Our previous study indicated that a single i.p. injection of 100 mg/kg stre
ptozotocin (STZ) is able to induce slowly progressive diabetes mellitus in
adult ICR mice. In the present study, the non-fasting serum insulin levels
of the mice administered 100 mg/kg STZ were normal throughout the 24-week-o
bservation after STZ injection. In the STZ-administered mice, the area of i
slets and the number of insulin-immunoreactive cells (beta -cells) were nor
mal at I week and then continued to decrease gradually as the time went on.
In contrast, there was a relative increase in the number of glucagon-immun
oreactive cells (alpha -cells) in these mice. In addition, in the STZ-admin
istered mice, the degree of glucose tolerance continued to reduce from 2 we
eks till 12 weeks when the experiment terminated. The rise in serum insulin
levels stimulated by glucose in the STZ-administered mice began to subside
from about 2 weeks and had completely ceased by 12 weeks. These results in
dicate that 100 mg/kg STZ-induced diabetic mouse model is non-insulin-depen
dent diabetes, which is characterized by impaired insulin response to gluco
se stimulation. (C) 2001 Elsevier Science B.V. All rights reserved.