2006 Fiscal Year Final Research Report Summary
Study for the etiology of polycystic ovary using a rat model
| Project/Area Number |
16591676
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Obstetrics and gynecology
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| Research Institution | Sapporo Medical University |
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Principal Investigator |
ENDO Toshiaki Sapporo Medical University, School of Medicine, Associate Professor, 医学部, 助教授 (90213595)
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| Co-Investigator(Kenkyū-buntansha) |
CHIBA Hideki Sapporo Medical University, School of Medicine, Associate Professor, 医学部, 助教授 (00295346)
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| Project Period (FY) |
2004 – 2006
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| Keywords | androgen / insulin resistance / polycystic ovary / follicle atresia / Fas Ligand / matrix metalloproteinase / adiponectin / claudin-5 |
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| Research Abstract |
One of the characteristics of polycystic ovary syndrome (PCOS) is the presence of cystic follicles in various stages of growth and atresia, the latter of which is known to be the result of apoptosis and tissue remodeling. To further investigate the process of follicular atresia, we compared ovarian expression and localization of Fas, Fas ligand (FasL), casapse-8 and membrane-type1 matrix metalloproteinase (MT1-MMP) in rats treated with dehydroepiandrosterone (DHEA) as a model of PCOS, and in control rats. We found that the numbers of TdT-mediated dUTP-biotin nick end-labeling (TUNEL)-positive follicles were significantly higher in ovaries from PCOS rats than in those from control rats, as were ovarian levels of FasL mRNA and protein, processed caspase-8 protein and MT1-MMP mRNA. Correspondingly, we also observed an increase in the level of MTI-MMP catalytic activity and a decrease in the level of pro-caspase-8 protein. In addition, immunohistochemical analyses showed that MT1-MMP and F
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asL co-localize with TUNEL-positive apoptotic granulosa cells within atretic follicles of PCOS ovaries. Our results suggest that under the PCOS-like conditions induced by DHEA, the Fas/FasL/Caspase-8 (death receptor dependent) pathway is pivotal for follicular atresia, and that increased levels of MT1-MMP likely play an important role in tissue remodeling during structural luteolysis
Recently adiponectin has been suggested to play important role in insulin sensitivity. And insulin resistance has been attracted attention in reproductive function. But the expression of adiponectin in ovaries and adiponectin function in reproductive function are not fully understood. Ovaries of immature Zucker fa/fa rats showed significantly increased number of atretic follicles, number of total follicles and the percentage of atretic follicels/total follicles compared to lean rats. Serum adiponectin expression in fa/fa rats was significantly decreased as they became older. Adiponectin and its receptors are expressed in rat ovaries of granulosa cells, thaca cells and colupus luteums. Furthermore western blot and realtime RT-PCR analysis showed the expression of adiponectin and its receptors in ovaries were decreased under hyperinsulinemia condition like adipose tissue, liver and skeletal muscle. Overall our present data firstly provide the altered ovarian morphology and altered expression and regulation of adiponectin and its receptors in insulin resistant rat ovaries. Thus insulin resistant might closely related to reproductive dysfunction and low adiponectin profile also might be one one of the main causes of infertility and PCOS like condition in Zucker fatty rats.
We investigated the mechanism by which a GnRH agonist (GnRHa) affects ovarian vascularity, vascular permeability, and expression of the tight junction protein claudin-5 in a rat model of ovarian hyperstimulation syndrome (OHSS). Ovarian vascular density and vessel endothelial area (percent) were assessed by immunohistochemical analysis of the distribution of von Willebrand factor, whereas vascular permeability was evaluated based on leakage of Evans blue. High doses of PMSG and hCG significantly increased ovarian weight, vascular permeability, vascular density, and the vessel endothelial area and significantly reduced expression of claudin-5 protein and mRNA. All of these effects were significantly and dose-dependently inhibited by administration of GnRHa. This suggests that reduced expression of claudin-5 plays a crucial role in the increased ovarian vascular permeability seen in OHSS and that its expression can be modulated by GnRHa treatment. Indeed, preventing redistribution of tight junction proteins in endothelial cells and the resultant loss of endothelial barrier architecture might be the key to protecting patients against massive extravascular fluid accumulation in cases of OHSS. Less
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Research Products
(10 results)
