Neuroprotection by propargylamines in Parkinson's disease: intracellular mechanism underlying the anti-apoptotic function and search for clinical markers.

In Parkinson's and other neurodegenerative diseases, a therapeutic strategy has been proposed to halt progressive cell death. Propargylamine derivatives, rasagiline and (-)deprenyl (selegiline), have been confirmed to protect neurons against cell death induced by various insults in cellular and animal models of neurodegenerative disorders. In this paper, the mechanism and the markers of the neuroprotection are reviewed. Propargylamines prevent the mitochondrial permeabilization, membrane potential decline, cytochrome c release, caspase activation and nuclear translocation of glyceraldehyde 3-phosphate dehydrogenase. At the same time, rasagiline induces anti-apoptotic pro-survival proteins, Bcl-2 and glial cell-line derived neurotrophic factor, which is mediated by activated ERK-NF-kappaB signal pathway. DNA array studies indicate that rasagiline increases the expression of the genes coding mitochondrial energy synthesis, inhibitors of apoptosis, transcription factors, kinases and ubiquitin-proteasome system, sequentially in a time-dependent way. Products of cell survival-related gene induced by propargylamines may be applied as markers of neuroprotection in clinical samples.

Overexpression of amyloid precursor protein induces susceptibility to oxidative stress in human neuroblastoma SH-SY5Y cells.

In Alzheimer's disease amyloid beta peptide (Abeta) produced from amyloid precursor protein (APP) is considered to induce cell death. To clarify the molecular mechanism underlying Abeta neurotoxicity, we established the cell line overexpressing wild or mutant (His684Arg) APP in human SH-SY5Y cells. This paper presents that overexpression of wild-APP in the cells (SH/w-APP) increased the levels of APP and Abeta(1-40) but not Abeta(1-42), and reduced Bcl-2 level and proteasome activity with increased susceptibility to oxidative stress. The intracellular levels of reactive oxygen species in SH/w-APP increased significantly by H(2)O(2) treatment. The level of Bcl-2 protein, but not mRNA, was markedly decreased in SH/w-APP cells, which was inversely correlated with APP expression among subcloned SH/w-APP cells. These results indicate that increased expression of wild type APP renders neuronal cells more vulnerable to oxidative stress leading to cell death.

Neuromelanin induces oxidative stress in mitochondria through release of iron: mechanism behind the inhibition of 26S proteasome.

Parkinson's disease is characterized by the selective depletion of dopamine neurons in the substantia nigra, particular those containing neuromelanin. Involvement of neuromelanin in the pathogenesis may be either cytotoxic or protective. Recently we found that neuromelanin reduces the activity of 26S proteasome. In this paper, the detailed mechanisms behind the reduced activity were studied using neuromelanin isolated from the human brain. Neuromelanin increased the oxidative stress, but synthetic melanin did not. Superoxide dismutase and deferoxamine completely suppressed the increase, indicating that superoxide produced by an iron-mediated reaction plays a central role. Iron was shown to reduce in situ 26S proteasome activity in SH-SY5Y cells and the reduction was protected by antioxidants. These results suggest that iron released from neuromelanin increases oxidative stress in mitochondria, and then causes mitochondrial dysfunction and reduces proteasome function. The role of neuromelanin is discussed in relation to the selective vulnerability of dopamine neurons in Parkinson's disease.

N-Propargylamine protects SH-SY5Y cells from apoptosis induced by an endogenous neurotoxin, N-methyl(R)salsolinol, through stabilization of mitochondrial membrane and induction of anti-apoptotic Bcl-2.

Propargylamine derivatives, rasagiline and (-)deprenyl, are anti-Parkinson agents and protect neurons from cell death as shown by in vivo and in vitro experiments. The studies on the chemical structure-activity relationship proved that the propargyl moiety is essentially required for the neuroprotective function. In this paper, neuroprotective activity of free N-propargylamine was studied using SH-SY5Y cells expressing only type A monoamine oxidase (MAO) against apoptosis induced by an endogenous dopaminergic neurotoxin, N-methyl(R)salsolinol. N-Propargylamine prevented apoptosis, whereas N-methylpropargylamine and propiolaldehyde did not. N-Propargylamine stabilized mitochondrial membrane potential and induced anti-apoptotic Bcl-2 at 1 microM-10 nM. N-Propargylamine inhibited MAO-A in competition to substrate with the apparent K(i) value of 28 microM, which was significantly higher than the concentration required for neuroprotection. It indicates that MAO inhibition is not prerequisite for the protective function of N-propargylamine. The anti-apoptotic function of N-propargylamine is discussed in terms of neuroprotection by propargylamines in neurodegenerative diseases, including Parkinson's disease.

