EFFECT OF DIETARY-PROTEIN LEVELS ON IMMUNE FUNCTION OF EXERCISED RATS

The purpose of this study was to determine the effects of different levels of dietary protein on cellular immune function of exercised rats. At 5 weeks old of age, male Fisher rats were fed diets composed of 5, 20, 40 and 60% casein levels and subjected daily to voluntary exercise on a wheel mill. At the end of an 8 week-training period, splenocytes and alveolar macrophages (AM) were isolated from exercised rats and from sedentary controls. Splenocyte proliferation induced by phytohemagglutinin (PHA), interleukin-1 (IL-1) production and phagocytosis of AM were measured, separately. It was found that exercise resulted in increases in IL-1 production and phagocytosis of AM in 20 or 40 % casein group compared with 5% casein group. However, in the 60% casein group, phagocytosis of AM decreased in both control and exercised rats. The above results suggest that the diets containing adequate level (20-40%) of protein are the most suitable for increasing cellular immunity in case of taking voluntary exercise. © 1990 Pergamon Press plc.