H. Yokoyama et al., EPR imaging for in vivo analysis of the half-life of a nitroxide radical in the hippocampus and cerebral cortex of rats after epileptic seizures, FREE RAD B, 27(3-4), 1999, pp. 442-448
Recently, we developed an in vivo temporal electron paramagnetic resonance
(EPR) imaging technique to be applied to the brain of a rat, into which a b
lood-brain barrier (BBB)-permeable nitroxide radical, 3-methoxycarbonyl-2,2
,5,5-tetramethylpyrrolidine-1-oxyl (PCAM) was injected intraperitoneally. T
his imaging technique made it possible to measure decay rates of a nitroxid
e radical in multiple regions of the brain simultaneously. Using this techn
ique, the half-life of PCAM was estimated from the exponential decay of the
signal intensity derived from the temporal EPR images in the hippocampus a
nd cerebral cortex of rats after a kainic acid (KA)-induced seizure. The hi
ppocampal half-life of PCAM after KA-induced seizures was significantly pro
longed (p < .01), whereas the prolongation of the cortical half-life was no
t significant. These findings suggest that following a KA-seizure, the intr
ahippocampal ability to reduce the nitroxide radical is impaired, but the a
bility is intact in the cerebral cortex, This is the first in vivo quantita
tive EPR imaging study that has a bearing on the pathogenesis of KA-induced
seizures in the brain. (C) 1999 Elsevier Science Inc.