The objective of this study was to investigate how changes in total nitric oxide (NO) and ovarian matrix metalloproteinase (MMP)-1 and MMP-2 correlated with luteinizing hormone (LH) and estradiol (E2) in infertile dairy cows with ovarian cysts. Holstein cows (n=21 infertile cows and 19 fertile) were studied during their estrous phase to minimize hormone fluctuations. Blood LH, E2 and NO were measured. Expression of the MMP-1 and MMP-2 genes in the ovaries was measured by real-time PCR and immunohistochemistry. LH, E2 and NO were less in infertile cows with ovarian cysts than in fertile cows (P<0.05). The mRNAs of MMP-1 and MMP-2 were less in infertile cows with ovarian cysts than in fertile cows (P<0.05). The immunohistochemical results showed that MMP-1 and MMP-2 genes were expressed in different parts of the ovarian tissues, including granulosa and theca cells of preovulatory follicles, epithelial follicular cells of small follicles, stromal cells and endothelial cells of blood vessels. The results showed that a decrease in MMP-1 and MMP-2 gene expression is accompanied with a decrease in NO concentrations in infertile cows affected with ovarian cysts. The expression of these marker genes might be risk factors of infertility in cows and might correlate with the hormonal profile. The present study suggests that the abnormal expression of the MMP-1/2 gene might be an important marker of ovarian follicular cysts in dairy cows.
Keywords: Estradiol; Infertility; Luteinizing hormone; Matrix metalloproteinase; Nitric oxide; Ovarian follicular cyst.
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