The effect of the ovarian varicose vein on the DNA methylation in the rat's oocyte.

Objectives: We intended to determine whether the ovarian varicose which is one of the common etiologies of the pelvic congestion syndrome, has the ability to interfere with the DNA methylation reprogramming in the oocyte and thereby affect the oocyte quality or not.

Materials and Methods: Varicose model was induced according to the Turner's method in the rats. Briefly, a 20-gauge needle was placed on the left renal vein and a thread was tied over both the needle and the renal vein medial to the insertion of the ovarian vein, and then the needle was removed. Evaluation of prooxidant-antioxidant balance (PAB) was assessed using specific kits and the expression level of the DNA methyltransferase genes Dnmt1, Dnmt3a and Dnmt3L was assessed by Real-time PCR. Immunofluorescent staining for 5-methylcytosine in the oocytes evaluated the global DNA methylation.

Results: A significant PAB increase in the ovaries from varicose group was seen. Real-time PCR demonstrated a remarkable decrease in the expression of the Dnmt3a and Dnmt3L which are responsible for de novo DNA methylation in the oocytes. Immunofluorescent staining for 5-mC showed a reduction in the fluorescence intensity in the oocytes collected from the varicose group.

Conclusion: Our findings from Real-time PCR and immunocytochemistry suggest that the epigenetic parameters in the oocyte could be affected by varicose induction and these epigenetic alteration has the potential to affect the oocyte quality. We suggest that the epigenetic changes could happen in the oocytes after the induction of ovarian varicose and lead to the oocyte quality reduction or even infertility.