The effects of skeletal muscle conditioned medium on oxidative stress and morphometry of murine testicles cultured in vitro.

This study aimed to evaluate the effects of conditioned medium derived from murine skeletal muscle (SMCM) on oxidative stress and testicular morphology in vitro. Initially, Wistar rats underwent treadmill familiarization and a maximal incremental test (MIT). Animals were then submitted to a single exercise session at 60% of the maximum speed established by MIT. In Experiment 1, femoral muscles from trained animals were cultured in αMEM supplemented with 1.25 mg/mL BSA to produce SMCM. In Experiment 2, testes from sedentary rats were fragmented and cultured for 24 h in αMEM alone or αMEM added to irisin at 100 ng/mL or αMEM added to SMCM at 25, 50, 75, or 100%. HPLC confirmed the presence of irisin in SMCM. Oxidative stress analyses demonstrated catalase activity was higher in irisin and 75% of SMCM treatments, while glutathione peroxidase (GPX) activity was significantly higher in the irisin when compared to fresh control. It is important to highlight that 25% of SMCM was similar to fresh control in GPX activity and thiol content. Histological assessment revealed structural alterations in cultured testes, although overall tubular organization was preserved. These findings suggest that skeletal muscle SMCM modulates oxidative balance and testicular structure, with the 25% concentration yielding the most favorable antioxidant profile.