Mild streptozotocin diabetic rats, characterized by normal or slighty elevated fasting
blood glucose levels and glucose intolerance, treated with excessive doses of monocomponent
pork insulin (0.5 U/day) (I) or glybenclamide (0.6 mg/day) (S) were compared to controls
(C) and streptozotocin-diabetic rats without treatment (D). Intravenous glucose tolerance
tests (0.75 g/kg) were performed in all animals and repeated after overtreatment.
Insulin binding and insulin-induced D-(U-14C)-glucose transport and oxidation were also determined in isolated epididymal adipocytes.
Diabetic rats showed a failure in the initial phase of insulin release and glucose
intolerance as compared with (C). In overtreated rats glucose tolerance worsened (p<0.05)
after therapy. Maximal insulin binding by isolated adipocytes at tracer insulin concentration
was unchanged after excessive insulin or sulfonylurea therapy. Besides, glucose transport
and oxidation in the cells of overtreated rats were greater than in D and even greater
than in C. These apparently divergent results, i.e. deterioration of glucose tolerance
with increased insulin action in adipocytes suggest that overtreatment induces a state
of resistance to hormone action in other target tissue(s) than the adipose one, possibly
muscle.
Hyperinsulinization - Streptozotocin Diabetes - Glucose Tolerance - Insulin Binding
- Glucose Transport in Adipocytes
