Follicular fluid concentrations of free insulin-like growth factor (IGF)-I during follicular development in mares
Issue Date
11-2005
Abstract
The objective of the present study was to evaluate changes in concentrations of free insulin-like growth factor (IGF)-I in follicular fluid (FFL) during follicle development in the mare. Mares (n = 14) were classified as either in the follicular phase (n = 8) or luteal phase (n = 6). Follicles (n = 92) were categorized as small (6-15 mm; n = 54), medium (16-25 mm; n = 23) or large (>25 mm; n = 15) and FFL was collected. Free IGF-I levels in FFL in large follicles of follicular phase mares were greater (P < 0.05) than in large follicles of luteal phase mares and small or medium follicles of luteal and follicular phase mares. Free IGF-I concentrations were greater (P < 0.05) in large follicles of luteal phase mares than small but not medium follicles of luteal phase mares. FFL ratio of estradiol:progesterone paralleled changes in free IGF-I. Free IGF-I concentrations were negatively correlated (P < 0.05) with insulin-like growth factor binding protein (IGFBP)-2, -4 and -5 but not IGFBP-3 levels. In addition, free IGF-I concentrations in FFL were positively correlated (P < 0.01) with FFL estradiol, progesterone, androstenedione, estradiol:progesterone ratio, total IGF-I and total IGF-II. We conclude that increases in intrafollicular levels of bioavailable (free) IGF-I are associated with increased steroidogenesis in developing mare follicles. © 2005 Elsevier Inc. All rights reserved.
Source or Periodical Title
Domestic Animal Endocrinology
ISSN
7397240
Volume
29
Issue
4
Page
573-581
Document Type
Article
Language
English
Subject
Follicle, Follicular fluid, Insulin-like growth factor, Mare
Recommended Citation
Spicer LJ, Santiago CA, Davidson TR, Bridges TS, Chamberlain CS (2005). Follicular fluid concentrations of free insulin-like growth factor (IGF)-I during follicular development in mares. Domest Anim Endocrinol .29(4):573-81
Identifier
DOI: 10.1016/j.domaniend.2005.03.003
Digital Copy
YES