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Selective vulnerability of brain regions to oxidative stress in a non-coma model of insulin-induced hypoglycemia
M L Haces1, T Montiel, L Massieu
1Departamento de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F., México.
Abstract:
Insulin-induced hypoglycemia causes the death of neurons in particular brain regions including the cerebral cortex, the striatum and the hippocampus, while the cerebellum and the brain stem are more resistant. The mechanisms underlying this selective vulnerability to hypoglycemic damage are unknown. In the present study we have analyzed the presence of lipoperoxidation products and nitrosilated protein residues in different rat brain regions during and after the induction of hypoglycemia. Insulin-injected hypoglycemic rats were sacrificed before the onset of the isoelectric period or infused with glucose to end hypoglycemia, and then sacrificed at different times. Increased lipoperoxidation levels were observed before the onset of the isoelectric period, while 3-nitrotyrosine (NT) residues in proteins and NT-positive cells were only observed after glucose reperfusion. These changes were found only in vulnerable brain regions, while none of them was evident in the cerebellum, suggesting a correlation between oxidative damage and vulnerability to hypoglycemic neuronal death in selective brain regions. Results suggest that a pro-oxidant state is promoted in certain brain regions during hypoglycemia and after the glucose reperfusion phase, which might result from the activation of several oxidative stress pathways and may be related to subsequent cell death.
Insights
Insulin-induced hypoglycemia selectively damages brain regions. Oxidative stress markers, like lipoperoxidation and nitrosilated proteins, appear in vulnerable areas during and after low blood sugar, correlating with neuronal death.
Area of Science:
- Neuroscience
- Biochemistry
Background:
- Insulin-induced hypoglycemia causes selective neuronal death in specific brain regions like the cerebral cortex and hippocampus.
- The mechanisms behind this regional vulnerability to hypoglycemic damage remain unclear.
Purpose of the Study:
- To investigate the role of oxidative stress in selective brain damage during and after insulin-induced hypoglycemia.
- To analyze lipoperoxidation products and nitrosilated protein residues in different rat brain regions.
Main Methods:
- Rats were subjected to insulin-induced hypoglycemia and sacrificed at various time points.
- Brain regions were analyzed for lipoperoxidation and 3-nitrotyrosine (NT) residues.
- Glucose infusion was used to terminate hypoglycemia in some rats before sacrifice.
Main Results:
- Increased lipoperoxidation was detected before the isoelectric period (loss of brain activity).
- 3-nitrotyrosine (NT) residues and NT-positive cells were observed post-glucose reperfusion in vulnerable brain regions.
- No significant oxidative changes were found in resistant regions like the cerebellum.
Conclusions:
- A pro-oxidant state is promoted in vulnerable brain regions during and after hypoglycemia.
- Oxidative damage, indicated by lipoperoxidation and nitrosylation, correlates with selective neuronal vulnerability and death.
- Activation of oxidative stress pathways may contribute to hypoglycemic neuronal damage.
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