RESUMO
We investigated whether low-dose radiation (LDR) can prevent late-stage diabetic cardiomyopathy and whether this protection is because of the induction of anti-apoptotic and anti-oxidant pathways. Streptozotocin-induced diabetic C57BL/6J mice were treated with/without whole-body LDR (12.5, 25, or 50 mGy) every 2 days. Twelve weeks after onset of diabetes, cardiomyopathy was diagnosed characterized by significant cardiac dysfunction, hypertrophy and histopathological abnormalities associated with increased oxidative stress and apoptosis, which was prevented by LDR (25 or 50 mGy only). Low-dose radiation-induced cardiac protection also associated with P53 inactivation, enhanced Nrf2 function and improved Akt activation. Next, for the mechanistic study, mouse primary cardiomyocytes were treated with high glucose (33 mmol/l) for 24 hrs and during the last 15 hrs bovine serum albumin-conjugated palmitate (62.5 µmol/l) was added into the medium to mimic diabetes, and cells were treated with LDR (25 mGy) every 6 hrs during the whole process of HG/Pal treatment. Data show that blocking Akt/MDM2/P53 or Akt/Nrf2 pathways with small interfering RNA of akt, mdm2 and nrf2 not only prevented LDR-induced anti-apoptotic and anti-oxidant effects but also prevented LDR-induced suppression on cardiomyocyte hypertrophy and fibrosis against HG/Pal. Low-dose radiation prevented diabetic cardiomyopathy by improving cardiac function and hypertrophic remodelling attributed to Akt/MDM2/P53-mediated anti-apoptotic and Akt/Nrf2-mediated anti-oxidant pathways simultaneously.