阿茲海默氏症(Alzheimer’s disease, AD)是目前最常見的神經退化性疾病之一，至今尚無顯著有效的治療方法。這種全球性的健康問題不論是對於個人或社會都有極大的影響。AD在病理學上主要有兩個病徵：類澱粉蛋白(β-amyloid peptides, Aβ)堆積成的斑塊(plaques)以及Tau蛋白過度磷酸化所導致的神經纖維糾結(neuro-fibrillary tangles, NFTs)。許多研究證實，在失智症病患腦中之腦源性神經滋養因子(Brain-derived neurotrophic factor, BDNF)濃度較低，且此現象可令更多的Aβ生成。BDNF及其受體原肌球蛋白相關激酶B(tropo-myosin-related kinase B, TrkB)，可調節長期增益效應(LTP)、長期抑制效應(long-term depre-ssion, LTD)、軸突出芽、樹突增生、突觸可塑性和神經元分化。7,8-二羥基黃酮(7,8-dihydroxyflavon, 7,8-DHF)是目前已知的TrkB促效劑，可與細胞膜上的TrkB受體結合並引發同源二聚化，啟動下游之訊息傳導。本研究是使用結構與7,8-DHF類似之12種新型的TrkB促效劑，經過MTT實驗評估發現12種促效劑對神經細胞都無明顯細胞毒性及神經突生長之影響。接著於小鼠海馬迴細胞初級培養給予Aβ25-35誘導神經損傷作為AD模式篩選平台，結果顯示LMDS-1能有效緩解因Aβ25-35寡聚體所導致的神經突長度及分支數目降低之現象，因此選擇LMDS-1進入動物實驗測試，並以7,8-DHF為正控制組。先利用立體定位注射Aβ25-35至小鼠海馬迴CA1區域以建立AD模式動物，再給予7,8-DHF或LMDS-1之處理，並於期間進行一系列行為實驗，結果顯示LMDS-1可有效改善因Aβ25-35誘導所導致的短期及長期記憶受損。在病理分析上，我們利用免疫組織化學染色和西方墨點法分析小鼠海馬迴組織，結果顯示LMDS-1可有效改善因Aβ25-35誘導所導致的Aβ堆積、成熟神經細胞缺失、pERK及synaptophysin表現量降低。由病理分析結果推論，LMDS-1可能是經由pY516TrkB活化Ras/MAPK路徑來激活CREB轉錄因子，進而上調mBDNF之表現量，改善因Aβ25-35所導致的記憶缺失。綜合上述結果，LMDS-1是具有治療AD潛力的新型TrkB促效劑，能夠改善動物記憶功能，並緩解AD代表性之病理特徵，希望能為日後AD研究提供一些新的方向與目標。

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases that without significant therapeutics currently. This global health problem has a huge impact on individuals and social interactions. The biological disorders of AD includes memory impairment and cognitive dysfunctions. The two main pathological features often identified are extracellular Aβ deposition and hyperphosphorylation of tau protein. Many studies have shown that abnormalities of neurotrophin, brain-derived neurotrophic factor (BDNF), occur in patients with dementia which promote synthesis of A peptides. BDNF and its receptor, tropomyosin-related kinase B (TrkB), regulate long-term depression (LTD) and long-term potentiation (LTP), axonal sprouting, proliferation of dendritic arbor, synaptic plasticity, and neuronal differentiation. It is shown 7,8-dihydroxyflavon (7,8-DHF) can bind to TrkB receptor on the cell membrane and initiate homodimerization, leading to the pathway activation. In this study, 12 novel TrkB agonists candidates similar in structure of 7,8-DHF were used. After evaluation by MTT assay, 12 compounds were found to have no obvious impact in cytotoxicity and neurite outgrowth on SH-SY5Y cells. We further used Aβ25-35 to induce neuronal damage in the mouse hippocampal primary culture and which was used as an AD model to screen the 12 compounds. The results showed that LMDS-1 can effectively alleviate the decrease in neurite length and number of branches caused by Aβ25-35 oligomers. LMDS-1 was further applied to animal experiments and uses 7,8-DHF as a positive control. AD model was generated by stereotactic injection of Aβ25-35 into the hippocampal CA1 region of mice, and then treated with 7,8-DHF and LMDS-1. A series of behavioral experiments were performed and the results showed that LMDS-1 could effectively improve the impairment in short-term and long-term memory caused by Aβ25-35 induction. In pathological analysis, we used immunohistochemical staining and western blotting showed that LMDS-1 can effectively alleviate the symptom of AD, including the accumulation of Aβ and the loss of mature nerve cells. The levels of pERK and synaptophysin were also attenuated by the treatment of LMDS-1.
