中文摘要 厚朴，採用厚朴植物之樹皮，是ㄧ種已知可應用於治療精神疾病的傳統天然藥物，例如：憂鬱症等。厚朴主要的有效多酚環成分已被證實具有抗氧化、抗發炎及抗興奮性毒殺等神經保護作用，因此，推測厚朴可作為一種潛在治療像是帕金森氏症這累神經退化性疾病之藥物。本研究之目的為探討厚朴是否可以預防與治療因百草枯及MPTP所誘導的毒害及學習、記憶和運動功能缺失等行為異常現象。本研究監測Oregon-R品系之果蠅(年齡：1-2, 20天或30天)之壽命在長期暴露於百草枯(5-20 mM)並先給予厚朴(100, 300或600 mg/L)治療之變化。其結果顯示，厚朴無法延長暴露在百草枯環境下之果蠅壽命。另外，我們給予雄性ICR小鼠(30-35 g)，連續五天，每日一劑MPTP(25 mg/kg, i.p.)，誘導神經毒性及行為異常現象。在共同投藥組別，在給予MPTP注射前一小時，先以灌餵方式給予小鼠厚朴(100或300 mg/kg)預防，連續五天後，只單獨給予厚朴治療連續十四天。後投藥組別，在給予最後一劑MPTP後，連續十四天給予厚朴(100或300 mg/kg).治療。在控制組別中，給予生理食鹽水(0.9%, i.p.)及灌餵玉米油。結果顯示，MPTP與厚朴並不影響小鼠之運動協調功能，然而，可利用新位置辨識能力測試及新物體辨識認知行為測試，檢測因MPTP所引起之認知功能障礙現象，由我們結果中顯示，不論是與MPTP共同給予厚朴治療抑或是後處理厚朴皆可恢復因MPTP所造成的認知功能障礙現象，此外，厚朴也可恢復因MPTP所造成多巴胺神經元及多巴胺轉運子受損之情形，另外，我們也初步發現，厚朴可在海馬迴中使Nrf2表現量提升。因此，初步結果表明，厚朴將可成為未來治療帕金森氏症之天然藥物。 / Cortex Magnoliae, the bark of Magnolia officinalis, has been prescribed in the traditional herbal medicine to treat a variety of mental disorders including depression. The main constituents of cortex Magnoliae contain the biphenyl compounds such as honokiol and magnolol. Both biphenyl compounds were shown to have the neuronal protective effect which is related to the anti-oxidation, anti-inflammation, and anti-excitatory toxicity. Thus, it was proposed that cortex Magnoliae may act as the potential therapeutic agent for the treatment of neurodegenerative disorders such as Parkinson’s disease (PD). The aim of the present study was to examine whether cortex Magnoliae exhibits the neuroprotective and therapeutic action against the neuronal toxicity and behavioral deficits in learning, memory, and motor function induced by neurotoxin paraquat and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in PD-like models. The lifespan of flies from Oregon-R strain of Drosophila melanogaster (age: 1-2, 20 or 30 days) chronically exposed to paraquat (5-20 mM) with pre-treatment of Cortex Magnoliae (100, 300 or 600 mg/L) were measured. Results showed that pre-treatment of Cortex Magnoliae could not extend the lifespan of the flies reduced by paraquat. On the other hand, male ICR mice (30-35g) were administered with MPTP (25 mg/kg, i.p.) once daily for 5 consecutive days to induce neurotoxicity and behavioral impairment. In co-treatment group, male mice were orally administrated with cortex Magnoliae (100 or 300 mg/kg) 1 hour before MPTP injection for 5 days and then followed by oral administration of cortex Magnoliae alone for consecutive 14 days. Mice in post-treatment group were orally administered with cortex Magnoliae (100 or 300 mg/kg) for consecutive 14 days after the final injection of MPTP. Mice in control group were injected with saline (0.9%, i.p.) and orally administrated with vehicle (corn oil). Our results showed that MPTP and cortex Magnoliae did not affect mouse coordination and balance in beam walking test. However, cortex Magnoliae improved the cognitive impairments determined by novel-location recognition task (NLRT) and novel-object recognition task (NORT) in MPTP-induced PD mouse. Additionally, cortex Magnoliae restored MPTP-induced loss of dopaminergic neurons and recovered MPTP-induced loss of dopamine transporters in striatum. Cortex Magnoliae also activated Nrf2 in hippocampus. Therefore, the preliminary results suggest that cortex Magnoliae may be a novel candidate for the treatment of Parkinson's disease in the future. The pharmacological mechanism of cortex Magnoliae in PD treatment needs further study.

