Neuroprotective effect of metformin in MPTP-induced Parkinson's disease in mice.

Metformin a well known antidiabetic drug has been recently investigated and proposed to promote neurogenesis and enhance the spatial memory formation. In the present study, we aim to investigate the neuroprotective effect of metformin with respect to Parkinson's disease (PD). MPTP (Sigma-Aldrich, St. Louis, MO, USA) (25mg/kg) along with Probenecid (250 mg/kg) was administrated for five consecutive days to induce Parkinsonism in mice. Metformin 500 mg/kg was administrated orally for 21 days. Motor co-ordination and locomotor activities were evaluated by rotarod and open-field tests. The oxidative stress levels were assessed by estimating the activity of superoxide dismutase (SOD), reduced glutathione (GSH), catalase (CAT) and lipid peroxidation (LPO) specifically in the midbrain. Dopaminergic degeneration was evaluated by analyzing the tyrosine hydroxylase (TH) by immunostaining and nissl staining of the substantia nigra (SN) region of the brain. In addition brain-derived neurotrophic factor (BDNF) was also estimated. Our findings demonstrated that long-term metformin treatment resulted in significant improvement of the locomotor and muscular activities in MPTP-treated mice than acute treatment. Metformin treatment significantly improved the antioxidant activity as compared to MPTP-treated group. TH-positive cells decreased up to 16% in MPTP-treated mice as compared to normal mice (P<0.001) and were found to be protected from degeneration in metformin-treated mice (47%, P<0.01). Interestingly, BDNF levels were found to be significantly elevated in metformin treatment group as compared to MPTP treatment mice (P<0.001). In conclusion, metformin possesses neuroprotective activity and provides preclinical support for therapeutic prospective of this compound in the treatment of PD.

Patil SP ，Jain PD ，Ghumatkar PJ ，Tambe R ，Sathaye S ... -  《-》

Therapeutic effects of paeonol on methyl-4-phenyl-1,2,3,6-tetrahydropyridine/probenecid-induced Parkinson's disease in mice.

Shi X ，Chen YH ，Liu H ，Qu HD ... -  《-》

Neuroprotective effects of madecassoside in early stage of Parkinson's disease induced by MPTP in rats.

In this study, we investigated the neuroprotective effects of madecassoside, isolated from the Chinese medicinal herb Centella asiatica, in the rat model of early phase of parkinsonism. During intragastric administrations of madecassoside for 7 days, the rats were injected with MPTP on the 7th day. And for the following 14 days, madecassoside were also administered. On the 14th day, the behavioral tests were assessed after 1h of administration. And then, the rats were sacrificed, substantia nigra and striatum were dissected. The content of DA, MDA, GSH, and Bcl-2/Bax gene expression levels and BDNF protein level was determined. Treatment with madecassoside was found to improve locomotor dysfunction and to protect dopaminergic neuron by antagonizing MPTP induced neurotoxicity. Madecassoside significantly attenuated the MPTP-induced reduction of dopamine in the striatum. The MDA contents were significantly decreased while the GSH levels, Bcl-2/Bax ratio and protein expression of BDNF were significantly increased in madecassoside treated groups. These results indicated that madecassoside was effective in recovering MPTP-induced early signs of parkinsonism via its neuroprotective effects including reversing the depletion of DA, antioxidant activity, increasing ratio of Bcl-2/Bax, increasing protein expression of BDNF.

Xu CL ，Qu R ，Zhang J ，Li LF ，Ma SP ... -  《-》

The influence and the mechanism of docosahexaenoic acid on a mouse model of Parkinson's disease.

This study aimed to investigate the effects of docosahexaenoic acid (DHA) on the oxidative stress that occurs in an experimental mouse model of Parkinson's disease (PD). An experimental model of PD was created by four intraperitoneal injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (4 × 20 mg/kg, at 12h intervals). Docosahexaenoic acid was given daily by gavage for 4 weeks (36 mg/kg/day). The motor activity of the mice was evaluated via the pole test, and the dopaminergic lesion was determined by immunohistochemical analysis for tyrosine hydroxylase (TH)-immunopositive cells. The activity of antioxidant enzymes in the brain were determined by spectrophotometric assays and the concentration of thiobarbituric acid-reactive substances (TBARS) were measured as an index of oxidative damage. The number of apoptotic dopaminergic cells significantly increased in MPTP-treated mice compared to controls. Although DHA significantly diminished the number of cell deaths in MPTP-treated mice, it did not improve the decreased motor activity observed in the experimental PD model. Docosahexaenoic acid significantly diminished the amount of cell death in the MPTP+DHA group as compared to the MPTP group. TBARS levels in the brain were significantly increased following MPTP treatment. Glutathione peroxidase (GPx) and catalase (CAT) activities of brain were unaltered in all groups. The activity of brain superoxide dismutase (SOD) was decreased in the MPTP-treated group compared to the control group, but DHA treatment did not have an effect on SOD activity in the MPTP+DHA group. Our current data show that DHA treatment exerts neuroprotective actions on an experimental mouse model of PD. There was a decrease tendency in brain lipid oxidation of MPTP mice but it did not significantly.

Ozsoy O ，Seval-Celik Y ，Hacioglu G ，Yargicoglu P ，Demir R ，Agar A ，Aslan M ... -  《-》

Neuroprotective effects of stemazole in the MPTP-induced acute model of Parkinson's disease: Involvement of the dopamine system.

Parkinson's disease is a neurodegenerative disorder characterized by a loss of nigrostriata dopaminergic neurons, which has been thought, at least in part, to result from oxidative stress. The present study aims to investigate the neuroprotective effects of stemazole (ST) on the dopamine (DA) system and its possible mechanisms of action in a mouse model of PD. Mice were injected intraperitoneally with MPTP (20mg/kg) four times at 2-h intervals for one day to induce Parkinsonism, and then treated with ST (10, 30 and 50mg/kg) or Madopar (120mg/kg) for 7days. Behavioral analyses were performed with locomotor activity measures and rotarod test. Tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels were detected by immunohistochemistry method. DA and its metabolites were determined by high-performance liquid chromatography with an electrochemical detector. Oxidative stress levels were assessed by measuring the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX). Our results demonstrated that ST treatment improved locomotor activity and motor coordination in MPTP mice. There was also a significant increase in TH-positive cells (∼24%, P<0.01) and DAT levels (∼26%, P<0.01) in MPTP mice treated with ST (50mg/kg) compared with the vehicle group. Madopar treatment showed weaker effects on TH-positive cells (∼21%, P<0.05) and DAT levels (∼21%, P<0.05). DA and its metabolite levels were significantly increased with ST (50mg/kg) treatment (P<0.01, compared with the vehicle group). In addition, SOD and GSH-PX activities were elevated notably in ST treatment groups compared with the vehicle group. In conclusion, these results suggest that ST has neuroprotective effect on the impaired DA system, potentially through enhancement of the cell's anti-oxidative capacity. Hence it may be used as a potential therapeutic agent for Parkinson's disease.

Guo Z ，Xu S ，Du N ，Liu J ，Huang Y ，Han M ... -  《-》