Analysis of pramipexole dose-response relationships in Parkinson's disease.

BACKGROUND: Pramipexole (PPX), a non-ergot dopamine receptor agonist, is a first-line treatment for Parkinson's disease (PD). A critical dose level above which a better benefit-to-harm ratio exists has not been examined. METHODS: Chinese PD patients (n=464) were retrospectively analyzed by PPX maintenance dose, PD stage, combined levodopa dose, and baseline tremor contribution. The sum score of Baseline Activities of Daily Living (part II) and Motor Examination (III) of the Unified Parkinson's Disease Rating Scale (UPDRS II+III) was used as a covariate for final score adjustment. RESULTS: Sustained-release (SR) and immediate-release (IR) PPX showed similar efficacy based on score changes at 18 weeks, with comparable tolerability. Approximately two-third of patients received PPX at ≥1.5 mg/d, and one fourth of patients had ≥20% tremor contribution to UPDRS II+III. After treatment, patients receiving PPX ≥1.5 mg/d showed better improvement in UPDRS II+III scores (P=0.0025), with similar trends with the IR and SR formulations. Patients with ≥20% tremor contribution showed better improvement in UPDRS II+III scores (P=0.0017). No differences were seen based on PD stage or combined levodopa dose. The overall proportions of adverse events (AEs) were similar. More patients discontinued because of intolerable side effects, and more investigator-defined drug-related AEs were recorded in the <1.5 mg/d subgroup. CONCLUSION: UPDRS II+III improvement was better with PPX ≥1.5 than with <1.5 mg/d in Chinese PD patients after 18 weeks of treatment, with similar trends seen with IR and SR formulations. The frequency of AEs in PPX ≥1.5 and <1.5 mg/d subgroups was similar.

Rotigotine in the treatment of primary restless legs syndrome: A meta-analysis of randomized placebo-controlled trials.

The aim of this study was to summarize the efficacy and tolerability of rotigotine in the treatment of primary restless legs syndrome (RLS). PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for English-language randomized controlled trials (RCTs) that assessed the effectiveness of rotigotine for RLS. The pooled mean change from baseline in International RLS (IRLS) Study Group Rating Scalescore and relative risk (RR) of response based on the Clinical Global Impression-Improvement (CGI-I) scale score were applied to evaluate the outcomes. The pooled proportions of adverse events (AEs) were also estimated. Six RCTs were included. The meta-analysis showed a favorable effectiveness of rotigotine versus placebo on RLS [mean change on IRLS score: mean difference (MD)=-4.80; 95% confidence interval (CI): -5.90 to -3.70; P<0.00001 and RR of response on CGI-I was 2.19; 95% CI: 1.86 to 2.58, P<0.00001]. The most common AEs were application site reactions, nausea, headache and fatigue. In general, rotigotine was well-tolerated in patients with primary RLS. Based on the findings from the meta-analysis, rotigotine was more significantly efficacious in the treatment of RLS than placebo. Nevertheless, long-term studies and more evidence of comparisons of rotigotine with other dopamine agonists are needed.

Changes of c-fos, malondialdehyde and lactate in brain tissue after global cerebral ischemia under different brain temperatures.

Under global cerebral ischemia, the effect of different brain temperature on cerebral ischemic injury was studied. Male Sprague-Dawley rats were divided into normothermic (37-38°C) ischemia, mild hypothermic (31-32°C) ischemia, hyperthermic (41-42°C) ischemia and sham-operated groups. Global cerebral ischemia was established using the Pulsinelli four-vessel occlusion model and brain temperature was maintained at defined level for 60 min after 20-min ischemia. The expression of c-fos protein and the levels of malondialdehyde (MDA) and lactate in brain regions were detected by immunochemistry and spectrophotometrical methods, respectively. C-fos positive neurons were found in the hippocampus and cerebral cortex after cerebral ischemia reperfusion. Mild hypothermia increased the expression of c-fos protein in both areas, whereas hyperthermia decreased the expression of c-fos protein in the hippocampus at 24 h reperfusion, and the cerebral cortex at 48 h reperfusion when compared to normothermic conditions. In normothermic, mild hypothermic and hyperthermic ischemia groups, the levels of MDA and lactate in brain tissue were increased at 24, 48 and 72 h reperfusion following 20-min ischemia as compared with the sham-operated group (P<0.01). The levels of MDA and lactate in mild hypothermic group were significantly lower than those in normothermic group (P<0.01). It is suggested that brain temperature influences the translation of the immunoreactive protein product of c-fos after global cerebral ischemia, and MDA and lactate are also affected by hypothermia and hyperthermia.

Chinese culture permeation in the treatment of Parkinson disease: a cross-sectional study in four regions of China.

BACKGROUND: Little is known about the clinical features and treatment of Chinese patients with Parkinson disease (PD). METHODS: A large cross-sectional survey of clinical features, medication use, and motor complications was conducted in 901 consecutive PD patients, from 42 randomly selected university-affiliated hospitals in four urban economic regions of China, between December 2006 and May 2007. RESULTS: The 901 PD patients had age range 30 to 88, and median disease duration 50 months. Most (737, 81.8%) used L-dopa (median 375 mg/day), and often added low doses of other antiparkinsonian agents. Among L-dopa-treated patients, the prevalence of motor complications was low (dyskinesias: 8.5%; motor fluctuations: 18.6%), even among patients with disease duration ≥11 years (dyskinesias: 18.1%; motor fluctuations: 42.2%). Higher L-dopa use was associated with higher occurrence of dyskinesias (OR 2.44; 95% CI 1.20-5.13) and motor fluctuations (OR 2.48; 95% CI 1.49-4.14). Initiating PD treatment with L-dopa alone (OR 0.46; 95% CI 0.22-0.95) or in combination with other medications (OR 0.41; 95% CI 0.19-0.87) was associated with less dyskinesia than treatment initiated with non-L-dopa medication. CONCLUSIONS: Many Chinese PD patients are treated with low-dose L-dopa and added low-dose antiparkinsonian agents, with a low prevalence of motor complications, which might be influenced by Chinese culture.

