Ischemia-induced glutamate release in the dentate gyrus. A microdialysis study in the gerbil.
The levels of extracellular glutamate were measured in the dentate gyrus by using an in vivo brain microdialysis method to determine whether the ischemia-induced glutamate release might be correlated with the neuronal vulnerability to ischemia. A microdialysis membrane was placed in CA4 (vulnerable to ischemia) and the molecular and granule cell layers of the dentate gyrus (resistant to ischemia) of gerbils. A significant increase in glutamate levels was induced in the normal dentate gyrus during 10-min ischemia. The increase was completely suppressed during the first 5 min of ischemia when CA4 neurons were eliminated. Thus, it was indicated that during the first 5 min of ischemia glutamate was released mostly from CA4 neurons but not from granule cells of the dentate gyrus. During the second half of 10-min ischemia, a significant increase in glutamate release was induced even in the dentate gyrus where CA4 neurons were eliminated; this increase was significantly suppressed by inhibiting proliferation of astrocytes. A large part of glutamate that was released during the second half of 10-min ischemia was considered to be attributable to glutamate release from astrocytes.
Cui
Y
Y
Department of Physiology, School of Medicine, Ehime University, Onsen-gun, Japan.
Zhang
L
L
Utsunomiya
K
K
Yanase
H
H
Mitani
A
A
Kataoka
K
K
D000818:Animals; D001253:Astrocytes / Q000737:chemistry / Q000378:metabolism; D018891:Dentate Gyrus / Q000098:blood supply* / Q000166:cytology / Q000378:metabolism*; D005849:Gerbillinae; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D018698:Glutamic Acid / Q000378:metabolism*; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D009474:Neurons / Q000378:metabolism
D005904:Glial Fibrillary Acidic Protein; D018698:Glutamic Acid