Impact of combined ischemic preconditioning and melatonin on renal ischemia-reperfusion injury in rats

Abstract

Objectives: Studying the effect of melatonin pretreatment and ischemic preconditioning on renal ischemia-reperfusion injury (IRI).

Materials and methods: Forty-eight Wistar rats were randomized into six groups: control, sham operation, IRI (IRI in left kidney + right nephrectomy), IRI+ischemic preconditioning, IRI+Melatonin, and IRI+ischemic preconditioning+Melatonin groups. Melatonin (10 mg/kg) was intraperitoneally injected for 4 weeks before renal IRI. Ischemic preconditioning was performed by three cycles of 2 min-ischemia followed by 5 min-reperfusion period. A right nephrectomy was initially done and the left renal artery was clamped for 45 min. After 24 hr of ischemia-reperfusion, rats were decapitated. Kidney tissue samples were taken for histopathological assessment and the determination of kidney proinflammatory and anti-inflammatory cytokines, apoptotic protein caspase-3, oxidative stress markers, and activities of antioxidant enzymes. Serum creatinine and blood urea nitrogen (BUN) concentrations were measured for evaluation of renal function.

Results: Renal IRI animals showed increased levels of creatinine, BUN, tumor necrosis factor-α (TNF-α), caspase-3, total nitrite/nitrate, and malondialdehyde (MDA), and decreased levels of interleukin-13 (IL-13), and activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD). Melatonin pretreatment or ischemic preconditioning resulted in decreased creatinine, BUN, TNF-α, caspase-3, nitrite/nitrate, and MDA, and increased IL-13, GPx, and SOD, with improved histopathological changes. Combined melatonin and ischemic preconditioning showed more effective improvement in renal IRI changes rather than melatonin or ischemic preconditioning alone.

Conclusion: Combined melatonin and ischemic preconditioning have better beneficial effects on renal IRI than applying each one alone.

Keywords: Ischemia-reperfusion injury; Ischemic preconditioning; Melatonin; Oxidative stress; Wistar rat.

Figure 1

Histopathological assessment of rat left kidney showing the degrees of renal tubular damage (9). (A) showing no change with neither necrosis of tubular epithelium nor cast formation in tubular lumina, score 0; (B) showing individual cell necrosis () with pyknotic nuclei and cytoplasmic vacuolization, score 1; (C) showing complete tubular necrosis with total loss of nuclei and tubular brush border () less than 25%, score 2; (D) showing tubular necrosis () between 25% and 50%, score 3; (E) showing tubular necrosis () more than 50%, score 4 (examined under a light microscope; Olympus bx41, H&E x200 for all)