Immunofluorescence and biochemical investigation of the protective effects of naringin and diosmin on the freezability of Merino ram semen

BACKGROUND: Various antioxidant substances are added to sperm extenders to protect spermatozoa against oxidative stress and cryodamage. OBJECTIVE: To investigate the effects of the flavonoid diosmin (DIO) and a flavanone glycoside naringin (NAR) on the freezability of ram semen. MATERIALS AND METHODS: In this study, six Merino rams were used during the breeding season. The ejaculates were pooled after collection from the rams. Pooled ejaculates were divided into six groups: control, NAR 1 mM, NAR 2 mM, NAR 4 mM, DIO 2 mM, and DIO 4 mM, and then diluted with a TRIS-based diluent. The pooled semen was equilibrated, placed in 0.25 mL pipettes with 10 × 107 sperm cells in each pipette, and frozen in liquid nitrogen vapor. After 24 h, the pipettes were thawed at 37°C for 25 s and analyzed in terms of spermatological parameters. RESULTS: The highest plasma membrane integrity ratio was found in the DIO 4 mM group, whereas a statistically significant difference was found between the NAR 1 mM and NAR 2 mM groups (p<0.05). While the DIO 4 mM group had the highest acrosome integrity rate, a statistically significant difference was found between the other groups (p<0.05). Mitochondrial activity was the highest in the NAR 4 mM, DIO 4 mM and DIO 2 mM groups (p<0.05). In the analysis of the sperm membrane lipid profile, it was observed that the DIO group had the highest lipid-phospholipid ratio. In sperm membrane protein profile analysis, it was found that both additives exerted protective effects at different levels. The highest total protein content was seen in the DIO 4 mM and NAR 4 mM groups. 8-hydroxydeoxyguanosine (8-OhDG) positivity was more common in the control group than in the DIO and NAR groups. Cu-Zn superoxide dismutase (SOD) expression was lower in the control group and more intense in all other groups. Positive results were especially observed in the acrosome of the sperm cells. CONCLUSION: The addition of NAR and DIO to the ram semen extender increased the quality of sperm parameters after the freeze-thaw process.