Photobiomodulation Improves Histological Parameters of Testis and Spermatogenesis in Adult Mice Exposed to Scrotal Hyperthermia in the Prepubertal Phase

Heat stress is one of the environmental causes of damage to the testis, whose effects are less known before puberty. The aim of the present study was to investigate the impact of photobiomodulation (PBM) on the testis of prepubertal mice subjected to hyperthermia.

Twenty-four three-week-old prepubertal male mice were allocated to the following groups: I) control, II) scrotal hyperthermia (Hyp), and III) Hyp+PBM (n=8/each group). In order to induce hyperthermia, the scrotum was placed in water at 43 °C for 20 minutes every other day for a total duration of 10 days. In the Hyp+PBM group, after hyperthermia induction, the testis of the mice was subjected to laser irradiation at a wavelength of 890 nm (0.03 J/cm2 for 30 seconds) for 35 days. After the mice were sacrificed, the testis and epididymis were removed for testing.

Compared with those of the Hyp group, the sperm parameters of the laser irradiation group improved notably. In addition, histological examinations revealed that the final number of testis cells and the volume of tissue in the Hyp+PBM group were dramatically greater than those in the Hyp group. The analysis of molecular data revealed an increase in the expression of mitotic genes and testosterone levels and a decrease in the formation of reactive oxygen species (ROS) and the expression of the apoptotic gene in the testis subjected to PBM.

Based on the present findings, laser therapy can reduce complications caused by scrotal hyperthermia during prepuberty and ameliorate spermatogenesis during puberty.