Diabetes, Vol 38, Issue 5 610-617, Copyright © 1989 by American Diabetes Association
Relation of insulin deficiency to impaired insulin action in NIDDM adult rats given streptozocin as neonates
O Blondel, D Bailbe and B Portha
Laboratory of Developmental Physiology, University of Paris, France.
We assessed the impact of chronic insulin deficiency on basal and
insulin-stimulated glucose utilization by the whole-body mass in vivo in
female albino Wistar rats. This assessment was based on a comparison of
results in rats given streptozocin (STZ) on day of birth (n0-STZ), when 2
days old (n2-STZ), or when 5 days old (n5-STZ). At 10 wk of age, the n2-STZ
rats exhibited characteristics similar to those obtained in the n0-STZ
rats: normal growth, modest elevation of basal plasma glucose (8.23 +/-
0.24 mM), glucose intolerance, depleted pancreatic insulin stores
(approximately 50% of normal value), and lack of insulin release in
response to glucose in vivo. In contrast, the n5-STZ rats exhibited frank
basal hyperglycemia (glucose 11.9 +/- 1.1 mM) and glucose intolerance,
increased glycosylated hemoglobins, strong reduction of the pancreatic
insulin stores (10% of normal value), decreased basal plasma insulin levels
(50% of normal value), and lack of insulin release in response to glucose
in vivo. Changes in the sensitivity of the neonatal beta-cell to STZ and
the regeneration capacity of the beta-cells during the 1st postnatal wk
were liable factors for the contrast. In vivo insulin action was assessed
with the euglycemic-hyperinsulinemic clamp technique in 10-wk-old
anesthetized animals. In the n2-STZ rats compared with controls 1)
endogenous glucose production was significantly higher despite a normal
plasma insulin level in the basal state, 2) endogenous glucose production
rate was similarly suppressed by hyperinsulinemia, and 3) glucose
utilization by the whole-body mass was similarly increased by
hyperglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)