The rate of protein synthesis and RNA concentration (mg RNA/g protein) in the brain decrease with age in rats after weaning. In the present study, we investigated whether the quantity and quality of dietary protein affected the rate of brain protein synthesis in aged rats. Experiments were conducted on three groups of 30-wk-old rats fed diets containing 0, 5 or 20g casein/100g, and fed diets containing 20g casein, 20g gluten or 20g gelatin/100g, respectively, for 10 days. The fractional rates of protein synthesis in the brain declined with the decrease in quantity of dietary protein. These rates in the brain also decreased as the quality of the dietary protein became poorer. In the brain, the RNA activity [g protein synthesized/g RNA d-1] was significantly correlated with the fractional rate of protein synthesis. The RNA concentration was not related to the fractional rate of protein synthesis in the brain. These results suggest that the rate of protein synthesis in the brain declines with the decrease in the quantity and quality of dietary protein in aged rats, and that RNA activity is at least partly related to the fractional rate of brain protein synthesis. On the other hand, the rate of protein synthesis in the brain declined with age. The RNA concentration was correlated with this rate when age was manipulated.
It is estimated that one fourth of Japan's population in the 21st century will be older than 65 years of age. Accompanying this increased percentage of elderly people will be an increased incidence of life-style-related diseases and infectious diseases associated with the reduced cellular immunity that occurs during aging. If this decrease of cellular immunity can be minimized, it might improve the health of older persons and prolong life expectancy. This paper summarizes the effect of nutrition and exercise on decreased cellular immunity in the aged. Obesity (BMI>30) in the aged induced marked decreases of T cell proliferation following in vitro activation with PHA or Con A and natural killer cell (NK) activity. In contrast, exercise training improved not only the decreased phagocytic activity but also the responsiveness to macrophage-activating factor (MAF) produced from activated T cells among alveolar macrophages (AM) in aged rats (24 months old). In addition, reduction in the activities of daily life (ADL) was closely associated with decreased NK activity in elderly people admitted to health service facilities for the aged. In conclusion, this study suggests that obesity is one of the risk factors for deteriorating health in the aged, and that maintenance of physical activity in the aged is important for retaining cellular immunity in this population group.
Ingestion of soy protein isolate (SPI) lowers the serum total cholesterol concentration in humans as well as experimental animals. Thus, SPI ingestion may reduce the risk of atherosclerosis. The antiatherogenic effect of SPI was reviewed based on our animal experiments. SPI was beneficial for reducing atherosclerosis in both hypercholesteromic rats and apolipoprotein E-deficient mice. This antiatherogenic effect of SPI was attributed to reduction of serum cholesterol and improvement of arterial lipid metabolism. The active component in SPI appeared to be in the protein part.
Physical exercise increases the rate of glucose uptake into skeletal muscle. The translocation of Glut4 from an intracellular location to the plasma membrane and transverse tubules is thought to be the major mechanism by which exercise increases speletal muscle glucose transport. Despite the physical importance of exercise in regulating glucose uptake in skeletal muscle, the molecular mechanisms that mediate this important phenomenon are still not fully understood. However, several studies suggest that the molecule AMPK is the critical mediator of exercise-stimulated glucose uptake.