol, and prolactin before ovulation in mares.
abstract: Changes in intrafollicular growth factors and hormones were evaluated in vivo in postdeviation and impending ovulation follicles. Mares (n = 30) were randomly assigned to five experimental groups based on target diameters of 25, 30, 35, 40 mm, and impending signs of ovulation. Furthermore, data belonging to two or more proximal diameter groups that were not different were combined and regrouped for each factor separately. Follicular fluid-free insulin-like growth factor 1 was highest (P < 0.003) in 35-mm follicles, followed by the 40-mm and impending ovulation follicle group, and the 25- to 30-mm follicle group. However, concentrations of insulin-like growth factor binding protein 2 in follicular fluid did not differ (P > 0.05) among groups. Additionally, follicular fluid activin A tended (P < 0.06) to be higher in impending ovulation follicles when compared with the 25- to 40-mm follicle group. Concentrations of intrafollicular estradiol were higher (P < 0.0001) in 40-mm and impending ovulation follicles than in the other follicle groups. Follicular fluid concentrations of inhibin A and vascular endothelial growth factor were lower (P < 0.05) in the 40-mm and the impending ovulation follicle group when compared with the 25- to 35-mm follicle group. Systemic and intrafollicular prolactin levels were lower (P < 0.05) in the impending ovulation group when compared with the 25- to 40-mm follicle group. Prolactin concentrations were higher (P < 0.05) in the follicular fluid than in the plasma. The novel findings of this study, a decrease in intrafollicular-free insulin-like growth factor 1, inhibin A, vascular endothelial growth factor, and prolactin during the final stages of follicular growth, document for the first time the occurrence of dynamic changes among intrafollicular factors and hormones during the stages of follicle dominance and as ovulation approaches.
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, Illinois, USA.
authors.forename: S T
authors.initials: ST
authors.lastname: Bashir
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, Illinois, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Ishak
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, Illinois, USA.
authors.forename: M O
authors.initials: MO
authors.lastname: Gastal
authors.affiliation: Department of Animal Science, University of California, Davis, California, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Roser
authors.affiliation: Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale, Illinois, USA. Electronic address: egastal@siu.edu.
authors.forename: E L
authors.initials: EL
authors.lastname: Gastal
mesh_terms: D028341:Activins / Q000378:metabolism; D000818:Animals; D004958:Estradiol / Q000378:metabolism; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism; D006736:Horses / Q000378:metabolism*; D007265:Inhibins / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D006080:Ovarian Follicle / Q000254:growth & development / Q000378:metabolism*; D010060:Ovulation / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism; D011897:Random Allocation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D042461:Vascular Endothelial Growth Factor A; C422405:activin A; C422362:inhibin A; D028341:Activins; D004958:Estradiol; D007265:Inhibins; D007334:Insulin-Like Growth Factor I; D011388:Prolactin
keywords: Follicle deviation; Hormone; Impending ovulation; Intrafollicular growth factor; Mare