Involvement of type A monoamine oxidase in neurodegeneration: regulation of mitochondrial signaling leading to cell death or neuroprotection.

In neurodegenerative diseases, including Parkinson's and Alzheimer's diseases, apoptosis is a common type of cell death, and mitochondria emerge as the major organelle to initiate death cascade. Monoamine oxidase (MAO) in the mitochondrial outer membrane produces hydrogen peroxide by oxidation of monoamine substrates, and induces oxidative stress resulting in neuronal degeneration. On the other hand, a series of inhibitors of type B MAO (MAO-B) protect neurons from cell death. These results suggest that MAO may be involved in the cell death process initiated in mitochondria. However, the direct involvement of MAO in the apoptotic signaling has been scarcely reported. In this paper, we present our recent results on the role of MAO in activating and regulating cell death processing in mitochondria. Type A MAO (MAO-A) was found to bind an endogenous dopaminergic neurotoxin, N-methyl(R)salsolinol, and induce apoptosis in dopaminergic SH-SY5Y cells containing only MAO-A. To examine the intervention of MAO-B in apoptotic process, human MAO-B cDNA was transfected to SH-SY5Y cells, but the sensitivity to N-methyl(R)salsolinol was not affected, even though the activity and protein of MAO-B were expressed markedly. MAO-B oxidized dopamine with production of hydrogen peroxide, whereas in control cells expressing only MAO-A, dopamine autoxidation produced superoxide and dopamine-quinone, and induced mitochondrial permeability transition and apoptosis. Rasagiline and other MAO-B inhibitors prevent the activation of apoptotic cascade and induce prosurvival genes, such as bcl-2 and glial cell line-derived neurotrophic factor, in MAO-A-containing cells. These results demonstrate a novel function of MAO-A in the induction and regulation of apoptosis. Future studies will clarify more detailed mechanism behind regulation of mitochondrial death signaling by MAO-A, and bring out new strategies to cure or ameliorate the decline of neurons in neurodegenerative disorders.

Expression of class II beta-tubulin by proliferative myoepithelial cells in canine mammary mixed tumors.

Benign mammary mixed tumors in dogs resemble human salivary pleomorphic adenomas with regard to their histogenesis, including the occurrence of cartilaginous or bony metaplasia as well as the expression pattern of cytoskeletal proteins in proliferative myoepithelial cells. Recently, a monoclonal antibody specific for class II beta-tubulin has been developed. The epitope it recognizes was determined to be the heptapeptide Glu-Glu-Glu-Glu-Gly-Glu-Asp, which is the common sequence found among the canine, rat, mouse, and human class II beta-tubulin-specific regions. We carried out immunohistochemical studies on mammary mixed tumors obtained from three female dogs using this the monoclonal antibody. The antibody to class II beta-tubulin reacted intensely with proliferative myoepithelial cells in canine mammary mixed tumors, whereas staining was barely detectable in normal myoepithelial cells surrounding alveoli and alveolar ducts within the tumor and adjacent normal tissue. Proliferative myoepithelial cells also expressed vimentin, but alpha-smooth muscle actin (alphaSMA) staining was barely detectable. Immunoblot analysis showed that class II beta-tubulin and vimentin were expressed in myoepithelial cell lines prepared from the three mammary mixed tumors. On the other hand, only one cell line, which was negative for alphaSMA, produced cartilage-specific type II collagen. These results suggest that class II beta-tubulin could be a new molecular marker of proliferating myoepithelial cells in canine mammary mixed tumors and that differential expression of cytoskeletal components is associated with cartilaginous metaplasia of proliferative myoepithelial cells in mixed mammary tumors.

Relation between voluntary physical activity and oxidant/antioxidant status in rats.

