Neuroprotective effects of riluzole in early phase Parkinson's disease on clinically relevant parameters in the marmoset MPTP model

The present study evaluates neuroprotection in a marmoset MPTP (1-methyl-1,2,3,6-tetrahydropyridine) model representing early Parkinson's disease (PD). The anti-glutamatergic compound riluzole is used as a model compound for neuroprotection. The compound is one of the few protective compounds used in the clinic for a neurodegenerative disorder.Marmoset monkeys were randomized into three groups of six: 1) an MPTP group receiving a total MPTP dose of 7 mg/kg (4 injections over two weeks, s.c.) 2) a riluzole group receiving besides MPTP, a twice daily dose of riluzole (10 mg/kg, p.o.), starting one week before MPTP and continuing for one week after the final MPTP injection and 3) a control group receiving saline instead of MPTP and riluzole. The marmosets' Parkinsonian symptoms were scored daily and their activity level, hand-eye coordination, jumping behavior, axial turning and night sleep parameters were tested and recorded weekly. At three weeks following the last MPTP challenge, brains were dissected and dopamine levels in the striatum and the tyrosine hydroxylase (TH) expressing dopamine (DA) neurons in the substantia nigra (SN) were compared. MPTP affected all behavioral parameters and sleep architecture and induced a relatively mild (50%) decline of DA neurons in the substantia nigra (SN). Riluzole relieved the Parkinsonian signs, and improved the hand-eye coordination as well as turning ability. Moreover, riluzole prevented the impact of MPTP on sleep architecture and rapid eye movement behavioral disorder (RBD). Riluzole also increased the number of surviving DA neurons in MPTP-treated marmosets to 75%. However, riluzole did not prevent the MPTP-induced impairments on locomotor activity and jumping activity.In conclusion, reduction of excitotoxicity by riluzole appeared to be effective in reducing progressive neurodegeneration and relieved several clinically relevant PD symptoms in an animal model representing the early phase of PD.     

Neuroprotection by tetrahydroxystilbene glucoside in the MPTP mouse model of Parkinson's disease

Our in vitro experiments suggested that tetrahydroxystilbene glucoside (TSG) affords a significant neuroprotective effect against MPP⁺-induced damage and apoptosis in PC12 cells though activation of the PI3K/Akt pathway. This study was aimed to investigate the potential neuroprotective effect of TSG in 1-methyl-4-phenyl-1,2,3,6-tetrahydropypridine (MPTP)-treated mouse model of Parkinson's disease (PD). We found that treatment of TSG protected dopaminergic neurons by preventing MPTP-induced decreases in substantia nigra tyrosine hydroxylase (TH)-positive cells and striatal dopaminergic transporter (DAT) protein levels. Furthermore, it was also associated with increasing striatal Akt and GSK3β phosphorylation, up-regulation of the Bcl-2/BAD ratio, and inhibition of the activation of caspase-9 and caspase-3. These results showed that TSG promoted dopamine neuron survival in vivo, the PI3K/Akt signaling pathway may have mediated the protection of TSG against MPTP, suggesting that TSG treatment might represent a neuroprotective treatment for PD.     

MPTP致帕金森模型小鼠海马区NGF基因的表达研究

目的检测帕金森(Parkinson’s disease,PD)模型小鼠海马区(hippocampus)神经生长因子(nerve growth factor,NGF)基因的表达。方法采用腹腔注射1-甲基-4-苯基-1,2,3,6-四氢吡啶(1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine,MPTP)建立PD小鼠模型;利用蛋白免疫印迹(Western blot)法和免疫荧光技术(immunofluorescence,IF)检测中脑酪氨酸羟化酶(tyrosine hydroxylase,TH)表达鉴定PD模型建立是否成功;采用足迹分析法和避暗法分别检测小鼠运动能力和认知能力;利用RT-PCR和原位杂交技术(in situ hybridization)检测小鼠海马区NGF基因的表达。结果与对照组相比,模型组的TH、NGF水平均降低,行为学指标偏离正常值,且差异有显著性。结论 NGF可能在PD认知障碍的病理学发生、发展过程中发挥重要作用。     

