Stress-induced increment on total bronchoalveolar cell count in OVA-sensitized rats

The influence of stress on total leukocyte count from bronchoalveolar lavag e (BAL) was investigated in rats sensitized and challenged with ovalbumin ( OVA). The animals were injected intraperitoneally with a suspension of OVA plus aluminum hydroxide in 0.9% NaCl (Day 0) and boosted at Day 7 with an i dentical OVA solution, administered subcutaneously From the first to the 13 th day after sensitization, rats were placed individually in a shuttle box where they received 50 escapable footshocks per day, always preceded by a s ound signal (S); the responses that occurred during both S and shocks cance led the stressful stimulation. On Day 14, animals were submitted to a singl e session of 50 inescapable footshocks, preceded by the same S; immediately after, the animals were submitted to a 1% OVA-inhalation challenge. Result s showed high levels of stress in the shocked animals as detected through b oth ultrasonic vocalizations (UVs) and social interaction test in an open f ield. Total leukocyte count in BAL, from stressed animals (24 h post-OVA ch allenge) revealed a significant increase in the number of inflammatory cell s in comparison to that measured in sensitized, nonstressed challenged rats . These data demonstrate that stress plays a relevant and important role on total bronchoalveolar cell count in OVA-sensitized rats. (C) 2001 Elsevier Science Inc. All rights reserved.