Follicular fluid concentrations of free insulin-like growth factor (IGF)-I during follicular development in mares.
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.
Publication Date: 2005-04-07 PubMed ID: 16213990DOI: 10.1016/j.domaniend.2005.03.003Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigated the changes in amounts of free insulin-like growth factor (IGF)-I during the development of a particular type of reproductive follicle (ovarian follicle) in mares. The findings suggest that increases in free IGF-I levels in follicular fluid are connected to increased steroid production in developing ovarian follicles in these animals.
Objectives and Methodology
- The main purpose of this research was to study the variations in concentrations of insulin-like growth factor (IGF-I), specifically the unbound or ‘free’ form, in the follicular fluid (FFL) during follicle development in mares, which are adult female horses.
- Fourteen mares participated in the study. They were classified into either the follicular phase (8 mares) or the luteal phase (6 mares) based on their reproductive cycle.
- Follicles, which are reproductive organs in mares that produce eggs, were categorized based on their size; small (6-15 millimeters; 54 counted), medium (16-25 millimeters; 23 counted), or large (greater than 25 millimeters; 15 counted).
- The researchers collected FFL from the categorized follicles for analysis.
Results and Findings
- The study observed that the levels of free IGF-I in FFL in large follicles during the follicular phase were significantly higher than in large follicles in the luteal phase as well as in small or medium follicles of both phases.
- Free IGF-I concentrations were more in large follicles during the luteal phase mares than in small-sized follicles, but not medium ones from the same phase.
- The ratio of estradiol to progesterone in FFL seemed to match the changes in free IGF-I, suggesting a correlation.
- There was a negative correlation between free IGF-I concentrations and certain types of insulin-like growth factor binding proteins (IGFBP-2, -4 and -5) which implies these proteins decrease when free IGF-I increases.
- Free IGF-I levels in FFL showed a positive correlation with estradiol, progesterone, androstenedione (steroid hormones), ratio of estradiol to progesterone, total IGF-I, and total IGF-II.
Conclusion
- It can be inferred that an increase in levels of free IGF-I in the follicular fluid is connected with increased production of steroids in developing follicles within the mares. This understanding could be important for improving breeding methods or fertility treatments in mares.
Cite This Article
APA
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), 573-581.
https://doi.org/10.1016/j.domaniend.2005.03.003 Publication
Researcher Affiliations
- Department of Animal Science, Oklahoma State University, Stillwater, OK 74078, USA. igf1Leo@okstate.edu
MeSH Terms
- Androstenedione / metabolism
- Animals
- Estradiol / metabolism
- Female
- Follicular Fluid / metabolism
- Follicular Phase / metabolism
- Horses / metabolism
- Insulin-Like Growth Factor Binding Proteins / metabolism
- Insulin-Like Growth Factor I / metabolism
- Luteal Phase / metabolism
- Ovarian Follicle / growth & development
- Ovarian Follicle / metabolism
- Progesterone / metabolism
Citations
This article has been cited 3 times.- Schütz LF, Schreiber NB, Gilliam JN, Cortinovis C, Totty ML, Caloni F, Evans JR, Spicer LJ. Changes in fibroblast growth factor 9 mRNA in granulosa and theca cells during ovarian follicular growth in dairy cattle.. J Dairy Sci 2016 Nov;99(11):9143-9151.
- Kafi M, Mesbah SF, Davoodian N, Kadivar A. Fine Structures of the Oocyte in Relation to Serum, Follicular Fluid Steroid Hormones and IGF-I in the Ovulatory-Sized Follicles in One-Humped Camel (Camelus dromedarius).. Avicenna J Med Biotechnol 2014 Jan;6(1):57-61.
- Hsieh M, Zamah AM, Conti M. Epidermal growth factor-like growth factors in the follicular fluid: role in oocyte development and maturation.. Semin Reprod Med 2009 Jan;27(1):52-61.
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