RESUMEN
The effects of castration on fat cell plasma membrane structure and enzyme activities (adenylate cyclase and 5'-nucleotidase) were studied in pig adipose tissues in two fat deposits (subcutaneous and perirenal). Castration induced a fat cell enlargement in both tissues. Membrane cholesterol content was reduced and fluidity was increased in perirenal fat from castrated animals. Castration had no effect on 5'-nucleotidase activity which was higher in subcutaneous than in perirenal in both kinds of animals. Adenylate cyclase activity was studied in the presence of different effectors: isoproterenol-stimulations of the enzyme were not affected by castration but were site-specific. GppNHp-stimulated activities were increased in subcutaneous fat from castrated animals. Castration had no influence on forskolin stimulations. The magnitude of GppNHp- and forskolin-stimulated activities were found to be tissue-dependent. Membrane results are discussed in relation with castration-induced fat cell enlargement.
Asunto(s)
5'-Nucleotidasa/metabolismo , Adenilil Ciclasas/metabolismo , Tejido Adiposo/citología , Tejido Adiposo/enzimología , Orquiectomía , 5'-Nucleotidasa/análisis , Adenilil Ciclasas/análisis , Tejido Adiposo/ultraestructura , Animales , Membrana Celular/química , Membrana Celular/fisiología , Membrana Celular/ultraestructura , Colesterol/análisis , Colforsina/farmacología , Isoproterenol/farmacología , Masculino , Fluidez de la Membrana/fisiología , Lípidos de la Membrana/análisis , Proteínas de la Membrana/análisis , Fosfolípidos/análisis , PorcinosRESUMEN
The effect of dietary (n-6) polyunsaturated fatty acids (sunflower oil) on pig adipocyte beta-adrenoreceptor and adenylate cyclase activity was examined. Two adipose sites (subcutaneous and perirenal) were compared. The existence of two affinity classes for beta-adrenoreceptors was evidenced. Adenylate cyclase stimulation by isoproterenol was higher in the perirenal fat than in the subcutaneous fat, in parallel to a higher beta-adrenoreceptor density. When sunflower oil was included in the diet, the adenylate cyclase response to beta-agonists was greater, particularly in perirenal fat, as was the affinity of the adrenoreceptors in their high affinity state. However, the number of beta-adrenoreceptors was lower, suggesting that these are spare receptors. Adenylate cyclase stimulation by 5'-guanylylimidophosphate also revealed site- and diet-specific variations indicating alterations at the Gs-protein level. The adenylate cyclase catalytic activity (reflected by the forskolin-stimulated response) in the control group was higher in the subcutaneous fat than in the perirenal fat. In the sunflower oil-fed pigs, the catalytic activity was greater in the perirenal fat relative to controls, leading to similar values in both adipose tissues of sunflower oil-fed pigs. This indicates that the cyclase catalytic subunit activity also depends on the anatomical site of the fat deposit and is influenced by the diet as well. Correlation between these changes in the adenylate cyclase system are discussed in relationship with alterations in the plasma membrane structure.
Asunto(s)
Tejido Adiposo/metabolismo , Grasas de la Dieta/farmacología , Ácidos Grasos/farmacología , Receptores Adrenérgicos beta/metabolismo , Adenilil Ciclasas/metabolismo , Tejido Adiposo/efectos de los fármacos , Animales , Membrana Celular/metabolismo , Proteínas de Unión al GTP/metabolismo , Guanilil Imidodifosfato/farmacología , Yodocianopindolol , Isoproterenol/farmacología , Masculino , Fluidez de la Membrana , Pindolol/análogos & derivados , Pindolol/metabolismo , Aceites de Plantas/administración & dosificación , Aceites de Plantas/farmacología , Aceite de Girasol , PorcinosRESUMEN
This study was conducted to examine the effect of insulin on lipid metabolism of adipocytes during pregnancy and lactation in ewes. During the first 3 mo of pregnancy, metabolism of adipocytes from omental adipose tissue was characterized by a high rate of de novo lipogenesis (90 to 125 nmol of acetate incorporated into lipids.2 h-1.10(6) cells-1) and a 38% reduction in response to beta-lipolytic stimulus (isoproterenol 10(-6) M). Simultaneously, there was a rise in the number of high-affinity insulin receptors (Kd = .2 nM), and insulin binding characteristics showed a decrease in the negative cooperativity phenomenon. Moreover, lipogenesis stimulated by insulin (1 mU/ml) increased in comparison with observations in nonpregnant ewes. The last third of pregnancy and early lactation were characterized by a marked fall in lipogenesis and a simultaneous increase in isoproterenol-stimulated lipolysis. During lactation, the number of total insulin receptors was decreased by 62% and insulin stimulation of lipogenesis became inefficient. Results suggest that insulin plays a direct role in adipose tissue metabolism during pregnancy.
