Whole body insulin sensitivity in Osborne-Mendel and S 5B/Pl rats eating a low- or high-fat diet.
To determine whether whole body insulin sensitivity differs between a rat strain that does not (S 5B/Pl) and a strain that does [Osborne-Mendel (OM)] become obese when eating a high-fat diet, we performed euglycemic clamp studies in animals from each strain during low- and high-fat feeding. Clamps were performed after 2 days ("initial clamp") and 9 days ("final clamp") on each diet. Plasma glucose and insulin levels during the final 60 min of initial and final clamps were similar in S 5B/Pl and OM rats regardless of diet. Insulin sensitivity, measured as the glucose clearance rate during the final 60 min of the clamp, averaged 35 +/- 3 ml.kg-1.min-1 in S 5B/Pl rats after 2 days on a low-fat diet. This did not change significantly during an additional 7 days on the low-fat diet. The high-fat diet was associated with a 13% reduction in insulin sensitivity after 2 days and a 30% reduction after 9 days in S 5B/Pl rats. OM rats exhibited similar patterns of insulin sensitivity during low- and high-fat diets, albeit at lower insulin sensitivity overall (P < 0.0005 vs. S 5B/Pl). Mean glucose clearance after 2 days on the low-fat diet was 27 +/- 2 mg.kg-1.min-1 and did not change significantly during seven more days of low-fat feeding. The high-fat diet was associated with a 19% reduction in glucose clearance after 2 days and a 38% reduction after 9 days in OM rats. The magnitude of reduction in insulin sensitivity during high-fat diets did not differ significantly between strains.(ABSTRACT TRUNCATED AT 250 WORDS)
Buchanan
T A
TA
Department of Medicine, University of Southern California Medical School, Los Angeles 90033.
Fisler
J S
JS
Underberger
S
S
Sipos
G F
GF
Bray
G A
GA
D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D004041:Dietary Fats / Q000494:pharmacology*; D004435:Eating; D005260:Female; D020022:Genetic Predisposition to Disease; D015309:Glucose Clamp Technique; D007333:Insulin Resistance / Q000235:genetics*; D009765:Obesity / Q000235:genetics*; D051381:Rats; D011919:Rats, Inbred Strains / Q000235:genetics* / Q000502:physiology
D004041:Dietary Fats