Anti-amyloidogenic activity of tannic acid and its activity to destabilize Alzheimer's beta-amyloid fibrils in vitro

Inhibition of the accumulation of amyloid beta-peptide (Abeta) and the formation of beta-amyloid fibrils (fAbeta) from Abeta, as well as the destabilization of preformed fAbeta in the CNS would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). We previously reported that nordihydroguaiaretic acid (NDGA) and wine-related polyphenols inhibit fAbeta formation from Abeta(1-40) and Abeta(1-42) as well as destabilizing preformed fAbeta(1-40) and fAbeta(1-42) dose-dependently in vitro. Using fluorescence spectroscopic analysis with thioflavin T and electron microscopic studies, we examined the effects of polymeric polyphenol, tannic acid (TA) on the formation, extension, and destabilization of fAbeta(1-40) and fAbeta(1-42) at pH 7.5 at 37 degrees C in vitro. We next compared the anti-amyloidogenic activities of TA with myricetin, rifampicin, tetracycline, and NDGA. TA dose-dependently inhibited fAbeta formation from Abeta(1-40) and Abeta(1-42), as well as their extension. Moreover, it dose-dependently destabilized preformed fAbetas. The effective concentrations (EC50) of TA for the formation, extension and destabilization of fAbetas were in the order of 0-0.1 microM. Although the mechanism by which TA inhibits fAbeta formation from Abeta as well as destabilizes preformed fAbeta in vitro is still unclear, it could be a key molecule for the development of therapeutics for AD.     

Ferulic acid destabilizes preformed beta-amyloid fibrils in vitro

Inhibition of the formation of beta-amyloid fibrils (fAbeta), as well as the destabilization of preformed fAbeta in the CNS, would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). We reported previously that curcumin (Cur) inhibits fAbeta formation from Abeta and destabilizes preformed fAbeta in vitro. Using fluorescence spectroscopic analysis with thioflavin T and electron microscopic studies, we examined the effects of ferulic acid (FA) on the formation, extension, and destabilization of fAbeta at pH 7.5 at 37 degrees C in vitro. We next compared the anti-amyloidogenic activities of FA with Cur, rifampicin, and tetracycline. Ferulic acid dose-dependently inhibited fAbeta formation from amyloid beta-peptide, as well as their extension. Moreover, it destabilized preformed fAbetas. The overall activity of the molecules examined was in the order of: Cur > FA > rifampicin = tetracycline. FA could be a key molecule for the development of therapeutics for AD.     

Potent anti-amyloidogenic and fibril-destabilizing effects of polyphenols in vitro: implications for the prevention and therapeutics of Alzheimer's disease

Cerebral deposition of amyloid beta-peptide (Abeta) in the brain is an invariant feature of Alzheimer's disease (AD). A consistent protective effect of wine consumption on AD has been documented by epidemiological studies. In the present study, we used fluorescence spectroscopy with thioflavin T and electron microscopy to examine the effects of wine-related polyphenols (myricetin, morin, quercetin, kaempferol (+)-catechin and (-)-epicatechin) on the formation, extension, and destabilization of beta-amyloid fibrils (fAbeta) at pH 7.5 at 37 degrees C in vitro. All examined polyphenols dose-dependently inhibited formation of fAbeta from fresh Abeta(1-40) and Abeta(1-42), as well as their extension. Moreover, these polyphenols dose-dependently destabilized preformed fAbetas. The overall activity of the molecules examined was in the order of: myricetin = morin = quercetin > kaempferol > (+)-catechin = (-)-epicatechin. The effective concentrations (EC50) of myricetin, morin and quercetin for the formation, extension and destabilization of fAbetas were in the order of 0.1-1 micro m. In cell culture experiments, myricetin-treated fAbeta were suggested to be less toxic than intact fAbeta, as demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Although the mechanisms by which these polyphenols inhibit fAbeta formation from Abeta, and destabilize pre-formed fAbetain vitro are still unclear, polyphenols could be a key molecule for the development of preventives and therapeutics for AD.     

Alpha-lipoic acid exhibits anti-amyloidogenicity for beta-amyloid fibrils in vitro

Inhibition of the formation of beta-amyloid fibrils (fAbeta), as well as the destabilization of preformed fAbeta in the CNS would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). Using fluorescence spectroscopic analysis with thioflavin T and electron microscopic studies, we examined the effects of alpha-lipoic acid (LA) and the metabolic product of LA, dihydrolipoic acid (DHLA), on the formation, extension, and destabilization of fAbeta at pH 7.5 at 37 degrees C in vitro. LA and DHLA dose-dependently inhibited fAbeta formation from amyloid beta-protein, as well as their extension. Moreover, they destabilized preformed fAbetas. LA and DHLA could be key molecules for the development of therapeutics for AD.     

