評估薑黃素對第十七型脊髓小腦萎縮症小鼠及組織切片培養之作用

Abstract

脊髓小腦萎縮症第十七型（SCA17）是一種由於多麩胺醯胺擴增片段出現在TATA 結合蛋白（TBP）上所造成的神經退化性疾病。多麩胺醯胺擴增片段造成的錯誤折疊累積在細胞核內對神經功能造成傷害，進而導致小腦萎縮、浦金氏細胞(Purkinje cells)丟失以致引起嚴重的臨床症狀如運動失調、痴呆症及癲癇等。薑黃素（diferuloylmethane）是一種已被證實能夠清除氧化壓力與降低發炎反應的傳統藥物，過去的研究中也證明薑黃素具有治療神經退化性疾病的潛力，因此我們在本研究中以餵食SCA17轉殖小鼠含有薑黃素的飼料來研究薑黃素對SCA17是否具有治療潛力。我們的結果顯示薑黃素能夠改善SCA17小鼠的神經行為缺陷，例如平衡能力以及肢體協調能力。病理檢驗也顯示薑黃素能夠改善SCA17小鼠小腦重量減輕情形、浦金氏細胞縮小並且有降低細胞凋亡的趨勢。此外，SCA17小鼠小腦的發炎反應及神經膠質增生現象也在餵食薑黃素後降低。為了更快速的檢測可能的SCA17治療藥物，我們使用七天大的小鼠建立了小腦組織切片培養的系統，在培養的小腦組織切片染色中我們可以觀察到突變的TBP堆積並在浦金式細胞周圍觀察到泛素（Ubiquitin）聚集。經由薑黃素處理五天後，觀察到浦金氏細胞存活率的提昇以及泛素聚集量降低的現象，顯示薑黃素處理對SCA17小鼠具有神經保護能力的治療潛力。Spinocerebellar ataxia type 17 (SCA17) is a neurodegenerative disease attributed to polyglutamine (polyQ) expansions within the human TATA-box binding protein (TBP). The misfolding of polyQ tract forms nuclear aggregates in SCA17 patients impact the neuron function, leading to cerebellar atrophy, Purkinje cell loss and severe clinical phenotype includes ataxia, dystonia, parkinsonism, dementia and seizures. Curcumin (diferuloylmethane) is well known for its ability to scavenge free radicals and inhibit inflammation. Several studies have suggested the potential of curcumin in treatment of neurodegenerative diseases. To investigate the therapeutic potential of curcumin for polyQ-mediated SCA17, we treated SCA17 transgenic mice with curcumin diet. Our data showed that curcumin could ameliorate the neurologic behavioral deficiency, balance function and motor coordination of SCA17 transgenic mice. Results of pathology examination indicated that curcumin diet could rescue cerebellar atrophy, reverse Purkinje cell shrinkage and trend to reduce apoptosis in mice. Moreover, the inflammatory level and gliosis were also reduced in curcumin treated SCA17 transgenic mice. To have a quick platform for evaluating potential compounds for SCA17, we also established an organotypic cerebellar slice culture system using postnatal day 7 mouse tissues. During the ex vivo culture, we observed the aggregation of mutant TBP in SCA17 transgenic cerebellar slice and increased ubiquitin signal around Purkinje cells. We found that Purkinje cell survival increased and the ubiquitin signal decreased in the slice culture after cucumin treatment for 5 days. These results reveal that curcumin might have potential in neuron protection.