Apocynin suppressed the nuclear factor-B pathway and attenuated lung injury in a rat hemorrhagic shock model

Abstract

BACKGROUND The aim of this study was to investigate whether a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) inhibitor, apocynin, reduces reactive oxygen species (ROS) production, suppresses the nuclear factor B (NF-B) pathway, attenuates lung injury, and improves survival in rat hemorrhagic shock (HS) model. METHODS Blood was drawn from male Sprague-Dawley rats (290-340 g) to maintain a mean arterial pressure of 20-25 mm Hg for 40 minutes. The rats were resuscitated with the drawn blood, and a vehicle (HS), a low dose of apocynin (20 mg/kg, LD-Apo), or a high dose of apocynin (40 mg/kg, HD-Apo) was administered intraperitoneally. The survival of the rats was observed for 72 hours. Then, a separated set of rats was euthanized at 6 hours post-HS induction. We measured gp91-phox (Nox2) expression, Nox activity, cytoplasmic phosphorylated inhibitor B- (p-IB-) expression, NF-B p65 DNA-binding activity, tumor necrosis factor- (TNF-) and interleukin-6 (IL-6) gene expressions, malondialdehyde (MDA) level, myeloperoxidase (MPO) activity, and histological damage in the lung tissues. RESULTS The survival rates of the sham, HS, HS + LD-Apo, and HS + HD-Apo groups were 100% (5/5), 30% (3/10), 40% (4/10), and 70% (7/10), respectively. A high dose of apocynin decreased gp91-phox expression, Nox activity, and MDA level in the lung tissues during HS and resuscitation. It also decreased p-IB- expression, NF-B p65 DNA-binding activity, TNF- and IL-6 gene expressions, and MPO activity in the lung tissues and attenuated histological lung injuries. However, a low dose of apocynin failed to show these benefits. CONCLUSIONS The administration of a high dose of apocynin inhibited Nox2 expression and Nox activity, reduced lipid peroxidation, suppressed the NF-B pathway and subsequent pro-inflammatory cytokines transcription in the lung tissues, and attenuated lung injury during HS and resuscitation in rats.