Delayed Treatment with Arundic Acid Reduces the MPTP-induced Neurotoxicity in Mice

The authors investigated the protective effects of a novel astrocyte-modulating agent, arundic acid, in a 1-methyl-4-phenyl-1,2,3,6-tetrahyropyridine (MPTP) mouse model of Parkinson’s disease. Male mice received four intraperitoneal (i.p.) injections of MPTP (20 mg/kg) at 2 h intervals. The content of dopamine and its metabolites in the striatum was reduced markedly 7 days after MPTP treatment. The delayed treatment with arundic acid (30 mg/kg, i.p.) administered 3, 4, 5 and 6 days after MPTP treatment did not affect the depletion of dopamine and its metabolites in the striatum. Our immunohistochemical study with anti-tyrosine hydroxylase antibody, anti-neuronal nuclei antibody, anti-glial fibrillary acidic protein antibody, anti-S100β antibody and anti-nestin antibody showed that the delayed treatment with arundic acid had a protective effect against MPTP-induced neuronal damage in the striatum and the substantia nigra of mice. Furthermore, this agent ameliorated the severe reductions in number of isolectin reactive microglia in the striatum and the substantia nigra 7 days after MPTP treatment. These results demonstrate that the inhibition of S100β synthesis in astrocytes may be the major component of the beneficial effect of arundic acid. Thus, our present findings provide that the therapeutic strategies targeted to astrocytic modulation with arundic acid offers a great potential for restoring the functional capacity of the surviving dopaminergic neurons in individuals affected with Parkinson’s disease.     

Systemic Administration of Proteasome Inhibitor Protects Against MPTP Neurotoxicity in Mice

Dysfunction of the proteasome has been suggested to contribute in the degeneration of nigrostriatal dopaminergic neurons. Here, we investigated to determine whether systematic administration of proteasome inhibitor, carbobenzoxy-l-γ-t-butyl-l-glutamyl-l-alanyl-l-leucinal (PSI) protects against MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) neurotoxicity in mice. Three administrations of MPTP at 1-h intervals to mice reduced significantly the concentration of dopamine, DOPAC (3,4-dihydroxyphenylacetic acid) and HVA (homovanillic acid) in the striatum after 5 days. In contrast, PSI (0.3 and 1.0 mg/kg) prevented a significant decrease in dopamine, DOPAC and HVA contents of the striatum 5 days after MPTP treatment. In our Western blot analysis study, PSI at a dose of 1.0 mg/kg prevented a significant decrease in TH (tyrosine hydroxylase) protein and a significant increase in glial fibrillary acidic protein 5 days after MPTP treatment. Furthermore, our immunohistochemical study showed that PSI at a dose of 1.0 mg/kg prevented a significant loss in TH immunopositive neurons in the striatum and substantia nigra 5 days after MPTP treatment. In contrast, PSI caused a significant increase in the number of intense ubiquitin immunopositive cells in the striatum and substantia nigra 5 days after MPTP treatment. These results indicate that proteasome inhibitors can protect against MPTP neurotoxicity in mice. The neuroprotective effect of PSI against dopaminergic cell damage may be mediated by the elevation of ubiquitination. Thus, our findings provide further valuable information for the pathogenesis of Parkinson’s disease. Takuya Oshikawa and Hayato Kuroiwa contributed equally to this work.     

Identification and kainic acid-induced up-regulation of low-affinity p75 neurotrophin receptor (p75NTR) in the nigral dopamine neurons of adult rats

