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Midkine is present in the early stage of cerebral infarct
1Department of Biochemistry, Faculty of Medicine, Kagoshima University, Japan.
Abstract:
Expression of midkine (MK), a growth factor with neurotrophic activities, was examined immunohistochemically in experimental cerebral infarct of rats. From postoperative day 1 to day 7 after the onset of infarct, anti-MK immunoreactivity was observed in the surrounding ischemic zone of the infarct but not in the necrotic lesion. The immunoreactive material was identified to be MK by Western blotting. On day 14, anti-MK immunoreactivity became negative. Absence of MK in the normal brain was verified both by immunohistochemical staining and Western blotting. The induced expression of MK is an early event: increased expression of glial fibrillary acidic protein (GFAP), a marker of astrocytes, started on day 4 and continued to day 14. These findings suggest that MK is produced around the site of nerve damage and plays a role as a reparative neurotrophic factor during the early phase of cerebral infarct.
Insights
Midkine (MK), a growth factor, is expressed in the early stages of experimental cerebral infarct in rats. This suggests MK acts as a reparative neurotrophic factor during the initial phase of brain injury.
Area of Science:
- Neuroscience
- Molecular Biology
- Pathology
Background:
- Midkine (MK) is a growth factor with known neurotrophic activities.
- Cerebral infarct involves nerve damage and subsequent repair processes.
- Understanding the molecular players in early infarct stages is crucial for therapeutic development.
Purpose of the Study:
- To investigate the spatiotemporal expression of midkine (MK) in an experimental model of cerebral infarct.
- To determine if MK expression correlates with early cellular responses to ischemic brain injury.
Main Methods:
- Immunohistochemistry was used to detect MK expression in rat cerebral infarct models.
- Western blotting confirmed the identity of the immunoreactive material as MK.
- Glial fibrillary acidic protein (GFAP) expression was monitored as a marker for astrocyte activation.
Main Results:
- MK immunoreactivity was detected in the ischemic zone surrounding the infarct from day 1 to day 7 post-injury.
- MK was absent in the necrotic lesion and in normal brain tissue.
- MK expression preceded the significant increase in GFAP expression, which began on day 4.
Conclusions:
- Midkine (MK) is induced in the early phase of experimental cerebral infarct.
- MK is produced in the vicinity of nerve damage, suggesting a localized role.
- These findings support MK's function as a reparative neurotrophic factor in the early stages of cerebral infarction.