Ortiz Maria Eugenia, Bühler Marta Inés, Zelarayán Liliana Isabel
Centro de Referencias para Lactobacilos (CERELA)-CONICET,Chacabuco 145,Tucumán,Argentina.
Instituto de Biología,Facultad de Bioqca,Qca. y Farmacia,INSIBIO-UNT,Chacabuco 461,Tucumán,Argentina.
Zygote. 2014 Nov;22(4):440-5. doi: 10.1017/S096719941200069X. Epub 2013 Feb 27.
In Rhinella arenarum, progesterone is the physiological nuclear maturation inducer that interacts with the oocyte surface and starts a cascade of events that leads to germinal vesicle breakdown (GVBD). Polyunsaturated fatty acids and their metabolites produced through cyclooxygenase (COX) and lipoxygenase (LOX) pathways play an important role in reproductive processes. In amphibians, to date, the role of arachidonic acid (AA) metabolites in progesterone (P4)-induced oocyte maturation has not been clarified. In this work we studied the participation of three enzymes involved in AA metabolism - phospholipase A2 (PLA2), COX and LOX in Rhinella arenarum oocyte maturation. PLA2 activation induced maturation in Rhinella arenarum oocytes in a dose-dependent manner. Oocytes when treated with 0.08 μM melittin showed the highest response (78 ± 6% GVBD). In follicles, PLA2 activation did not significantly induce maturation at the assayed doses (12 ± 3% GVBD). PLA2 inhibition with quinacrine prevented melittin-induced GVBD in a dose-dependent manner, however PLA2 inactivation did not affect P4-induced maturation. This finding suggests that PLA2 is not the only phospholipase involved in P4-induced maturation in this species. P4-induced oocyte maturation was inhibited by the COX inhibitors indomethacin and rofecoxib (65 ± 3% and 63 ± 3% GVBD, respectively), although COX activity was never blocked by their addition. Follicles showed a similar response following the addition of these inhibitors. Participation of LOX metabolites in maturation seems to be correlated with seasonal variation in ovarian response to P4. During the February to June period (low P4 response), LOX inhibition by nordihydroguaiaretic acid or lysine clonixinate increased maturation by up to 70%. In contrast, during the July to January period (high P4 response), LOX inhibition had no effect on hormone-induced maturation.
在阿根廷短头蟾中，孕酮是生理性核成熟诱导剂，它与卵母细胞表面相互作用并启动一系列导致生发泡破裂（GVBD）的事件。多不饱和脂肪酸及其通过环氧化酶（COX）和脂氧合酶（LOX）途径产生的代谢产物在生殖过程中发挥重要作用。在两栖动物中，迄今为止，花生四烯酸（AA）代谢产物在孕酮（P4）诱导的卵母细胞成熟中的作用尚未阐明。在这项研究中，我们研究了参与阿根廷短头蟾卵母细胞成熟的AA代谢的三种酶——磷脂酶A2（PLA2）、COX和LOX的作用。PLA2激活以剂量依赖的方式诱导阿根廷短头蟾卵母细胞成熟。用0.08μM蜂毒肽处理的卵母细胞显示出最高反应（78±6%GVBD）。在卵泡中，在所检测的剂量下，PLA2激活并未显著诱导成熟（12±3%GVBD）。用奎纳克林抑制PLA2以剂量依赖的方式阻止了蜂毒肽诱导的GVBD，然而PLA2失活并不影响P4诱导的成熟。这一发现表明，PLA2不是该物种中参与P4诱导成熟的唯一磷脂酶。COX抑制剂吲哚美辛和罗非昔布抑制了P4诱导的卵母细胞成熟（分别为65±3%和63±3%GVBD），尽管添加这些抑制剂从未阻断COX活性。添加这些抑制剂后，卵泡显示出类似的反应。LOX代谢产物在成熟中的参与似乎与卵巢对P4反应的季节性变化相关。在2月至6月期间（P4反应低），去甲二氢愈创木酸或氯尼辛赖氨酸抑制LOX可使成熟率提高多达70%。相反，在7月至1月期间（P4反应高），抑制LOX对激素诱导的成熟没有影响。
