Korean J Neurotrauma.  2015 Oct;11(2):44-51. 10.13004/kjnt.2015.11.2.44.

Time Course and Characteristics of Astrocyte Activation in the Rat Brain after Injury

• Lee HH
• Park SC
• Choe IS
• Kim Y
• Ha YS

• KMID: 2378257
• DOI: http://doi.org/10.13004/kjnt.2015.11.2.44

Abstract

OBJECTIVE
After injury to the central nervous system (CNS), glial scar tissue is formed in the process of wound healing. This can be is a clinical problem because it interferes with axonal regeneration and functional recovery. It is known that intracellular proteins, including the glial fibrillary acidic protein (GFAP), nestin, and vimentin increase in the astrocytes after an injury to the CNS. By studying the time course and co-expression pattern of these intracellular proteins, this study will attempt to prove that these proteins are involved in the processes of glial scar formation.
METHODS
Twenty-five male Sprague-Dawley rats were used in this study. Bregma of the cerebral cortex, an area was incised with a sharp blade, and perfusion was performed. The expressions of the intracellular proteins were assayed, while the co-localization of the intermediate filament (GFAP, nestin, and vimentin) and A2B5 were examined.
RESULTS
At 12 hours, the GFAP was expressed in the white matter underlying the lesion, and in the cerebral cortex. Nestin was expressed in the astrocytes in the perilesional area after 3 days, while A2B5 was observed in the edge of the wound at 12 hours post-injury, with its expression reaching a peak at 7 days. Vimentin was detected in the white matter at 12 hours, and in the cortex, reaching a peak at 7 days.
CONCLUSION
In the processes of glial scar formation, nestin, vimentin, and A2B5 were revealed in the astrocytes, and these factors may be involved in the division, proliferation, and transportation of the astrocytes.

Keyword

Astrocyte; Glial fibrillary acidic protein; Nestin; Vimentin; Gliosis

MeSH Terms

Animals
Astrocytes*
Axons
Brain*
Central Nervous System
Cerebral Cortex
Cicatrix
Glial Fibrillary Acidic Protein
Gliosis
Humans
Intermediate Filaments
Male
Nestin
Perfusion
Rats*
Rats, Sprague-Dawley
Regeneration
Transportation
Vimentin
Wound Healing
Wounds and Injuries
Glial Fibrillary Acidic Protein
Vimentin

Figure

• 

  FIGURE 1 Glial fibrillary acidic protein upregulation in white matter; proliferation of astrocytes in white matter at the early stage of scar formation (×100). A: 12 hours. B: 1 day. C: 3 days. D: 7 days. E: 14 days.

• 

  FIGURE 2 Nestin is usually detected in multipotential stem and reactivated astrocytes. This finding suggests that activation and differentiation of astrocytes should be involved in the process of scar formation (×100). A: 12 hours. B: 1 day. C: 3 days. D: 7 days. E: 14 days.

• 

  FIGURE 3 Vimentin is an embryonic protein. Its upregulation might be associated with cellular differentiation. It is known that vimentin is involved in cellular motility, so vimentin positive astrocyte might be postulated to migrate from the white matter to the injury site, and to constitute scar later (×100). A: 12 hours. B: 1 day. C: 3 days. D: 7 days. E: 14 days.

• 

  FIGURE 4 A: Vimentin was increased in the white matter. B: Nestin was increased along the wound edge (×100).

• 

  FIGURE 5 A2B5 upregulation surrounding injury site means that the process of activation, differentiation of astrocytes is involved in the glial scar formation (×100). A: 12 hours. B: 1 day. C: 3 days. D: 7 days. E: 14 days.

• 

  FIGURE 6 Seven days after the surgical damage, the nestin, vimentin, and A2B5 were revealed, together with glial fibrillary acidic protein (GFAP) expression (×100). A-C: Colocalization of GFAP and A2B5. D-F: Colocalization of GFAP and nestin. G-I: Colocalization of GFAP and vimentin.

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