2,2'-Azobis (2-Amidinopropane) Dihydrochloride Is a Useful Tool to Impair Lung Function in Rats.

Maria D Moreira Gomes,Jose H Leal-Cardoso,Giovanna M C Carvalho,Natalia V Casquilho,Walter A Zin,Samuel S Valença,Andressa C P Araújo

doi:10.3389/fphys.2016.00475

Abstract

Recently, several studies have reported that respiratory disease may be associated with an increased production of free radicals. In this context, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) is a free radical-generating compound widely used to mimic the oxidative stress state. We aimed to investigate whether AAPH can generate lung functional, inflammatory, histological and biochemical impairments in the lung. Wistar rats were divided into five groups and instilled with saline solution (714 μL/kg, CTRL group) or different amounts of AAPH (25, 50, 100, and 200 mg/kg, 714 μL/kg, AAPH groups). Seventy-two hours later the animals were anesthetized, paralyzed, intubated and static elastance (Est), viscoelastic component of elastance (ΔE), resistive (ΔP1) and viscoelastic (ΔP2) pressures were measured. Oxidative damage, inflammatory markers and lung morphometry were analyzed. ΔP1 and Est were significantly higher in AAPH100 and AAPH200 than in the other groups. The bronchoconstriction indexes were larger in AAPH groups than in CTRL. The area occupied by collagen and elastic fibers, polymorpho- and mononuclear cells, malondialdehyde and carbonyl groups levels were significantly higher in AAPH200 than in CTRL. In comparison to CTRL, AAPH200 showed significant decrease and increase in the activities of superoxide dismutase and catalase, respectively. AAPH augmented the release of pro-inflammatory cytokines IL-1β, IL-6 e TNF-α. Hence, exposure to AAPH caused significant inflammatory alterations and redox imbalance accompanied by altered lung mechanics and histology. Furthermore, we disclosed that exposure to AAPH may represent a useful in vivo tool to trigger lung lesions.

Highlights

Several studies have reported that increased free radicals production may be associated with respiratory diseases, such as asthma, pulmonar fibrosis, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI) and lung cancer (Valko et al, 2007; Ciencewicki et al, 2008; Park et al, 2009)
Control (CTRL; n = 8) and experimental (AAPH; n = 8/group) animals received one intranasal instillation (i.n.) of sterile saline solution (0.9% NaCl, 37◦C) or different amounts of azobis (2-amidinopropane) dihydrochloride (AAPH) (25, 50, 100 and 200 mg/kg in saline solution, respectively). These doses were chosen based on preliminary experiments, which allowed the determination of the volume of saline solution (714 μL/kg body wt) in which the highest dose of AAPH would be completely diluted
P1 was significantly higher in AAPH100 and AAPH200 rats than in CTRL and AAPH25 groups that did not differ among them

Summary

Introduction

Several studies have reported that increased free radicals production may be associated with respiratory diseases, such as asthma, pulmonar fibrosis, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI) and lung cancer (Valko et al, 2007; Ciencewicki et al, 2008; Park et al, 2009) In this line, the lung is continuously exposed to high levels of oxidants, which together with its large surface area and blood supply render it prone to injury mediated by free radicals (Rahman, 2002, 2012; Park et al, 2009). Mechanical properties can be altered considerably, which contributes importantly to a decline in lung function (Suki et al, 2003; Bates et al, 2007; Gladysheva et al, 2010). Prior studies report changes in lung resistance and elastance resulting from lung diseases in which oxidative stress plays a key role (Suki et al, 2003; Bezerra et al, 2011; Lima-Trajano et al, 2011)

Objectives

Methods

Results