Sex differences in motor behavior in the MPTP mouse model of Parkinson's disease

Sex differences in Parkinson's disease (PD) have been reported in humans and rodent models, with a higher incidence in men and increased severity in male rodents. The current study examined sex differences and the effects of gonadal steroid hormones in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model of PD. Male (n = 51) and female (n = 50) mice were gonadectomized and received physiologic replacement with testosterone or estrogen (Experiment 1), or no hormones (Experiment 2). Two weeks later, mice received either MPTP (10 mg/kg per day for 5 days) or saline. Higher doses killed female mice. Mice were tested one week after MPTP for motor performance using rotarod, pole and gait tests. In hormone-treated mice, males significantly outperformed females in all three tests (p < 0.05). Compared with females, males had a greater overall rotarod performance (ORP: 1317.1 ± 98.3 vs. 988.1 ± 95.6), descended a pole faster (7.1 ± 0.6 vs. 9.6 ± 0.7 s), and had longer stride lengths (hindlimb 7.3 ± 0.1 vs. 6.8 ± 0.1 cm). By contrast, ovariectomized female mice receiving saline outperformed castrated males on the rotarod (1296.6 ± 83.3 vs. 811.2 ± 113.7, p < 0.05) and descended a pole faster (9.7 ± 2.0 vs. 15.6 ± 1.9 s, p < 0.05). MPTP significantly impaired ORP (p < 0.05) in hormone-treated males (703.7 ± 65.5) and females (432.8 ± 88.6, p < 0.05). After MPTP, stride length was selectively decreased in males (hindlimb 6.6 ± 0.1 cm, p < 0.05), and pole test performance was unimpaired in either sex. After gonadectomy, MPTP did not decrease motor performance in males (p > 0.05) but significantly reduced ORP in females (975.9 ± 110.3 vs. saline females, p < 0.05). Our results show that small, chronic doses of MPTP produce subtle, sexually-dimorphic impairments in motor performance, but without a loss of tyrosine hydroxylase-positive neurons in the substantia nigra. In gonadectomized mice, this sex difference is reversed.     

Apoptotic mechanisms and antiapoptotic therapy in the MPTP model of Parkinson's disease

The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model constitutes the best-characterized toxin paradigm for Parkinson's disease, faithfully replicating most of its clinical and pathological hallmarks. Many lines of evidence point to a significant contribution of apoptosis to cell death after application of 1-methyl-4-phenylpyridinium (MPP(+)) in cell culture or MPTP in vivo. This holds true for apoptotic DNA strand breaks, activation of the JNK pathway and caspases, induction of Par-4 protein and the protection conferred by interference with p53, Apaf-1 or Bax signalling. In MPTP models, intervention in upstream events of apoptosis, e.g. by inhibition of the JNK pathway, provides morphological and functional rescue. In contrast, inhibition of the propagation and execution phase of apoptosis, e.g. by inhibition of caspases, blocks or delays cell death but may not recover neuronal function. At this stage, the combination of an anti-apoptotic together with a neurorestorative therapy may be promising.     

The PPARgamma agonist pioglitazone is effective in the MPTP mouse model of Parkinson's disease through inhibition of monoamine oxidase B

BACKGROUND AND PURPOSE: The peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist pioglitazone has previously been shown to attenuate dopaminergic cell loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease, an effect attributed to its anti-inflammatory properties. In the present investigation, we provide evidence that pioglitazone is effective in the MPTP mouse model, not via an anti-inflammatory action, but through inhibition of MAO-B, the enzyme required to biotransform MPTP to its active neurotoxic metabolite 1-methyl-4-phenylpyridinium (MPP+). EXPERIMENTAL APPROACH: Mice were treated with pioglitazone (20 mg kg(-1) b.i.d. (twice a day), p.o., for 7 days), prior and post or post-MPTP (30 mg kg(-1) s.c.) treatment. Mice were then assessed for motor impairments on a beam-walking apparatus and for reductions in TH immunoreactivity in the substantia nigra and depletions in striatal dopamine. The effects of pioglitazone on striatal MPP+ levels and MAO-B activity were also assessed. KEY RESULTS: Mice treated with MPTP showed deficits in motor performance, marked depletions in striatal dopamine levels and a concomitant reduction in TH immunoreactivity in the substantia nigra. Pretreatment with pioglitazone completely prevented these effects of MPTP. However, pretreatment with pioglitazone also significantly inhibited the MPTP-induced production of striatal MPP+ and the activity of MAO-B in the striatum. CONCLUSIONS AND IMPLICATIONS: The neuroprotection observed with pioglitazone pretreatment in the MPTP mouse model was due to the blockade of the conversion of MPTP to its active toxic metabolite MPP+, via inhibition of MAO-B.     

