分娩及び新生児における脂質の変動について

新生児初期における脂質代謝を検討すべく,分娩時母体血,さい帯血,生后第1日,第3日,第5日の血液を採取し,血清脂質の経日変化を測定した.分娩時に胎児は母体とは異なる独立した脂質環境を形成するが,代謝系の機能的成熟は完成しており,出生后の飢餓に伴なう生理的低血糖の進展にともなって,糖一脂肪酸回路を介して脂質分解が促進される.この様な異化過程の亢進は哺乳量の増大にともなって改善され,生后第3日以降は同化過程へと移行する.すなわち,新生児期の脂質代謝平衡は子宮外生活への適応過程と平行して変動するが,生后第5日に到って成人類似の安定平衡が達せられると結論される.

The present study was aimed to evaluate a homeostasis of lipid metabolism in the extra-uterine adaptation after birth. Serum lipid concentration and fatty acid analysis of phospholipid, triglycerides, free fatty acid and cholesterol esters were determined uterizing a colorimetric, thin layerand gas liquid chromatgraphic techniques. An effect of feeding in serum lipid concentration was found to be minimized in 3 to 4 hours after feeding. Serum total lipids, phospholipid, triglycerides, free fatty acid and cholesterol esters in umbilical cord blood showed lower concentration compared with that of maternal blood. It was characteristic that a large propotion of phospholipids was found in the umbilical cord blood. The concentration in all lipid fraction was steadily increasd during early neonatal period and F. F. A. concentration was markedly increased at 1 day of life. Then the F. F. A. concentration was gradually decreased. In fatty acid analysis, an increase of C18:1 in F. F. A. and T. G. fractions was remarkable at 1 day of life compared with that of umbilical cord blood. An increase of C18:2 in P. L. and a decrease of C18:1 in F. F. A. fractions were significantly noted at 3 days of life. Both concentration and fatty acid composition in all lipid fraction at 5 days of life were shown the same tendency as that of maternal blood. It may be concluded that the lipid metabolism of the fetus is functioning independentry to the maternal environment. The 1 day in the neonatal period reflects the adaptation of the lipid metabolism to the extra-uterine life. An increase in serum lipid concentration after birth, particulary in F. F. A. fraction is indicating lipolytic dominance to substitute a glucose depletion due to physiological hypoglycemia. A homeostasis in lipid metabolism of the newborn as well as that of the adult may be obtained at 5 days after birth.