Abstract
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.
Key words
Fish Oil - Olive Oil - Adipocytes - Muscle - Glucose Transport - Dietary Insulin Resistance
References
in vivo insulin action, thermogenesis, and obesity in rats.
Am J Clin Nutr.
1988;
47
420-427
salwa.rizkalla@htd.ap-hop-paris.fr
