  Some biochemical and metabolic characteristics of bovine sperm cells
irradiated with low-level laser were probed and correlated to the irradiation
parameters. Bovine spermatozoa were exposed to spatially filtered light from a
He-Ne laser (633 nm) with fluences from 150 to 600 mJ/cm2. General biochemical
alterations were assessed by vibrational spectroscopy (micro-Fourier-Transform
Infrared technique). The mitochondrial membrane potential was assessed by flow
cytometry. Lipid peroxidation due to reactive oxygen species (ROS) production
was assessed by thiobarbituric acid reactive substances (TBARS) assay. Sperm
morphologic characteristics changes were probed by atomic force microscopy
(AFM) technique. LLLI was able to induce, at different fluences, changes in
lipid, DNA and protein contents. Moreover, LLLI also induced changes in TBARS
production, suggesting an irradiation effect on lipid peroxidation. Acrosomal
reaction induction evidences was found based on changes in protein structure
(Amides I and II bands) and AFM characterization. The most interesting result,
however, was the changes in methyl and DNA groups, which strongly suggests that
LLLI can modify DNA methylation patterns, important for pregnancy
establishment. The observed changes in the above-cited parameters have direct
impact on sperm quality. The low-level laser irradiation has the potential to
improve the fertilizing capacity of bovine sperm cells.
