Real time monitoring of glutamate following fluid percussion brain injury with hypoxia in the rat.
In this study, extracellular glutamate (Glu) was monitored in real time using a biosensor following traumatic brain injury (TBI) either with or without inducing hypoxia in the rat Fluid-percussion model. We also measured the cortical contusion volume at 3 days after the insult. The animals were divided into 3 groups. Group 1 was subjected to TBI only, Group 2 to TBI followed by 20 min of moderate hypoxia (FiO2: 10%) and Group 3 to 20 min of moderate hypoxia without TBI. The surge increase in the extracellular Glu concentration occurred immediately after TBI in Groups 1 and 2. Group 2 showed a prolonged efflux of Glu during hypoxia. Group 3 Glu showed low continuous steady levels. The contusion volume in Group 2 was significantly larger than in Group 1. To test the possible involvement of apoptosis in Groups 1 and 2, rats were sacrificed at 1, 6, 24 and 72 h after TBI. Immunohistochemical studies showed an increased number of both CPP32 positive cells at 24 h and TUNEL cells at 72 h in Group 2. These results suggest that TBI with moderate hypoxia induced a prolonged efflux of Glu that resulted more cortical damage due to necrosis and apoptosis.
Matsushita
Y
Y
Department of Neurosurgery, National Defense Medical College, Tokorozawa, Saitama, Japan.
Shima
K
K
Nawashiro
H
H
Wada
K
K
Tsuzuki
N
N
Miyazawa
T
T
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015374:Biosensing Techniques; D001924:Brain Concussion / Q000473:pathology / Q000503:physiopathology*; D001929:Brain Edema / Q000473:pathology / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D018698:Glutamic Acid / Q000378:metabolism*; D002534:Hypoxia, Brain / Q000473:pathology / Q000503:physiopathology*; D020287:In Situ Nick-End Labeling; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted
D018698:Glutamic Acid