靈芝子實體萃取物對三氯化鋁誘導大鼠大腦病變的作用

Abstract

在腦部的退化性疾病當中，以阿滋海默症(Alzheimer’s disease, 以下簡稱AD)最受矚目。其主要成因為大量β型類澱粉蛋白斑塊(β-amyloid plaques, 以下簡稱Aβ plaques)累積所造成的腦部病變。近來的研究顯示，長期過量攝取含鋁離子的水或食物，容易引起Aβ plaques累積於腦部邊緣系統，導致AD的發生。AD是一種漸進性腦細胞退化疾病，患者的腦部記憶功能會逐漸衰退，導致失能，進而造成癡呆。近年來AD病患體內微循環障礙的病理徵象，漸為臨床醫師所重視。過去研究顯示，靈芝子實體萃取物可以有效促進免疫功能、改善循環與增強抗氧化作用。本研究目的在探討松杉靈芝子實體萃取物，對三氯化鋁誘導腦部病變改善作用。評估對於提昇血液動力學、學習記憶能力、減少β型類澱粉蛋白斑塊及抗氧化能力之影響。 本研究設計在同時使用多種不同的檢測方法包括 : 水迷宮測量(Morris Water Maze)、磁振造影測試(MRI Test)、腦部血流量測量(ASL-rCBF Test)、磁振頻譜的腦部代謝物質測量(MRS Test)、血液血球分析、血液流變參數分析以及血清生化學參數分析、大鼠腦脊髓液定量白蛋白與Aβ濃度、血液及腦組織抗氧化能力分析、IHC免疫組織化學染色分析Aβ plaques狀態等指標，進行三氯化鋁誘發阿茲海默症大鼠各項病態檢測與餵食松杉靈芝子實體萃取物前後各項指標的變化。 研究結果顯示經三氯化鋁誘發阿茲海默症的腦病變組大鼠，在全血黏度、血漿黏度、纖維蛋白原濃度、血清HsCRP濃度、腦脊髓液中Aβ / Il6 / TNF-α濃度、紅血球中乙醯膽鹼酯酶(Acetylcholinesterase, AChE-RBC)與MDA活性、腦部皮質與海馬迴組織中MDA活性、腦部皮質與海馬迴組織中Aβ plaque數量皆顯著高於正常組大鼠；三氯化鋁誘導腦病變組中大鼠中紅血球變形度、腦部血流量及N-acetyl aspartate (NAA)濃度則顯著低於正常組大鼠。經松杉靈芝子實體熱水萃取物YL1或松杉靈芝子實體乙醇萃取物YL2 60天後，皆能明顯改善三氯化鋁誘發阿茲海默症病態大鼠的血液黏度、氧化壓、NAA濃度、乙醯膽鹼酯酶濃度、Aβ plaque累積量與腦部血流量，並於水迷宮試驗中顯示學習與記憶能力的改善。 本研究結合血液流變學與MRI動脈自旋標記(Arterial Spin Labeling, ASL)技術，呈現腦部功能障礙大鼠體內的血流動力學變化，證實松杉靈芝子實體萃取物具有改善三氯化鋁誘導大鼠大腦病變、保護腦部神經血管的作用，為預防或治療阿茲海默症提供新的契機。

Alzheimer’s disease (AD) has received the most attention among all neurodegenerative disorders because it is considered one of the costliest diseases to society in developed countries. The causes and progression of the disease are not well understood; some studies maintain that it is caused by the pathological changes to the brain due to accumulation of beta-amyloid plaques (Aβ plaques). Recent research has indicated that prolonged, excessive consumption of food or water containing aluminum results in the accumulation of Aβ plaques in the limbic system of the brain, leading to AD. As a progressive degenerative disease of the brain cells, AD causes patients’ memory and other brain functions to deteriorate gradually, leading to functional loss and eventually dementia. In recent years, clinical physicians have come to realize the importance of the pathological signs of microcirculation disturbances in patients with AD. Previous research has indicated that the extract of Ganoderma lucidum (G. tsugae) can effectively stimulate autoimmune functions, improve metabolism, and enhance anti-oxidation. The objective of this study is to explore how the herb affects hemodynamics, learning and memory functions, the reduction of Aβ plaques, and oxidation inhibition by administering extracts of G. tsugae fruiting bodies to rats exposed to aluminum tri-chloride (AlCl3). The study uses an experimental design utilizing multiple measurement and quantitation methods including the Morris water maze test, Magnetic Resonance Imaging test (MRI), Arterial Spin Label–regional Cerebral Blood Flow test (ASL-rCBF test), Magnetic Resonance Spectroscopy (MRS) test, blood cell count analysis, hemorheological parameter analysis, serum chemistry parameter analysis, cerebrospinal fluid test and Aβ plaque concentration, as well as anti-oxidation capacity test on blood plasma viscosity and fibrinogen concentration, serum HsCRP concentration, Aβ / Il6 /TNF-α concentration and tests on acetyl cholinesterase (AChE-RBC) activity and malondialdehyde concentration. Through combinative implementation of these methods study hopes to examine the changes in the indicators of various AD symptoms before and after rats, afflicted with AD due to AlCl3, were given G. tsugae fruiting bodies. In addition, the study also carries out comparative research to explore more specific phenomena using multiple modalities. Results of this study indicate that AD rats, in the positive control group, induced by AlCl3 showed higher levels of whole blood viscosity, blood plasma viscosity, fibrinogen concentration, serum HsCRP concentration, Aβ / Il6 /TNF-α concentration in the cerebrospinal fluid, acetylcholinesterase (AChE-RBC) activity and malondialdehyde (MDA) in red blood cells, and MDA and Aβ plaque in the cerebral cortex and hippocampal tissue than those in the control group. Conversely, the rats in the positive control group exhibited significantly lower erythrocyte deformability, cerebral blood flow, and N-acetylaspartate (NAA) concentrations than those in the control group. The rats in the YL1 (G. tsugae extracts by using hot water) and YL2 (G. tsugae extracts by using ethanol) groups, which were exposed to AlCl3 and then orally given the G. tsugae extract for 60 days, exhibited marked improvement in blood viscosity, oxidative stress, NAA concentrations, AChE-RBC concentrations, Aβ plaque accumulation levels, and cerebral blood flow. The results of the water maze tests also indicated improvement in learning and memory. Hemorheology and MRI arterial spin labeling technology were combined in this study to demonstrate changes in the hemodynamics of rats with AlCl3-induced brain dysfunction. It is, therefore, the conclusion of this study that treatment with G. tsugae can protect neural nerves and blood vessels as well as combat related pathological changes induced by AlCl3 in rats. The study hopes to provide a reference point for future researches on the preventive or reversal methods for Alzheimer’s disease.