Nordihydroguaiaretic acid potently breaks down pre-formed Alzheimer's beta-amyloid fibrils in vitro

Inhibition of the accumulation of amyloid beta-peptide (Abeta) and the formation of beta-amyloid fibrils (fAbeta) from Abeta, as well as the degradation of pre-formed fAbeta in the CNS would be attractive therapeutic objectives for the treatment of Alzheimer's disease (AD). We previously reported that nordihydroguaiaretic acid (NDGA) inhibited fAbeta formation from Abeta(1-40) and Abeta(1-42) dose-dependently in the range of 10-30 micromin vitro. Utilizing fluorescence spectroscopic analysis with thioflavin T and electron microscopic study, we show here that NDGA dose-dependently breaks down fAbeta(1-40) and fAbeta(1-42) within a few hours at pH 7.5 at 37 degrees C. At 4 h, the fluorescence of fAbeta(1-40) and fAbeta(1-42) incubated with 50 microm NDGA was 5% and 10% of the initial fluorescence, respectively. The activity of NDGA to break down these fAbetas was observed even at a low concentration of 0.1 microm. At 1 h, many short, sheared fibrils were observed in the mixture incubated with 50 microm NDGA, and at 4 h, the number of fibrils reduced markedly, and small amorphous aggregates were observed. We next compared the activity of NDGA to break down fAbeta(1-40) and fAbeta(1-42), with other molecules reported to inhibit fAbeta formation from Abeta and/or to degrade pre-formed fAbeta both in vivo and in vitro. At a concentration of 50 microm, the overall activity of the molecules examined in this study was in the order of: NDGA > rifampicin = tetracycline > poly(vinylsulfonic acid, sodium salt) = 1,3-propanedisulfonic acid, disodium salt > beta-sheet breaker peptide (iAbeta5). In cell culture experiments, fAbeta disrupted by NDGA were less toxic than intact fAbeta, as demonstrated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Although the mechanisms by which NDGA inhibits fAbeta formation from Abeta, as well as breaking down pre-formed fAbetain vitro, are still unclear, NDGA could be a key molecule for the development of therapeutics for AD.     

Anti-amyloidogenic effects of antioxidants: implications for the prevention and therapeutics of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common dementing disorders and has profound medical and social consequences. The initiating molecular event is unknown, and its pathophysiology is highly complex. However, free radical injury appears to be a fundamental process contributing to the neuronal death seen in this disorder, and many studies using surrogate markers of oxidative damage have provided evidence supporting this hypothesis. Various compounds with antioxidant ability attenuated the oxidative stress induced by amyloid beta-protein (Abeta) in studies done in vitro and in vivo. Moreover, various antioxidants have been reported to inhibit the formation and extension of beta-amyloid fibrils (fAbeta), as well as to destabilize preformed fAbeta in vitro. In cell culture experiments, destabilized fAbeta were suggested to be less toxic than intact fAbeta. In transgenic mice model studies, some antioxidant compounds reduced plaque burden in vivo. In this article, we review the recent advances in the research on the antioxidants that inhibit the formation of fAbeta, as well as destabilize preformed fAbeta. Although the mechanisms by which these compounds inhibit fAbeta formation from Abeta, and destabilize preformed fAbeta are still unclear, they could be key molecules for the development of preventives and therapeutics for AD.     

Salvianolic acid B inhibits Abeta fibril formation and disaggregates preformed fibrils and protects against Abeta-induced cytotoxicty

