Y. Demarne

Effects of dietary fat and adipose tissue location on insulin action in young boar adipocytes

1. Regulation of lipogenesis and lipolysis by insulin was studied on adipocytes isolated from 100 kg Large white male pigs. Two adipose tissues were studied: subcutaneous and perirenal. Animals were fed either a control low fat diet or a diet containing 14.7% sunflower seed oil. 2. The cell diameter was higher in the group fed the sunflower diet. 3. De novo lipogenesis was decreased for each adipose tissue in the group fed the sunflower diet. The perirenal site had a higher lipogenic activity than subcutaneous site whatever the diet. 4. Insulin did not significantly stimulate lipogenesis but had an important antilipolytic effect on stimulated lipolysis by isoproterenol. 5. The antilipolytic action of insulin was higher in perirenal adipocytes with the control diet. With the sunflower diet, the decrease was about 54.4% for subcutaneous adipocytes, whereas the inhibition was decreased in perirenal adipocytes. Addition of theophylline reversed the antilipolytic action of insulin. 6. Insulin binding was not affected neither by the dietary fat nor by the adipose tissue location. 7. Absence of de novo lipogenesis stimulation by insulin was not due to an impairment in insulin binding. 8. The different effects of dietary fat and adipose tissue location on the antilipolytic action of insulin could not be explained by a modification of insulin binding but rather by a latter event, probably at a post-insulin binding stage.

Comparative study of triacylglycerol fatty acids in milk fat from two leporidae species: rabbit (oryctolagus cuniculus) and hare (Lepus europaeus)

1. Fatty-acid composition of hare milk triacylglycerols markedly differed from that of rabbit milk and was essentially characterized by a 2.1 times lower concentration of medium-chain fatty-acids (M.C.F.A.). 2. Consequently, very high levels (greater than 70 moles %) of M.C.F.A., previously reported for rabbit milk, cannot be considered as a general characteristic of the Leporidae. 3. General tendencies recorded for intramolecular fatty acid distribution in hare milk triacylglycerols agreed with those reported for other animal species.

Comparison of Long Term Lipogenic Effects of Two Different Medium-Chain Triglycerides (TRI C8: 0 and TRI C12: 0) in the Growing Rat

AbstractDuring the growth (35 g-340 g), and as compared to results obtained with a lipid-free diet or a diet containing long-chain fatty acids, high levels of Tri C8: 0 or Tri C12: 0 did not change die quantitative aspects of proteinogenesis and lipogenesis balances. The incorporation of Tri C8: 0 into the diet dit not change the fatty acid composition of body lipid stores while the incorporation of Tri C12: 0 induced a lipogenesis characterized by the disappearance of about 50% of the n-9 and n-7 unsaturated fatty acids, the emergence of an equivalent amount of saturated fatty acids in C12 and C14, and the decrease of hexadecanoic or palmitic acid concentration. Titers of saturated fatty acids with a melting point higher than 40°C increased from 34% to 64%. Results suggested an efficient inhibition of fatty acid biosynthesis de novo by C12: 0, associated with an impossibility for microsomal enzymes to assume the elongation of a sufficient amount of C12: 0 to maintain C16: 0 concentration and to furnish a...

Effects of castration, dietary fat and adipose tissue sites on adipocyte plasma-membranes cyclic AMP phosphodiesterase activity in the pig

1. cAMP Phosphodiesterase activity and kinetic parameters (Km and Vmax) were measured in subcutaneous and perirenal adipocyte plasma membranes from Large White male and castrated pigs. The animals were fed a control low fat diet or a sunflower diet enriched with linoleic acid (C18:2 n-6). 2. Phosphodiesterase activity, low Km and Vmax were lowered by castration. 3. In animals fed the sunflower diet, phosphodiesterase activity decreased without affecting either Km or Vmax. 4. Phosphodiesterase activity was higher in perirenal sites than in subcutaneous ones, particularly in male pigs. This may be explained by a lower Km or a higher cAMP phosphodiesterase affinity to cAMP in perirenal sites. 5. Theophylline was a potent inhibitor of phosphodiesterase activity principally in perirenal sites. 6. The intermediate role of cAMP phosphodiesterase in adenylate cyclase activity and lipolytic processes is discussed.

