Immunomodulation by 8‐week voluntary exercise in mice

This study was designed to evaluate the effects of voluntary exercise on macrophage and lymphocyte functions in mice. Male A/He inbred mice aged 19 weeks were divided into two groups: a group given voluntary exercise and a control group (n = 10 in each group). Exercise consisted of spontaneous running in wheels for 8 weeks (3 days week^–1). Glucose consumption of peritoneal macrophages in the exercise group during incubation up to 72 h was significantly higher than that in the control group (70 and 13%, respectively). Also, activities of acid phosphatase (APH) (10.75 ± 0.37 IU), β‐glucuronidase (GLU) (1.55 ± 0.07 IU) and lactate dehydrogenase (LDH) (43.3 ± 0.7 IU) in the peritoneal macrophages in the exercise group was significantly increased (P < 0.01). Compared with the control group, the exercise group had a significant increase of about twofold in macrophage production of nitric oxide (NO₂^–) stimulated by lipopolysaccharide (LPS) (11.1 ± 0.1 vs. 5.9 ± 0.1 μM mL^–1 in exercise and control groups, respectively; P < 0.01). Stimulation indices both by concanavalin A (Con A) and phytohaemagglutinin were also significantly higher in the exercise group (P < 0.01). A significant increase in the splenocyte production of interleukin‐2 (IL‐2) stimulated by Con A was noticed in the exercise group (354.1 ± 28.8 vs. 218.9 ± 23.5 pg mL^–1 in exercise and control groups, respectively; P < 0.01). These findings suggest that voluntary exercise enhances not only macrophage function but also lymphocyte responsiveness in mice. In the studies of voluntary exercise, evaluation of NO₂^– production, as an indicator of macrophage function, is recommended.