Wl. Lowe et al., REGULATION OF GROWTH-FACTOR MESSENGER-RNA LEVELS IN THE EYES OF DIABETIC RATS, Metabolism, clinical and experimental, 44(8), 1995, pp. 1038-1045
The underlying etiology of diabetic microvascular disease remains unkn
own. To examine the potential contribution of basic fibroblast growth
factor (bFGF), which is an angiogenic factor, and insulin-like growth
factor-I (IGF-I) to the development of diabetic microvascular disease,
bFGF and IGF-I mRNA levels were measured in tissues of control, diabe
tic, and insulin-treated diabetic rats. Diabetes was induced in rats b
y intravenous injection of streptozotocin (STZ) 65 mg/kg, and the rats
were maintained for 21 days. bFGF mRNA levels increased threefold in
the eyes of diabetic versus control rats, whereas a consistent change
in bFGF mRNA levels was not observed in other tissues. In contrast, IG
F-I mRNA levels decreased in the eyes and other tissues, including kid
ney, lung, and skeletal muscle, of diabetic as compared with control r
ats. Insulin treatment prevented the diabetes-induced increase in bFGF
and decrease in IGF-I mRNA levels. Acidic FGF (aFGF) mRNA levels were
unchanged in eyes from diabetic versus control rats. In partially pur
ified retinas, diabetes increased bFGF mRNA levels twofold as compared
with levels in control retinas, whereas IGF-I mRNA levels decreased t
o 58% of control levels in retinas from diabetic rats. Insulin treatme
nt again prevented the diabetes-induced increase in IGF-I mRNA levels
in the retina but had no effect on the diabetes-induced increase in bF
GF mRNA levels. bFGF peptide levels were minimally increased in diabet
ic versus control retinas. Treatment of diabetic rats with the aldose
reductase inhibitor sorbinil prevented the diabetes-induced increase i
n sorbitol accumulation and myo-inositol depletion in the lens, but it
did not affect the diabetes-induced increase in bFGF and decrease in
IGF-I mRNA levels in the retina. Induction of hypoinsulinemia by fasti
ng the animals did decrease IGF-I mRNA levels but did not reproduce th
e diabetes-induced increase in bFGF mRNA levels in the eye. In conclus
ion, these data demonstrate that the effect of diabetes on growth fact
or mRNA levels in the eye is gene-specific, suggest that different met
abolic abnormalities are responsible for diabetes-induced alterations
in the production of different growth factors in the eye, and are cons
istent with a role for bFGF in the development of diabetic retinopathy
. Copyright (C) 1995 by W.B. Saunders Company