Parkinson's disease is a common and severe debilitating neurological disease that results from massive and progressive degenerative death of dopamine neurons in the substantia nigra, but the mechanisms of neuronal degeneration and disease progression remains largely obscure. We are interested in possible implications of low-affinity p75 neurotrophin receptor (p75NTR), which may mediate neuronal apoptosis in the central nervous system, in triggering cell death of the nigral dopamine neurons. The RT-PCR and immunohistochemistry were carried out to detect if p75NTR is expressed in these nigral neurons and up-regulated by kainic acid (KA) insult in adult rats. It revealed p75NTR-positive immunoreactivity in the substantia nigra, and co-localization of p75NTR and tyrosine hydroxylase (TH) was found in a large number of substantia nigra neurons beside confirmation of p75NTR in the choline acetyltransferase (ChAT)-positive forebrain neurons. Cell count data further indicated that about 47-100% of TH-positive nigral neurons and 98-100% of ChAT-positive forebrain neurons express p75NTR. More interestingly, significant increasing in both p75NTR mRNA and p75NTR-positive neurons occurred rapidly following KA insult in the substantia nigra of animal model. The present study has provided first evidence on p75NTR expression and KA-inducing p75NTR up-regulation in substantia nigra neurons in rodent animals. Taken together with previous data on p75NTR functions in neuronal apoptosis, this study also suggests that p75NTR may play important roles in neuronal cell survival or excitotoxic degeneration of dopamine neurons in the substantia nigra in pathogenesis of Parkinson's disease in human beings.     

MTH1, an oxidized purine nucleoside triphosphatase, protects the dopamine neurons from oxidative damage in nucleic acids caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

We previously reported that 8-oxoguanine (8-oxoG) accumulates in the cytoplasm of dopamine neurons in the substantia nigra of patients with Parkinson's disease and the expression of MTH1 carrying an oxidized purine nucleoside triphosphatase activity increases in these neurons, thus suggesting that oxidative damage in nucleic acids is involved in dopamine neuron loss. In the present study, we found that levels of 8-oxoG in cellular DNA and RNA increased in the mouse nigrostriatal system during the tyrosine hydroxylase (TH)-positive dopamine neuron loss induced by the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MTH1-null mice exhibited a greater accumulation of 8-oxoG in mitochondrial DNA accompanied by a more significant decrease in TH and dopamine transporter immunoreactivities in the striatum after MPTP administration, than in wild-type mice. We thus demonstrated that MTH1 protects the dopamine neurons from oxidative damage in the nucleic acids, especially in the mitochondrial DNA of striatal nerve terminals of dopamine neurons.     

Pramipexole protects against MPTP toxicity in non-human primates

The neurotoxin MPTP induces nigral dopaminergic cell death in primates and produces a partial model of Parkinson's disease (PD). Pramipexole is a D2/D3 dopamine receptor agonist used in the symptomatic treatment of PD, and which also protects neuronal cells against dopaminergic toxins in vitro. We now demonstrate that pramipexole partially prevents MPTP toxicity in vivo in a primate species. Common marmosets were repeatedly treated with pramipexole either before, coincidentally with, or after low-dose MPTP treatment designed to induce a partial lesion of the substantia nigra. Animals pretreated with pramipexole had a significantly greater number of surviving tyrosine hydroxylase (TH) positive neurones in the pars compacta of the substantia nigra. Pramipexole pretreatment also prevented degeneration of striatal dopamine terminals. Treatment with pramipexole concurrently with MPTP or following MPTP did not prevent TH-positive cell loss. Pramipexole pretreatment appears to induce adaptive changes that protect against dopaminergic cell loss in primates.     

Dopamine synthesis by non-dopaminergic neurons of the rat fetus arquate nucleus

Our hypothesis was tested in respect to dopamine synthesis by non-dopaminergic neurons expressing individual complementary enzymes of the DA synthetic pathway. According to the hypothesis, L-dihydroxyphenylalanine (L-DOPA) synthesised in tyrosine hydroxylase(TH)-expressing neurons for conversion to dopamine. The mediobasal hypothalamus of rats on the 21st embryonic day was used as an experimental model. The fetal substantia nigra containing dopaminergic neurons served as control. Dopamine and L-DOPA were measured by high performance liquid chromatography in cell extracts and incubation medium in presence or absence of L-tyrosine. L-tyrosine administration increased L-DOPA synthesis in the mediobasal hypothalamus and substantia nigra. Moreover, L-tyrosine provoked an increase of dopamine synthesis in substantia nigra and a decrease in the mediobasal hypothalamus. This is, probably, due to an L-tyrosine-induced competitive inhibition of the L-DOPA transport to monoenzymatic AADC neurons after its release from the monoenzymatic TH neurons. This study provides a convincing evidence of dopamine synthesis by non-dopaminergic neurons expressing TH or AADC, in cooperation.     

