J Vet Sci.  2007 Dec;8(4):323-327. 10.4142/jvs.2007.8.4.323.

Increased phosphorylation of caveolin-1 in the spinal cord of irradiated rats

• Kim H
• Moon C
• Kim J
• Ahn M
• Hyun JW
• Park JW
• Kim SH
• Kim S
• Shin T

• KMID: 1106210
• DOI: http://doi.org/10.4142/jvs.2007.8.4.323

Abstract

Phosphorylation of caveolin-1 occurs during cell activation by various stimuli. In this study, the involvement of caveolin-1 in an irradiation injured spinal cord was examined by analyzing the phosphorylation of caveolin-1 in the spinal cord of rats after irradiation with a single dose of 15 Gray from a (60)Co gamma-ray source at 24 h post-irradiation (PI). A Western blot analysis showed that the phosphorylated form of caveolin-1 (p-caveolin-1) was expressed constitutively in the normal spinal cords and was significantly higher in the spinal cord of irradiated rats at 24 h PI. The increased expression of ED1, which is a marker of activated microglia/macrophages, was matched with that of p-caveolin-1. In the irradiated spinal cords, there was a higher level of p-caveolin-1 immunoreactivity in the isolectin B4-positive microglial, ependymal, and vascular endothelial cells, in which p-caveolin-1 was weakly and constitutively expressed in the normal control spinal cords. These results suggest that total body irradiation induces activation of microglial cells in the spinal cord through the phosphorylation of caveolin-1.

Keyword

caveolin-1; irradiation; microglia; phosphorylation; spinal cord

MeSH Terms

Animals
Blotting, Western/veterinary
Caveolin 1/*metabolism
Gene Expression Regulation/*radiation effects
Immunohistochemistry/veterinary
Male
Phosphorylation/radiation effects
Rats
Rats, Sprague-Dawley
Spinal Cord/physiopathology/*radiation effects
Spinal Cord Injuries/physiopathology/*veterinary

Figure

• 

  Fig. 1 Western blot analysis for p-caveolin-1 (A), ED1 (B), fibronectin (C) in the spinal cords of the normal control rats (Normal controls) and irradiated rats at day 1 post-irradiation (Irradiation). The photographs represent the Western blot for p-caveolin-1 (A), ED1 (B), fibronectin (C) and beta-actin. The p-caveolin-1, ED1, and fibronectin immunoreactivities were detected at low levels in the spinal cords of the normal controls (n = 7) and were found to be significantly greater at day 1 post-irradiation (n = 7; p < 0.05). The arrowheads indicate the positions of p-caveolin-1 (approximately 22 kDa), ED1 (110 kDa), fibronectin (220 kDa) and beta-actin (45 kDa).

• 

  Fig. 2 Immunohistochemical staining of p-caveolin-1 in the spinal cord of the normal control (A, B) and irradiated rats at 24 h post-irradiation (C, D). p-caveolin-1 was weakly detected in some glial (A, arrow), vascular endothelial (A, arrowhead), and ependymal cells (B, arrow) in the normal control spinal cords. Conversely, intense p-caveolin-1 immunoreactivity was detected in the ramified glial (C, arrows), vascular endothelial (C, arrowheads), and ependymal cells (D, arrow) from the irradiated spinal cords which were counterstained with hematoxylin. Scale bars = 30 µm.

• 

  Fig. 3 Identification of p-caveolin-1-positive cells in the spinal cord of the irradiated rats at 24 h post-irradiation. The immunoreactivity of p-caveolin-1 (A, green) was co-localized in some isolectin B4-positive microglia (arrows) and some vascular endothelial cells (arrowhead) in the parenchyma (B, red) (C, merge). Some p-caveolin-1-positive cells (D, green, arrow) tested positive for scarce amounts of glial fibrillary acidic protein GFAP (E, red, arrow) in the white matter (F, merge, arrow). Scale bars = 20 µm.

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