Some effects of dietary conditions on the metabolism of nucleic acid and protein in organs of the Albino Rats have been studied.
The young rats to be examined were fed on the control diet and the diets deprived of one component among protein, carbohydrate, and lipid, sucti as protein free diet (PF: 432 kcal/1008), carbohydrate free diet (CF: 432 kcal/1008), and lipid free diet (LF: 392 kcal/1008) for three, seven, and fifteen days, respectively.
The contents of DNA and RNA in the liver and the brain, and also those of protein-nitrogen (PN) and nonprotein- nitrogen (NPN) in the liver, the brain, and the serum have been measured.
The results are as follows:
1. The. contents of DNA per gram of liver were increased by feeding on protein free diet. It is concluded that the critical factor for the result is not the increase in the rates of DNA syntheses, but the decrease in the turnover rates of DNA.
2. The metabolism of DNA.in the liver showed the normal status by feeding on carbohydrate free diet. On the other hand, the rates of DNA syntheses were increased by feeding on lipid free diet.
3. The rates of DNA syntheses in the brain were decreased by feeding on the unbalanced diet, such as protein free, carbohydrete free, and lipid free diet.
4. In the liver and the brain, the rates of DNA syntheses were decreased by feeding on protein free diet. But the rates showed the normal status by feeding on the carbohydrate free diet, and also showed the similar metabolism to that in the case of the control group by feeding on lipid free diet.
5. In the liver, the rates of protein syntheses were decreased, whereas the contents of nonprotein-nitrogen were increased by feeding on protein free diet.
6. In the liver and the brain, the protein syntheses showea the more increasing rates than the rates in the case of the control diet by feeding on lipid free diet.
7. In the serum, the contents of protein did not change in a short period, also the insufficient feeding on protein was examined.
It is clear that in the liver the rates of protein syntheses are decreased and the rate- of protein catabolism are increased, since the rates of nucleic acid syntheses are decreased b,´ feeding on
the protein free diet. On the other hand, it is considered that in the brain the turnover rates of protein does not have correlation with the rates of nucleic acid syntheses, also these are decreased by feding on protein free diet.
And also it is believed that the phenomena of homeostasis for carrying the normal metabolism of nucleic acid and protein in the liver and the brain are operated in a short period as possible, by feeding on carbohydrate free and lipid free diets.
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