Effects of stress and neuropeptides on airway responses in ovalbumin-sensitized rats.

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.