松果菊苷对帕金森病模型小鼠黑质纹状体蛋白表达影响的双向电泳分析

目的观察松果菊苷对MPTP致小鼠帕金森病(PD)模型中对动物行为学和对黑质纹状体组织蛋白表达的影响,在蛋白质水平探讨松果菊苷的多巴胺能神经元保护作用机制。方法以MPTP损伤建立C57BL/6小鼠PD模型,通过自主活动实验和滚筒实验观察动物行为学表现,用双向电泳、图像分析、质谱鉴定等蛋白质组学技术研究松果菊苷对MPTP致小鼠PD模型行为学的影响和黑质纹状体组织蛋白表达的变化。结果①经MPTP诱导,小鼠的自主活动次数、滚筒运动潜伏期均低于对照组(P<0.01);经松果菊苷(20mg.kg-1)预处理后,MPTP诱导小鼠的行为学表现明显改善(P<0.01)。②经过双向电泳及PDQuest软件分析,硝酸银染色,对照组、模型组和松果菊苷给药组分别分离出282个、269个和236个的蛋白质斑点。对一个稳定差异表达的斑点进行MALDI-TOF质谱鉴定,数据库检索结果为胆绿素还原酶B。结论松果菊苷对MPTP致小鼠PD模型的行为学障碍具有改善作用,其神经保护作用机制可能与胆绿素还原酶B水平降低有关。     

Neuroprotective effect of kaempferol against a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of Parkinson's disease

In the present study, we investigated the neuroprotective effects of kaempferol in the mouse model of Parkinson's disease, which was induced by neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We confirmed that MPTP led to behavioral deficits, depletion of dopamine and its metabolites, reduction in superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity, and the elevation of malondialdehyde (MDA) levels in the substantia nigra. When administered prior to MPTP, kaempferol improved motor coordination, raised striatal dopamine and its metabolite levels, increased SOD and GSH-PX activity, and reduced the content of MDA compared with mice treated with MPTP alone. Immunohistochemical studies using anti-tyrosine hydroxylase (TH) antibody showed that medication of kaempferol could prevent the loss of TH-positive neurons induced by MPTP. Taken together, we propose that kaempferol has shown anti-parkinsonian properties in our studies. More work is needed to explore detailed mechanisms of action.     

Rapid effects of MPTP in the mouse colon

Mechanical responses of the mouse colon to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were measured in vitro. MPTP caused muscle relaxation with an onset time of about 10 s. This relaxation was inhibited by propranolol. Pretreatment of the animals with reserpine significantly reduced the MPTP-induced relaxation. These observations indicate that MPTP liberates a catecholamine (presumably noradrenaline) from nerve terminals in the colon wall. The mechanism underlying this effect is not yet clear but it appears that oxidation to 1-methyl-4-phenyl-pyridinium is not required.     

Behavioral and biochemical effects of nicotine in an MPTP-induced mouse model of Parkinson's disease

This study examined the effects of nicotine on locomotor activity and on the level of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum and olfactory tubercle of mice that had been treated with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP significantly lowered the spontaneous locomotor activity 1-2 weeks and 2 months after 2 injections of MPTP (30 mg/kg SC, 24 hr apart) in young adult (3 months) and old mice (22-24 months old). The effect of nicotine on locomotion was biphasic; an initial stimulation of locomotor (0-5 min after nicotine) followed by a depressant period lasting from 5 to 20 min after injection. Tolerance to the depressant effect of nicotine developed after the 5th day of daily injections of nicotine (0.4 mg/kg SC, twice daily). Tolerance did not occur by day 8 to the initial stimulatory effect of nicotine. A similar effect of nicotine on locomotor activity was seen in mice treated with MPTP. The levels of DOPAC and HVA in the striatum were reduced by about 20% in the chronic nicotine-treated animals. The levels of DOPAC, DA, and HVA were reduced in the MPTP-treated mice; however, acute and chronic nicotine did not cause an additional change in the amine levels. The results suggest that nicotine has an influence on locomotor activity in MPTP-treated mice and that this effect is not due to changes in DA receptor activity in the striatum caused by chronic nicotine.     

