視丘傳導性功能迴路之錳離子增益性磁振造影法研究

Activity-dependent manganese-enhanced magnetic resonance imaging (MEMRI) study of nociceptive connectivity of thalamus

何旭偉(Shu-Wei Ho)

指導教授 ： 嚴震東

國立臺灣大學/生命科學院/動物學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01022

摘要

在神經迴路及活性的研究上，錳離子增益性磁振造影(MEMRI)已被普遍認為是一個強而有力的工具。錳離子為一順磁性物質，可在核磁共振T1影像下產生明顯對比訊號，又錳離子可以利用電壓依賴性鈣離子通道通過並進入受到刺激而活化的神經細胞，並在細胞中利用傳輸小泡和運輸蛋白進行跨突觸性的傳導。故在神經中樞神經系統中可以經由分析錳離子的傳導量及分布區域，反映出特定神經區域的活性大小。本實驗利用電壓驅使離子流動的方式，將錳離子微量注射至右側視丘的腹後側核區側邊(VPL)、中央下核(Sm)以及中央背側視丘(MDM)。並使用鋼針刺入大鼠的左前腳掌後給予痛覺刺激，持續八小時。接著使用VOI及Voxel -wise之統計腦影像進行分析，比較有接受痛覺刺激的老鼠跟腳掌同樣刺入鋼針但未受到痛覺刺激的老鼠是否有差異。T1影像下顯示若將錳離子注射至VPL，接受痛覺刺激的組別與控制組相比，錳離子訊號在紋狀體(striatum)外側及初級感覺皮質上有明顯增加。若是將錳離子注射在MDM，則發現在中側紋狀體及腦導皮質(insular cortex)處有明顯增加的錳離子訊號。相反的將錳離子注射至Sm，則發現錳離子訊號在紋狀體中側及腹側邊眼眶面皮質(ventrolateral orbital cortex)在刺激組明顯下降。實驗結果顯示利用錳離子增益性磁振造影法可以結合神經活性之層面，在活體狀態下去檢視痛覺迴路之傳導。

關鍵字

磁振造影 ； 痛覺迴路

並列摘要

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.

並列關鍵字

MEMRI ； pain pathway

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