One of the major pathological features of Alzheimer's disease (AD) is the appearance of senile plaques characterized by extracellular aggregation of amyloid beta-peptide (Abeta) fibrils. Inhibition of Abeta fibril aggregation is therefore viewed as one possible method to halt the progression of AD. Salvianolic acid B (Sal B) is an active ingredient isolated from Salvia miltiorrhiza, a Chinese herbal medicine commonly used for the treatment of cardiovascular and cerebrovascular disorders. Recent findings show that Sal B prevents Abeta-induced cytotoxicity in a rat neural cell line. To understand the mechanism of Sal B-mediated neuroprotection, its effects on the inhibition of Abeta1-40 fibril formation and destabilization of the preformed Abeta1-40 fibrils were studied. The results were obtained using Thioflavin T fluorescence assay and Abeta aggregating immunoassay. We found that Sal B can inhibit fibril aggregation (IC(50): 1.54-5.37 microM) as well as destabilize preformed Abeta fibril (IC(50): 5.00-5.19 microM) in a dose- and time-dependent manner. Sal B is a better aggregation inhibitor than ferulic acid but less active than curcumin in the inhibition of Abeta1-40 aggregation. In electron microscope study, Sal B-treated Abeta1-40 fibrils are seen in various stages of shortening or wrinkling with numerous deformed aggregates of amorphous structure. Circular dichroism data indicate that Sal B dose dependently prevents the formation of beta-structured aggregates of Abeta1-40. Addition of preincubated Sal B with Abeta1-42 significantly reduces its cytotoxic effects on human neuroblastoma SH-SY5Y cells. These results suggest that Sal B has therapeutic potential in the treatment of AD, and warrant its study in animal models.     

Antioxidant compounds have potent anti-fibrillogenic and fibril-destabilizing effects for alpha-synuclein fibrils in vitro

The aggregation of alpha-synuclein (alphaS) in the brain has been implicated as a critical step in the development of Lewy body diseases (LBD) and multiple system atrophy (MSA). Various antioxidants not only inhibit the formation of beta-amyloid fibrils (fAbeta), but also destabilize preformed fAb in vitro. Using fluorescence spectroscopy with thioflavin S and electron microscopy, here we examined the effects of the antioxidants nordihydroguaiaretic acid, curcumin, rosmarinic acid, ferulic acid, wine-related polyphenols [tannic acid, myricetin, kaempferol (+)-catechin and (-)-epicatechin], docosahexaenoic acid, eicosapentaenoic acid, rifampicin and tetracycline on the formation of alphaS fibrils (falphaS) and on preformed falphaS. All molecules, except for docosahexaenoic acid and eicosapentaenoic acid, dose-dependently inhibited the formation of falphaS. Moreover, these molecules dose-dependently destabilized preformed falphaS. The overall activity of the molecules examined was in the order of: tannic acid=nordihydroguaiaretic acid=curcumin=rosmarinic acid=myricetin>kaempferol=ferulic acid>(+)-catechin=(-)-epicatechin>rifampicin=tetracycline. These compounds with anti-fibrillogenic as well as antioxidant activities could be key molecules for the development of preventives and therapeutics for LBD and MSA as well as Alzheimer's disease.     

The anti-amyloidogenic effect is exerted against Alzheimer's beta-amyloid fibrils in vitro by preferential and reversible binding of flavonoids to the amyloid fibril structure

How various anti-amyloidogenic compounds inhibit the formation of Alzheimer's beta-amyloid fibrils (fAbeta) from amyloid beta-peptide (Abeta) and destabilize fAbeta remains poorly understood. Using spectrophotometry, spectrofluorometry, atomic force microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and surface plasmon resonance (SPR), we investigated the anti-amyloidogenic effects of five flavonoids on fAbeta in vitro. Oxidized flavonoids generally inhibited fAbeta(1-40) formation significantly more potently than fresh compounds. Characterization of the novel fluorescence of myricetin (Myr) emitted at 575 nm with an excitation maximum at 430 nm in the presence of fAbeta(1-40) revealed the specific binding of Myr to fAbeta(1-40). By SPR analysis, distinct association and dissociation reactions of Myr with fAbeta(1-40) were observed, in contrast to the very weak binding to the Abeta monomer. A significant decrease in the rate of fibril extension was observed when >0.5 microM Myr was injected into the SPR experimental system. These findings suggest that flavonoids, especially Myr, exert an anti-amyloidogenic effect in vitro by preferentially and reversibly binding to the amyloid fibril structure of fAbeta, rather than to Abeta monomers.     