Time-course of nigrostriatal degeneration in a progressive MPTP-lesioned macaque model of parkinson’s disease

Parkinson’s disease (PD) is characterized by a progressive loss of substantia nigra pars compacta (SNc) neurons. The onset of clinical symptoms only occurs after the degeneration has exceeded a certain threshold. In most of the current 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) nonhuman primate models, nigrostriatal lesions and the onset of PD symptoms are the result of an immediate neuronal degeneration in the SNc caused by acute injection of the toxin. In order to develop a model that more closely mimics the degeneration pattern of human PD, we eventually established a protocol that produces a progressive parkinsonian state by treating monkeys repeatedly with MPTP for 15 ± 2 d. Mean onset of parkinsonian symptoms occurred after 13.2 d of treatment. At this time, 56.8 ± 6.3% of tyrosine hydroxylase immunoreactive neurons and 75.2 ± 6.2% of Nissl-stained cells remained in the SNc. Striatal dopamine transporter (DAT) binding and dopamine (DA) content decreased to 19.7 ± 4.9% and 18.2 ± 5.6% of untreated monkeys. Parallel ¹²³I-PEI single-photon emission computed tomography (SPECT) imaging in living animals showed a similar decrease in striatal DAT binding. In this article, we examine how this and other chronic MPTP models fit with human pathology.     

Neurochemical Evidence for Agmatine Modulation of 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP) Neurotoxicity

Agmatine treatment is known to exert neuroprotective effects in several models of neurotoxic and ischemic brain and spinal cord injuries. Here we sought to find out whether agmatine treatment would also prove to be neuroprotective in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson’s disease. Concomitant daily treatment (intraperitoneal injections) with agmatine (100 mg/kg for 5 days) and MPTP (40 mg/kg for 2 days) exacerbated MPTP-related toxicity as evidenced by a larger reduction in dopamine uptake into striatal synaptosomes (42.4% as compared to 58.3% of control, respectively). In contrast, agmatine treatment commencing after MPTP, produced partial protection (31%) against MPTP dopaminergic toxicity. The findings implicate agmatine in mechanisms regulating MPTP neurotoxicity, but underscore the characteristic neuroprotective efficacy of agmatine when applied after the insult.     

Mapping P2X and P2Y receptor proteins in striatum and substantia nigra: An immunohistological study

Our work aimed to provide a topographical analysis of all known ionotropic P2X_1–7 and metabotropic P2Y_{1,2,4,6,11–14} receptors that are present in vivo at the protein level in the basal ganglia nuclei and particularly in rat brain slices from striatum and substantia nigra. By immunohistochemistry-confocal and Western blotting techniques, we show that, with the exception of P2Y_11,13 receptors, all other subtypes are specifically expressed in these areas in different amounts, with ratings of low (P2X_5,6 and P2Y_1,6,14 in striatum), medium (P2X₃ in striatum and substantia nigra, P2X_6,7 and P2Y₁ in substantia nigra) and high. Moreover, we describe that P2 receptors are localized on neurons (colocalizing with neurofilament light, medium and heavy chains) with features that are either dopaminergic (colocalizing with tyrosine hydroxylase) or GABAergic (colocalizing with parvalbumin and calbindin), and they are also present on astrocytes (P2Y_2,4, colocalizing with glial fibrillary acidic protein). In addition, we aimed to investigate the expression of P2 receptors after dopamine denervation, obtained by using unilateral injection of 6-hydroxydopamine as an animal model of Parkinson’s disease. This generates a rearrangement of P2 proteins: most P2X and P2Y receptors are decreased on GABAergic and dopaminergic neurons, in the lesioned striatum and substantia nigra, respectively, as a consequence of dopaminergic denervation and/or neuronal degeneration. Conversely, P2X_1,3,4,6 on GABAergic neurons and P2Y₄ on astrocytes augment their expression exclusively in the lesioned substantia nigra reticulata, probably as a compensatory reaction to dopamine shortage. These results disclose the presence of P2 receptors in the normal and lesioned nigro-striatal circuit, and suggest their potential participation in the mechanisms of Parkinson’s disease.     