Inferred from the pathological analysis results, LMDS-1 may activate the Ras/MAPK pathway via pY516TrkB to activate the CREB transcription factor, thereby upregulating the expression of mBDNF.
　　Based on the above results, LMDS-1 is a novel TrkB agonist with the potential to treat AD. It can improve the memory function of animals and alleviate the pathological features of AD. It hopes to provide some new directions and goals for future AD research.

Arancibia S, Silhol M, Moulière F, Meffre J, Höllinger I, Maurice T, Tapia-Arancibia L (2008) Protective effect of BDNF against beta-amyloid induced neurotoxicity in vitro and in vivo in rats. Neurobiology of Disease 31:316-326.
Blurton-Jones M, Kitazawa M, Martinez-Coria H, Castello NA, Müller F-J, Loring JF, Yamasaki TR, Poon WW, Green KN, LaFerla FM (2009) Neural stem cells improve cognition via BDNF in a transgenic model of Alzheimer disease. Proc Natl Acad Sci U S A 106:13594-13599.
Brothers HM, Gosztyla ML, Robinson SR (2018) The Physiological Roles of Amyloid-β Peptide Hint at New Ways to Treat Alzheimer's Disease. Frontiers in Aging Neuroscience 10.
Calissano P, Matrone C, Amadoro G (2010) Nerve growth factor as a paradigm of neurotrophins related to Alzheimer's disease. Developmental Neurobiology 70:372-383.
Castello NA, Nguyen MH, Tran JD, Cheng D, Green KN, LaFerla FM (2014) 7,8-Dihydroxyflavone, a small molecule TrkB agonist, improves spatial memory and increases thin spine density in a mouse model of Alzheimer disease-like neuronal loss. PLoS One 9:e91453-e91453.
Chung JA, Cummings JL (2000) NEUROBEHAVIORAL AND NEUROPSYCHIATRIC SYMPTOMS IN ALZHEIMER'S DISEASE: Characteristics and Treatment. Neurologic Clinics 18:829-846.
Colombo E, Farina C (2016) Astrocytes: Key Regulators of Neuroinflammation. Trends in Immunology 37:608-620.
Criscuolo C, Fabiani C, Bonadonna C, Origlia N, Domenici L (2015) BDNF prevents amyloid-dependent impairment of LTP in the entorhinal cortex by attenuating p38 MAPK phosphorylation. Neurobiology of Aging 36:1303-1309.
Dalle-Donne I, Rossi R, Colombo R, Giustarini D, Milzani A (2006) Biomarkers of Oxidative Damage in Human Disease. Clinical Chemistry 52:601.
DaRocha-Souto B, Coma M, Pérez-Nievas BG, Scotton TC, Siao M, Sánchez-Ferrer P, Hashimoto T, Fan Z, Hudry E, Barroeta I, Serenó L, Rodríguez M, Sánchez MB, Hyman BT, Gómez-Isla T (2012) Activation of glycogen synthase kinase-3 beta mediates β-amyloid induced neuritic damage in Alzheimer's disease. Neurobiology of disease 45:425-437.
Du J, Feng L, Yang F, Lu B (2000) Activity- and Ca(2+)-dependent modulation of surface expression of brain-derived neurotrophic factor receptors in hippocampal neurons. J Cell Biol 150:1423-1434.
