Protective Effect of Short -Term Dietary Restriction Against Renal Ischemia Reperfusion Injury in Male Rats

Dietary restriction (DR) causes a variety of improvements related to overall health and is effective in reducing oxidative stress. Ischemia reperfusion (IR) is considered a clinical form of oxidative stress. These experiments were designed to investigate the influence of DR on IR injury and to elucidate the mechanisms responsible for the beneficial effect of short-term DR on renal IR injury. To examine whether DR protects against IR injury, 6 mo -old male rats were assigned to either a control (fed ad libitum) or DR (70% diet of control for 2 weeks) groups (ALG DRG respectively). Kidney function tests, insulin sensitivity (measured by Homeostasis model assessment of insulin resistance, HOMAIR), tumor necrosis factor -alpha (TNF-α) and renal expression of insulin like growth factor-1 (IGF-1) were measured before renal IR and one and two days after renal IR. The results of the present study demonstrated that after 2 weeks of DR, the body weight of DRG was significantly less (p 0.05) than ALG, however relative kidney weight showed insignificant difference between the two groups. After renal IR, the deterioration of kidney function wasless in DRG than that in ALG, there was a significant decrease (p 0.05) in blood urea nitrogen and creatinine in DRG compared to ALG. Fasting plasma levels of insulin and glucose were significantly less (p 0.05) and consequently insulin sensitivity was higher in DRG than in ALG. The rise in TNF-α after renal IR was significantly less (p 0.05) in DRG than ALG. Renal expression of IGF-1 was less in DRG than ALG before renal IR but it increased significantly (p 0.05) 48 hrs after IR compared to corresponding values before IR injury. The present study suggests that dietary restriction protects against IR injury. The mechanism of this protection is partly through alteration in renal expression of IGF-1 and moderating the production of some markers of inflammation that are up-regulated during ischemia reperfusion injury . Preoperative DR may therefore be a non-invasive way to reduce ischemia reperfusion injury following organ transplantation.