Damage to Sorubim cuspicaudus Sperm Cryopreserved with Ethylene Glycol

SIMPLE SUMMARY: The study aimed to evaluate the damage suffered by cryopreserved semen of S cuspicaudus in mitochondria (Mit-d), plasmatic membranes (Mem-d), and DNA fragmentation (DNA-f) with an extender composed of ethylene glycol (6, 8, 10% EG), glucose (6%) and skim milk powder (5%). Sperm kinetics and damage in fresh, pre-frozen, and thawed semen were evaluated. In pre-frozen semen, sperm kinetics decreased, and Mit-d (11 to 13 times), Mem-d (2.4 to 4 times), and DNA-f (2.8 to 4 times) damages increased regarding fresh semen. In thawed semen, damage continued to rise in Mit-d (34 to 37 times), Mem-d (24.5 to 26.6 times), and DNA-f (13 to 18.5 times). Fertility (37–59%) and hatching (29–46%) rates of thawed-cryopreserved semen were reduced to half that recorded for fresh semen. In conclusion, the present study demonstrated that mitochondria, membrane, and DNA suffer considerable damage in pre-freezing and freezing–thawing, affecting their fertilizing capacity, which is reduced to half regarding fresh semen. ABSTRACT: The study aimed to evaluate cryo-injury during the cryopreservation in Sorubim cuspicaudus sperm with ethylene glycol (EG) at different rates (6, 8, 10%). Fresh, prefrozen, and post-thawed sperm quality as motility total, velocities, mitochondria damage (Mit-d), membrane damage (Mem-d), and DNA fragmentation (DNA-f), were examined. The Mit-d, Mem-d, and DNA-f were evaluated through flow cytometry. High motility (>95%) and a low percentage of Mem-d (1.0 ± 0.5%), Mit-d (1.4 ± 0.9%), and DNA-f (2.4 ± 0.8%) were recorded for fresh semen. Prefrozen semen increases in Mit-d and DNA-f were observed compared to fresh semen (p < 0.05). In thawed semen, increased Mit-d (2.6 to 3-fold), Mem-d (6 to 1-fold), and DNA-f (3.3 to 6.6-fold) compared to prefrozen was observed. Thawed semen showed Mit-d (34 to 37-fold), Mem-d (24.5 to 26.6-fold) and DNA-f (13 to 18.5-fold) increased high. In conclusion, the present study demonstrated that mitochondria, membrane, and DNA integrity undergo significant damage during both pre-freezing and freezing/thawing with EG inclusion percentages from 6 to 10% that affect its fertilizing capacity, which is reduced to half of that obtained with fresh semen. It is suggested that a cryoprotective solution composed of 6% EG, 6% glucose, and 5% skimmed milk powder is a useful protocol for the cryopreservation of S. cuspicaudus semen.