Egan MF, Kojima M, Callicott JH, Goldberg TE, Kolachana BS, Bertolino A, Zaitsev E, Gold B, Goldman D, Dean M, Lu B, Weinberger DR (2003) The BDNF val66met Polymorphism Affects Activity-Dependent Secretion of BDNF and Human Memory and Hippocampal Function. Cell 112:257-269.
Elliott E, Atlas R, Lange A, Ginzburg I (2005) Brain-derived neurotrophic factor induces a rapid dephosphorylation of tau protein through a PI-3Kinase signalling mechanism. European Journal of Neuroscience 22:1081-1089.
Ferreira ST, Klein WL (2011) The Aβ oligomer hypothesis for synapse failure and memory loss in Alzheimer's disease. Neurobiol Learn Mem 96:529-543.
Gao L, Tian M, Zhao H-Y, Xu Q-Q, Huang Y-M, Si Q-C, Tian Q, Wu Q-M, Hu X-M, Sun L-B, McClintock SM, Zeng Y (2016) TrkB activation by 7, 8-dihydroxyflavone increases synapse AMPA subunits and ameliorates spatial memory deficits in a mouse model of Alzheimer's disease. Journal of Neurochemistry 136:620-636.
Ginsberg SD, Alldred MJ, Counts SE, Cataldo AM, Neve RL, Jiang Y, Wuu J, Chao MV, Mufson EJ, Nixon RA, Che S (2010) Microarray analysis of hippocampal CA1 neurons implicates early endosomal dysfunction during Alzheimer's disease progression. Biol Psychiatry 68:885-893.
Hardy J, Allsop D (1991) Amyloid deposition as the central event in the aetiology of Alzheimer's disease. Trends in Pharmacological Sciences 12:383-388.
Hardy JA, Higgins GA (1992) Alzheimer's disease: the amyloid cascade hypothesis. Science 256:184.
Holback S, Adlerz L, Iverfeldt K (2005) Increased processing of APLP2 and APP with concomitant formation of APP intracellular domains in BDNF and retinoic acid-differentiated human neuroblastoma cells. Journal of Neurochemistry 95:1059-1068.
Honea R, Verchinski BA, Pezawas L, Kolachana BS, Callicott JH, Mattay VS, Weinberger DR, Meyer-Lindenberg A (2009) Impact of interacting functional variants in COMT on regional gray matter volume in human brain. Neuroimage 45:44-51.
Hu Y, Russek SJ (2008) BDNF and the diseased nervous system: a delicate balance between adaptive and pathological processes of gene regulation. Journal of Neurochemistry 105:1-17.
Iqbal K, Liu F, Gong C-X, Alonso ADC, Grundke-Iqbal I (2009) Mechanisms of tau-induced neurodegeneration. Acta Neuropathol 118:53-69.
Jang S-W, Liu X, Yepes M, Shepherd KR, Miller GW, Liu Y, Wilson WD, Xiao G, Blanchi B, Sun YE, Ye K (2010a) A selective TrkB agonist with potent neurotrophic activities by 7,8-dihydroxyflavone. Proc Natl Acad Sci U S A 107:2687-2692.
Jang S-W, Liu X, Chan CB, France SA, Sayeed I, Tang W, Lin X, Xiao G, Andero R, Chang Q, Ressler KJ, Ye K (2010b) Deoxygedunin, a Natural Product with Potent Neurotrophic Activity in Mice. PLoS One 5:e11528.
Jiang J-M, Zhou C-F, Gao S-L, Tian Y, Wang C-Y, Wang L, Gu H-F, Tang X-Q (2015) BDNF-TrkB pathway mediates neuroprotection of hydrogen sulfide against formaldehyde-induced toxicity to PC12 cells. PLoS One 10:e0119478-e0119478.
Jiao SS, Shen LL, Zhu C, Bu XL, Liu YH, Liu CH, Yao XQ, Zhang LL, Zhou HD, Walker DG, Tan J, Götz J, Zhou XF, Wang YJ (2016) Brain-derived neurotrophic factor protects against tau-related neurodegeneration of Alzheimer's disease. Transl Psychiatry 6:e907-e907.