漢厚朴酚是從木蘭科植物中萃取之天然化合物，已知具有抗氧化、抗發炎及神經保護之生理活性功能。先前的研究證明漢厚朴酚可以保護多巴胺神經元對抗6-OHDA所引起的細胞傷害，並且可以減緩6-OHDA 動物模式由apomorphine所誘發的旋轉行為，但漢厚朴酚對於神經保護之分子機制的相關研究尚未釐清。蛋白激酶CK2是具有多功能的絲氨酸/蘇氨酸激酶，高度表現在大腦紋狀體中，先前的研究證實蛋白激酶CK2參與調節神經系統功能和具有神經保護之作用。先前研究也指出轉錄因子Nrf1（Nuclear factor E2-related factor 1）是蛋白激酶CK2下游磷酸化受質，會調控小鼠胚胎纖維細胞中蛋白酶體基因的表現。抗細胞凋亡蛋白Mcl-1 (myeloid cell leukemia 1) 屬於Bcl-2蛋白家族的成員之一，在細胞凋亡的過程中，其蛋白含量減少與細胞凋亡有密切關聯性，抑制Mcl-1蛋白的降解可以延遲細胞死亡。因此本論文主要探討漢厚朴酚的神經細胞保護機制是否透過CK2-Nrf1細胞訊息路徑調控蛋白酶體活性，進而減少Mcl-1的降解速率。實驗結果顯示，轉染CK2α-EGFP DNA質體會增加Nrf1磷酸化並抑制蛋白酶體活性，泛素化之Mcl-1蛋白含量亦伴隨增加；轉染CK2α siRNA則會降低Nrf1磷酸化並促進蛋白酶體活性，導致naive Mcl-1蛋白質含量減少24小時的漢厚朴酚後處理（post-treatment）可以部份恢復因轉染CK2α siRNA所造成之CK2蛋白、Phosphoserine蛋白和Mcl-1蛋白質含量減少，在設計縮短間隔5小時漢厚朴酚後處理（post-treatment）的實驗結果雖然仍無法有效恢復CK2蛋白含量，但對於Phosphoserine和Mcl-1蛋白含量以及蛋白酶體活性則具有部份恢復的功效。利用過氧化氫造成細胞氧化壓力環境下，實驗發現間隔3小時的漢厚朴酚後處理才能有效恢復細胞存活率，間隔5小時的漢厚朴酚後處理則無法恢復細胞存活率。在大白鼠紋狀體腦區給予漢厚朴酚微量注射則對pTH、TH和GAD蛋白質含量皆有促進增加的作用，乙醯化的Histone H3蛋白含量也有顯著增加。綜合以上結果，推測漢厚朴酚對細胞保護作用的其中一個機制是參與調控CK2-Nrf1路徑而抑制蛋白酶體活性，減少Mcl-1蛋白質降解速率和提升氧化壓力下之細胞存活能力；此外，從活體動物的實驗結果顯示漢厚朴酚亦可能參與調控多巴胺和γ-氨基丁酸神經細胞功能的機制之中。 / Honokiol is a natural compound, extracted from the Magnolia officinalis, and is known as its anti-oxidative, anti-inflammatory and neuroprotective effects. The previous study has been demonstrated that the honokiol can protect striatal dopamine neuron against 6-OHDA induced damage and reverse the apomorphine-induced rotational behavior in Parkinson’s disease model of rats. However, the cellular mechanisms for its neuroprotective effects are not fully investigated. Protein kinase Casine kinase 2 (CK2) is a serine/threonine kinase has a highly abundant expression in the striatum compared with other brain areas. Further, CK2 is shown to regulate many neuronal functions including neuroprotection. The nuclear factor E2-related factor 1 (Nrf1) has been identified as one of the substrate proteins for CK2 and is indicated to involve in the induction of proteasome subunits gene expressions in mouse embryonic fibroblasts. The anti-apoptotic protein myeloid cell leukemia 1 (Mcl-1) is shown to play a critical initiation role during the apoptosis process due to its synthesis blockage and proteasome degradation. The present study is aimed to investigate whether one of protective effects of honokiol is through CK2-mediated Nrf1 signaling pathway to regulate the proteasome activity in the mouse N2a neuroblastoma cell line. In the current results, transfection of the CK2α-EGFP plasmid DNA increased Nrf1 phosphorylation accompanied with the decrease in the proteasome activity but increased the ubiquitinated Mcl-1 protein. Whereas, transfection of CK2α siRNA decreased Nrf1 phosphorylation leading to the increase in proteasome activity and Mcl-1 protein degradation. The 24 hr duration of honokiol post-treatment only slightly reversed the knock-down effect of CK2α siRNA on CK2α and Mcl-1 protein levels. However, 5 hr duration of honokiol post-treatment could partially reverse the Mcl-1 protein level and proteasome activity but no effect on CK2α protein levels. In the H2O2-induced oxidative stress condition, only 3 hr duration of honokiol post-treatment could protect cells against H2O2-induced cell death. In the experiments of in vivo rat animal model, local administration of honokiol was found to increase phospho-TH, naive TH, GAD as well as acetylated Histone H3 protein levels. These above results suggest one of the protective mechanisms of honokiol might be through CK2-mediated Nrf1 signaling to inhibit the proteasome activity. and to promote cell survival under oxidative stress. Beside these functions, honokiol might also involve in the regulation of nurophysiological functions of dopamine and GABA neurons.