diphenylhexatriene and Obesity

The production of pork with moderate amounts of intramuscular fat (IMF) without an increase in subcutaneous fat is highly desirable for the meat industry. Several studies indicate that dietary protein reduction during the growing-finishing period of pigs enhances IMF content, but its consequence on carcass fat deposition is still contradictory. In this study, we hypothesized that the effects of reduced protein diets (RPD), corrected or not with the limiting amino acid lysine, on subcutaneous fat deposition from pigs with distinct genotypes are mediated by adipose membranes biophysical properties. In total, 36 crossbred (Large White×Landrace×Pietrain - a lean genotype) and purebred (Alentejana breed - a fatty genotype) male pigs were randomly assigned to the control group, the RPD group or the reduced protein diet equilibrated for lysine (RPDL) group, allowing a 2×3 factorial arrangement (n=6). Backfat thickness and total fatty acid content were higher in Alentejana relative to crossbred pigs. Although dietary treatments did not change backfat thickness, RPD and RPDL increased total fatty acids content of subcutaneous fat. In order to understand this effect, adipose tissue membranes isolated from pig's subcutaneous fat were assayed for glycerol permeability and fluidity, using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4-(trimethylamino)-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) probes. The glycerol transport across adipose membranes was not mediated by aquaglyceroporins and remained unchanged across dietary groups. Regardless of lysine correction, RPD increased membrane fluidity at the hydrocarbon region (lower DPH fluorescence anisotropy) in both genotypes of pigs. This result was associated with a lower ratio between oleic acid and linoleic acid on membrane's fatty acid composition. Adipose membrane's cholesterol content was independent from genotype and diet. Taken together, the present study shows that dietary protein reduction is successful in maintaining backfat thickness, although a negative side effect was observed on total fatty acids in subcutaneous fat, which may be due to changes in the fluidity of adipose membranes.

Topics: Adipose Tissue; Animals; Body Composition; Breeding; Diet, Protein-Restricted; Dietary Proteins; Diphenylhexatriene; Fatty Acids; Lysine; Male; Membrane Fluidity; Obesity; Red Meat; Subcutaneous Fat; Swine

The objectives of this study were to investigate the rheological properties of the erythrocyte in patients with morbid obesity and to follow them up after a short-term weight loss. A fluorescent polarization method was used to assess erythrocyte membrane biorheology and to measure its fluidity. Eighteen subjects participated in the study: 8 healthy controls and 10 patients with morbid obesity. The erythrocyte membrane fluidity was obtained in the healthy subjects and in the patients with morbid obesity prior to and after a ten-day zero-calorie diet. Fluidity was determined by steady-state fluorescence polarization after incorporation of the lipophilic probe 1,6-diphenyl-1,3,5 hexatriene (DPH). With this method, the anisotropy parameter at 37 degrees C, which is inversely related to membrane fluidity, was obtained. The patients with morbid obesity revealed an abnormal erythrocyte rheology. The exhibited an abnormally low erythrocyte membrane fluidity as compared with normal subjects. The anisotropy parameter at 37 degrees C was 1.417 +/- 0.093 in these obese patients compared with 1.279 +/- 0.043 in normal-weight controls (p < 0.01). Upon a short-term significant weight loss from a body mass index (BMI) (weight/height2) of 39 +/- 5 to 36 +/- 5 kg/m2 (p < 0.05), the anisotropy parameter did not change (1.401 +/- 0.190). Thus, fluidity measurements permit recognition of an abnormal erythrocyte rheology in patients with morbid obesity. This abnormality may partially explain the excess cardiovascular and thromboembolic morbidity in morbid obesity.

Topics: Adult; Diphenylhexatriene; Energy Intake; Erythrocyte Membrane; Fluorescence Polarization; Humans; Membrane Fluidity; Middle Aged; Obesity; Temperature; Weight Loss

Fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene has been used to investigate the physical state of erythrocyte membranes from 36 obese children in absence of endocrine and metabolic disorders involving alterations of blood lipid pattern. A decrease of membrane fluidity, as shown by an increase of fluorescence polarization, was evident in obese subjects in comparison with the controls. The study of membrane composition has revealed an increase of cholesterol content and of cholesterol to phospholipid molar ratio, both being positively correlated with the observed changes of membrane fluidity. Moreover a correlation of membrane fluidity is also observed with body-mass index and plasma cholesterol levels. The results are discussed in the light of the possible use of erythrocyte membrane as a model to detect early alterations in the exchanges between erythrocyte membrane and lipoproteins in obesity.

Topics: Adolescent; Child; Diphenylhexatriene; Erythrocyte Membrane; Female; Humans; Lipids; Male; Membrane Fluidity; Obesity; Spectrometry, Fluorescence

Using 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5,hexatriene (TMA-DPH) as fluorescent probe, we have studied platelet membrane fluidity and thrombin induced exocytosis in ten obese children and fifteen controls. Our results indicate a decrease of membrane fluidity, as shown by an increase of fluorescence anisotropy, in platelets from obese patients in comparison with the controls. Associated with the changes in membrane fluidity, platelets of obese subjects showed a decreased sensitivity to thrombin stimulation.

Topics: Adolescent; Affinity Labels; Blood Platelets; Diphenylhexatriene; Exocytosis; Female; Fluorescence Polarization; Humans; Kinetics; Male; Mast Cells; Membrane Fluidity; Obesity; Platelet Aggregation; Polyenes; Thrombin