Asunto(s)
Tejido Adiposo/metabolismo , Insulina/fisiología , Lactancia/metabolismo , Preñez/metabolismo , Ovinos/metabolismo , Animales , Femenino , Metabolismo de los Lípidos , Lípidos/biosíntesis , Lipólisis , Epiplón , Embarazo , Receptor de Insulina/análisis , PielRESUMEN
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.
Asunto(s)
3',5'-AMP Cíclico Fosfodiesterasas/metabolismo , Tejido Adiposo/metabolismo , Membrana Celular/enzimología , Grasas de la Dieta/farmacología , Testículo/fisiología , Tejido Adiposo/citología , Tejido Adiposo/efectos de los fármacos , Animales , Castración , Riñón/citología , Riñón/metabolismo , Ácido Linoleico , Ácidos Linoleicos , Masculino , Aceites de Plantas , Piel/citología , Piel/metabolismo , Aceite de Girasol , Porcinos , Teofilina/farmacologíaRESUMEN
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.
Asunto(s)
Tejido Adiposo/efectos de los fármacos , Insulina/farmacología , Tejido Adiposo/citología , Tejido Adiposo/metabolismo , Animales , Membrana Celular/metabolismo , Grasas de la Dieta/administración & dosificación , Técnicas In Vitro , Insulina/metabolismo , Cinética , Metabolismo de los Lípidos , Lipólisis/efectos de los fármacos , Masculino , PorcinosRESUMEN
The effect of dietary n-6 polyunsaturated fatty acid content on pig adipocyte plasma membrane was studied with two types of adipose tissues: subcutaneous backfat layer and perirenal fat. When pigs were fed a diet containing 15 percent sunflower oil, the n-6 polyunsaturated fatty acid content in the membranes increased in both tissues parallel to a decrease in the n-9 monounsaturated fatty acid content. An increase in membrane fluidity measured by fluorescence polarization was observed particularly in subcutaneous tissue, in spite of a higher level of some membrane rigid components: the sphingomyelin/phosphatidylcholine ratio was increased in the subcutaneous tissue, whereas the cholesterol/phospholipid ratio was increased in the perirenal one. The latter results gave evidence for a depot-dependent modification in the membrane structure by dietary lipids.
Asunto(s)
Tejido Adiposo/efectos de los fármacos , Membrana Celular/efectos de los fármacos , Grasas de la Dieta/farmacología , Ácidos Grasos Insaturados/farmacología , Ácidos Linoleicos/farmacología , Tejido Adiposo/anatomía & histología , Tejido Adiposo/citología , Animales , Membrana Celular/enzimología , Reductasas del Citocromo/metabolismo , Grasas de la Dieta/administración & dosificación , Ácidos Grasos Insaturados/administración & dosificación , Ácidos Linoleicos/administración & dosificación , Masculino , Nucleotidasas/metabolismo , Succinato Deshidrogenasa/metabolismo , PorcinosRESUMEN
The effect of dietary fats on phospholipid class distribution and fatty acid composition was studied in rat fat cell plasma membrane. Three groups of male Wistar weanling rats were fed for 8 wk three diets differing in the amount and nature of the fats: 1.5% sunflower oil (low fat control; LFC), 10% sunflower oil (high fat, unsaturated; HFU), 1.5% sunflower oil + 8.5% cocoa butter (high fat, saturated; HFS). Plasma membranes were prepared from epididymal adipocytes. The amount and type of dietary fat significantly altered membrane phospholipid distribution. Phospholipid content was lowered with HFU as compared to LFC or HFS diets, but no changes were observed for cholesterol. Phosphatidylinositol (PI) and phosphatidylserine (PS) were less affected by dietary changes than were other phospholipid classes. Major changes were detected for phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM) contents. No large changes in PC and PE fatty acid compositions were observed between the LFC and HFS groups, but the HFU diet induced several changes. Correlations with plasma membrane 5'-nucleotidase activities are discussed.
