The state of intermediate astraglia filaments, the indices of apoptosis and oxidative stress in brain tissue and the retina of rats with streptozotocin-induced hyperglycemia and the action of fullerene C60
The thesis is devoted to the determination of the role of intermediate filaments of
astroglia, PAPP, NF-kB during oxidative stress generation in the brain and retina of rats
under conditions of streptotrozine-induced hyperglycemia and the effect of fullerene C60
on the prevention of astrocytic reactivation.
It has been established that hyperglycemia able to induce the development of oxidative
stress in the hippocampus, the cerebral cortex, and the cerebellum. In the retina of
hyperglycemic rats, the development of oxidative stress is associated with a disturbance of
the content of molecular markers that reflect a metabolic disorder. Observed results
evidence the fact that oxidative stress generation in the retina of diabetic rats associates
with impaired expression of molecular markers of metabolic disorder. The results of
western blot shown that the reactivation of GFAP-positive cells in the retina of
hyperglycemic rats is accompanied with an increment of the content of degraded
polypeptide fragments of GFAP with a molecular weight 47-40 kDa.
A comparative analysis of the immunohistochemical staining of the samples of the fixed
slices of the retina showed significantly increased proliferation and hypertrophy of GFAP-
positive cells in the retina of the rats in hyperglycemic group compared to the animals in
the control group. A reliable increase in the main indicators of hyperglycemia in the blood
of animals with STZ-induced diabetes was revealed. Obtained results demonstrate that the
concentration of glucose and glycosylated hemoglobin was higher by 24.7% and 279%,
respectively, and insulin was lower by 169% in hyperglycemic rats group relative to the
animals of the control group. This indicates the development of stable hyperglycemia in
rats within 90 days after STZ exposure.
There was found that consumption of C60 fullerene prevents the development of
oxidative stress in the brain and retina, substantially prevents metabolic disturbances in
retina cells. In particular, the level of content of all investigated proteins was lower than
hyperglycemic: GFAP by 67%, PARP 1/2 by 70%, caspase-3 by 68%, the ratio of NF-kB
content into nuclear fraction to this content into cytosolic fraction 1.6 times. The results
observed in presented study demonstrated the positive correlation between the changes in
the expression of molecular markers of astrocyte cytoskeleton, transcriptional activity,
apoptosis and DNA damage in the retina of hyperglycemic rats and hyperglycemic
animals that consumed the C60 fullerene with drinking water. The presented results allow
conclude that unmodified hydrated fullerene (C60HyFn) prevents the development of
cytoskeleton rearrangement and excessive reactivation of retinal astroglia in a rat group
with hyperglycemia. Fullerene C 60 HyFn can be used as a molecular tool for studying the
mechanisms of reciprocal regulation between endothelium, microglia and ganglion cells of
the retina in conditions of hyperglycemia. The integrative study of cytoskeleton and
transcriptional factors in both brain and retina of diabetic retinopathy animal model can be
fruitful for the comprehension of molecular and cellular mechanisms of hyperglycemic
disorders in neural tissue.
There was observed the positive correlation between the changes in the expression of
molecular markers of the metabolic disorder in the retina of diabetic rats and diabetic
animals that consumed the C60 fullerene with drinking water. The results suggest that
nonmodified hydrated fullerene (C60HyFn) prevents an abuse and excessive cytoskeleton
reactivation retinal glial cells in diabetes rat group. Fullerene C60HyFn can be used as a
molecular tool for studying the mechanisms of reciprocal regulation between the
endothelium, microglia and retinal ganglion cells under hyperglycemia.
Keywords: glial fibrillary acidic protein (GFAP), diabetic retinopathy (DR),
astrogliosis, apoptosis, neuroprotective effect, streptozotocin-induced diabetes.