Melatonin improves the maturation and developmental ability of bovine oocytes by up-regulating GJA4 to enhance gap junction intercellular communication

Abstract

Melatonin (MT) increases oocyte maturation by reducing reactive oxygen species level and enhancing oocyte antioxidant capacity. However, the mechanisms via which MT works are still poorly understood. In the present study, the effects of MT on the maturation rate and development ability of bovine oocytes were investigated. Then, the transcriptome of oocytes treated by MT was sequenced. Finally, the expression of gap junction protein alpha 4 (GJA4) protein and cAMP level were detected in bovine oocytes, and isoprenaline (enhancer of gap junctional intercellular communication (GJIC)) and heptanol (inhibitor of GJIC) were used to investigate the effect of MT on GJIC activity in bovine oocytes. Our results showed that MT significantly improved the maturation, developmental ability and mRNA expression of GJA4 of bovine oocytes. Meanwhile, MT significantly increased GJA4 protein level and cAMP level in bovine oocytes. In contrast to heptanol, both isoproterenol and MT significantly increased GJIC activity, nuclear maturation and the development ability of bovine oocytes. However, MT significantly restored the nuclear maturation and developmental ability of oocytes treated by heptanol. In conclusion, our results showed that MT improves the maturation and developmental ability of bovine oocytes by enhancing GJIC activity via up-regulating GJA4 protein expression in IVM progress.

Melatonin Protects Mitochondrial Function and Inhibits Oxidative Damage against the Decline of Human Oocytes Development Caused by Prolonged Cryopreservation

“…Melatonin (N-acetyl-5-methoxytryptophan, MT) is a type of indole compound, synthesized by the mammalian pineal gland, with high lipid solubility and low water solubility [ 12 ]. It is a powerful free radical scavenger and antioxidant [ 13 , 14 ] that has a wide range of physiological functions, including antioxidation [ 15 ], anti-aging [ 12 ], sleep promotion [ 16 ] and so on. MT and its metabolites can directly scavenge reactive oxygen species (ROS), activate antioxidant enzymes, increase the expression level and activity of Glutathione (GSH), regulate the expression of antioxidant genes, and inhibit prooxidative enzymes, thereby protecting cells from oxidative damage [ 17 , 18 ].…”

Exogenous Melatonin Directly and Indirectly Influences Sheep Oocytes

“…Understanding how MT directly and indirectly influences sheep oocyte development competence is an important goal. MT also significantly promoted the development of embryos in vitro , for example, in mice ( 31 ), bovines ( 32 ), swine ( 33 ), and goats ( 34 ).…”

“…An important function of it used in vitro is antioxidation. As an effective antioxidant, MT can significantly reduce the level of intracellular ROS and improve the in vitro maturation (IVM) of oocytes and the in vitro developmental potential of embryos ( 32 ). MT can significantly reduce the apoptosis of cultured cells and improve the quality of embryos.…”

“…The accumulation of ROS in the ovary will reduce the quality of oocytes and lead to the apoptosis of granulosa cells ( 47 ). MT can significantly reduce the level of intracellular ROS ( 32 ). It can penetrate the blood-testis barrier ( 48 ).…”

Combination of CNP, MT and FLI during IVM Significantly Improved the Quality and Development Abilities of Bovine Oocytes and IVF-Derived Embryos

“…The oocytes were washed 3 times in DPBS and then immediately examined by the fluorescence microscopy (Nikon, Tokyo, Japan). The fluorescence intensity of calcein-AM is in pixels [ 28 ]. The fluorescent pixel values of the oocytes were measured from 10 different cytoplasmic regions, and each region had the same area; then, the background fluorescence values were subtracted from the final values, and the statistically significant differences among the groups were analyzed.…”