Leptin attenuates ischemia-reperfusion injury in the rat liver

Leptin is an adipocytokine that reduces ischemic damage in several organs including brain and heart. STAT3 activation is a key step for the attainment of leptin effects in various tissues. We evaluated the possible effect of leptin on liver viability and STAT3 activation, in a rat model of ischemiareperfusion injury. Rat livers, flushed and stored with Belzer solution (4 degrees C for 24 h), were warmly reperfused (3.5 ml/min/g liver for 1 h at 37 degrees C with O2) with KrebsRinger bicarbonate. Treatment group underwent an identical protocol with the adjunct of Leptin (10 ng/ml). Liver effluent was harvested to assess LDH and AST output. Liver tissue was used for pSTAT3 expression (western blot and immunostaining), optical microscopy, TUNEL, and Cell Death Detection assays. The pSTAT3 expression was enhanced by administration of leptin. In parallel, LDH and AST output were reduced (P = 0.04 and P = 0.02 for LDH and AST, respectively). Optical microscopy, TUNEL, and Cell Death Detection assay results demonstrated increased viability in livers treated with leptin in comparison with others (Optical microscopy P = 0.02; TUNEL P = 0.01; Cell death Detection assay P = 0.003). In conclusion, cold storage and reperfusion with leptin reduce liver ischemiareperfusion injury. This effect is associated with an increased expression of pSTAT-3.