The carbonyl scavenger carnosine ameliorates dyslipidaemia and renal function in Zucker obese rats

ABSTRACT The metabolic syndrome is a risk factor that increases the risk for development of renal and vascular complications. This study addresses the effects of chronic administration of the endogenous dipeptide carnosine (beta-alanyl-L-histidine, L-CAR) and of its enantiomer (beta-alanyl-D-histidine, D-CAR) on hyperlipidemia, hypertension, advanced glycation end products (AGEs), advanced lipoxidation end products (ALEs) formation, and development of nephropathy in the non-diabetic, Zucker obese rat. The Zucker rats received a daily dose of L-CAR or D-CAR (30 mg/kg in drinking water) for 24 weeks. Systolic blood pressure (SBP) was recorded monthly. At the end of the treatment, plasma levels of triglycerides, total cholesterol, glucose, insulin, creatinine, and urinary levels of total protein, albumin, creatinine were measured. Several indices of oxidative/carbonyl stress were also measured in plasma, urine and renal tissue. We found that both L- and D-CAR greatly reduced obese-related diseases in obese Zucker rat, by significantly restraining the development of dyslipidemia, hypertension and renal injury, as demonstrated by both urinary parameters and electron microscopy examinations of renal tissue. Because the protective effect elicited by L- and D-CAR was almost superimposable, we exclude that the pharmacological action of L-CAR is due to a pro-histaminic effect (D-CAR is not a precursor of histidine, since stable to peptidic hydrolysis), and prompted us to propose that some of the biological effects can be mediated by a direct carbonyl quenching mechanism.