P27 Changes in the hydrogen sulfide (H2S) system arising from administration of high fat diet

Abstract

Atherosclerosis is a progressive disease characterized by endothelial dysfunction and accumulation of lipids, cellular debris and fibrous elements within the intima of the vessel wall. Eventually, atherosclerosis triggers plaque formation, vascular remodeling and luminal obstruction [1] . It is becoming increasingly clear that atherosclerosis is an inflammatory disease, dependent on the interaction between inflammatory cells recruited in response to endothelial lipid accumulation, and to the local, wound-healing response of surrounding vascular smooth muscle cells. H2S is a gasomediator synthesized from cysteine predominantly by cystathionine-γ-lyase (CSE) [2] and been reported to exhibit both pro- and anti-inflammatory effects [3] . Administration of high fat diet over an extended period results in the development of a low grade inflammatory response which can predispose to atherosclerosis. In the present work we therefore investigated the role of H2S in high fat (HF) fed mice. Mice (C57/Black, male, 25 g) were fed either normally or given a HF diet (16% fat, 12.5% cholesterol and 5% sodium cholic acid) for up to 16 weeks. At the end of 8, 12 or 16 weeks, groups of mice were anaesthetised, blood obtained by cardiac puncture and centrifuged for plasma and heart, liver, kidney and lungs removed for biochemical and histological analyses. H2S synthesizing enzyme activity was measured in lung, kidney and liver homogenates incubated with l -cysteine(10 mM) and pyridoxal 5’-phosphate (2 mM) by the zinc trapping spectrophotometric assay. Plasma H2S levels were determined by high-performance liquid chromatography (HPLC) [4] . Lung, kidney and liver homogenates were used for western blotting of cystathionine-β-synthetase (CBS), CSE and 3-mercaptopyruvate synthase (3-MST). A range of cytokines and chemokines were also assayed in mouse plasma using a Bio-Plex Pro™ Assay. Plasma serum amyloid A (SAA) and C-reactive protein (CRP) levels were measured using ELISA kits. Oil red O staining was performed on aorta samples. Compared to normal diet mice, HF mice showed similar H2S synthesizing activity for lung (normal mice 0.28 ± 0.04 nmol/mg, n = 7; HF mice 0.22 ± 0.03 nmol/mg, n = 7), and decreased H2S synthesizing activity for kidney (normal mice 2.49 ± 0.79 nmol/mg, n = 7; HF mice 1.16 ± 0.32 nmol/mg, n = 7) and liver (normal mice 9.21 ± 2.44 nmol/mg, n = 7; HF mice 1.65 ± 0.34 nmol/mg, n = 7) (p