P5 Protective effects of hydrogen sulfide in the development of atherosclerosis in hyperlipidemic rabbit

Abstract

Several studies have showed the protective effects of Hydrogen sulfide (H 2 S) in hypertension, ischemia/reperfusion and Alzheimer’s disease, but its effects and mechanisms on atherosclerosis are still unknown. This study aims to examine the protection of H 2 S in a hyperlipidemic rabbit model of atherosclerosis. Thirty-six male New Zealand White rabbits (6 groups, n = 6) were fed a normal diet or a high-cholesterol diet (1%). Rabbits fed on high-cholesterol diet received treatments of saline, NaHS (1, 10, 30 μmol/kg/d) or PAG. After 8 weeks, animals underwent ultrasonographic imaging then sacrificed for further pathological and molecular biological analysis. We found that H 2 S attenuated atherosclerotic lesions though regulating redox status by interrupting oxidative modification of LDL and enhancing antioxidative abilities in vascular environment. The examination of plasma H 2 S levels, aortic CSE activities, and protein and gene expressions of CSE indicated the involvement of CSE/H 2 S pathway during atherosclerosis. The morphologic changes, observed by H & E, showed that the increased initma-media thickness and atherosclerotic plaques stimulated by high cholesterol diet can be reversed by exposure of H 2 S or exacerbated by CSE inhibitor, PAG. High resolution ultrasonography performed at carotids also supported H & E results. TEM showed ultrastructures of aorta in hyperlipidemic rabbits, presenting messy collagens, lipid droplets and vacuoles in thicken subendothelium and swollen mitochondria, condensate chromatin and expanding endoplasmic reticulum with cell debris and lipid droplets in smooth muscle cells, which were rarely observed in treatments of H 2 S. Next, the lipid profile in plasma showed that the increased levels of ox-LDL in hyperlipidemic rabbits were decreased by expose of H 2 S. Moreover, the regulation of modification of LDL by H 2 S also represented that the highly induced malonaldehyde (MDA) was inhibited by H 2 S and exposure of H 2 S elevated the expression of cardioprotective enzyme, heme oxygenase-1 (HO-1). Finally, the activities and protein expressions of antioxidants enzymes (SOD, CAT, GST, GPx) and GSH were retained by H 2 S showing its antioxidative effects. Propargylglycine (PAG), a selective inhibitor of CSE, abolished the protective effects of H 2 S used in the current model. In this rabbit atherosclerosis model, H 2 S implemented cardioprotection from moderating the oxidative modification of LDL, attenuating the progression of atherosclerotic lesion and ameliorating oxidative stress, which are though CSE/H 2 S pathway. This study analyzed for the first time that, regulatory effects of H 2 S on redox status though influencing modification of LDL and antioxidative abilities in in vivo study. These findings suggest that H 2 S might be a potential agent for treatment of atherosclerosis.