DNA damage, oxidative stress, decreased viability and motility in common carp (Cyprinuscarpio L.) spermatozoa induced by tryptophan, phenylalanine and cysteine amino acids during short-term storage

Free amino acids are found in spermatozoa and seminal plasma. Their qualitative and quantitative presence have been affected by many factors. Under in vitro storage conditions, their effects on spermatozoa in animal species and also human have been concerned over the last decades. In this study, the effects of tryptophan, phenylalanine and cysteine on DNA integrity, lipid peroxidation, viability and motility parameters in spermatozoa of the common carp (Cyprinuscarpio) were assessed during short-term storage. Spermatozoa were incubated at 1, 5, 25, and 50 mM of these amino acids in vitro at 4 'V in a time-dependent manner (6, 24, and 48 h). The supplementation of cysteine, phenylalanine and >5 mM of tryptophan to the incubation medium attenuated the spermatozoa motility parameters and viability. Particularly, >1 mM of cysteine completely inhibited progressive motility and decreased viability to <50%. Cysteine and phenylalanine at all concentrations significantly caused the increases in lipid peroxidation products in spermatozoa and seminal plasma, and hereby induced the percentage of DNA damage in spermatozoa. Cysteine had more detrimental effects than phenylalanine and tryptophan. Our data provide evidence that these amino acids are not beneficial for the maintaining of carp spermatozoa at 4 degrees C.