Diffuse brain injury induces local expression of Na+/myo-inositol cotransporter in the rat brain.
We studied expression of an osmoprotective gene, sodium/myo-inositol cotransporter (SMIT) in Marmarou's animal model for human diffuse brain injury by in situ hybridization and immunohistochemistry. In rats with diffuse brain injury, transient upregulation of SMIT mRNA was exclusively observed in the lateral area of pyramidal tract in lower brainstem. The expression was induced at 1 h after injury, peaked at 24 h, and returned to almost control levels at 48 h. Upregulated expression was found mainly in small glia-like cells. By immunohistochemistry using antibodies to phosphorylated mitogen-activated protein (MAP) kinases, inductions of phosphorylated p44/42 MAP kinase were also observed after diffuse brain injury. Interestingly, the distribution patterns of induced phosphorylated p44/42 MAP kinase were completely coincident with those of upregulated SMIT mRNA after diffuse brain injury. These results suggest that diffuse brain injury induces local expression of SMIT by activation of p44/42 MAP kinase cascade. The confined SMIT induction may reflect regional differences of damage and/or cellular differences in sensitivity to neuropathological stresses caused by this injury.
Ueda
T
T
Department of Anatomy II, Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku, 467-8601, Nagoya, Japan. tueda@med.nagoya-cu.ac.jp
Iwata
A
A
Komatsu
H
H
Aihara
N
N
Yamada
K
K
Ugawa
S
S
Shimada
S
S
D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D001930:Brain Injuries / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics*; D004195:Disease Models, Animal; D015870:Gene Expression / Q000502:physiology; D006360:Heat-Shock Proteins / Q000032:analysis / Q000235:genetics*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D027981:Symporters
D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D027981:Symporters; C073884:SLC5A3 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases