Effects of Stress and Neuropeptides on Airway Responses in Ovalbumin-Sensitized Rats

Abstract

Objective: The aim of this study was to investigate the influence of stress and neuropeptides on airway responses in ovalbumin (OVA)-sensitized rats. Methods: Three experimental conditions were employed: neonatal capsaicin treatment, foot shock stress and OVA sensitization. For neuropeptide depletion, male Wistar rats were neonatally treated with capsaicin (50 mg/kg) or with control solution 2 days after birth. Ninety days later, they were injected with OVA and aluminum hydroxide (ED0) or no injection. Thereafter, rats of the stressed groups were individually placed in a shuttle box where they received 50 mild escapable foot shocks/day; the stressful stimuli were repeated until ED14, when the animals received OVA aerosol. Pulmonary mechanic function was measured before and after OVA challenge in anesthetized and mechanically ventilated rats. Results: Data on ultrasonic vocalizations and corticosterone showed high levels of anxiety in stressed animals. As expected, a significant increment in airway elastance and resistance after the OVA challenge was found in sensitized rats compared to non-sensitized ones. Capsaicin treatment decreased the values of elastance in sensitized and non-stressed rats; however, after the OVA challenge, elastance was increased in stressed animals. No differences were found in the levels of resistance among sensitized and non-stressed rats; however, a reduced increment in resistance was verified in capsaicin-treated, stressed animals. Conclusions: Our results suggest that neurokinin depletion and stress may affect smooth muscle tonus around the airways during an anaphylactic reaction. These data suggest that stress and neuropeptides play a significant role in pulmonary function in OVA-sensitized rats.

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Inducible Nitric Oxide Synthase Inhibition Attenuates Physical Stress-Induced Lung Hyper-Responsiveness and Oxidative Stress in Animals with Lung Inflammation

“…Concerning the effects of stress on lung function, some authors have tried to elucidate the mechanisms involved, both in human and animal models [16,21,[51][52][53] . …”

Effects of Repeated Stress on Distal Airway Inflammation, Remodeling and Mechanics in an Animal Model of Chronic Airway Inflammation

“…There are several animal models of stress induction [12][13][14][15][16][17] . The forced swim stress is a type of unavoidable stress that induces an effort to survive with an escape deficit [16,17] .…”

“…The forced swim stress is a type of unavoidable stress that induces an effort to survive with an escape deficit [16,17] . Furthermore, this method has been used as an animal model of behavioral despair/depression associated with the modulation of inflammatory cells and cytokines [16][17][18][19] . It is important to emphasize that this stress animal model includes both psychological and physical stressors, which in turn influence allergic responses induced by repeated ovalbumin exposures.…”