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), beta-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 microM 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.