Abstract/Details

The impact of insulin on the matrix metalloproteinase system during equine follicular development and atresia

Sessions, Dawn Renee.  University of Kentucky. ProQuest Dissertations Publishing, 2008. 3463193.

Abstract (summary)

Obesity, insulin resistance, and resulting hyperinsulinemia have been associated with disturbances in the duration of the breeding season and the estrous cycle. Matrix metalloproteinascs (MMP) and tissue inhibitor of metalloproteinases (TIMP) are involved in the tissue remodeling events necessary for follicle growth, ovulation, and atresia essential to normal ovarian cyclicity. The studies in this dissertation were designed to gain an understanding of the role MMP-2, MMP-9, TIMP-1, and TIMP-2 have in follicular development in the horse, and test the hypothesis that elevated insulin causes disruptions in the expression and translation of these enzymes, thereby interfering with tissue remodeling. The first study examined the MMP system in granulosa cells both in vivo and in vitro. The results indicate that the MMP system is dynamic and does undergo changes during follicular growth, the preovulatory period, and during atresia. The second study was designed to test the impact of elevated insulin on the MMP system in vitro. The results of this study indicate that elevated insulin does in fact alter MMP and TIMP expression in vitro, especially in samples collected from preovulatory and atretic follicles. The final study examined if this impact was also present in vivo, and also to examine the role of insulin resistance itself on the MMP system. The results indicate that insulin impacts MMP-9 and TIMP-1 but not MMP-2 and TIMP-2, which are more affected by health of the follicle, than elevated insulin. Interestingly, insulin resistance itself had more of a relationship with the MMP system. However, serum concentrations of glucose have an even stronger relationship to the MMP system. The results of the studies demonstrate the importance of the MMP system to follicle turnover in the ovary, and that elevated insulin, insulin resistance, and glucose are important to their regulation. Obesity and insulin resistance have been associated with disturbances in the duration of the breeding season and the estrous cycle regulation in the ovary. This study has implications to ovarian syndromes in humans as well as, to other tissues in the horse that contribute to very serious diseases.

KEYWORDS: Follicle Maturation, Atresia, Insulin, Horse, Matrix Metalloproteinase

Indexing (details)


Subject
Veterinary services
Classification
0778: Veterinary services
Identifier / keyword
Biological sciences; Atresia; Equine; Follicular maturation; Houses; Insulin; Matrix metalloproteinase
Title
The impact of insulin on the matrix metalloproteinase system during equine follicular development and atresia
Author
Sessions, Dawn Renee
Number of pages
182
Degree date
2008
School code
0102
Source
DAI-B 72/10, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
978-1-124-75147-4
Advisor
Fitzgerald, Barry
University/institution
University of Kentucky
University location
United States -- Kentucky
Degree
Ph.D.
Source type
Dissertation or Thesis
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3463193
ProQuest document ID
882379227
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
https://www.proquest.com/docview/882379227/previewPDF