The irradiation of rabbit sperm cells with He–Ne laser prevents their in vitro liquid storage dependent damage

The aim of the study was to investigate the effects of different energy doses of helium–neon (He–Ne) laser irradiation on both mitochondrial bioenergetics functions and functional quality of rabbit spermatozoa during 48 h of in vitro liquid storage at 15 °C.11 rabbit semen pools were each divided into four aliquots: three of them were irradiated with He–Ne laser with different energy doses (3.96, 6.12 and 9.00 J/cm2) being the last control kept under the same experimental conditions without irradiation. Sperm motility, viability and acrosome integrity were monitored together with cytochrome c oxidase (COX) activity and the cell energy charge (EC) at 0, 24 and 48 h of storage.Irradiated samples stored for 24 and 48 h better maintained motility (P < 0.01), acrosome integrity (P < 0.01) and viability (P < 0.05) with respect to the control, particularly with the energy dose of 6.12 J/cm2 that showed the most intense biostimulative effect. COX activity and EC were immediately increased by irradiation particularly in the treatments 6.12 and 9.00 J/cm2 (P < 0.05), that maintained their levels higher with respect to the control after 48 h of storage (P < 0.01). COX activity of rabbit sperm cells was positively correlated with EC (P < 0.05), viability (P < 0.01) and acrosome integrity (P < 0.05) parameters.These results indicate that the effects of He–Ne laser irradiation on sperm cells are mediated through the stimulation of the sperm mitochondrial respiratory chain and that this effect plays a significant role in the augmentation of the rabbit sperm cells’ capability to survive during liquid storage conditions.