Asunto(s)
Tejido Adiposo/metabolismo , Membrana Celular/metabolismo , Grasas de la Dieta/farmacología , Fosfolípidos/metabolismo , Tejido Adiposo/citología , Tejido Adiposo/ultraestructura , Animales , División Celular/fisiología , Colesterol/metabolismo , Grasas Insaturadas en la Dieta/farmacología , Ácidos Grasos/metabolismo , Lisofosfatidilcolinas/metabolismo , Masculino , Fosfatidilcolinas/metabolismo , Fosfatidiletanolaminas/metabolismo , Ratas , Ratas Endogámicas , Esfingomielinas/metabolismoRESUMEN
1. The efficiency and time course of dietary fatty acid incorporation into lipids of egg yolk and abdominal adipose tissue was compared in "White Leghorn", normal (Dw) and dwarf (dw) laying hens at 56 weeks of age, using 14C labelled linoleic acid. 2. The sex-linked dwarfing gene, dw, was shown to reduce not only body weight and abdominal fat pad deposition, but also yolk production and the average clutch size. 3. Higher peak incorporation and total recovery of the linoleic acid radioactivity into yolk lipids, but lower label recovery into adipose tissue triglycerides were found in dwarf hens. 4. The higher esterification of the dietary linoleic acid in its native form into dwarf yolk triglycerides indicates that dwarf hens use more dietary lipids to synthesise yolk lipids but these results also suggest that the dw allele might reduce the lipogenic capacities of the liver and adipose tissue in laying hens.
Asunto(s)
Pollos/genética , Grasas de la Dieta/metabolismo , Enanismo/veterinaria , Lípidos/biosíntesis , Enfermedades de las Aves de Corral/genética , Tejido Adiposo/crecimiento & desarrollo , Tejido Adiposo/metabolismo , Animales , Peso Corporal/genética , Enanismo/genética , Yema de Huevo , Ácidos Grasos/metabolismo , Femenino , Ligamiento Genético , Genotipo , Ácidos Linoleicos/metabolismo , Hígado/crecimiento & desarrollo , Hígado/metabolismo , Tamaño de los Órganos , Triglicéridos/biosíntesis , Cromosoma XRESUMEN
1. 5'-Nucleotidase activity has been examined in pig adipocyte plasma membrane, in two different adipose sites. 2. Membrane fluidity has been investigated using 1,6-diphenylhexatriene (DPH). 3. In this work, evidence was found for a tissue specificity of 5'-nucleotidase (E.C. 3.1.3.5) activity. 4. The enzyme activity was highly correlated to the membrane phosphatidylcholine content. 5. The latter parameters remained unmodified when large alterations in membrane composition and physical state were produced by means of the dietary n-6 PUFA content manipulations.
Asunto(s)
5'-Nucleotidasa/metabolismo , Tejido Adiposo/metabolismo , Fosfatidilcolinas/metabolismo , Animales , Membrana Celular/metabolismo , Grasas Insaturadas en la Dieta/administración & dosificación , Técnicas In Vitro , Masculino , Fluidez de la Membrana , PorcinosRESUMEN
The levels and fatty acid composition of lipids were determined in very low density lipoproteins (VLDL, d less than 1.006), yolk and abdominal adipose tissue of normal (Dw) and sex-linked dwarf (dw) White Leghorn laying hens. Effects of adding 4% tallow to the diet were also examined. In 40-wk-old hens, neither plasma lipids (triglycerides, phospholipids and cholesterol), VLDL levels, nor the chemical composition of VLDL was altered by the dw gene or dietary fat. Dwarfism reduced egg and yolk weights. Though the yolk lipid content was similar in normal and dwarf hens, yolk from dwarfs had slightly more phospholipids and less triglycerides than yolk from normal hens. Higher linoleic acid [18:2(n-6)] and lower oleic acid [18:1(n-9)] levels were observed in triglycerides of VLDL, yolk and adipose tissue from dwarf hens. In addition, the dietary fatty acid pattern had a greater influence on the fatty acid composition of the yolk lipid major precursors (VLDL triglycerides) in dwarf laying hens than in normal hens. These results suggest that the dwarfing gene might reduce the hepatic de novo fatty acid synthesis and/or dwarf hens might incorporate more dietary lipids into yolk than do normal hens.
