ABSTRACT
PURPOSE: We evaluated the role of tumor necrosis factor alpha (TNFα) in rat ovulation and granulosa cell death of ovarian follicles during the periovulatory stage. METHODS: Immature rats primed with pregnant mare serum gonadotropin were injected intraperitoneally with human chorionic gonadotropin (hCG), and TNFα was injected into the bursa 48 h later. The total number of released oocytes was counted. Apoptosis was measured with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and the expression of cleaved caspase 3 and Bax/Bcl-2. Autophagy was assessed by the expression of light chain protein 3 (LC3) and autophagosomes under transmission electron microscopy. RESULTS: TNFα significantly decreased the number of released oocytes, and many unruptured follicles were observed. TUNEL analysis revealed a larger number of apoptotic cells, and the cleaved caspase 3 and Bax/Bcl-2 increased more than that of the control 12 h after hCG administration. Furthermore, the expression of LC3 wwas significantly higher than that of the control, and autophagosomes were observed in the cytoplasm. CONCLUSIONS: Our data indicated that TNFα is an important mediator of ovulation in terms of decreasing the number of released oocytes and inducing granulosa cell death of unruptured follicles via apoptosis and autophagy for remodeling ovarian tissues.
ABSTRACT
It is reported that okadaic acid (OA)-sensitive phosphatase is related to mitogen-activated protein kinase (MAPK)/p90rsk activation in mammalian oocytes. OA is also involved in the positive feedback loop between M phase-promoting factor (MPF) and cdc25c in Xenopus oocytes during meiotic maturation. However, the effect of phosphatase inhibition by OA on MPF and MAPK activities at the MII/G1 in oocytes remains unknown. The aim of this study is to clarify the relationship between OA-sensitive phosphatase and mitosis MII/G1 transition in mouse oocytes. MII-arrested oocytes were, isolated from mice, inseminated and cultured in TYH medium (control group) or TYH medium supplemented with 2.5 µM of OA (OA group). Histone H1 kinase and myelin basic protein (MBP) kinase activities were measured as indicators of MPF and p42 MAPK activities after insemination. Phosphorylation of cdc25c after insemination was analized in OA and control group by western blotting. Seven hours after insemination a pronucleus (PN) was formed in 84.1% (69/85) of oocytes in the control group. However, no PN was formed in oocytes of the OA group (p < 0.001). Although MPF and MAPK activities in the control group significantly decreased at 3, 4, 5, and 7 h after insemination, these decreases were significantly inhibited by OA addition (p < 0.05). Furthermore, OA addition prevented cdc25c dephosphorylation 7 h after insemination. In conclusion, OA-sensitive phosphatase correlates with inactivation of MPF and MAPK, and with the dephosphorylation of cdc25c at the MII/G1 transition in mouse oocytes.
Subject(s)
Okadaic Acid/pharmacology , Oocytes/drug effects , Oocytes/enzymology , Phosphoprotein Phosphatases/metabolism , Animals , Cell Division/drug effects , Cell Nucleus/metabolism , Cells, Cultured , Enzyme Inhibitors/pharmacology , Female , Fertilization in Vitro/drug effects , G1 Phase/drug effects , Male , Maturation-Promoting Factor/metabolism , Mesothelin , Mice , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/metabolism , Oocytes/cytology , Phosphorylation , Protein Kinases/metabolism , cdc25 Phosphatases/antagonists & inhibitors , cdc25 Phosphatases/metabolismABSTRACT
AIM: To examine whether the bromocriptine-rebound (BR) method improves pregnancy outcomes after previous unsuccessful assisted reproductive technology (ART) attempts. PATIENTS/STUDY DESIGN: In this study we retrospectively analyzed data from a total of 121 women with normal serum prolactin (PRL) levels and a history of repeated unsuccessful ART procedures. Pregnancy outcomes and hormonal data were compared between the long protocol and BR method. Both procedures were similar, except that in the BR method, bromocriptine was administered daily from day 5 of the preceding cycle until 7 days before ovarian stimulation. RESULTS: The number of fertilized oocytes, cleaved embryos and transplant embryos were significantly higher with the BR method than with the long protocol even though the numbers of retrieved oocyte were same in both groups. The ratio of the good embryos, the clinical pregnancy rate was higher with the BR method than with the long protocol. The embryo score with the BR method were significantly higher than that with the long protocol. CONCLUSION: BR method could provide the better embryos and improve the transplantation rate in women with previous unsuccessful ART attempts.