Matrix metalloproteinase-9 degrades amyloid-beta fibrils in vitro and compact plaques in situ

The pathological hallmark of Alzheimer disease is the senile plaque principally composed of tightly aggregated amyloid-beta fibrils (fAbeta), which are thought to be resistant to degradation and clearance. In this study, we explored whether proteases capable of degrading soluble Abeta (sAbeta) could degrade fAbeta as well. We demonstrate that matrix metalloproteinase-9 (MMP-9) can degrade fAbeta and that this ability is not shared by other sAbeta-degrading enzymes examined, including endothelin-converting enzyme, insulin-degrading enzyme, and neprilysin. fAbeta was decreased in samples incubated with MMP-9 compared with other proteases, assessed using thioflavin-T. Furthermore, fAbeta breakdown with MMP-9 but not with other proteases was demonstrated by transmission electron microscopy. Proteolytic digests of purified fAbeta were analyzed with matrix-assisted laser desorption ionization time-of-flight mass spectrometry to identify sites of Abeta that are cleaved during its degradation. Only MMP-9 digests contained fragments (Abeta(1-20) and Abeta(1-30)) from fAbeta(1-42) substrate; the corresponding cleavage sites are thought to be important for beta-pleated sheet formation. To determine whether MMP-9 can degrade plaques formed in vivo, fresh brain slices from aged APP/PS1 mice were incubated with proteases. MMP-9 digestion resulted in a decrease in thioflavin-S (ThS) staining. Consistent with a role for endogenous MMP-9 in this process in vivo, MMP-9 immunoreactivity was detected in astrocytes surrounding amyloid plaques in the brains of aged APP/PS1 and APPsw mice, and increased MMP activity was selectively observed in compact ThS-positive plaques. These findings suggest that MMP-9 can degrade fAbeta and may contribute to ongoing clearance of plaques from amyloid-laden brains.     

Disassembly of amyloid beta-protein fibril by basement membrane components

Amyloid beta-protein (A3) fibril in senile plaque may be related to the pathogenesis of Alzheimer's disease (AD). Basement membrane (BM) components are associated with the plaques in AD brain. It suggests that the BM components may play an important role in the deposition of the plaque. We investigated the potential of BM components, such as type IV collagen (collagen IV) and entactin, to induce disassembly of preformed Abeta1-42 (Abeta42) fibrils in direct comparison to laminin. Thioflavin T assays revealed that these BM components disrupted preformed Abeta42 fibrils in a dose-dependent manner. The high concentration of BM components, 100 microg/mL laminin, 50 microg/mL collagen IV and 50 microg/mL entactin, had most effect on disassembly of preformed Abeta42 fibrils (Molar ratio; Abeta42:laminin = 90:1, Abeta42:collagen IV = 34:1, Abeta42:entactin = 20:1). Circular dichroism spectroscopy data indicated that the high concentration of BM components induced structural transition in Abeta42 from beta-sheet to random structures. These results suggest that collagen IV and entactin, as well as laminin, are effective inducers of disassembly of Abeta42 fibrils. The ability of these BM components to induce random structures may be linked to the disassembly of preformed Abeta42 fibrils.     

Inhibitory activity of stilbenes on Alzheimer's beta-amyloid fibrils in vitro

Polymerization of the amyloid beta-peptide (Abeta) has been identified as one of the major characteristics of Alzheimer's disease (AD). Thus, finding molecules to prevent the aggregation of Abeta could be of therapeutic value in AD. We describe an original routine in vitro assay to search for inhibitors of Abeta(25-35) fibril formation which uses UV-visible measurements and electron microscopy (EM). In particular, this routine assay was used to examine the effects of stilbenes, a well-known polyphenol class, as inhibitors of Abeta fibril formation. The inhibitory properties of resveratrol (RES), piceid (PIC), resveratrol diglucoside (DIG), piceatannol (PIA), astringine (AST), and viniferin (VIN) were characterized and compared. RES and PIC effectively and dose-dependently inhibited Abeta polymerization while other polyphenols exerted less inhibition. Although the mechanism of anti-amyloidogenic activity is still unknown, these results support the hypothesis that stilbenes could be of therapeutic value in AD.     

Bromocriptine Markedly Suppresses Levodopa-Induced Abnormal Increase of Dopamine Turnover in the Parkinsonian Striatum

Bromocriptine, a dopamine agonist, is commonly used in combination with levodopa for the treatment of Parkinson's disease (PD). To investigate the theoretical basis of such combination therapy, we examined the effects of bromocriptine administered alone or in combination with levodopa on dopamine turnover in the striatum of hemi-parkinsonism rats. The parkinsonian striatum showed a 3.4-fold increase of dopamine turnover relative to the control striatum, as often observed in the brain of PD patients. A 7-day course of levodopa therapy markedly increased dopamine turnover in the parkinsonian striatum (53-fold of control level) than in the control striatum (5-fold of the control level). However, bromocriptine specifically and markedly suppressed the levodopa-induced abnormal activation of dopamine turnover in the parkinsonian striatum. Our findings explain the pharmacological basis for the introduction of bromocriptine during long-term levodopa therapy.     

