Abstract
NF-E2 related factor 2 (Nrf2) is a major transcription factor and acts as a key regulator of antioxidant genes to exogenous stimulations. The aim of current study was to determine whether Nrf2/ARE pathway is involved in the protective effect of electroacupuncture on the injured lung in a rabbit model of endotoxic shock. A dose of lipopolysaccharide (LPS) 5 mg/kg was administered intravenously to replicate the model of acute lung injury induced by endotoxic shock. Electroacupuncture pretreatment was handled bilaterally at Zusanli and Feishu acupoints for five consecutive days while sham electroacupuncture punctured at non-acupoints. Fourty anesthetized New England male rabbits were randomized into normal control group (group C), LPS group (group L), electroacupuncture + LPS group (group EL) and sham electroacupuncture + LPS (group SEL). At 6 h after LPS administration, the animals were sacrificed and the blood samples were collected for biochemical measurements. The lungs were removed for calculation of wet-to-dry weight ratios (W/D), histopathologic examination, determination of heme oxygenase (HO)-1 protein and mRNA, Nrf2 total and nucleoprotein, as well as Nrf2 mRNA expression, and evaluation of the intracellular distribution of Nrf2 nucleoprotein. LPS caused extensive morphologic lung damage, which was lessened by electroacupuncture treatment. Besides, lung W/D ratios were significantly decreased, the level of malondialdehyde was inhibited, plasma levels of TNF-α and interleukin-6 were decreased, while the activities of superoxide dismutase, glutathione peroxidase and catalase were enhanced in the electroacupucnture treated animals. In addition, electroacupuncture stimulation distinctly increased the expressions of HO-1 and Nrf2 protein including Nrf2 total protein and nucleoprotein as well as mRNA in lung tissue, while these effects were blunted in the sham electroacupuncture group. We concluded that electroacupuncture treatment at ST36 and BL13 effectively attenuates lung injury in a rabbit model of endotoxic shock through activation of Nrf2/ARE pathway and following up-regulation of HO-1 expression.
Highlights
Pulmonary dysfunction is documented as a hallmark of sepsis, and diffuse lung injury resulting in acute respiratory distress syndrome has been put forward as the major characters of pulmonary dysfunction after endotoxin administration [1]
Oxidative stress is defined as a condition of imbalance between reactive oxygen species (ROS) formation and cellular antioxidant capacity owing to overproduction of ROS or dysfunction of the antioxidant system [4].repairing the imbalance status by scavenging ROS or enhancing cellular antioxidant capacity may have implication for a wide array of pathology and disease models
Hemodynamic and oxygenation indexes Mean arterial blood pressure (MAP) in rabbits were remained stable throughout the experiment and the baseline MAP of each group were similar (105,109 mmHg)
Summary
Pulmonary dysfunction is documented as a hallmark of sepsis, and diffuse lung injury resulting in acute respiratory distress syndrome has been put forward as the major characters of pulmonary dysfunction after endotoxin administration [1]. The precise mechanism involved in the formation of acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) induced by endotoxin is not, as yet, fully understood. It is worthy of applying acupuncture to specific acupoints to achieve favorable regional or systemic effects [5]. Feishu (BL13) acupoint is considered of choice to treat lung diseases and regulate pulmonary functions, Pan et al reported that treatment with electroacupuncture on BL13 showed beneficial effects on hypoxia-induced pulmonary hypertention in rats [7]. Acupuncture at Zusanli (ST36) acupoints was known as the modulation of immune functions and is often used in clinical disorders of the immune system [8]
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