| Summary: | 碩士 === 國立臺灣大學 === 動物學研究所 === 99 === Manganese enhanced MRI (MEMRI) is a powerful imaging tools for in-vivo animals studies. Manganese (Mn2+) ion enters neural cells via voltage-gated calcium channels, transports along axons and across synapses activity-dependently. In the present study, we used MEMRI to investigate nociceptive projection of the thalamus, especially the submedius(Sm), lateral ventroposterior nucleus (VPL) and medial division of the mediodorsal (MDM) nuclei of the rat. Rats were anesthetized by urethane and microinjected with manganese chloride into the right part of the thalamus. Noxious (at a 5-mA intensity for 2 ms) electrical stimuli were applied through a pair of needles inserted in the left forepaw once every 6 s for 8 h. VOI and voxel-wise statistical comparison were made against sham control group in which manganese ions were injected in the same thalamic target, needle were injected in the same forepaw but not stimulated. Enhanced transport of Mn2+ were found in lateral striatum and primary somatosensory cortex (forelimb part) when injected VPL was injected. Microinject MnCl2 into the MDM showed significant increase at medial striatum and insular cortex. In contrast, noxious electrical stimuli group shows decreased Mn2+ transportation, including medial part of striatum and ventral lateral orbital cortex, compared with the control group when Sm was injected. The results indicate that MEMRI with activity-induced contrast is useful for demonstrating functional connections in the pain pathway.
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