Selegiline Reverses Aβ25–35-Induced Cognitive Deficit in Male Mice

Alzheimer’s disease (AD) is biochemically characterized by the occurrence of extracellular deposits of amyloid beta peptide (Aβ) and intracellular deposits of the hyperphosphorylated tau protein, which are causally related to the pathological hallmarks senile plaques and neurofibrillary tangles. Monoamine oxidase B (MAO-B) activity, involved in the oxidation of biogenic monoamines, is particularly high around the senile plaques and increased in AD patients in middle to late clinical stages of the disease. Selegiline is a selective and irreversible MAO-B inhibitor and, although clinical trials already shown the beneficial effect of selegiline on cognition of AD patients, its mechanism of action remains to be elucidated. Therefore, we first investigated whether selegiline reverses the impairment of object recognition memory induced by Aβ_25–35 in mice, an established model of AD. In addition, we investigated whether selegiline alters MAO-B and MAO-A activities in the hippocampus, perirhinal and remaining cerebral cortices of Aβ_25–35-injected male mice. Acute (1 and 10 mg/kg, p.o., immediately post-training) and subchronic (10 mg/kg, p.o., seven days after Aβ_25–35 injection and immediately post-training) administration of selegiline reversed the cognitive impairment induced by Aβ_25–35 (3 nmol, i.c.v.). Acute administration of selegiline (1 mg/kg, p.o.) in combination with Aβ_25–35 (3 nmol) decreased MAO-B activity in the perirhinal and remaining cerebral cortices. Acute administration of selegiline (10 mg/kg, p.o.) decreased MAO-B activity in hippocampus, perirhinal and remaining cerebral cortices, regardless of Aβ_25–35 or Aβ_35–25 treatment. MAO-A activity was not altered by selegiline or Aβ_25–35. In summary, the current findings further support a role for cortical monoaminergic transmission in the cognitive deficits observed in AD.     

Drug treatment of Parkinson's disease.

A wide variety of drugs is available for treating Parkinson''s disease, including anticholinergics, amantadine levodopa, dopamine agonists, and selegiline. In younger patients (less than 50) levodopa is usually delayed provided that adequate relief of symptoms can be achieved with other drugs. In older patients (greater than 70) levodopa should be started as soon as symptom relief is required. Between these ages there is no consensus, but at present most such patients should probably be given controlled release levodopa before a dopamine agonist is added. Fluctuations can often be alleviated by giving controlled release preparations of levodopa, by giving small doses at frequent intervals, by adding selegiline or a long acting oral agonist, or by subcutaneous apomorphine. Dyskinesia can be peak dose, diphasic, or "off period." The diphasic form is hardest to alleviate. Psychiatric side effects should initially be managed by changing the antiparkinsonian treatment before resorting to antipsychotic drugs.     

Uptake, degradation, and release of fibrillar and soluble forms of Alzheimer's amyloid beta-peptide by microglial cells.

Microglia are phagocytic cells that are the main inflammatory response cells of the central nervous system. In Alzheimer's disease brain, activated microglia are concentrated in regions of compact amyloid deposits that contain the 39-43-amino acid Abeta peptide. We examined the uptake, degradation, and release of small aggregates of fibrillar Abeta (fAbeta) or soluble Abeta (sAbeta) by microglia. We found that although some degradation of fAbeta was observed over 3 days, no further degradation was observed over the next 9 days. Instead, there was a slow release of intact Abeta. The poor degradation was not due to inhibition of lysosomal function, since the rate of alpha2-macroglobulin degradation was not affected by the presence of fAbeta in the late endosomes/lysosomes. In contrast to fAbeta, internalization of sAbeta was not saturable. After internalization, sAbeta was released rapidly from microglia, and very little was degraded. These data show that fAbeta and sAbeta interact differently with microglia but that after internalization a large fraction of both are released without degradation.     