Neuroprotective effects of xanthone extract from Swertia punicea Hemsl against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of Parkinson’s disease

As a widely used traditional Chinese medicine (TCM), Swertia punicea Hemsl has exhibited effects on anti-hepatitis B virus (HBV), liver protection, hypoglycemic activity and cholecystitis. In this study, we confirmed that xanthone extract from Swertia punicea Hemsl (XSPH) improved the motor deficit, increased the levels of striatal dopamine (DA) and homovanilic acid (HVA), and alleviated the loss of tyrosine hydroxylase (TH)-positive neurons located in substantia nigra pars compacta (SNpc) in MPTP-induced mouse model of Parkinson’s disease (PD). In conclusion, the present results indicated that XSPH offered neuroprotective effects against the neurotoxicity of MPTP and it might be a potential treatment for PD.     

Neuroprotective profiles of anti-aging gene Klotho in Alzheimer disease mouse model

OBJECTIVE Alzheimer disease(AD) is the most common type of senile dementia. The anti-aging gene Klotho is reported to decline in the brain of patients and animals with AD. However, the role of Klotho in the progression of AD remains elusive. The present study explored the effects and underlying mechanism of Klotho in amyloid precursor protein/presenilin 1(APP/PS1) transgenic mice. METHODS The upregulation of cerebral Klotho expression was mediated by intracerebroventricular administration of a lentiviral vector that encoded Klotho(LV-KL) in APP/PS1 transgenicmice.RESULTS LV-KL significantly increased Klotho overexpression and effectively ameliorated cognitive deficits and AD-like pathology in aged AD mice. LV-KL might induce autophagy activation and protein kinase B/mammalian target of rapamycin inhibition in both AD mice and cultured BV2 murine microglia. Meanwhile, LV-KL altered the expression of low density lipoprotein receptor-related protein 1(LRP-1), receptor for advanced glycation end products, P-glycoprotein and ABCA1 both at the brain microvascular and choroid plexus as well as the contents of plasma s LRP-1 in aged AD mice.CONCLUSION The current results indicate that Klotho plays a crucial role in the clearance of cerebral amyloid β protein and the progression of AD in mice. These findings highlight the preventive and therapeutic potential of Klotho for the treatment of AD.     

Neuroprotective effects of a selective N-methyl-D-aspartate NR2B receptor antagonist in the 6-hydroxydopamine rat model of Parkinson's disease

1. Current pharmacotherapies for the treatment of Parkinson's disease (PD) are largely symptomatic and do not attenuate the characteristic nigral (dopamine) cell loss. 2. Using the 6-hydroxydopamine (6-OHDA) rat model of PD, we investigated the novel, potentially neuroprotective compound BZAD-01, which is an N-methyl-D-aspartate (NMDA) glutamate receptor antagonist selective for the NR2B subunit. 3. Forty female Sprague-Dawley rats were pretreated with either 10 mg/kg BZAD-01 or vehicle (5% sucrose and 0.1% ascorbate) in their drinking water for 11 days prior to and for 3 days following 6-OHDA surgery. During surgery, rats received an injection of either a toxic dose of 16 microg 6-OHDA or a non-toxic dose of 1 microg 6-OHDA (sham) into the medial forebrain bundle. A series of behavioural tests, including curling (measuring body axis bias), head position bias and narrow beam, was performed fortnightly for 8 weeks after surgery to assess the effects of BZAD-01 pretreatment on parkinsonism. Drug-induced rotational asymmetry was also assessed just before rats were killed. Post-mortem immunohistochemistry was performed to quantify the degree of nigral dopamine cell loss. 4. Pretreatment of 6-OHDA-lesioned rats with BZAD-01 significantly reduced the amount of dopamine cell loss and significantly improved all behavioural measures. Furthermore, there was no significant difference in any of the behavioural measures between lesioned rats pretreated with BZAD-01 and rats that underwent sham surgery.     

中药提取物CTE对MPTP所致帕金森病小鼠模型的神经保护作用

目的:研究中药提取物CTE对1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)所致帕金森病小鼠模型是否具有神经保护作用。方法:首先建立MPTP所致帕金森病小鼠模型,连续4 d给予MPTP(30 mg.kg-1,qd,ip)。用高低剂量(50和100 mg.kg-1,qd,ig)中药提取物CTE预处理MPTP所致帕金森模型小鼠。之后进行行为学检测,包括一般行为学检测和滚筒实验。最后,用HPLC-EC法测定纹状体中多巴胺(DA)及其代谢产物二羟苯乙酸(DOPAC)和高香草酸(HVA)含量。结果:在MPTP所致的帕金森病小鼠模型,中药提取物CTE能显著改善小鼠的行为能力;且能显著提高小鼠纹状体内多巴胺含量。结论:中药提取物CTE对MPTP所致帕金森病小鼠模型有神经保护作用。     