Effects of Hydroxysafflor Yellow A in the Attenuation of MPTP Neurotoxicity in Mice

Parkinson’s disease (PD) is a progressive neurodegenerative disorder whose etiology is not understood. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mouse model is widely used for studying PD. The present study was undertaken to investigate the effect of hydroxysafflor yellow A (HSYA) on MPTP-induced neurotoxicity in mice. Pretreatment with HSYA at a dose of 2, 8 mg/kg for a week was followed by intraperitoneal injection with MPTP (30 mg/kg) for five consecutive days. Next, the subsequent behavior, biochemical index and immunohistochemical manifestations in mice were determined. Behavioral testing showed that MPTP-treated mice exhibited motor deficits but HSYA at dose of 8 mg/kg prevented the appearance of motor abnormalities. Treatment with HSYA at dose of 8 mg/kg attenuated the reduction of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in striatum. It also showed that the activity of SOD, catalase activity and GSH levels were significantly higher, while the levels of malondialdehyde (MDA) and hydroxyl radicals was lower, in the HSYA-treated mice compared to the MPTP-treated mice. The MPTP-treated mice exhibited the loss of tyrosine hydroxylase-containing dopaminergic neurons in substantia nigra. However, HSYA-treated mice showed a protective effect. Our results indicated that HSYA possesses neuroprotective effects and is a promising anti-Parkinson’s disease drug which is worthy of further study.     

A Highlights from MBoC Selection: Peptide TFP5/TP5 derived from Cdk5 activator P35 provides neuroprotection in the MPTP model of Parkinson’s disease

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by the loss of dopamine neurons in the substantia nigra, decreased striatal dopamine levels, and consequent extrapyramidal motor dysfunction. Recent evidence indicates that cyclin-dependent kinase 5 (Cdk5) is inappropriately activated in several neurodegenerative conditions, including PD. To date, strategies to specifically inhibit Cdk5 hyperactivity have not been successful without affecting normal Cdk5 activity. Previously we reported that TFP5 peptide has neuroprotective effects in animal models of Alzheimer’s disease. Here we show that TFP5/TP5 selective inhibition of Cdk5/p25 hyperactivation in vivo and in vitro rescues nigrostriatal dopaminergic neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP/MPP+) in a mouse model of PD. TP5 peptide treatment also blocked dopamine depletion in the striatum and improved gait dysfunction after MPTP administration. The neuroprotective effect of TFP5/TP5 peptide is also associated with marked reduction in neuroinflammation and apoptosis. Here we show selective inhibition of Cdk5/p25 ­hyperactivation by TFP5/TP5 peptide, which identifies the kinase as a potential therapeutic target to reduce neurodegeneration in Parkinson’s disease.     

Mitophagy,a Form of Selective Autophagy,Plays an Essential Role in Mitochondrial Dynamics of Parkinson’s Disease

Cellular and Molecular Neurobiology - Parkinson’s disease (PD) is a severe neurodegenerative disorder caused by the progressive loss of dopaminergic neurons in the substantia nigra and...     

Protection by pioglitazone in the MPTP model of Parkinson's disease correlates with I kappa B alpha induction and block of NF kappa B and iNOS activation

Inflammation has been implicated in the pathogenesis of Parkinson's disease (PD). In the chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD, inducible NO synthase (iNOS) derived nitric oxide (NO) is an important mediator of dopaminergic cell death. Ligands of the peroxisome proliferator-activated receptor (PPAR) exert anti-inflammatory effects. We here investigated whether pioglitazone, a PPARgamma agonist, protected mice from MPTP-induced dopaminergic cell loss, glial activation, and loss of catecholamines in the striatum. As shown by western blot, PPARgamma was expressed in the striatum and the substantia nigra of vehicle- and MPTP-treated mice. Oral administration of 20 mg/(kg day) of pioglitazone protected tyrosine hydroxylase (TH)-positive substantia nigra neurons from death induced by 5 x 30 mg/kg MPTP. However, the decrease of dopamine in the striatum was only partially prevented. In mice treated with pioglitazone, there were a reduced activation of microglia, reduced induction of iNOS-positive cells and less glial fibrillary acidic protein positive cells in both striatum and substantia nigra pars compacta. In addition, treatment with pioglitazone almost completely blocked staining of TH-positive neurons for nitrotyrosine, a marker of NO-mediated cell damage. Because an increase in inhibitory protein-kappa-Balpha (IkappaBalpha) expression and inhibition of translocation of the nuclear factor kappaB (NFkappaB) subunit p65 to the nucleus in dopaminergic neurons, glial cells and astrocytes correlated with the protective effects of pioglitazone, our results suggest that pioglitazone sequentially acts through PPARgamma activation, IkappaBalpha induction, block of NFkappaB activation, iNOS induction and NO-mediated toxicity. In conclusion, treatment with pioglitazone may offer a treatment opportunity in PD to slow the progression of disease that is mediated by inflammation.     