Kim EK, Choi E-J (2010) Pathological roles of MAPK signaling pathways in human diseases. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease 1802:396-405.
Kitiyanant N, Kitiyanant Y, N Svendsen C, Thangnipon W (2011) BDNF-, IGF-1-and GDNF-Secreting Human Neural Progenitor Cells Rescue Amyloid beta-Induced Toxicity in Cultured Rat Septal Neurons. Neurochemical research 37:143-152.
Koponen E, Võikar V, Riekki R, Saarelainen T, Rauramaa T, Rauvala H, Taira T, Castrén E (2004) Transgenic mice overexpressing the full-length neurotrophin receptor trkB exhibit increased activation of the trkB–PLCγ pathway, reduced anxiety, and facilitated learning. Molecular and Cellular Neuroscience 26:166-181.
Lee JG, Shin BS, You YS, Kim JE, Yoon SW, Jeon DW, Baek JH, Park SW, Kim YH (2009) Decreased serum brain-derived neurotrophic factor levels in elderly korean with dementia. Psychiatry Investig 6:299-305.
Lessmann V, Gottmann K, Malcangio M (2003) Neurotrophin secretion: current facts and future prospects. Progress in Neurobiology 69:341-374.
Lin Y-Y, Huang C-S (2015) Aging in Taiwan: Building a Society for Active Aging and Aging in Place. The Gerontologist 56:176-183.
Masters CL, Selkoe DJ (2012) Biochemistry of amyloid β-protein and amyloid deposits in Alzheimer disease. Cold Spring Harb Perspect Med 2:a006262-a006262.
Minichiello L (2009) TrkB signalling pathways in LTP and learning. Nature Reviews Neuroscience 10:850.
Murer MG, Yan Q, Raisman-Vozari R (2001) Brain-derived neurotrophic factor in the control human brain, and in Alzheimer's disease and Parkinson's disease. Prog Neurobiol 63:71-124.
Murer MG, Boissiere F, Yan Q, Hunot S, Villares J, Faucheux B, Agid Y, Hirsch E, Raisman-Vozari R (1999) An immunohistochemical study of the distribution of brain-derived neurotrophic factor in the adult human brain, with particular reference to Alzheimer's disease. Neuroscience 88:1015-1032.
Nagahara AH, Merrill DA, Coppola G, Tsukada S, Schroeder BE, Shaked GM, Wang L, Blesch A, Kim A, Conner JM, Rockenstein E, Chao MV, Koo EH, Geschwind D, Masliah E, Chiba AA, Tuszynski MH (2009) Neuroprotective effects of brain-derived neurotrophic factor in rodent and primate models of Alzheimer's disease. Nat Med 15:331-337.
Narisawa-Saito M, Wakabayashi K, Tsuji S, Takahashi H, Nawa H (1996) Regional specificity of alterations in NGF, BDNF and NT-3 levels in Alzheimer's disease. Neuroreport 7:2925-2928.
Noble W, Planel E, Zehr C, Olm V, Meyerson J, Suleman F, Gaynor K, Wang L, LaFrancois J, Feinstein B, Burns M, Krishnamurthy P, Wen Y, Bhat R, Lewis J, Dickson D, Duff K (2005) Inhibition of glycogen synthase kinase-3 by lithium correlates with reduced tauopathy and degeneration in vivo. Proc Natl Acad Sci U S A 102:6990-6995.
Ochs G, D Penn R, York M, Giess R, Beck M, Tonn J, Haigh J, Malta E, Traub M, Sendtner M, V Toyka K (2000) A phase I/II trial of recombinant methionyl human brain derived neurotrophic factor administered by intrathecal infusion to patients with amyotrophic lateral sclerosis. Amyotrophic lateral sclerosis and other motor neuron disorders : official publication of the World Federation of Neurology, Research Group on Motor Neuron Diseases 1:201-206.