Neuroprotective effect of benzylideneacetophenone derivative on the MPTP model of neurodegeneration in mice

In this study, we investigated the neuroprotective effect of a benzylideneacetophenone derivative, JC3, in a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD). C57BL/6 mice were treated with MPTP (30 mg/kg, i.p.) for 5 consecutive days. JC3 (10 mg/kg, i.p.) treatment was initiated 2 h after the first administration of MPTP and then at 24-h intervals for 3 consecutive days. The mice were sacrificed for analyses 7 days after the last MPTP injection. Immunohistochemistry and Western blot were used to determine the expression levels of tyrosine hydroxylase (TH), dopamine transporter (DAT), OX-42 (a marker of microglial activation), and glial fibrillary acid protein (GFAP, a marker of astrocyte activation) in the substantia nigra (SN) and striatum (ST). The results of these experiments demonstrated that JC3 restored the decreased TH-immunoreactivity (IR) and DAT and JC3 attenuated the increase in OX-42, GFAP, and COX-2 on the SN and ST on day 7 post-MPTP injection. These results suggest that JC3 can be a neuroprotective agent in an MPTP-induced model of PD.     

Neuroprotective effects of TEMPOL in central and peripheral nervous system models of Parkinson's disease

TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl) is a stable nitroxyl antioxidant. Previous studies have suggested that TEMPOL is protective in acute disorders thought to involve reactive oxygen species (ROS), such as ischemic stroke and cardiac reperfusion injury. Oxidized TEMPOL can be recycled to its redox-active reducing form by co-administration with polynitroxylated albumin, making it a candidate as a pharmacological "reservoir" for reducing potential of use in chronic disorders involving ROS. The present studies examine the efficacy of TEMPOL in cell culture and animal models of the central and peripheral dysfunction associated with Parkinson's disease, a disorder in the pathogenesis of which ROS generated from dopamine have been implicated. Antioxidants have been proposed as both preventive and symptomatic therapy for Parkinson's disease. TEMPOL protects MN9D dopaminergic mesencephalic cells in culture from 6-hydroxydopamine (6-OHDA)-induced apoptosis. Translocation of the p65 component of NF-kappaB to the nucleus accompanies protection by TEMPOL. In vivo, intraperitoneal TEMPOL protects mice from intrastriatal 6-OHDA-induced cell and dopamine metabolite loss in the striatum. TEMPOL also protects mice against the 6-OHDA-induced rotational behavior elicited by intrastriatal administration of d-amphetamine. In addition, TEMPOL protects mice from the ptosis, activity level decrement, and mortality induced by intraperitoneal administration of 6-OHDA, a model of autonomic dysfunction in Parkinson's disease. Adjunctive use of polynitroxylated albumin enhances the in vitro and in vivo effects of TEMPOL.     

类叶升麻苷对MPTP所致帕金森病小鼠模型的神经保护作用

目的研究类叶升麻苷在MPTP诱导的C57小鼠的帕金森病(PD)模型中的神经保护作用及机制。方法通过自主活动实验和滚筒实验研究动物的行为表现,通过高效液相电化学检测方法观察脑纹状体多巴胺的变化,通过脑黑质酪氨酸羟化酶(tyroxinehydroxylase,TH)免疫组化染色观察多巴胺能神经元的损伤程度。并对黑质纹状体进行α-突触核蛋白(α-synuclein)的免疫印迹分析以探讨药物作用机制。结果①经MPTP诱导的C57小鼠,其自主活动次数、滚筒运动潜伏期均低于对照组(P<0·01);纹状体多巴胺含量明显降低(P<0·01);多巴胺能神经元数量明显减少;黑质纹状体α-synuclein蛋白水平下降。②经类叶升麻苷(10、30mg·kg-1)预处理后能明显改善MPTP诱导的C57小鼠的行为学表现,增加脑内多巴胺递质的含量,增加多巴胺能神经元的数量,增加黑质纹状体α-synuclein蛋白水平。结论类叶升麻苷具有神经保护作用,能对抗MPTP诱导的C57小鼠PD模型中的神经损伤。其机制可能与上调α-synuclein蛋白水平有关。