The present series of experiments aim mainly at investigating the possible influence of changes in the com-position of dietary
lipids (
sunflower oil,
salmon oil,
safflower oil) upon the
metabolic syndrome found in rats exposed to a
fructose-rich diet. For purpose of comparison, a control group of rats received the
sunflower oil diet with substitution of
fructose by
starch. An intraperitoneal
glucose tolerance test, performed after overnight
starvation fifty days after the start of the experiments at the 6th week after birth, indicated, as expected, impaired tolerance to
glucose and deterioration of
insulin sensitivity (HOMA index), without changes in the insulinogenic index, when comparing the
fructose-fed rats to the
starch-fed rats both exposed to the
sunflower oil diet. In the
fructose-fed rats, enrichment of the diet by long-chain polyunsaturated ω3
fatty acids supplied by
salmon oil, a modest improvement of
insulin sensitivity was opposed, in term of
glucose homeostasis, by a decreased secretory response to
glucose of
insulin-producing cells. Last, in the
fructose-fed rats, the partial substitution of
sunflower oil by
safflower oil rich in long-chain polyunsaturated ω6
fatty acids further deteriorated
glucose homeostasis, with a higher mean HOMA index and a severe decrease of the insulinogenic index. These findings justify further investigations on such items as the time course for changes in metabolic and hormonal variables and both the metabolic and secretory responses of isolated pancreatic islets to selected nutrient
secretagogues.