2021 年 58 巻 3 号 p. 186-191
Sperm motility is considered as one of the most important traits for successful fertilization, but the motility of an ejaculated sperm decreases with time when stored as liquid. It is reported that seminal plasma serves as a nutrient rich medium for sperm and plays an important role in sperm motility and its fertilization ability. Several studies have reported that imidazole dipeptides such as anserine and carnosine affect sperm motility and its fertilization ability in mammals. In this study, we report the presence of anserine and carnosine in the male reproductive tract of the Japanese quail. Abundant levels of anserine (44.46 µM) and carnosine (41.75 µM) were detected in the testicular fluid and seminal plasma respectively using the amino acid analyzer; however, seminal plasma solely contained carnosine. When the ejaculates were incubated with anserine or carnosine, we found that both the dipeptides improve sperm motility parameters such as straight line velocity, curvilinear velocity, average path velocity and amplitude of lateral head displacement after in vitro sperm storage at 15°C. These results indicate that imidazole dipeptides are present in the male reproductive tract and may improve sperm quality during in vitro sperm storage in the liquid states.