Abstract:
The clinical and morphological picture of diabetic microangiopathy
is rather specific. Diabetic retinal ischemia can lead to irreversible damage to
retinal neural elements and choroidal capillaries. Diabetic nephropathy can lead
to progressive renal dysfunction and chronic renal failure. Choroidal and retinal
capillaries are structurally and functionally similar to those of the intestinal
mucosa and renal tissue.
Purpose: To assess vascular ultrastructural changes in the choroid, retina, and
renal glomerular and tubular system in a rat model of pyelonephritis in the
presence of type 2 diabetes.
Material and Methods: Samples were obtained from 95 Wistar rats divided into
three groups: group 1 (or control group) of 30 intact animals; group 2 of 15
animals with type 2 diabetes induced by intraperitoneal streptozotocin 15.0 mg/
kg for 5 consecutive days; and group 3 of 50 animals with acute pyelonephritis
in the presence of type 2 diabetes (streptozotocin 35.0 mg/kg on 2 days spaced
by a week). Acute pyelonephritis was induced by Escherichia coli administration
(107 CFU/kg) rectally. The ultrastructure of rat choroidal, retinal and renal
glomerular-and-tubular vessels was examined with electron microscopy (PEM-
100-01 electron microscope).
Results: In rats with induced type 2 diabetes, the most significant ocular vascular
changes and renal vascular changes were found in endothelial cells. These
changes included findings of vacuolar degeneration in some epithelial cells, basal
membrane thickening and focal necrosis of individual epithelial cells. Vessel
lumens appeared focally narrowed or expanded, with red blood cells forming
clumps or sludge in lumens. Some capillaries were obliterated. These changes
obviously caused secondary changes in the surrounding structures. Common
ocular changes included focal destruction in retinal pigment epithelium cells,
destruction of retinal photoreceptor inner segments and choroidal stromal edema.
Common renal changes included destruction of the podocytes of the glomerular
capillary network and homogenization of the basal membrane. Vascular
ultrastructural changes in the renal glomerular system were more marked in rats
with experimental type 2 diabetes and pyelonephritis than in those with type 2
diabetes only.
Conclusion: Electron microscopy micrographs demonstrated the ultrastructural
changes in the retinal and uveal vascular systems which were of a similar type
to those in the renal glomerular-and-tubular system in rats with experimental
pyelonephritis in the presence of type 2 diabetes.
