Abnormal oral glucose tolerance in genetically obese (fa/fa) rats.
The effect of intravenous glucose or tolbutamide administration on plasma glucose and insulin levels was compared with that following spontaneous ingestion of glucose in freely moving 6- to 7-wk- and 13- to 14-wk-old lean and obese (fa/fa) rats. Irrespective of age, the obese rats had a normal blood glucose tolerance when glucose or tolbutamide load was given intravenously, whereas the glucose ingestion [oral glucose tolerance test (OGTT) caused a marked glucose intolerance that became more pronounced with the duration of the syndrome. This suggests that factors other than insulin resistance could play a role in the occurrence of abnormal OGTT in obese rats. When blood insulin levels were expressed as percent change over base line and when compared with age-matched normal rats, the 6- to 7-wk obese rats showed a normal and even higher beta-cell responsiveness to intravenous or oral glucose as well as to tolbutamide. In contrast, the 13- to 14-wk obese rats presented a decreased beta-cell responsiveness to all such stimuli. Thus the beta-cell function of obese rats worsens with time. Inasmuch as 13- to 14-wk-old obese fa/fa rats have insulin resistance, high basal glycemia, and abnormal oral glucose tolerance, they can be viewed as a potential model of type II diabetes.
D000367:Age Factors; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D005947:Glucose / Q000008:administration & dosage*; D005951:Glucose Tolerance Test; D007328:Insulin / Q000032:analysis; D007333:Insulin Resistance; D008297:Male; D008433:Mathematics; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D051381:Rats; D011924:Rats, Zucker; D014044:Tolbutamide / Q000494:pharmacology
D001786:Blood Glucose; D007328:Insulin; D014044:Tolbutamide; D005947:Glucose