Abstract

Low-level laser irradiation (LLLI) increases ATP production and energy supply to the cell which could increase sperm motility, acrossomal reaction and consequently the fertilizing potential. The aim of this study was to characterize the biochemical and topological changes induced by low power laser irradiation on bull sperm cells. Post-thawing sperm were irradiated with a 633nm laser with fluence rates of 30, 150 and 300mJ.cm^-2 (power of 5mW for 1, 5 and 10minutes, respectively); 45, 230, and 450mJ.cm^-2 (7.5mW for 1, 5 and 10 minutes); and 60, 300 and 600mJ.cm^-2 (10mW for 1, 5 and 10 minutes). Biochemical and metabolical changes were analyzed by FTIR and flow cytometry; oxygen reactive species production was assessed by TBARS and the morphological changes were evaluated by AFM. Motility had no difference among times or powers of irradiation. Increasing in ROS generation was observed with power of 5mW compared to 7.5 and 10mW, and with 10min of irradiation in comparison with 5 and 1min of irradiation. This higher ROS generation was related to an increase in acrossomal and plasma membrane damage. FTIR results showed that the amount of lipids was inversely proportional to the quantity of ROS generated. AFM images showed morphological differences in plasma/acrossomal membrane, mainly on the equatorial region. We conclude that LLLI is an effective method to induce changes on sperm cell metabolism but more studies are necessary to establish an optimal dose to increase the fertility potential of these cells.

© 2011 OSA/SPIE