Asunto(s)
Tejido Adiposo/análisis , Pollos/genética , Grasas de la Dieta/farmacología , Enanismo/genética , Yema de Huevo/análisis , Regulación de la Expresión Génica , Genes Recesivos/fisiología , Lípidos/genética , Cromosomas Sexuales/fisiología , Animales , Colesterol/análisis , Colesterol/genética , Enanismo/metabolismo , Ácidos Grasos/análisis , Ácidos Grasos/biosíntesis , Ácidos Grasos/genética , Femenino , Lípidos/sangre , Lipoproteínas VLDL/análisis , Lipoproteínas VLDL/genética , Hígado/metabolismo , Ovulación/genética , Fosfolípidos/análisis , Fosfolípidos/genética , Triglicéridos/análisis , Triglicéridos/genéticaRESUMEN
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.
Asunto(s)
Pollos/genética , Lípidos/biosíntesis , Lipólisis , Tejido Adiposo/metabolismo , Alimentación Animal , Animales , Catecolaminas/farmacología , Grasas de la Dieta/administración & dosificación , Enanismo/metabolismo , Femenino , Glucagón/farmacología , Glucosa/metabolismo , Insulina/farmacología , Hígado/metabolismo , Oxidación-ReducciónRESUMEN
Male Wistar rats were fed for 6 wk either a control low fat diet (1.5% sunflower seed oil) or a diet containing 10% fat: either saturated (coconut oil, cocoa butter) or unsaturated (olive oil, sunflower seed oil). In each dietary condition, in vitro incorporation of exogenously added fatty acids (ranging from capric to oleic acid) was studied in epididymal adipose glycerides. Analysis of variance of data revealed that there was a significant effect of the diet x substrate interaction. When results were expressed per cell lipid weight medium-chain fatty acids (capric and lauric) were esterified to a lesser extent than long-chain fatty acids regardless of the nature of dietary fat (saturated vs. unsaturated). The nature of dietary fat was found to have no effect on the incorporation of medium-chain fatty acids. Feeding saturated fats resulted in an increase of incorporation of long-chain fatty acids into adipose glycerides whereas feeding unsaturated fats did not modify fatty acid incorporation. Modifications of mean fat cell size by dietary fat could not account for all the observed variations.
Asunto(s)
Tejido Adiposo/metabolismo , Grasas de la Dieta/farmacología , Ácidos Grasos/metabolismo , Glicéridos/metabolismo , Tejido Adiposo/análisis , Animales , Ácidos Grasos/análisis , Glicéridos/análisis , Masculino , Ratas , Ratas EndogámicasRESUMEN
During pregnancy and lactation, three phases of beta-adrenergic stimulation of lipolysis appeared in adipocytes isolated from omental adipose tissue of ewes: During the first 90 days of pregnancy, there was a fall in the maximal lipolytic effect of isoproterenol. The maximum response to beta-lipolytic stimulus was reduced by 38% on day 90 (815 nmol/2 h/10(6) cells, compared to 1304 for controls) without any change in system sensitivity. Between days 90 and 120 of pregnancy (switch in adipose metabolism), this lipolytic effect increased progressively and became significantly larger (34%) than in non-pregnant ewes around parturition. The system sensitivity was then higher (0.05-0.11 vs. 0.21 microM) and remained so throughout lactation. During the first 3 weeks of lactation, this stimulated rate was twice as great as in controls.
Asunto(s)
Adaptación Fisiológica , Isoproterenol/farmacología , Lactancia/metabolismo , Lipólisis/efectos de los fármacos , Preñez/metabolismo , Tejido Adiposo/metabolismo , Animales , Femenino , Técnicas In Vitro , Movilización Lipídica , Embarazo , OvinosRESUMEN
Four successive biopsies of omental adipose tissue were performed at 43,100,140 days and during the 3rd week of lactation on 6 "Pré-Alpes" ewes. Using isolated adipocyte incubation, we studied the evolution of both basal lipolysis and stimulated lipolysis in response to different stimuli during these physiologic periods. The basal lipolysis increased from 53 +/- 10 micrograms glycerol/4 hr incubation/g total lipids (TL) at 43 days of pregnancy and 55 +/- 11 micrograms/4 hr/g TL at 100 days of pregnancy to a maximum value of 204 +/- 10 micrograms/4 h/g TL observed one week before parturition. Basal lipolysis remained at a high level during lactation: 153 +/- 27 micrograms/4 hr/g TL. The sensitivity of the fat cells to the lipolytic effects of isoproterenol, theophylline and adenosine-deaminase evolved with profiles comparable to that observed for basal lipolysis. The threshold concentration of stimuli necessary to observe an effect was decreased and the maximum response was increased. Bovine growth hormone (bGH) did not exhibit a direct lipolytic effect during pregnancy and lactation. Nevertheless, bGH provoked a significant potentiation of 20% of the lipolysis stimulated by isoproterenol and theophylline at 43 and 100 days of pregnancy. Ovine placental lactogene hormone (oPL) did not modulate, directely or undirectely, lipolysis.
