Caloric restriction ameliorates kidney ischaemia/reperfusion injury through PGC-1-eNOS pathway and enhanced autophagy

Aim: We investigated whether preconditioning with caloric restriction (CR) ameliorates kidney ischaemia/reperfusion (I/R) injury and whether the salutary effects of CR are mediated through enhanced autophagy and/or activation of key metabolic sensors SIRT1, AMP-kinase and PGC-1. Methods: Six- to seven-week-old Wistar rats were divided into three groups: (i) sham-operated group; (ii) I/R group (40-min ischaemia followed by 24h of reperfusion); and (iii) I/R group kept under CR (energy intake 70%) for 2weeks before surgery. In additional experiments, sirtinol and 3-methyladenine (3-MA) were used as inhibitors of SIRT1 and autophagy respectively. Renal function was measured, and acute tubular damage and nitrotyrosine expression were scored. Kidney adenosine monophosphate-activated kinase (AMPK), SIRT1, eNOS, PGC-1 and LC-3B expressions were measured. Results: Caloric restriction improved renal function, protected against the development of acute tubular necrosis and attenuated I/R-induced nitrosative stress. Kidney I/R injury decreased eNOS and PGC-1 expression, inhibit autophagy and increased SIRT1 and AMPK expressions by 2.6- and fourfold respectively. However, phosphorylation level of AMPK was decreased. As compared with I/R injury group, CR further increased kidney SIRT1 expression by 1.8-fold, promoted autophagy and counteracted I/R-induced decreases in the expression of eNOS and PGC-1. 3-MA abolished the renoprotective effects of CR, whereas sirtinol did not influence renal function in CR rats with I/R injury. Conclusions: Caloric restriction ameliorates acute kidney I/R injury through enhanced autophagy and counteraction of I/R-induced decreases in the renal expression of eNOS and PGC-1.