Expression of genes related to oxidative/nitrosative stress in mouse hearts: effect of preconditioning and cholesterol diet.

Background: The aim of our study was to explore the effect of high-cholesterol diet and preconditioning on cardiac gene expression patterns in mouse hearts, focusing on genes involved in nitric oxide (NO) and free radical signaling and the mevalonate pathway.

Material/methods: Mice were fed 2% high-cholesterol or normal diet for 8 weeks. Hearts isolated from both groups were subjected to either a preconditioning (PC) protocol (3 cycles of 5 min ischemia and 5 min aerobic perfusion) or a time-matched non-preconditioning protocol followed by 30 min global test ischemia and 2 hour reperfusion.

Results: PC altered gene expression only in the mice subjected to a normal diet, as shown in neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS) and the superoxide-producing enzymes xanthine oxidase (XO) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases 1 and 4. The rate-limiting enzyme of the mevalonate pathway, 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase showed differential expression in the myocardium in response to I/R and PC in mice on normal diet but not in cholesterol-fed animals.

Conclusions: We conclude that cholesterol-enriched diet leads to alterations in preconditioning-induced gene expression in the mouse heart, which might lead to marked changes of oxidative/nitrosative stress signaling and to the attenuation of the cardioprotective effect of preconditioning.