Apoptotic-like changes in equine spermatozoa separated by density-gradient centrifugation or after cryopreservation

The objective was to evaluate apoptotic markers in ejaculated equine spermatozoa after separation by density-gradient centrifugation and after cryopreservation. Subpopulations of percoll-separated equine spermatozoa differed (P < 0.05) in the percentage of live, caspase-activated spermatozoa (2.9 +/- 0.7% vs 14.2 +/- 6.4%; mean +/- S.E.M.), low mitochondrial membrane potential (MMP; 6.8 +/- 1.1 vs 23.8 +/- 3.7), altered plasma membrane permeability (1.3 +/- 0.2 vs 3.0 +/- 0.5), DNA fragmentation (2.0 +/- 1.3 vs 14.3 +/- 3.6), total motility (81.8 +/- 3.3 vs 35.1 +/- 5.4), and progressive motility (66.3 +/- 4.3 vs 24.1 +/- 4.5) for high-density versus low-density subpopulations, respectively. Phosphatidylserine externalization did not differ (P = 0.67) between the high- and low-density subpopulations (2.6 +/- 0.7 vs 3.1 +/- 0.9). After cryopreservation, equine spermatozoa differed (P < 0.01) in the percentage of active caspases (19.1 +/- 1.6 vs 52.1 +/- 2.8), low MMP (18.2 +/- 2.5 vs 48.7 +/- 2.6), altered plasma membrane permeability (6.8 +/- 1.7 vs 17.6 +/- 2.0), total motility (75.5 +/- 2.4 vs 45.2 +/- 5.6), and progressive motility (53.9 +/- 3.1 vs 28.3 +/- 4.5) for pre-freeze versus cryopreserved spermatozoa. There was no difference (P = 0.2 1) in percentage of DNA fragmented cells before (5.5 +/- 1.2) versus after cryopreservation (6.6 +/- 1.1). We concluded that apoptotic-like changes were detectable in ejaculated equine spermatozoa and were more prevalent after cryopreservation. (C) 2008 Elsevier Inc. All rights reserved.