加齢に伴う脳タンパク質合成の変動におけるタンパク質栄養の役割に関する研究

Abstract

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.