Changes in the lipoprotein lipase (clearing-factor lipase) activity of white adipose tissue during development of the rat

Abstract

The lipoprotein lipase (clearing-factor lipase) activity of the white adipose tissue from rats aged between 1 and 145 days was determined. Five adipose-tissue sites (epididymal, uterine, subcutaneous, perirenal and intramuscular) together with serum concentrations of triacylglycerol, cholesterol and glucose were studied. The pattern of enzyme-activity change was remarkably similar in all the sites studied, although the growth of the tissues proceeded non-uniformly. After a peak of activity early in suckling, lipoprotein lipase activity fell to low values by 20 days of age. At weaning (21 days) the activity increased sharply and within 5 days high values were regained. The serum triacylglycerol and cholesterol concentrations were low at birth and reached peaks of concentration coincidentally with the minima of white-adipose-tissue lipoprotein lipase activities, seen late in suckling. The changes in enzyme activity were related to other metabolic changes in adipose tissue and with the known changes in plasma insulin concentrations occurring during development.

Modulation of Very Low-Density Lipoprotein Secretion by Dietary Protein Is Age-Dependent in Rats

“…A 27% decline of choles terol levels with age was observed only in the casein groups (table II). These changes with age, although not reaching statistical signifi cance, were in accordance with earlier reports from other investigators [9,[18][19][20][21], with one exception [22], Triglyceride levels in 25-week-old rats were lower by 52% (casein) or 43% (soy) than those in 10-week-old rats. These data are in agreement with earlier reports [22],…”

Changes in energy metabolism during the suckling and weaning period in the newborn

“…In the human newborn, glycerol could contribute to 15 % of the glucose synthetized de novo (Bougnères et al, 1982). Lactate which comes from the incomplete oxidation of glucose in various tissues is a good gluconeogenic precursor in the newborn rat (Ferré et al, 1980 Jones, 1978aJones, , 1978b. At weaning lipoprotein lipase activity decreases in skeletal muscles and brown adipose tissue but remains elevated in the heart (Cryer and Jones, 1978aJones, , 1978b The capacity to oxidize long-chain fatty acids in extra-hepatic tissues is low in the fetal rat heart, skeletal muscle, kidney and small intestine but increases shortly after birth (Warshaw, 1972(Warshaw, , 1974Glatz and Veerkamp, 1982 ;Freund, Sedraoui and Geloso, 1984).…”

“…This suggests that during the suckling period, the high thermogenic activity of this tissue (Himms-Hagen, 1976) is supported by the oxidation of circulating triacylglycerol fatty acids. In white adipose tissue, the lipogenic rate is low during the suckling period (Tsujikawa and Kimura, nomenon is concomitant of fat accretion (Cryer and Jones, 1978a (Pégorier, Ferré and Girard, 1977 ;Ferré et al, 1978Ferré et al, , 1979 and in the human (Bougnères et al, 1981 ). NEFA oxidation provides energy and the necessary cofactors for gluconeogenesis (Ferré et al, 1979).…”

“…Lactate which comes from the incomplete oxidation of glucose in various tissues is a good gluconeogenic precursor in the newborn rat (Ferré et al, 1980 Jones, 1978aJones, , 1978b. At weaning lipoprotein lipase activity decreases in skeletal muscles and brown adipose tissue but remains elevated in the heart (Cryer and Jones, 1978aJones, , 1978b The capacity to oxidize long-chain fatty acids in extra-hepatic tissues is low in the fetal rat heart, skeletal muscle, kidney and small intestine but increases shortly after birth (Warshaw, 1972(Warshaw, , 1974Glatz and Veerkamp, 1982 ;Freund, Sedraoui and Geloso, 1984). It has been suggested that this is linked to a low activity during the fetal life of carnitine acyltransferase, the enzyme which catalyzes the entry of long-chain acylcoa inside the mitochondria, followed by its increase after birth, as well as to the increased concentration of its obligatory cofactor, carnitine, provided to the newborn via the milk (Robles-Valdes, McGarry and Foster, 1976 ;Borum, 1978 ;Hahn and Skala, 1972 ;Caroll et al, 1983).…”

Lipoprotein lipase and the uptake of lipids by adipose cells during development

“…As might be expected, the low level of circulating triglyceride concentrations found in the fetus are elevated up to four times the normal adult level throughout suckling in the rat (Cryer and Jones, 1978b) (Cryer and Jones, 1978a ;Pequignot-Planche et al, 19771. During the first six hours of life however, during which time no accumulation of triglyceride occurs in the tissue, the enzyme activity declines somewhat in response that is probably related to a fall in plasma insulin levels within the first six hours of birth (Blasquez et al, 1974 ;19751. During the 6-24 h period of postnatal life both the lipoprotein lipase activity and triglyceride content of the tissue increases substantially. This increase is sustained progressively over the first 10 days of life such that levels of activity 2-4 times greater than adult levels are achieved by midsuckling.…”