Olabarria M, Noristani HN, Verkhratsky A, Rodríguez JJ (2010) Concomitant astroglial atrophy and astrogliosis in a triple transgenic animal model of Alzheimer's disease. Glia 58:831-838.
Pandi-Perumal SR, BaHammam AS, Brown GM, Spence DW, Bharti VK, Kaur C, Hardeland R, Cardinali DP (2013) Melatonin Antioxidative Defense: Therapeutical Implications for Aging and Neurodegenerative Processes. Neurotoxicity Research 23:267-300.
Peng S, Wuu J, Mufson EJ, Fahnestock M (2005) Precursor form of brain-derived neurotrophic factor and mature brain-derived neurotrophic factor are decreased in the pre-clinical stages of Alzheimer's disease. Journal of Neurochemistry 93:1412-1421.
Phillips HS, Hains JM, Armanini M, Laramee GR, Johnson SA, Winslow JW (1991) BDNF mRNA is decreased in the hippocampus of individuals with Alzheimer's disease. Neuron 7:695-702.
Poon WW, Carlos AJ, Aguilar BL, Berchtold NC, Kawano CK, Zograbyan V, Yaopruke T, Shelanski M, Cotman CW (2013) β-Amyloid (Aβ) oligomers impair brain-derived neurotrophic factor retrograde trafficking by down-regulating ubiquitin C-terminal hydrolase, UCH-L1. J Biol Chem 288:16937-16948.
Qi G, Mi Y, Wang Y, Li R, Huang S, Li X, Liu X (2017) Neuroprotective action of tea polyphenols on oxidative stress-induced apoptosis through the activation of the TrkB/CREB/BDNF pathway and Keap1/Nrf2 signaling pathway in SH-SY5Y cells and mice brain. Food & Function 8:4421-4432.
Reisberg B FS, de Leon MJ, Crook T. (1982) The Global Deterioration Scale for assessment of primary degenerative dementia. American Journal of Psychiatry 139:1136-1139.
Riemenschneider M, Schwarz S, Wagenpfeil S, Diehl J, Müller U, Förstl H, Kurz A (2002) A polymorphism of the brain-derived neurotrophic factor (BDNF) is associated with Alzheimer's disease in patients lacking the Apolipoprotein E ε4 allele. Molecular Psychiatry 7:782-785.
Robinson SR (2000) Neuronal expression of glutamine synthetase in Alzheimer’s disease indicates a profound impairment of metabolic interactions with astrocytes. Neurochemistry International 36:471-482.
Rosa E, Fahnestock M (2015) CREB expression mediates amyloid β-induced basal BDNF downregulation. Neurobiology of Aging 36:2406-2413.
S Kudriavtsev F, V Solov'ev I, N Korovin R, F Shurchilov A (1977) [Effect of izatizon and OL-56 on the reproductive and transformational properties of Marek's disease virus]. Veterinariia:45-46.
Saarelainen T, Lukkarinen JA, Koponen S, Gröhn OHJ, Jolkkonen J, Koponen E, Haapasalo A, Alhonen L, Wong G, Koistinaho J, Kauppinen RA, Castrén E (2000) Transgenic Mice Overexpressing Truncated trkB Neurotrophin Receptors in Neurons Show Increased Susceptibility to Cortical Injury after Focal Cerebral Ischemia. Molecular and Cellular Neuroscience 16:87-96.
Sakakibara Y, Sekiya M, Saito T, Saido TC, Iijima KM (2019) Amyloid-β plaque formation and reactive gliosis are required for induction of cognitive deficits in App knock-in mouse models of Alzheimer’s disease. BMC Neuroscience 20:13.
Sendtner M, Holtmann B, Kolbeck R, Thoenen H, Barde YA (1992) Brain-derived neurotrophic factor prevents the death of motoneurons in newborn rats after nerve section. Nature 360:757-759.
