Stress-Induced Downregulation of Macrophage Phagocytic Function Is Attenuated by Exercise Training in Rats

<i>Background/Aims:</i> Acute restraint stress may induce impaired macrophage phagocytic function. Moderate physical training is associated with beneficial effects on immunological functions. We investigated the effects of moderate physical training on phagocytic function of alveolar macrophages in rats submitted to acute restraint stress. <i>Methods:</i> Thirty male Wistar rats weighing 210–226 g were randomly divided into 4 groups: nontrained rats (n = 7), nontrained rats submitted to stress (n = 8), trained rats (n = 7) and trained rats submitted to stress (n = 8). Trained rats were submitted to a program of moderate running training over a period of 8 weeks. Rats subjected to restraint stress were kept immobilized in glass cylinders (8 cm in diameter and 24 cm long) during 60 min. Phagocytosis capacity of macrophages was evaluated by either <i>Escherichia coli</i> orzymosan stimuli. <i>Results:</i> Restraint stress induced a decrease in phagocytosis of <i>E. coli</i> and zymosan particle stimulation by macrophages. Neither of these alterations was observed in trained animals submitted to acute restraint stress. <i>Conclusions:</i> Our data confirm that acute restraint stress is associated with impaired function of macrophages. Moreover, moderate physical training attenuates the effects of acute stress by a mechanism that involves an increase in tolerance of macrophages.