Asunto(s)
Tejido Adiposo/metabolismo , Lactancia , Lipólisis , Preñez/metabolismo , Adenosina Desaminasa/metabolismo , Tejido Adiposo/efectos de los fármacos , Animales , Dexametasona/farmacología , Femenino , Hormona del Crecimiento/farmacología , Técnicas In Vitro , Isoproterenol/farmacología , Lipólisis/efectos de los fármacos , Embarazo , Prolactina/farmacología , Ovinos , Teofilina/farmacologíaRESUMEN
Four successive biopsies of omental adipose tissue were performed on the 43rd, 100th, 140th days of pregnancy and during the 3rd week of lactation in 6 "Pré-Alpes" ewes. Using incubated isolated adipocytes, we studied the evolution of the antilipolytic effect of adenosine. Adenosine presented a significant inhibitory effect on basal lipolysis only at the end of pregnancy. The antilipolytic effect of adenosine on the stimulated lipolysis by a beta-agonist (isoproterenol 400 nM) increased during pregnancy. The maximal effect was observed 1 week before parturition. The level of inhibition remained high during lactation. The lipolytic effect of adenosine-deaminase was enhanced during pregnancy and lactation and evolved similar to the observed action of adenosine. Results suggest that the antilipolytic action of adenosine may have a physiologic importance.
Asunto(s)
Adenosina/farmacología , Tejido Adiposo/metabolismo , Lipólisis/efectos de los fármacos , Tejido Adiposo/efectos de los fármacos , Animales , Femenino , Técnicas In Vitro , Cinética , Lactancia , Embarazo , OvinosRESUMEN
Milk lipids of lactating rabbit mammary epithelial cells were labelled in vitro during a 3-min pulse with 14C-Na butyrate. After 1 h of incubation in the presence or not of prolactin, the different classes of lipids, in the tissues and the incubating mediums, were separated by thin-layer chromatography. The radioactivity of spots corresponding to the different classes of lipids (compared with the standards) was counted by liquid scintillation. In the tissues, triglycerides were the most strongly labelled constituent (97.7% of the radioactivity was bound to triglycerides). In the medium, triglyceride radioactivity was less; only 70.9% was bound to the triglycerides. In the presence of prolactin (10 micrograms/ml) the distribution of radioactivity in the tissues was not modified but in the medium, secreted triglycerides were more radioactive than in the control medium. In the presence of protamine sulfate (100 micrograms/ml), an inhibitor of lipoprotein-lipase, radioactivity in the secreted triglycerides decreased less, suggesting that this decrease was due to hydrolysis by lipoprotein lipase, probably during the process of exocytosis. Morphological evaluation on electron micrographs of the number of intracellular and extracellular lipid globules showed that prolactin increased the number of extracellular lipid globules; this suggested a higher secretion. These results show that the radioactivity of neosynthesized lipid constituents was modified during the secretion of milk lipids. Prolactin, which increased the total labelled lipids secreted, had an effect on the distribution of the radioactivity of the different lipid classes.
