melatonin (退黑激素) 可改善卵子有絲分裂狀況

Hum Reprod. 2017 Nov 3:1-12. doi: 10.1093/humrep/dex331. [Epub ahead of print]

The protective role of melatonin in porcine oocyte meiotic failure caused by the exposure to benzo(a)pyrene.

Miao Y1, Zhou C1, Bai Q2, Cui Z1, ShiYang X1, Lu Y1, Zhang M1, Dai X1, Xiong B1.

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Abstract

STUDY QUESTION:

Does melatonin restore the benzo(a)pyrene (BaP)-induced meiotic failure in porcine oocytes?

SUMMARY ANSWER:

Melatonin effectively inhibits the increased reactive oxygen species (ROS) level and apoptotic rate in BaP-exposed porcine oocytes to recover the meiotic failure.

WHAT IS KNOWN ALREADY:

BaP, a widespread environmental carcinogen found in particulate matter, 2.5 µm or less (PM2.5), has been shown to have toxicity at the level of the reproductive systems. BaP exposure disrupts the steroid balance, alters the expression of ovarian estrogen receptor and causes premature ovarian failure through the rapid depletion of the primordial follicle pool. In addition, acute exposure to BaP has transient adverse effects on the follicle growth, ovulation and formation of corpora lutea, which results in transient infertility.

STUDY DESIGN, SIZE, DURATION:

Porcine oocytes were randomly assigned to control, BaP-exposed and melatonin-supplemented groups. BaP was dissolved in dimethylsulphoxide and diluted to a final concentration of 50, 100 or 250 μM with maturation medium, respectively. Melatonin was dissolved in the absolute ethanol and diluted with maturation medium to a final concentration of 1 nM, 100 nM, 10 μM and 1 mM, respectively. The in vitro cultured oocytes from each group after treatment were applied to the subsequent analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS:

Acquisition of oocyte meiotic competence was assessed using immunostaining, fluorescent intensity quantification and/or immunoblotting to analyse the cytoskeleton assembly, mitochondrial integrity, cortical granule dynamics, ovastacin distribution, ROS level and apoptotic rate. Fertilization ability of oocytes was examined by sperm binding assay and IVF.

MAIN RESULTS AND THE ROLE OF CHANCE:

BaP exposure resulted in the oocyte meiotic failure (P = 0.001) via impairing the meiotic apparatus, showing a prominently defective spindle assembly (P = 0.003), actin dynamics (P < 0.001) and mitochondrion integrity (P < 0.001). In addition, BaP exposure caused the abnormal distribution of cortical granules (P < 0.001) and ovastacin (P = 0.003), which were consistent with the observation that fewer sperm bound to the zona pellucida surrounding the unfertilized BaP-exposed eggs (P < 0.001), contributing to the fertilization failure (P < 0.001). Conversely, melatonin supplementation recovered, at least partially, all the meiotic defects caused by BaP exposure through inhibiting the rise in ROS level (P = 0.015) and apoptotic rate (P = 0.001).