Stagni F, Giacomini A, Guidi S, Emili M, Uguagliati B, Salvalai ME, Bortolotto V, Grilli M, Rimondini R, Bartesaghi R (2017) A flavonoid agonist of the TrkB receptor for BDNF improves hippocampal neurogenesis and hippocampus-dependent memory in the Ts65Dn mouse model of DS. Experimental Neurology 298:79-96.
Sultana R, Banks WA, Butterfield DA (2010) Decreased levels of PSD95 and two associated proteins and increased levels of BCl2 and caspase 3 in hippocampus from subjects with amnestic mild cognitive impairment: Insights into their potential roles for loss of synapses and memory, accumulation of Abeta, and neurodegeneration in a prodromal stage of Alzheimer's disease. J Neurosci Res 88:469-477.
Tan Y, Nie S, Zhu W, Liu F, Guo H, Chu J, Cao XB, Jiang X, Zhang Y, Li Y (2016) 7,8-Dihydroxyflavone Ameliorates Cognitive Impairment by Inhibiting Expression of Tau Pathology in ApoE-Knockout Mice. Frontiers in aging neuroscience 8:287-287.
Tapia-Arancibia L, Rage F, Givalois L, Arancibia S (2004) Physiology of BDNF: focus on hypothalamic function. Frontiers in Neuroendocrinology 25:77-107.
Tong L, Balazs R, Thornton PL, Cotman CW (2004) β-Amyloid Peptide at Sublethal Concentrations Downregulates Brain-Derived Neurotrophic Factor Functions in Cultured Cortical Neurons. The Journal of Neuroscience 24:6799.
Tyler WJ, Alonso M, Bramham CR, Pozzo-Miller LD (2002) From acquisition to consolidation: on the role of brain-derived neurotrophic factor signaling in hippocampal-dependent learning. Learn Mem 9:224-237.
Vitolo OV, Sant, Angelo A, Costanzo V, Battaglia F, Arancio O, Shelanski M (2002) Amyloid β-peptide inhibition of the PKA/CREB pathway and long-term potentiation: Reversibility by drugs that enhance cAMP signaling. Proceedings of the National Academy of Sciences 99:13217.
Wang C, Wei Z, Jiang G, Liu H (2017) Neuroprotective mechanisms of miR-124 activating PI3K/Akt signaling pathway in ischemic stroke. Experimental and therapeutic medicine 13:3315-3318.
West AE, Griffith EC, Greenberg ME (2002) Regulation of transcription factors by neuronal activity. Nature Reviews Neuroscience 3:921-931.
Xu D, Lian D, Wu J, Liu Y, Zhu M, Sun J, He D, Li L (2017) Brain-derived neurotrophic factor reduces inflammation and hippocampal apoptosis in experimental Streptococcus pneumoniae meningitis. J Neuroinflammation 14:156-156.
Yan Q, Rosenfeld RD, Matheson CR, Hawkins N, Lopez OT, Bennett L, Welcher AA (1997) Expression of brain-derived neurotrophic factor protein in the adult rat central nervous system. Neuroscience 78:431-448.
Zeng Y, Zhao D, Xie C-W (2010) Neurotrophins enhance CaMKII activity and rescue amyloid-β-induced deficits in hippocampal synaptic plasticity. J Alzheimers Dis 21:823-831.
Zhang J-C, Yao W, Hashimoto K (2016) Brain-derived Neurotrophic Factor (BDNF)-TrkB Signaling in Inflammation-related Depression and Potential Therapeutic Targets. Curr Neuropharmacol 14:721-731.
Zhang Z, Liu X, Schroeder JP, Chan C-B, Song M, Yu SP, Weinshenker D, Ye K (2014) 7,8-dihydroxyflavone prevents synaptic loss and memory deficits in a mouse model of Alzheimer's disease. Neuropsychopharmacology 39:638-650.
Zheng Z, Sabirzhanov B, Keifer J (2010) Oligomeric amyloid-{beta} inhibits the proteolytic conversion of brain-derived neurotrophic factor (BDNF), AMPA receptor trafficking, and classical conditioning. J Biol Chem 285:34708-34717.