Regulation of glucose transport and transporter 4 (GLUT-4) in muscle and adipocytes of sucrose-fed rats: effects of N-3 poly- and monounsaturated fatty acids.
The goal of this study was to compare the short-term effects of dietary n-3 polyunsaturated (fish oil) and monounsaturated (olive oil) fatty acids on glucose transport, plasma glucose and lipid controls in a dietary insulin resistance model using sucrose-fed rats. The underlying cellular and molecular mechanisms were also determined in the muscle and adipose tissue. Male Sprague-Dawley rats (5 weeks old) were randomized for diets containing 57.5 % (w/w) sucrose and 14 % lipids as either fish oil (SF), olive oil (SO) or a mixture of standard oils (SC) for 3 weeks. A fourth control group (C) was fed a diet containing 57.5 % starch and 14 % standard oils. After three weeks on the diet, body weight was comparable in the four groups. The sucrose-fed rats were hyperglycemic and hyperinsulinemic in response to glucose load. The presence of fish oil in the sucrose diet prevented sucrose-induced hyperinsulinemia and hypertriglyceridemia, but had no effect on plasma glucose levels. Insulin-stimulated glucose transport in adipocytes increased after feeding with fish oil (p < 0.005). These modifications were associated with increased Glut-4 protein (p < 0.05) and mRNA levels in adipocytes. In the muscle, no effect was found on Glut-4 protein levels. Olive oil, however, could not bring about any improvement in plasma insulin, plasma lipids or Glut-4 protein levels. We therefore conclude that the presence of fish oil, in contrast to olive oil, prevents insulin resistance and hypertriglyceridemia in rats on a sucrose diet, and restores Glut-4 protein quantity in adipocytes but not in muscle at basal levels. Dietary regulation of Glut-4 proteins appears to be tissue specific and might depend on insulin stimulation and/or duration of dietary interventions.
Department of Diabetes-INSERM U341, Hôtel-Dieu Hospital, Paris, France.
E
E
Peyron-Caso
S
S
Fluteau-Nadler
M
M
Kabir
M
M
Guerre-Millo
A
A
Quignard-Boulangé
G
G
Slama
S W
SW
Rizkalla
D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002469:Cell Separation; D004032:Diet; D004435:Eating; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D051275:Glucose Transporter Type 4; D066298:In Vitro Techniques; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D000069463:Olive Oil; D009929:Organ Size / Q000187:drug effects; D010938:Plant Oils / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000494:pharmacology*
D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D000069463:Olive Oil; D010938:Plant Oils; D012333:RNA, Messenger; C495694:Slc2a4 protein, rat; D013395:Sucrose; D005947:Glucose