Assessment of ESR-CT imaging by comparison with autoradiography for the distribution of a blood-brain-barrier permeable spin probe, MC-PROXYL, to rodent brain.
Blood-brain-barrier (BBB)-permeable, 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-yloxy (MC-PROXYL) and BBB-impermeable carbamoyl-PROXYL were used to assess the ESR imaging technique by comparing with autoradiography. For this purpose, spin probes, 14C-labeled at their five-membered ring, [14C]MC-PROXYL and [14C]carbamoyl-PROXYL, were newly synthesized. These probes were i.p. or i.v. injected into rats and autoradiograms were recorded. The autoradiograms of rat head showed that [14C]MC-PROXYL distributed well in the brain compared to [14C]carbamoyl-PROXYL. In vivo ESR spectra and two-dimensional ESR images of isolated rat brain treated with MC- or carbamoyl-PROXYL also indicated the extensive distribution of MC-PROXYL but not carbamoyl-PROXYL in the rat brain. The three-dimensional ESR images of the head of rats and mice were consistent with the fact that MC-PROXYL but not carbamoyl-PROXYL is incorporated into the brain. The ESR-CT images were better for mice than rats. However, the quality of the ESR-CT images was still not satisfactory. Although the resolution and sensitivity of the ESR-CT images were worse than those of the autoradiographic images, the former technique has unique features and advantages; e.g., functional, noninvasive and three-dimensional detection.
Anzai
Kazunori
K
National Institute of Radiological Sciences, Anagawa, Chiba 263-8555, Japan. anzai@nirs.go.jp
Saito
Keita
K
Takeshita
Keizo
K
Takahashi
Sentaro
S
Miyazaki
Hiroyuki
H
Shoji
Hirofumi
H
Lee
Masaichi Chang-il
MC
Masumizu
Toshiki
T
Ozawa
Toshihiko
T
D000818:Animals; D001345:Autoradiography; D001812:Blood-Brain Barrier; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism; D003497:Cyclic N-Oxides; D003952:Diagnostic Imaging / Q000379:methods; D004578:Electron Spin Resonance Spectroscopy; D008297:Male; D051379:Mice; D018384:Oxidative Stress; D011759:Pyrrolidines; D051381:Rats; D017208:Rats, Wistar; D013113:Spin Labels
D003497:Cyclic N-Oxides; C109806:MCPROXYL; D011759:Pyrrolidines; D013113:Spin Labels