Asunto(s)
Lactancia/efectos de los fármacos , Metabolismo de los Lípidos , Glándulas Mamarias Animales/metabolismo , Prolactina/farmacología , Animales , Butiratos/metabolismo , Ácido Butírico , Radioisótopos de Carbono , Epitelio/efectos de los fármacos , Epitelio/metabolismo , Epitelio/ultraestructura , Ácidos Grasos/metabolismo , Femenino , Glicéridos/metabolismo , Glándulas Mamarias Animales/efectos de los fármacos , Glándulas Mamarias Animales/ultraestructura , Microscopía Electrónica , Leche , Fosfolípidos/metabolismo , Embarazo , ConejosRESUMEN
The relative fatty acid profiles of perirenal adipose tissue and muscle tissue of the hind legs were studied in New Zealand rabbits 21 to 140 days old. The rabbits were fed a low-fat diet covering the essential fatty acid requirements and distributed either ad libitum or in rationed amounts. The whole of the fatty acids were established earlier in hind leg muscle tissue than in perirenal adipose tissue. In the latter, the growth allometry of fatty acids in relation to the carcass was already higher between 21 and 74 days (a = 1.39) and distinctly higher between 74 and 140 days (a = 2.68). In the muscle tissue, an isometric phase (a = 0.96) preceded a major allometric phase (a = 1.76). In young suckling rabbits, the fatty acid profile of perirenal lipids was influenced by that of the milk lipids. In the muscle tissue, the presence of a large proportion of phospholipids resulted in a higher percentage of stearic acid and polyunsaturated fatty acids of the (n-6) family (linoleic, dihomo-gamma-linolenic and arachidonic acids). After weaning, the proportion of saturated fatty acids (C greater than or equal to 14) in the perirenal adipose tissue remained constant. The endogenous production of monounsaturated fatty acids (higher allometry) caused a progressive dilution of polyunsaturated fatty acids (lower allometry). This dilution was slowed down when the diet was rationed. Changes in the fatty acid composition of muscle tissue were, in general, comparable to those of perirenal adipose tissue. The differences observed could be attributed to the more active participation of phospholipids in the total lipids of the muscle tissue. Stearic acid, abundant in the phospholipids, showed a lower allometry compared to total fatty acids. Its dilution was an expression of triglyceride dilution of the phospholipids during growth. The same was true of polyunsaturated fatty acids. Rationing had the reverse effect.
Asunto(s)
Tejido Adiposo/metabolismo , Grasas de la Dieta/farmacología , Ácidos Grasos/análisis , Metabolismo de los Lípidos , Músculos/metabolismo , Envejecimiento , Animales , Ácidos Grasos Insaturados/análisis , Femenino , Masculino , Fosfolípidos/metabolismo , Conejos , DesteteRESUMEN
The use of hydrogenated coconut oil as a putative substance for correcting an excess of unsaturated fatty acids in reserve lipids was tested in growing rats. Young rats with a live weight of about 70 g were given diet A including 4% of sunflower oil which very rapidly created a triglyceride store containing 25 to 30% of linoleic acid (18:2 n-6). At different weights (200, 300 and 350 g), diet A was replaced by diet B containing 15% of hydrogenated coconut oil so that there was the same number of animals in each group. All the rats were killed at 400 g, and diet-A and B were compared as to final fatty acid composition of body lipids (i.e. values taken all during growth from 70 to 400 g). Hydrogenated coconut oil was a very effective substance for rapidly decreasing levels of reserve lipid linoleic acid and for increasing triglyceride melting-point. The impact on the decrease in total unsaturated fatty acid concentrations was more marked the earlier the diet was replaced. However, the latest replacements (at 300 and 350 g) still permitted 70 and 50%, respectively, of the maximal effect observed in rats eating diet B from 70 g. The present experiment shows that when coconut oil was introduced in the diet over a period corresponding to the last one-eight of total body growth in rat, the final concentrations of unsaturated fatty acids could still be considerably reduced, particularly that of linoleic acid. In the same way, there was increasing esterification of myristic acid (14:0), and especially of lauric acid (12:0), which appeared preferentially in sn-1 and sn-3 positions in triglycerides. This esterification of medium-chain fatty acids led to a modification in the mode of other fatty acid distribution. Analysis of liver phospholipids showed that when diet A was replaced above 200 g by diet B, there was no biochemical evidence of any deficiency of essential fatty acids of the n-6 series.
Asunto(s)
Grasas de la Dieta/farmacología , Ácidos Grasos Insaturados/metabolismo , Metabolismo de los Lípidos , Ratas Endogámicas/crecimiento & desarrollo , Animales , Hígado/análisis , Fosfolípidos/análisis , Ratas , Temperatura , Triglicéridos/análisisRESUMEN
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 hare's milk were similar to those in rabbit's milk The amino acid composition of total protein resembled that of rabbit's milk. There were fewer medium-chain fatty acids (8:0-14:0) in here's milk than in rabbit's 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.