Effect of superoxide dismutase, catalase, and glutathione peroxidase supplementation in the extender on chilled semen of fertile and hypofertile dogs

Abstract

This study investigated the correlation between oxidative stress status and key canine sperm parameters and the effect of addition of a superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) combination in egg yolk tris-citrate glucose (EYT-G) extender on semen during 10 days of storage at 4℃. Ten Boxer dogs were divided into two groups, fertile (F) and hypofertile (H), depending on pregnancy and live birth rate status in the previous year. Semen evaluation was performed on the day of collection (D0) and after 5 (D5) and 10 (D10) days of cooled storage. Sperm motility, kinetic parameters, and DNA integrity were assessed. A correlation between oxidative status and key semen parameters in both F and H groups was observed. Total and progressive motilities were significantly higher in the treated (SOD, CAT, and GPx addition) versus control groups at D10 in both F and H groups, and at D5 in the H group. DNA integrity was significantly higher in both treated groups (H and F) at D5 and D10. In conclusion, the addition of SOD, CAT, and GPx in the extender allows preservation of semen quality for up to 10 days of storage at 4℃ in both fertile and hypofertile dogs.

Keywords: antioxidants; canine sperm; fertility; oxidative stress; semen preservation.

Fig. 1. Representative image of canine spermatozoa stained with an APO-BrdU TUNEL Assay Kit with anti-brdU Alexa Fluor 488 and using fluorescence microscopy at 400× magnification. Propidium iodide stains the nucleus of all sperm cells red and anti-brdU Alexa Fluor 488 stains spermatozoa with fragmented DNA in yellow. TUNEL-negative (red) and TUNEL-positive (yellow).

Fig. 2. Results of analysis of fresh diluted semen parameters in fertile and hypofertile groups: percentages of oxidative stress index (OSi), DNA integrity, total and progressive motilities (A); velocity parameters (B), and motion variables (C). VAP, average path velocity; VSL, straight line velocity; VCL, curvilinear velocity; STR, straightness; LIN, linearity. Significant differences between groups are denoted by ^*p < 0.05.

Fig. 3. Results of assessment of percentages of total (A) and progressive (B) motilities and DNA fragmentation (C) of diluted semen after 5 and 10 days of cooled storage in control and experimental groups of hypofertile (H) and fertile (F) dogs. Significant differences (^*p < 0.05) between control and experiment groups.