ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2019, Vol. 50 ›› Issue (2): 314-322.doi: 10.11843/j.issn.0366-6964.2019.02.009

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The Effect of Melatonin on the Maturation of Oocyte in vitro and Its Receptor-mediated Mechanism in Buffalo

GUO Zhenwei, HUANG Yongjun, FAN Weihong, WEN Dongmei, SHEN Penglei, PAN Erke, LU Fenghua*, SHI Deshun*   

  1. State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning 530004, China
  • Received:2018-01-26 Online:2019-02-23 Published:2019-02-23

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Abstract:

The purpose of this study was to investigate the effects of exogenous melatonin on in vitro maturation of buffalo oocytes and their receptor mediated mechanisms. The following tests:1)The expression of melatonin receptors MT1 and MT2 in cumulus cell and oocytes of buffalo were detected by immunofluorescence.2)The effects of different concentrations of melatonin (10-9, 10-8, 10-7 mol·L-1) added in the maturation medium on the efficiency of buffalo oocytes IVM and the development of the embryos after in vitro fertilization (IVF) were explored.3)According to the optimal concentration of melatonin, different treatment combinations were added into the mature liquid:untreated,melatonin (10-8 mol·L-1 MT),melatonin receptor antagonist (10-8 mol·L-1 LZU),melatonin receptor agonist (10-8 mol·L-1 ⅡK7),melatonin+ melatonin receptor antagonist (10-8 mol·L-1 MT+10-8 mol·L-1 LZU).The first polar body excretion rate of oocyte was calculated and the first polar body oocytes were detected by ELISA Kit after 24 h,and then mature oocytes were fertilized in vitro and their rates of division and blastocyst were calculated.The results showed that:1)The both of the MT1 and MT2 receptors were presented in the buffalo cumulus cells and oocytes; 2)The first polar body exhaust rates of oocytes cultured in the maturation medium added with different concentrations of melatonin (10-9,10-8,10-7 mol·L-1) were significantly higher than the 0 mol·L-1MT group and the embryonic cleavage rate in each treatment group was also significantly higher than in 0 mol·L-1 MT group (P<0.05),moreover,the blastocyst rate of 10-8 and 10-7 mol·L-1 MT groups was significantly higher than that of control group (P<0.05); 3)The oocyte maturation rate, division rate and blastocyst rate of embryo in the melatonin receptor antagonist group (10-8 mol·L-1 LZU) were not significantly different from those in the untreated group (P>0.05).The oocyte maturation rate, embryo division rate and blastocyst rate after in vitro fertilization were significantly higher in the group of melatonin receptor agonist group(10-8 mol·L-1 ⅡK7) than these in the untreated group(P<0.05),however, the difference was not significant compared with the melatonin group (10-8 mol·L-1 MT) (P>0.05); The oocyte maturation rate,division rate and blastocyst rate of embryo in melatonin+melatonin receptor antagonist group (10-8 mol·L-1 MT+10-8 mol·L-1 LZU) were not significantly different compared with that in untreated group (P>0.05). 4) The concentration of cAMP in the oocyte of melatonin group was significantly reduced compared with that of the untreated group, but the concentration of cGMP was significantly increased than the untreated group (P<0.05). It can be seen from this study, by binding to the cell membrane G protein coupled receptor MT1 and MT2, melatonin inhibits cAMP synthesis and increases cGMP content, thereby promoting the mature and early embryonic development of oocytes.

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