Adaptation to Severe Protein Deficiency

Abstract

In recent studies on dynamic aspect of protein metabolism, there are culminating evidences which indicate that the muscle protein is rather labile and its turnover rate is very sensitive to low protein intake. In an attempt to clarify the physiological role of muscle protein in severe protein deficiency, by taking account of its largest mass in the body, the authors designed a series of experiments with pregnant rats fed protein free diet. Much protein is required in pregnancy for development of reproductive organs including foetus. Thus the rats fed on protein free diet suffer from severe protein deficiency which results in reabsorption of foetus and the pregnancy is interrupted. By injecting subcutaneously 4 mg progesterone and 0.5 μg esterone daily, the pregnancy can be maintained until parturition. With the pregnant rats thus treated, their body weight and protein contents of various organs were compared with the control non-pregnant rats fed on protein free diet which started on the same day with the pregnant. The comparisons were made at the early (around the 7th day), the middle (around 12th day) and the last stage (after 16th day) of pregnancy.