Kinetics of changes in plasma membrane related to apoptosis and necrosis in bovine sperm cells at different incubation times

Abstract

Incubation time induce damages in sperm cells by necrosis and/or apoptosis. The aim of this study was the evaluation of changes in plasma membrane related to apoptosis and necrosis in bovine sperm cells through 2 hours of incubation. Sperm cells were incubated at 5% (v/v) CO2 in air for 0, 30, 60, 90 and 120 minutes. After each period, sperm cells were incubated with fluorescent probes Yo-pro and propidium iodide (PI) to detect change in plasma membrane related to apoptosis and necrosis respectively. Using Yo-pro/PI assay, three different subpopulations of sperm cells were detected by flow cytometry: a) necrotic sperm cells (PI+ and Yo-pro-/+); b) apoptotic sperm cells (Yo-pro+ and PI-) and c) living cells (Yo-pro- and PI-). The percentage of live cells (plasma membrane integrity) significantly decreases over 2 hour of incubation, on the other hand, the percentage of necrotic and apoptotic cells increase during incubation. Changes in plasma membrane integrity were correlated to incubation time. While live cells were negatively correlated with the increase of incubation time, necrosis and apoptosis were positively correlated. It was also observed that necrosis was the main damage in sperm cells in all incubation times. In conclusion, incubation time induces changes in plasma membrane integrity related to necrosis and apoptosis, whether necrosis is present in higher quantity in all incubation times.