The metabolism of subcutaneous adipose tissue in the immediate postnatal period of human neonates. 3. Role of fetal glycogen in lipolysis and fatty acid esterification in the first hours of life.

Abstract

Extract: Total glycogen phosphorylase activity in neonatal adipose tissue is significantly increased immediately after birth (0–6 hr) and rapidly decreases to a relatively constant level. Fluoride-stimulated adenyl cyclase activity in homogenates of adipose tissue from neonates is directly correlated with the length of time from the onset of labor (y = 0.665 + 7.88x; P < 0.02). No significant differences are found between infants 1–10 hr of age and 2–4 days of age. The ATP content decreases rapidly in the first hours of life and is inversely correlated with the length of time since the onset of labor (log y = −0.657 - 0.0164x; P < 0.01). The ATP content starts to increase approximately 24 hr after birth. Changes in ATP content are directly correlated with glycogen content and glycerol release from neonatal adipose tissue.Speculation: The intensity of lipolysis in neonatal adipose tissue depends on various factors, one of the most important being an adequate energy supply. The increased glycogen content in adipose tissue immediately after birth and the rapid rate of utilization of glycogen-derived glucose appear to be major factors involved in the production of ATP required for glycogenolysis, lipolysis, and fatty acid activation during the early adaptation of the neonate to extrauterine life.