Protective action of the peroxisome proliferator-activated receptor-gamma agonist pioglitazone in a mouse model of Parkinson's disease

We examined the effect of pioglitazone, a peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist of the thiazolidinedione class, on dopaminergic nerve cell death and glial activation in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. The acute intoxication of C57BL/6 mice with MPTP led to nigrostriatal injury, as determined by tyrosine hydroxylase (TH) immunocytochemistry, and HPLC detection of striatal dopamine and metabolites. Damage to the nigrostriatal dopamine system was accompanied by a transient activation of microglia, as determined by macrophage antigen-1 (Mac-1) and inducible nitric oxide synthase (iNOS) immunoreactivity, and a prolonged astrocytic response. Orally administered pioglitazone (approximately 20 mg/kg/day) attenuated the MPTP-induced glial activation and prevented the dopaminergic cell loss in the substantia nigra pars compacta (SNpc). In contrast, there was little reduction of MPTP-induced dopamine depletion, with no detectable effect on loss of TH immunoreactivity and glial response in the striatum of pioglitazone-treated animals. Low levels of PPARgamma expression were detected in the ventral mesencephalon and striatum, and were unaffected by MPTP or pioglitazone treatment. Since pioglitazone affects primarily the SNpc in our model, different PPARgamma-independent mechanisms may regulate glial activation in the dopaminergic terminals compared with the dopaminergic cell bodies after acute MPTP intoxication.     

Overexpression of parkin ameliorates dopaminergic neurodegeneration induced by 1- methyl-4-phenyl-1,2,3,6-tetrahydropyridine in mice

Mutations in the parkin gene are currently thought to be the most common cause of recessive familial Parkinsonism. Parkin functions as an E3 ligase to regulate protein turnover, and its function in mitochondrial quality control has been reported recently. Overexpression of parkin has been found to prevent neuronal degeneration under various conditions both in vivo and in vitro. Here, we generated a transgenic mouse model in which expression of wild type parkin was driven by neuron-specific enolase (NSE) promoter. We reported that both young and old parkin transgenic mice exhibited less reduction of striatal TH protein and number of TH positive neurons in the substantia nigra induced by 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP), compared to wild type littermates. MPTP-induced mitochondrial impairment in the substantia nigra was improved in young parkin transgenic mice. Decreased striatal α-synuclein was demonstrated in old parkin transgenic mice. These results provide reliable evidence from the transgenic mouse model for parkin that overexpression of parkin may attenuate dopaminergic neurodegeneration induced by MPTP through protection of mitochondria and reduction of α-synuclein in the nigrostriatal pathway.     

Therapeutic Effect of Hydrogen Sulfide-Releasing L-Dopa Derivative ACS84 on 6-OHDA-Induced Parkinson’s Disease Rat Model

Parkinson’s disease (PD), characterized by loss of dopaminergic neurons in the substantia nigra, is a neurodegenerative disorder of central nervous system. The present study was designed to investigate the therapeutic effect of ACS84, a hydrogen sulfide-releasing-L-Dopa derivative compound, in a 6-hydroxydopamine (6-OHDA)-induced PD model. ACS84 protected the SH-SY5Y cells against 6-OHDA-induced cell injury and oxidative stress. The protective effect resulted from stimulation of Nrf-2 nuclear translocation and promotion of anti-oxidant enzymes expression. In the 6-OHDA-induced PD rat model, intragastric administration of ACS84 relieved the movement dysfunction of the model animals. Immunofluorescence staining and High-performance liquid chromatography analysis showed that ACS84 alleviated the loss of tyrosine-hydroxylase positive neurons in the substantia nigra and the declined dopamine concentration in the injured striatums of the 6-OHDA-induced PD model. Moreover, ACS84 reversed the elevated malondialdehyde level and the decreased glutathione level in vivo. In conclusion, ACS84 may prevent neurodegeneration via the anti-oxidative mechanism and has potential therapeutic values for Parkinson’s disease.     

