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Is neuronal injury caused by hypoglycemic coma of the necrotic or apoptotic type?
1Center for the Study of Neurological Disease, The Queen's Medical Center, Honolulu, Hawaii 96813, USA. yibing@cns.queens.org
Abstract:
In this study, we explored if a 30 minute period of hypoglycemic coma yields damage which shows some features associated with apoptosis. To that end, we induced insulin-hypoglycemic coma of 30 min duration, and studied brain tissues after the coma period, and after recovery period of 30 min, 3 h, and 6 h. Histopathological data confirmed neuronal damage in all of the vulnerable neuronal populations. Release of cytochrome c (cyt c), assessed by Western Blot, was observed in the neocortex and caudoputamen after 3 and 6 h of recovery. In these regions, the caspase-like activity increased above control after 6 h of recovery. By laser-scanning confocal microscopy, a clear expression of Bax was observed after 30 min of coma in the superficial layers of the neocortex, reaching a peak after 30 min of recovery. Punctuate immunolabeling surrounding nuclei in soma and dendrites in cortical pyramidal neurons likely represents mitochondria, which suggests that Bax protein assembled at the surface of mitochondria in vulnerable neocortical neurons. It is concluded that although previous morphological data have suggested that cells die by necrosis, neuronal damage after hypoglycemic coma shows some features of apoptosis.
Insights
Hypoglycemic coma causes neuronal damage with features of apoptosis. Key indicators like Bax protein expression and cytochrome c release suggest programmed cell death pathways are activated in the brain.
Area of Science:
- Neuroscience
- Cell Biology
- Pathology
Background:
- Hypoglycemic coma can lead to neuronal damage.
- The precise mechanisms of cell death, whether necrosis or apoptosis, remain under investigation.
Purpose of the Study:
- To investigate if a 30-minute hypoglycemic coma induces brain damage with apoptotic features.
- To analyze the temporal changes in apoptotic markers following hypoglycemic coma.
Main Methods:
- Induction of insulin-hypoglycemic coma (30 minutes) in study models.
- Histopathological examination of brain tissues at various recovery time points (30 min, 3 h, 6 h).
- Western Blot for cytochrome c release, caspase-like activity assays, and laser-scanning confocal microscopy for Bax expression.
Main Results:
- Neuronal damage was confirmed in vulnerable populations post-coma.
- Cytochrome c release and increased caspase-like activity were observed in the neocortex and caudoputamen after 3 and 6 hours of recovery.
- Bax protein expression, indicative of apoptosis, was detected in the neocortex, peaking after 30 minutes of recovery, suggesting mitochondrial localization.
Conclusions:
- Neuronal damage following hypoglycemic coma exhibits characteristics of apoptosis.
- The findings suggest that programmed cell death pathways are involved in the neuropathology of hypoglycemic coma.