The relationship between voluntary distance running and antioxidant capacity was studied in rats after three weeks voluntary running. Hydroxyl radical level, reduced glutathione level, activities of glutathione reductase and superoxide dismutase were measured in plasma, liver, brain, soleus and gastrocnemius white muscle. Hydroxyl radical level of liver negatively correlated with the running distance (r=-0.616, P<0.001). The reduced glutathione levels of liver and brain increased depending on the running distance and the correlation was confirmed between them in liver (r=0.638, P<0.01) and brain (r=0.766, P<0.001). The hydroxyl radical level in liver positively correlated with the activities of glutathione reductase (r=0.464, P<0.05) and superoxide dismutase (r=0.549, P<0.05). A significant positive correlation was detected between the hydroxyl radical level and superoxide dismutase activity in brain (r=0.488, P<0.05). These results demonstrate that physical activity correlates well with glutathione level and anti-oxidant enzyme activities in liver, suggesting a close relation between physical activity and induction of antioxidant systems.

Mitochondria determine the survival and death in apoptosis by an endogenous neurotoxin, N-methyl(R)salsolinol, and neuroprotection by propargylamines.

In neurodegenerative disorders, such as Parkinson's disease, selective neuronal death characterizes clinical signs and symptoms. Recently apoptosis was reported to be a common type of cell death in some disorders, and well-controlled apoptotic cascade is proposed to be a target of neuroprotective therapy. In our studies to find endogenous neurotoxins as a pathogenic factor in Parkinson's disease, dopamine-derived N-methyl(R)salsolinol was found to induce apoptosis in dopamine neurons of rat models of Parkinson's disease. In human dopaminergic SH-SY5Y cells, apoptosis was initiated by decline in mitochondrial membrane potential, and anti-apoptotic Bcl-2 family protein regulated apoptotic signal transduction. In addition, a series of propargylamines were found to prevent apoptosis through stabilization of mitochondrial membrane potential, which also involved Bcl-2. The role of mitochondria and the involvement of Bcl-2 in apoptosis and neuroprotection were clearly demonstrated using isolated mitochondria. These results indicate that mitochondria are the site to determine the cell death induced by neurotoxins and also the neuroprotection by anti-apoptotic propargylamines.

The anti-Parkinson drug, rasagiline, prevents apoptotic DNA damage induced by peroxynitrite in human dopaminergic neuroblastoma SH-SY5Y cells.

Clinical trials for treatment of Parkinson's disease suggest that (-)deprenyl (selegiline), an inhibitor of type B monoamine oxidase, may slow the disease progression. However, the mechanism underlying protection of nigral dopamine neurons by selegiline remains an enigma. Recently, rasagiline, (R)(+)-N-propargyl-1-aminoindan, was reported to be neuroprotective by in vivo and in vitro experiments, which is another selective irreversible inhibitor of type B monoamine oxidase and not metabolized into amphetamine-like derivatives as in the case of selegiline. In this paper, the mechanism of the neuroprotection was examined using human dopaminergic neuroblastoma SH-SY5Y cells against apoptosis induced by peroxynitrite generated from SIN-1. After treatment with SIN-1, the apoptotic DNA damage in the cells was quantified by a single cell gel electrophoresis (comet) assay and by staining with Hoechst 33342. Change in mitochondrial membrane potential, Deltapsim, was measured by use of a fluorescent indicator, JC-1. Rasagiline reduced apoptosis with much more potency than selegiline, and the protection required 20 min pre-incubation before SIN-1 treatment. The protection by rasagiline was proved to be due to stabilization of mitochondrial membrane potential against the collapse induced by SIN-1, whereas rasagiline did not scavenge peroxynitrite directly. The studies on structure-activity relationship showed that a propargylamine group and a hydrophobic group with an adequate intermediate space were required for the protection. These results suggest that rasagiline may protect declining neurons through its anti-apoptotic activity in neurodegenerative diseases.

Selective nitration of mitochondrial complex I by peroxynitrite: involvement in mitochondria dysfunction and cell death of dopaminergic SH-SY5Y cells.

3-Nitrotyrosine (3-NT) is a specific marker of protein nitration by peroxynitrite (ONOO-) produced from nitric oxide and superoxide. Increase in 3-NT containing protein (3-NT protein) was reported in brains from patients with some neurodegenerative disorders and aging. In this paper, intracellular localization of 3-NT protein was examined in dopaminergic SH-SY5Y cells using the selective antibody against protein-bound 3-NT. 3-NT protein was detected in plasma membrane/nucleus and mitochondria fractions, and interestingly in polypeptide composition of mitochondrial complex I. ONOO--generating SIN-1 induced apoptotic cell death with concomitant increase in 3-NT protein and reduction in mitochondrial ATP synthesis. In addition, an inhibitor of proteasomes, carbobenzoxy-L-isoleucyl-gamma-t-butyl-L-glutamyl-L-alanyl-L-leucinal, enhanced the effects of ONOO-. These results suggest that ONOO- may induce mitochondrial dysfunction and cell death in neurons through nitration of mitochondrial complex I subunits.

