ABSTRACT
Multiple sclerosis (MS) is an intractable disease of the central nervous system that results from destruction of the myelin sheath. Direct measurement of de- and remyelination is required for monitoring the disease stage of MS, but no useful method has been established. In this study, we characterized four diaryl oxadiazole derivatives as novel myelin-imaging probes for single photon emission computed tomography (SPECT). All the diaryl oxadiazole derivatives penetrated the blood-brain barrier in normal mice. Among them, the highest ratio of radioactivity accumulation in the white matter (myelin-rich region) against the gray matter (myelin-deficient region) was observed at 60 min postinjection of [125I]1,3,4-PODP-DM in ex vivo autoradiography using normal mice. In the blocking study with ex vivo autoradiography, the radioactivity accumulation of [125I]1,3,4-PODP-DM in the white matter markedly reduced. [125I]1,3,4-PODP-DM detected demyelination in the ex vivo autoradiographic images of not only the spinal cord of the experimental autoimmune encephalomyelitis mice but also the brain after lysophosphatidylcholine (LPC) injection. In addition, [123I]1,3,4-PODP-DM could image LPC-induced demyelination in the mouse brain with SPECT. These results suggest that [123I]1,3,4-PODP-DM may be a potential SPECT probe for imaging myelin in MS.
