NAD(P)H oxidase-induced oxidative stress in sympathetic ganglia of apolipoprotein E deficient mice

Abstract

Superoxide anion (O 2 •−) is increased throughout the arterial wall in atherosclerosis. The oxidative stress contributes to lesion formation and vascular dysfunction. In the present study, we tested the hypothesis that NAD(P)H oxidase-derived O 2 •− is increased in nodose sensory ganglia and sympathetic ganglia of apolipoprotein E deficient (apoE −/−) mice, an established animal model of atherosclerosis. O 2 •− measured ex vivo by L-012-enhanced chemiluminescence was increased by 79 ± 17% in whole sympathetic ganglia from apoE −/− mice ( n = 5) compared with sympathetic ganglia from control mice ( n = 5) ( P < 0.05). In contrast, O 2 •− was not elevated in nodose ganglia from apoE −/− mice. Dihydroethidium staining confirmed the selective increase in O 2 •− in sympathetic ganglia of apoE −/− mice, and revealed the contribution of both neurons and non-neuronal cells to the O 2 •− generation. We investigated the enzymatic source of increased O 2 •− in sympathetic ganglia of apoE −/− mice. The mRNA expression of gp91phox, p22phox, p67phox, and p47phox subunits of NAD(P)H oxidase measured by real time RT-PCR was increased ∼ 3–4 fold in sympathetic ganglia of apoE −/− mice ( n = 5) compared with control ganglia ( n = 5). NADPH oxidase activity measured by lucigenin chemiluminescence was increased by 68 ± 12% in homogenates of sympathetic ganglia from apoE −/− mice ( n = 7) compared with control ganglia ( n = 7) ( P < 0.05). The results identify sympathetic ganglia as a novel site of oxidative stress in atherosclerosis, and suggest that upregulation of NAD(P)H oxidase is the source of increased O 2 •− generation. We speculate that oxidative stress in sympathetic ganglia may contribute to impaired baroreflex control of sympathetic nerve activity.