环加氧酶-2对帕金森病小鼠黑质多巴胺能神经元的影响

目的和方法 :选用C5 7BL种系环加氧酶 2 (cyclooxygenase 2 ,COX 2 )缺陷小鼠 ,腹腔注射 1 甲基 4 苯基 1,2 ,3,6 四氢吡啶 (MPTP)制备帕金森病小鼠模型 ,用免疫组织化学方法观察COX 2对帕金森病小鼠黑质多巴胺能神经元的影响。结果 :行为学及免疫组织化学观察显示 ,野生型帕金森病小鼠的死亡率明显高于COX 2缺陷杂合子帕金森病小鼠 (P <0 .0 1) ,野生型帕金森病小鼠黑质致密部酪氨酸羟化酶 (tyrosinehydroxylase,TH)免疫反应阳性神经元数目较杂合子帕金森病小鼠明显减少 (P <0 .0 1)。结论 :COX 2可能与帕金森病时黑质多巴胺能神经元的损伤有关     

Granulocyte-colony stimulating factor is neuroprotective in a model of Parkinson's disease

We have recently shown that the hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) is neuroprotective in rodent stroke models, and that this action appears to be mediated via a neuronal G-CSF receptor. Here, we report that the G-CSF receptor is expressed in rodent dopaminergic substantia nigra neurons, suggesting that G-CSF might be neuroprotective for dopaminergic neurons and a candidate molecule for the treatment of Parkinson's disease. Thus, we investigated protective effects of G-CSF in 1-methyl-4-phenylpyridinium (MPP+)-challenged PC12 cells and primary neuronal midbrain cultures, as well as in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease. Substantial protection was found against MPP+-induced dopaminergic cell death in vitro. Moreover, subcutaneous application of G-CSF at a dose of 40 microg/Kg body weight daily over 13 days rescued dopaminergic substantia nigra neurons from MPTP-induced death in aged mice, as shown by quantification of tyrosine hydroxylase-positive substantia nigra cells. Using HPLC, a corresponding reduction in striatal dopamine depletion after MPTP application was observed in G-CSF-treated mice. Thus our data suggest that G-CSF is a novel therapeutic opportunity for the treatment of Parkinson's disease, because it is well-tolerated and already approved for the treatment of neutropenic conditions in humans.     

Gene disruption of caspase-3 prevents MPTP-induced Parkinson's disease in mice

The development of Parkinson’s disease is accompanied by concurrent activation of caspase-3 and apoptosis of dopaminergic neurons of human patients and rodent models. The role of caspase-3, a final executioner of apoptosis, in the pathogenesis of Parkinson’s disease, however, remains to be determined. Here, we show that gene disruption of caspase-3 protects mice from 1-methyle-4-phenyl-1,2,3,6-tetrahmydropyridine (MPTP)-induced Parkinsonian syndrome, as reflected by reversal of MPTP-induced bradykinesia and decreased tyrosine hydroxylase expression in the nigra-striatum. MPTP treatment resulted in increased caspase-3 activation and apoptosis in the substantia nigra of wild-type mice at 24 h after the inception of MPTP treatment, as compared with vehicle-treated control animals. Gene disruption of caspase-3 prevented MPTP-induced apoptosis in the substantia nigra. At 7 days after MPTP treatment, tyrosine hydroxylase expression was suppressed and infiltration of activated microglia and astrocytes was markedly increased in the nigra-striatum of wild-type mice. All of these alterations following MPTP treatment were blocked by disruption of caspase-3 in mice. These results clearly indicate that caspase-3 activation is required for the development of MPTP-induced Parkinson’s disease in mice. These findings suggest that activation of caspase-3-mediated apoptosis of dopaminergic neurons in the early stage may play an important role in the pathogenesis of Parkinson’s disease.