Salsolinol is a putative endogenous neuro-intermediate lobe prolactin-releasing factor.

The isolation and identification of a prolactin-releasing factor (PRF) from the neuro-intermediate lobe of the pituitary gland has been pursued for over a decade. Using high-pressure liquid chromatography with electrochemical detection (HPLC-ECD) and gas chromatography/mass spectrometry (GC/MS) (R)-salsolinol (SAL) (a dopamine-related stereo-specific tetrahydroisoquinoline) was found to be present in neuro-intermediate lobe as well as median eminence extracts of male, intact-, and ovariectomized female rats. Moreover, analysis of SAL concentrations in neuro-intermediate lobe revealed parallel increases with plasma prolactin in lactating rats exposed to a brief (10 min) suckling stimulus following 4-h separation. SAL appears to be a selective and potent stimulator of prolactin secretion in vivo and it was without effect on the secretion of other pituitary hormones. We have also found that SAL can elevate prolactin release, although to a lesser extent, in pituitary cell cultures as well as in hypophysectomized rats bearing anterior lobe transplants under the kidney capsule. Lack of interference of SAL with [3H]-spiperone binding to AP homogenates indicates that SAL does not act at the dopamine D2 receptor. Moreover, [3H]-SAL binds specifically to homogenate of AL as well as neuro-intermediate lobe obtained from lactating rats. Taken together, our data clearly suggest that SAL is synthesized in situ and this compound can play a role in the regulation of pituitary prolactin secretion.

Norharman, an indoleamine-derived beta-carboline, but not Trp-P-2, a gamma-carboline, induces apoptotic cell death in human neuroblastoma SH-SY5Y cells.

Carbolines, azaheterocyclic amines derived from indoleamines, have various biological activities, such as neurotoxicity of beta-carbolines and potent mutagenicity of gamma-carbolines. In this study, structural significance among these carbolines was investigated in relation to the types of cell death, apoptosis and necrosis, using human neuroblastoma SH-SY5Y cells. DNA damage was quantitatively analyzed by a single-cell gel electrophoresis assay. DNA damage was induced by both beta-carbolines, harman and norharman, and gamma-carbolines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-4-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), in a dose dependent manner. Gamma-carbolines were more potent to damage DNA than beta-carbolines. Alkaline lysis of the cells prevented DNA damage induced by beta-carboline, and pre-treatment of the cells with cycloheximide, an inhibitor of protein synthesis, reduced DNA damage caused by norharman. Morphological observation showed condensed and fragmented nuclei typical for apoptosis, in the cells treated with norharman. Thus, DNA damage induced by norharman was proved to be apoptotic. However, harman, which had a methyl substitution at the position 1, might induce necrosis in the cells. On the other hand, gamma-carbolines, Trp-P-1 and Trp-P-2, directly damaged DNA. Thus, the nitrogen atom at the gamma-position and/or an amino group in carboline structure would be required to induce the direct DNA cleavage.

[A case of hepatic metastasis of gastric cancer responding to TS-1, administered for two consecutive weeks and one week rest].

We have treated a case of hepatic metastasis of gastric cancer that has responded well to TS-1. The patient was a 68-year-old male, who underwent distal gastrectomy for gastric cancer. After surgery 5'-deoxy-5-fluorouridine (5'-DFUR) 800 mg/day was administered orally for two months. Grade 4 diarrhea appeared, so administration of 5'-DFUR was discontinued. Afterward the patient was followed with no chemotherapy. Liver metastasis (S6, 3 cm in diameter) was found at twelve months after surgery. 5'-DFUR (800 mg/day) was administered orally everyday. Grade 3 diarrhea appeared and metastasis showed NC after four weeks. 5'-DFUR administration was discontinued. Seventeen days later TS-1 (80 mg/day) was administered orally everyday for 2 weeks, followed by 1 week rest, as one course. Two courses of TS-1 administration resulted in a marked reduction of the liver metastasis, for a PR (75% reduction). After 3 courses, the liver metastasis showed CR. The patient is alive without recurrence after 12 courses. This TS-1 administration regimen was effective and tolerable for a patient with liver metastasis from gastric cancer.

Future of neuroprotection in Parkinson's disease.

