Diabetes, Vol 38, Issue 6 691-697, Copyright © 1989 by American Diabetes Association

ARTICLES

Comparison of insulin secretory patterns in obese nondiabetic LA/N-cp and obese diabetic SHR/N-cp rats. Role of hyperglycemia

L Recant, NR Voyles, KI Timmers, SJ Bhathena, D Solomon, S Wilkins and OE Michaelis
Diabetes Research Laboratory, Veterans Administration Medical Center, Washington, DC 20422.

Obese diabetic SHR/N-(cp/cp) rats are a genetic model for non-insulin-dependent diabetes mellitus. When SHR/N-cp rats are overtly diabetic, they are hyperinsulinemic and hyperglycemic in the fed state when consuming commercial chow or semipurified high-carbohydrate diets. Obese SHR/N-cp rats were hyperinsulinemic by 4 wk of age, although hyperglycemia did not appear until 3-4 wk later and was exacerbated by a high-sucrose diet (mean +/- SE 1488 +/- 238 microU/ml insulin and 425 +/- 51 mg/dl glucose). The control SHR/N-cp rats (+/?) on the sucrose diet remained lean and normoglycemic. The obese diabetic SHR/N-cp rats showed three alterations in pancreas perfusion data (not present in control rats): 1) paradoxically high insulin secretion at low glucose levels (2.5 mM), 2) secretion of insulin in response to arginine (10 mM) in the absence of glucose, and 3) impaired response of insulin secretion to high glucose (16.7 mM). To determine whether hyperglycemia was responsible for the abnormalities of insulin secretion, perfusion studies were conducted in obese nondiabetic LA/N-cp rats and compared with the SHR/N-cp rats. The obese LA/N-cp rats resembled the corpulent SHR/N-cp rats in every way, except that they were normoglycemic on the sucrose diet. The obese LA/N-cp rats had two of the three alterations in insulin secretion shown by obese SHR/N-cp rats, lacking only the impaired response to high glucose, suggesting that hyperglycemia was required for that defect to occur.(ABSTRACT TRUNCATED AT 250 WORDS)
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