| Melatonin (MLT) is an indole hormone, in human and mammalian melatonin is mainly secreted by pineal gland in the brain, other organs and cells have a small amount of secretion, light has a great impact on secretion, and showed circadian rhythm, usually secreted more melatonin at night than daytime. MT is a good water-soluble and fat-soluble substance, it can through the cell membrane and a variety of membrane structure into the cell and many organelles to play the role of antioxidant, Melatonin also stimulates the activity of antioxidant enzymes like superoxide dismutase and glutathione reductase, currently melatonin antioxidant, anti-apoptosis have been reported in vitro maturation of oocytes and early embryos in the mouse, pig, sheep, chickens and other animals, however, there were few reports of bovine oocytes in vitro maturation. In this research, bovine was taken to be study, we investigated melatonin on the in vitro oocyte maturation and embryonic development. The main results are as follows:1 Effect of melatonin on bovine oocytes maturation, endocrine and metabolic function(1) Effect of melatonin on bovine oocytes maturationTook 940 bovine oocytes at vesicle stage (GV period), this oocytes were divided into 4 groups, they were cultured in IVM with four MLT concentration (Opmol/ml,10 pmol/ml, 20 pmol/mnl,30 pmol/ml) at 38.5℃,5% CO2,100% humidity for 24h, then compared the maturation rate of oocytes. It was found that melatonin can improve the rate of oocyte maturation, and with the increase of the concentration, the maturation rate also showed an increasing trend. MLT concentration 30pmol/ml group oocyte maturation rate (66.13%) was more than twice as high (P<0.05) than the control group (30.36%).(2) Effect of melatonin on the reproductive hormone secretion of bovine oocyteIn this experiment, by determining hormones in the maturation medium, the results showed that melatonin could significantly improve the secretion of hormones of COCs to improve the content of hormones in maturation medium. Where:P, E2, FSH secretion were increased as the concentration of melatonin rised, the secretion of P in 30pmol/ml group (0.35 mlU/ml) was about six times than the control group (0.06 mIU/ml), LH level of lOpmol/ml group and 20pmol/ml group were decreased than control group, but 30pmol/ml group was high (5.42 vs.3.97, P<0.05) than the control group. (3) Effect of melatonin on bovine oocytes ROS levelsIn this experiment, by measuring bovine oocyte ROS levels in maturation medium with different concentrations of melatonin, we found that melatonin significantly reduced bovine oocytes ROS levels, there was a negative correlation between the reduced role and the concentration of MLT.2 Effect of melatonin on bovine parthenogenetic embryo development and its mechanismIn this experiment, by adding 0pmol/ml,10 pmol/ml,20 pmol/ml,30 pmol/ml melatonin in the embryo culture medium SOF, when cultured 7d we found that melatonin could increase the cleavage rate, morula and blastocyst rates of parthenogenetic embryos, especially when the MLT concentration was 10pmol/ml, cleavage rate:(70.23%) compared to the control group (42.32%) increased nearly 30%; morula rate:(66.09%) was twice compared to the control group (31.54%); blastocyst rate:(23.90%) was four times compared to the control group (6.00%)Compared to the control, the high blastocyst rate (MLT concentration was 10 pmol/ml) group, the number of inner cell mass, trophoblast cells and total cell number were significantly increased (34.67 vs 19.66,71.33 vs.43.67,106.00 vs.63.33, P<0.05),The results showed that melatonin could promote the development of embryos by improving bovine parthenogenetic embryo cells.MLT receptors in different developmental stage of bovine parthenogenetic embryos were detected by immunohistochemistry The results showed that melatonin receptors expressed in bovine parthenogenetic embryos, melatonin receptor expressed basically on the surface of the embryo, and with the development of embryos, the expression of receptors showed in a increasing trend.3 Effect of melatonin on bovine androgenetic embryos developmentIn this experiment, by adding 0 pmol/ml,10 pmol/ml,20 pmol/ml,30 pmol/ml melatonin in the embryo culture medium SOF. When cultured 7d,the results showed that melatonin can improve the cleavage rate, morula and blastocyst rate of androgenetic embryos, cleavage rates:30 pmol/ml(77.25%) was increased 20% compared with the control group(55.46%); morula rate:20 pmol/ml(38.06%) was twice compared to the control group(19.22%); blastocyst rate; 20 pmol/ml (10.96%) was increased 10% when compared to the control(0%). |
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