Food intake in captive leverets before weaning and the composition of the milk of the brown doe-hare (Lepus europaeus)

Daily milk and solid food intakes were studied in leverets before weaning and during 52 lactations in captive doe-hares. Changes in milk composition were studied in parallel during 11 other lactations. With the mode of feeding used (one nursing per 24 hr), milk and solid food intakes were recorded for the first 30 neonatal days. The profile of milk intake had three phases: it showed an increase between D0 and D12, a plateau between D12 and D22, and a decrease between D22 and D30. Solid food intake began at D7 and increased significantly from D14. The mean levels of dry matter, fat and protein in doe hares milk were similar to those in rabbits milk The amino acid composition of total protein resembled that of rabbits milk. There were fewer medium-chain fatty acids (8:0-14:0) in heres milk than in rabbits milk and the levels of some major minerals (Ca, P, K) were also different. The levels of protein and medium-chain fatty acids (except 14:0) increased significantly with time. On the other hand, the levels of long-chain fatty acids (except 18:0 and 18:3, N = 3) decreased significantly. There was no significant change in the other factors studied.

Effect of castration on lipid metabolism in porcine isolated adipocytes from two anatomical locations

Abstract 1. 1. In vitro activities of de novo lipogenesis and lipolysis were compared in isolated adipocytes from male and castrated large white pigs. 2. 2. Castration increased fat cell size and de novo lipogenesis in both subcutaneous and perirenal adipocytes. Lipogenesis was higher in perirenal than in subcutaneous sites. 3. 3. Basal lipolysis was not modified by castration. Addition of theophylline and adenosine deaminase increased the basal rate of lipolysis only in male castrates. 4. 4. Castration reduced the isoproterenol-stimulated lipolysis in both adipose tissues. Theophylline and adenosine deaminase partly restored the isoproterenol-stimulated lipolysis presumably via inhibition of cAMP phosphodiesterase activity. 5. 5. Contrary to male pigs, insulin had no significant antilipolytic action in both adipose tissues in castrated pigs.

De novo lipogenesis and lipolysis activities in normal (Dw) and dwarf (dw) White Leghorn laying hens.

1. In vitro activities of glucose oxidation, de novo lipogenesis and lipolysis were compared in normal (Dw) and dwarf (dw) laying hens. 2. Dwarfism reduced the hepatic glucose oxidation while de novo lipogenesis was not altered. As liver weight was depressed, total liver lipogenesis capacity was probably reduced by dwarfism. 3. As compared to normal hens, de novo lipogenesis and basal or stimulated lipolysis were lower in dwarf adipose tissue while its lipid content was enhanced in dwarfs. 4. Results suggest that in laying hens dwarfism reduces the adipose tissue lipid mobilization but probably also the liver de novo lipogenesis.

Effects of Two Different Medium-Chain Triglycerides (Tri C8 :0 and Tri C12 :0) on Liver Lipids in the Growing Rat

Results presented in this study emphasize the long-term effects of dietary fatty acid chain length on some biochemical parameters of the liver in the growing rat. High levels of medium-chain fatty acids feeding (C8:O and C12:O) from 40 to 340 g of body weight induced liver growth and lipid contents intermediary between values recorded with a lipid-free diet and with a diet containing long-chain fatty acids. No steatosis was recorded but neutral lipid contents appeared to be correlated with the dietary fatty acid chain length while phospholipid contents remained much more stable. In the four tested nutritional conditions, only dodecanoïc or lauric acid (C12:O) feeding induced important alterations in the fatty acid pattern of liver neutral lipids. Medium-chain fatty acids, and even lauric acid which was intensely esterified in adipose tissue triglycerides, did not appreciably modify the fatty acid composition of liver phospholipids and were not esterified in it.