In Parkinson's disease neuroprotective therapy to rescue dopamine neurons has been proposed. Selegiline is one of neuroprotective drug candidates, as proved by in vivo and in vitro experiments. In this paper, the mechanism underlying neuroprotection by selegiline and related propargylamines was studied against apoptosis induced by an endogenous toxin, N-methyl(R)salsolinol, synthetic 6-hydroxydopamine and peroxynitrite in dopaminergic SH-SY5Y cells. Propargylamines prevented apoptotic DNA damage, through suppression of collapse in mitochondrial membrane potential and following activation of caspase 3 and signal transduction to nuclei. These results suggest that propargylamines may rescue or protect dopamine neurons in Parkinson's disease.

Transfection-enforced Bcl-2 overexpression and an anti-Parkinson drug, rasagiline, prevent nuclear accumulation of glyceraldehyde-3-phosphate dehydrogenase induced by an endogenous dopaminergic neurotoxin, N-methyl(R)salsolinol.

An endogenous dopaminergic neurotoxin, N-methyl(R)salsolinol, was found to induce apoptosis in human dopaminergic SH-SY5Y cells by step-wise activation of apoptotic cascade; collapse in mitochondrial membrane potential, DeltaPsim, activation of caspases, and fragmentation of DNA. Recently, accumulation of gylceraldehyde-3-phosphate dehydrogenase (GAPDH) in nuclei was proposed to play an important role in apoptosis. In this paper, involvement of GAPDH in apoptosis induced by N-methyl(R)salsolinol was studied. The isoquinoline reduced DeltaPsim within 3 h, as detected by a fluorescence indicator, JC-1, then after 16 h incubation, GAPDH accumulated in nuclei by detection with immunostaining. To clarify the role of GAPDH in apoptotic process, a stable cell line of Bcl-2 overexpressed SH-SY5Y cells was established. Overexpression of Bcl-2 prevented the decline in DeltaPsim and also apoptotic DNA damage induced by N-methyl(R)salsolinol. In Bcl-2 transfected cells, nuclear translocation of GAPDH was also completely suppressed. In addition, a novel antiparkinsonian drug, rasagiline, prevented nuclear accumulation of GAPDH induced by N-methyl(R)salsolinol in control cells. These results suggest that GAPDH may accumulate in nuclei as a consequence of signal transduction, which is antagonized by anti-apoptotic Bcl-2 protein family and rasagiline. The results are discussed in concern to intracellular mechanism underlying anti-apoptotic function of rasagiline analogues.

Enantio-specific induction of apoptosis by an endogenous neurotoxin, N-methyl(R)salsolinol, in dopaminergic SH-SY5Y cells: suppression of apoptosis by N-(2-heptyl)-N-methylpropargylamine.

Endogenous N-methyl(R)salsolinol, which caused parkinsonism in rats by injection in the striatum, was found to induce apoptosis in dopaminergic neuroblastoma SH-SY5Y cells. After 12-h incubation with 500[microM N-methyl(R)salsolinol, almost all the cells died with apoptosis and necrotic cell death was negligible. N-Methyl(R)salsolinol was much more potent to induce apoptosis than the (S)-enantiomer. The mechanism of apoptosis was studied in relation to changes in mitochondrial membrane potential, deltapsi(m), using a fluorescent indicator, JC-1. Red fluorescence of J-aggregates representing hyperpolarized deltapsi(m) was found to decrease significantly within 60 min after incubation with N-methyl(R)salsolinol, but not by the (S)-enantiomer at the same concentration. It suggests that mitochondria may recognize the stereo-chemical structure of N-methyl(R) salsolinol. Aliphatic propargylamines, (R)-N-(2-heptyl)-N-methylpropargylamine and (R)-N-(2-heptyl)propargylamine, were found to prevent deltapsim loss and subsequent apoptosis induced by N-methyl(R)salsolinol. These results suggest that mitochondria play a key role in the induction of apoptosis by the neurotoxin and the prevention by aliphatic propargylamines.

Involvement of endogenous N-methyl(R)salsolinol in Parkinson's disease: induction of apoptosis and protection by (-)deprenyl.

