Differential activation of mitogen-activated protein kinase pathways after traumatic brain injury in the rat hippocampus.
Mitogen-activated protein kinases, which play a crucial role in signal transduction, are activated by phosphorylation in response to a variety of mitogenic signals. In the present study, the authors used Western blot analysis and immunohistochemistry to show that phosphorylated extracellular signal-regulated protein kinase (p-ERK) and c-Jun NH2-terminal kinase (p-JNK), but not p38 mitogen-activated protein kinase, significantly increased in both the neurons and astrocytes after traumatic brain injury in the rat hippocampus. Different immunoreactivities of p-ERK and p-JNK were observed in the pyramidal cell layers and dentate hilar cells immediately after traumatic brain injury. Immunoreactivity for p-JNK was uniformly induced but was only transiently induced throughout all pyramidal cell layers. However, strong immunoreactivity for p-ERK was observed in the dentate hilar cells and the damaged CA3 neurons, along with the appearance of pyknotic morphologic changes. In addition, immunoreactivity for p-ERK was seen in astrocytes surrounding dentate and CA3 pyramidal neurons 6 hours after traumatic brain injury. These findings suggest that ERK and JNK but not p38 cascades may be closely involved in signal transduction in the rat hippocampus after traumatic brain injury.
Otani
Naoki
N
Department of Neurosurgery, National Defense Medical College, Tokorozawa, Japan. grd1405@gr.ndmc.ac.jp
Nawashiro
Hiroshi
H
Fukui
Shinji
S
Nomura
Namiko
N
Yano
Akiko
A
Miyazawa
Takahito
T
Shima
Katsuji
K
D000818:Animals; D001794:Blood Pressure; D015153:Blotting, Western; D001831:Body Temperature; D001930:Brain Injuries / Q000473:pathology / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley
D002245:Carbon Dioxide; D020928:Mitogen-Activated Protein Kinases; D010100:Oxygen