Diabetic nephropathy is still a hallmark of diabetes mellitus and one of the main causes of death, although the pathogenesis of diabetic nephropathy remains controversial. To investigate the sequential histopathologic changes of the kidney in
diabetes
and the effects of early insulin therapy on the diabetic nephropathy, and also to correlate their possible pathogenesis with the histologic changes, the author performed an experimental study on 14 streptozotocin induced diabetic mice (group I)
and
13
insulin (NPH) treated diabetic mice(group II).
@ES The results were as follows.
@EN 1. There was no difference in the thickness of glomerular basement membranes between insulin non-treated diabetic mice(group I) and insulin treated diabetic mice (group II) in the periods of 4, 8, 10 weeks after streptozotocin injection
comparing to
5 normal control mice.
2. Mesangial widening with increase of mesangial matrix and mesangial cells were observed in group I diabetic mice (13/14) and in group II insulin treated diabetic mice (12/13) at the 4th, 8th and 10th week. But the average percentage of
glomerular
invovement is 72%, 84% and 20% at the 4th, 8th and 10th week, respectively in the group I diabetic mice and 30%, 60% and 10% at each same periods in the group II insulin treated diabetic mice.
3. Electron dense deposits were observed in mesangial regions in all group I diabetic mice and group II insulin treated diabetic mice. There were more abundant at 8th week than at 4th, 10th week, however that was not corresponding to the blood
glucose
level.
4. Glomerular hypertrophy was observed at 10th week in group I diabetic mice and in insulin treated non diabetic mice, but at 4th and 8th week there was no discernible glomerular hypertrophy in group I diabetic and group II insulin treated
diabetic
mice.
Taken the above results mesangial widening with increase in mesangial matrix and cells and electron dense deposits were the earliest changes of diabetic nephropathy in streptozotocin induced diabetic mice. Those changes were diminished by the
early
administration of insulin. Thereafter glomerular hypertrophy was followed, which was not changed by insulin therapy. On the contrary to known knowledge, the thickness of glomerular basement membrane had not been changed until 10 weeks after
streptozotocin injection.
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