Blood-based neurochemical diagnosis of vascular dementia: a pilot study

Blood-based tests for the differential diagnosis of Alzheimer's disease (AD) are under intensive investigation and have shown promising results with regard to Abeta40 and Abeta42 peptide species in incipient AD. Moreover, plasma Abeta40 was suggested as an independent cerebrovascular risk factor candidate. These considerations prompted us to analyse a total of 72 plasma samples in vascular dementias (VAD, n = 15), AD with cerebrovascular disease (AD with CVD, n = 7), AD (n = 15), Parkinson's disease and Parkinson's disease dementia (PD/PDD, n = 20) and 15 patients with depression that served as controls (DC) for distinct plasma amyloid-beta (Abeta) peptide patterns. For the analysis of plasma we used immunoprecipitation followed by the quantitative Abeta-SDS-PAGE/immunoblot. For comparison, CSF tau and Abeta1-42 analyses were performed. The major outcome was an increase in Abeta1-40 in plasma of VAD paralleled by a decrease in the ratio of Abeta1-38/Abeta1-40. The ratio Abeta1-38/Abeta1-40 in plasma enabled contrasts of beyond 85% and 80% for discriminating VAD from DC and all other patients, respectively. In CSF, we confirmed the typical CSF biomarker constellation of increased tau and diminished Abeta1-42 levels for AD. The diagnostic accuracy of plasma Abeta1-38/Abeta1-40 for VAD resembled the accuracy of CSF biomarkers for AD. From the presented results, we consider the ratio of plasma Abeta1-38/Abeta1-40 peptides to be a blood-based biomarker candidate for VAD.     

Regulation of Brain-Derived Neurotrophic Factor (BDNF) and Cerebral Dopamine Neurotrophic Factor (CDNF) by Anti-Parkinsonian Drug Therapy In Vivo

Available treatment for Parkinson’s disease (PD) is mainly symptomatic instead of halting or reversing degenerative processes affecting the disease. Research on the molecular pathogenesis of PD has suggested reduced trophic support as a possible cause or mediator of neurodegeneration. In animal models of the disease, neurotrophic factors prevent neurodegeneration and induce behavioral recovery. Some anti-Parkinsonian drugs show neuroprotective activity, but it is not known whether the drug-induced neuroprotection is mediated by neurotrophic factors. In this study, we have investigated the influence of two neuroprotective anti-Parkinsonian drugs, the monoamine oxidase B inhibitor selegiline and the adenosine A_2A antagonist SCH 58261, on the levels of brain-derived neurotrophic factor (BDNF) and cerebral dopamine neurotrophic factor (CDNF) in the mouse brain. Protein levels of BDNF and CDNF were quantified by western blot after 2 weeks of treatment with either of the drugs or placebo. CDNF levels were not significantly influenced by selegiline or SCH 58261 in any brain area studied. Selegiline treatment significantly increased BDNF levels in the anterior cingulate cortex (1.55 ± 0.22, P < 0.05, Student’s t-test). In the striatum, selegiline increased BDNF content by 32%, but this change did not reach statistical significance (1.32 ± 0.15, P < 0.13, Student’s t-test). Our data suggest that neurotrophic factors, particularly BDNF may play a role in the neuroprotective effects of selegiline, but do not support the hypothesis that anti-Parkinsonian drugs would work by increasing the levels of CDNF in brain.     

Effects of selegiline,a monoamine oxidase B inhibitor,on differentiation of P19 embryonal carcinoma stem cells,into neuron-like cells

Selegiline, the irreversible inhibitor of monoamine oxidase B (MAO-B), is currently used to treat Parkinson’s disease. However, the mechanism of action of selegiline is complex and cannot be explained solely by its MAO-B inhibitory action. It stimulates gene expression, as well as expression of a number of mRNAs or proteins in nerve and glial cells. Direct neuroprotective and anti-apoptotic actions of selegiline have previously been observed in vitro. Previous studies showed that selegiline can induce neuronal phenotype in cultured bone marrow stem cells and embryonic stem cells. Embryonal carcinoma (EC) cells are developmentaly pluripotene cells which can be differentiated into all cell types under the appropriate conditions. The present study was carried out to examine the effects of selegiline on undifferentiated P19 EC cells. The results showed that selegiline treatment had a dramatic effect on neuronal morphology. It induced the differentiation of EC cells into neuron-like cells in a concentration-dependent manner. The peak response was in a dose of selegiline significantly lower than required for MAO-B inhibition. The differentiated cells were immunoreactive for neuron-specific proteins, synaptophysin, and β-III tubulin. Stem cell therapy has been considered as an ideal option for the treatment of neurodegenerative diseases. Generation of neurons from stem cells could serve as a source for potential cell therapy. This study suggests the potential use of combined selegiline and stem cell therapy to improve deficits in neurodegenerative diseases.