1998 年 25 巻 3 号 p. 149-157
Significant alteration in the glycosaminoglycans (GAG) and glycoproteins is observed in the brain of protein calorie-malnourished rats. There was a significant decrease in the protein in the brain, and the changes in the GAG and glycoproteins may be a consequence of this decrease. The GAG in the brain showed a significant increase, and the increase in heparan sulfate is particularly significant since it can lead to increased heparan sulfate-protein complex formation and accumulation in the brain, possibly affecting brain function. The activity of many enzymes involved in the catabolism of proteoglycans was increased in the brain of malnourished rats. The fact that there was an increase in most of the glycosaminoglycans in spite of the increased activity of the catabolizing enzymes may indicate some form of resistance of the proteoglycans to degradation. On the other hand, the carbohydrate components of brain glycoproteins—total hexose, fucose, and sialic acid—decreased in the malnourished rats, whereas there was increase in the concentration of dolichol. The activity of enzymes concerned with the catabolism of glycoproteins also showed an increase. The decrease in the carbohydrate components of glycoproteins in the brain in the malnourished rats in spite of increased availability of dolichol for glycosylation, may be due to their decreased biosynthesis and glycosylation and increased catabolism. The nature of the changes in various carbohydrate components was different, indicating formation of altered glycoproteins. The altered glycoproteins in the brain in malnourished rats may affect receptor function of the neuronal cell membrane. Thus alteration in both glycosaminoglycans and glycoproteins can lead to changes in the brain function in malnutrition.