An endogenous dopamine-derived N-methyl(R)salsolinol has been suggested to be involved in the pathogenesis of Parkinson's disease. In Parkinson's disease, the level of N-methyl(R)salsolinol increased in cerebrospinal fluid and the high activity of a synthesizing enzyme, (R)salsolinol N-methyltransferase, was detected in lymphocytes. This isoquinoline induced apoptotic DNA damage in human dopaminergic neuroblastoma SH-SY5Y cells. Among catechol isoquinolines, only N-methylsalsolinol induced apoptosis in the cells, and the scavengers of hydroxyl radicals and antioxidants suppressed DNA damage, suggesting that reactive oxygen species initiate apoptosis. The isoquinoline activated caspase-3 like proteases and a caspase-3 inhibitor protected the cells from DNA damage. (-)Deprenyl, but neither clorgyline nor pargyline, prevented apoptotic cell death. The mechanism of the protection was due to stabilization of mitochondrial membrane potential reduced by the toxin. In Parkinson's disease apoptosis may be induced in dopamine neurons by this endogenous neurotoxin, and (-)deprenyl may protect them from apoptotic death process.

Apoptosis induced by an endogenous neurotoxin, N-methyl(R)salsolinol, in dopamine neurons.

A dopamine-derived neurotoxin, 1(R),2(N)-dimethyl-6,7-dihydroxy-1,2, 3,4-tetrahydroisoquinoline [N-methyl(R)salsolinol] was found to cause parkinsonian in rats and to deplete selectively dopamine neurons in the substantia nigra after infusion in the striatum. This isoquinoline occurs enantio-specifically in the nigra-striatum of human brains. The biosynthesis from dopamine is catalyzed by two enzymes, (R)salsolinol synthase and (R)salsolinol N-methyltransferase. The isoquinoline increases in the cerebrospinal fluid from parkinsonian patients, and the increase is ascribed to high activity of its synthesizing neutral (R)salsolinol N-methyltransferase, as shown by analyses in lymphocytes. The cell death caused by this neurotoxin in dopaminergic human neuroblastoma SH-SY5Y cells proved to be apoptotic. Apoptosis by this neurotoxin is mediated by intracellular sequential process, loss of mitochondrial membrane potential, activation of caspases and DNA fragmentation. These results are discussed in relation to the role of apoptosis in neurodegenerative diseases and the involvement of the endogenous toxin in the pathogenesis of Parkinson's disease.

Anti-apoptotic function of L-(-)deprenyl (Selegiline) and related compounds.

(-)Deprenyl has been proposed to be neuroprotective to dopamine neurons in the parkinsonian brains. To clarify the mechanism, the effects of (-)deprenyl and structurally related compounds on apoptosis induced by a neurotoxin, N-methyl(R)-salsolinol, and reactive oxygen species, nitric oxide and peroxynitrite, were examined in dopaminergic SH-SY5Y cells. DNA damage was quantified by the single cell gel electrophoresis (comet) assay. (-)-Deprenyl protected the cells from apoptosis in a dose-dependent way, which required pre-treatment at least for 20 min. The effect was confirmed even after washing out of (-)deprenyl, indicating that (-)-deprenyl initiates the intracellular process to antagonize the apoptotic death program. The studies on the structure-activity relationship reveal that N-propargyl residue with hydrophobic structure is essential for the anti-apoptotic function. These results suggest that (-)deprenyl and related compounds may be applicable as neuroprotective agents in neurodegenerative diseases.

Mechanism underlying anti-apoptotic activity of a (-)deprenyl-related propargylamine, rasagiline.

A potent inhibitor of type B monoamine oxidase, (-)deprenyl, is known to protect or rescue dying neurons, independent of inhibition of the enzyme activity. After long term administration to rodents, a propargylamine structurally related to (-)deprenyl, (R)(+)-N-propargyl-1-aminoindan (rasagiline) increased the activities of anti-oxidative enzymes, superoxide dismutase and catalase. Rasagiline protected in vitro dopamine cells from apoptosis induced by oxidative stress or neurotoxins. The mechanism of the anti-apoptotic effect was studied by in vitro experiments using human dopaminergic neuroblastoma, SH-SY5Y cells. Peroxynitrite-generating N-morpholino sydonimine (SIN-1) induced apoptosis in SH-SY5Y cells via disruption of mitochondrial membrane potential (DeltaPsim), followed by caspase 3 activation. Rasagiline prevented the loss of DeltaPsim, the initial step to apoptosis, and also following caspase 3-activation and DNA fragmentation. The results suggest that rasagiline may interact with the specific molecule in the mitochondria and suppress the death signal transduction. By the anti-apoptotic function, rasagiline may rescue or protect declining neurons in aging and neurodegenerative disorders, such as Parkinson's disease.