錳離子增益性磁振造影法之大鼠長期觀測研究方法探討

順磁性的錳離子其通透鈣離子通道之特性，使其可進入活化的神經細胞並順向經由運輸蛋白與突觸小泡傳輸到後突觸細胞。透過量測不同腦區的T1 影像強度可得知各腦區的不同活化程度。這些特徵使得錳離子成為在神經迴路造影研究上一有利的工具。本研究在建立一個慢性埋管給予錳離子的方法來探測神經網路的可塑性變化。首先測試錳離子注射之穩定性及急性神經毒性，實驗顯示等濃度錳離子注射之容積與影像體素大小呈一線性相關。比較初級感覺皮質前掌區(S1FL)之誘發電位振幅在局部注射同側視丘腹後核側邊(VPL) 40 mM 0.5 μl之錳離子後無顯著差異。其次使用長期埋管的動物在單次錳離子注射後觀察錳離子在腦內的清除狀況，實驗顯示腦內錳離子清除半衰期約為26.57小時。最後使用長期埋管在VPL測試40 mM, 0.5 μl之低劑量錳離子是否可鑑別傷害性疼痛刺激，實驗顯示此劑量可成功分辨由福馬林前掌注射之周邊感覺刺激或是食鹽水前掌注射組。以上實驗顯示0.5 μl, 40 mM錳離子以8天以上的間隔可以在慢性埋管中重複施打於腦中來探測神經網路的長期變化。

關鍵字

錳離子增益性磁振造影；視丘下侧腹核；感覺皮質前肢區；長程觀察研究；疼痛

並列摘要

The paramagnetic Mn2+ enters voltage-gated calcium channels and transported anterogradly in active neurons. Using these advantages, neuronal activity in different brain regions can be estimated in manganese-enhanced magnetic resonance imaging (MEMRI). The present study tested the injection constancy, toxicity, clearance rate and detectability of intracranial manganese ion to establish a longitudinal MEMRI protocol. In acute experiment, first we found with constant concentration solution, injected volumes linearly correlated to the voxel numbers in the T1 images. Next we estimated the acute Mn2+ toxicity by recording evoked field potentials in the primary somatosensory cortex (SI) and injecting 40 mM, 0.5 μl Mn2+ solutions in the ventroposterior thalamic nucleus (VPL). The amplitudes showed no significantly differences after Mn2+ administration. In chronic implanted animals, images acquired in different time intervals after a single 0.5 μl, 40 mM Mn2+ injection showed a clearance rate in a half-life of 26.57 hours. For a functional test, we used forepaw formalin pain model. At the dosage of 40 mM and 0.5 μl, using a counter-balanced repetitive Mn2+ injection design, we found transported Mn2+ signal in the SI could be clearly differentiated from saline control. These result indicated 40 mM 0.5μl Mn2+ can be used for longitudinal MEMRI method to test long-term change in neural circuit plasticity.

並列關鍵字

MEMRI ； ventroposterior thalamic nucleus ； forelimb of somatosensory cortex ； longitudinal study ； pain

參考文獻

Aoki I, Wu YJ, Silva AC, Lynch RM, Koretsky AP (2004) In vivo detection of neuroarchitecture in the rodent brain using manganese-enhanced MRI. NeuroImage 22:1046-1059.

Baliki MN, Geha PY, Apkarian AV, Chialvo DR (2008) Beyond feeling: chronic pain hurts the brain, disrupting the default-mode network dynamics. The Journal of neuroscience : the official journal of the Society for Neuroscience 28:1398-1403.

Canals S, Beyerlein M, Keller AL, Murayama Y, Logothetis NK (2008) Magnetic resonance imaging of cortical connectivity in vivo. NeuroImage 40:458-472.

Cao YQ (2006) Voltage-gated calcium channels and pain. Pain 126:5-9.

Chuang KH, Belluscio L, Koretsky AP (2010) In vivo detection of individual glomeruli in the rodent olfactory bulb using manganese enhanced MRI. NeuroImage 49:1350-1356.

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錳離子增益性磁振造影法之大鼠長期觀測研究方法探討

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