Effects of small interfering RNA targeting sphingosine kinase-1 gene on the animal model of Alzheimer's disease.

Alzheimer's disease (AD) is an age-related, progressive neurodegenerative disorder that occurs gradually and results in memory, behavior, and personality changes. Abnormal sphingolipid metabolism was reported in AD previously. This study aimed to investigate whether sphK1 could exacerbate the accumulation of amyloid protein (Aß) and sharpen the learning and memory ability of the animal model of AD using siRNA interference. An adenovirus vector expressing small interfering RNA (siRNA) against the sphK1 gene (sphK1-siRNA) was designed, and the effects of sphK1-siRNA on the APP/PS1 mouse four weeks after treatment with sphK1-siRNA hippocampal injection were examined. SphK1 protein expression was confirmed by using Western blotting and ceramide content coupled with S1P secretion was evaluated by enzyme-linked immunosorbent assay (ELISA). Aß load was detected by immunohistochemical staining and ELISA. Morris water maze was adopted to test the learning and memory ability of the APP/PS1 mice. A significant difference in the expression of sphK1 protein and mRNA was observed between the siRNA group and the control group. Aß load in transfected mice was accelerated in vivo, with significant aggravation of the learning and memory ability. The sphK1 gene modulation in the Aß load and the learning and memory ability in the animal model of AD may be important for the treatment of AD.

[Adenovirus vector mediated human 14-3-3 γ gene transfer protects dopaminergic cells against rotenone-induced injury].

OBJECTIVE: To explore the protective effect of human 14-3-3 γ gene transfer on dopaminergic cells against rotenone-induced injury. METHODS: Adenovirus vector carrying the gene of 14-3-3 γ (Ad/14-3-3 γ) was employed to transfect PC12 cells. Then the cells were exposed to rotenone as a model of Parkinson's disease. Methyl thiazolyl tetrazolium (MTT) was used to assay the viability of PC12 cells. The 4',6-diamidino-2-phenylindole (DAPI) staining was used to analyze the apoptotic ratio of PC12 cells among the groups of control, Ad/14-3-3 γ, Ad-null and Rotenone. And high performance liquid chromatography (HPLC) was performed to detect the secreting functions of PC12 cells. The aggregates of α-Synuclein protein were detected under confocal microscopy. RESULTS: MTT showed that the cell absorbance A(570) of Ad/14-3-3 γ group (0.46 ± 0.09) was higher than that of Ad-null group (0.19 ± 0.08) and rotenone group (0.16 ± 0.07), but lower than that of normal control (0.63 ± 0.11), (all P < 0.01); HPLC-ECD showed that the levels of dopamine (189 ± 11) ng/ml and noradrenalin (55 ± 8) ng/ml in the culture fluid of Ad/14-3-3 γ group were higher than those of Ad-null group (79 ± 12, 38 ± 7) ng/ml and rotenone group (81 ± 13, 39 ± 7) ng/ml (all P < 0.01). DAPI staining showed that cell apoptosis ratio of group Ad/14-3-3 γ (27% ± 64%) was lower than that of group Ad-null (53% ± 10%) and rotenone group (56% ± 12%, P < 0.01), but higher than that of control group (10% ± 5%, P < 0.01). Under confocal microscopy, the aggregates of α-synuclein protein in PC12 cells were detected more in Ad-null group and rotenone group than that in Ad/14-3-3 γ group. CONCLUSION: Gene transfer of Ad/14-3-3 γ has a protective effect on dopaminergic cells against rotenone-induced injury.

Efficacy and safety of pramipexole in chinese patients with restless legs syndrome: results from a multi-center, randomized, double-blind, placebo-controlled trial.

BACKGROUND: We performed a six-week study of pramipexole vs. a placebo in Chinese restless legs syndrome patients. METHODS: Overall, 305 enrolled patients were assigned randomly in a 2:1 ratio to the pramipexole group (N=202) and the placebo group (N=103). RESULTS: Of 287 patients in the full analysis set, the pramipexole group showed significant improvement compared with the placebo group in the change of their International Restless Legs Syndrome Study Group Rating Scale of Severity (IRLS) total score from baseline to week 6 after adjustment of centers and baseline characters (-15.87±0.66 vs. -11.35±0.92, p<0.0001) and in the proportion of patients who were "much improved" and "very much improved" when measured by Clinical Global Impressions-Improvement (81.9% vs. 54.3%, p<0.0001). At week 6, the IRLS responder rate was 73.8% (pramipexole) and 48.9% (placebo) (p<0.0001) and the patient global impression responder rate was 68.6% (pramipexole) and 43.5% (placebo) (p<0.0001). The proportion of adverse events was 62.9% in the pramipexole group and 43.7% in the placebo group, respectively. No deaths occurred. CONCLUSION: Pramipexole was effective and well-tolerated in Chinese patients with restless legs syndrome.

1,5-dicaffeoylquinic acid protects primary neurons from amyloid ß 1-42-induced apoptosis via PI3K/Akt signaling pathway.

BACKGROUND: Recently, 1,5-dicaffeoylquinic acid (1,5-DQA), a caffeoylquinic acid derivative isolated from Aster scaber, was found to have neuroprotective effects. However, the protective mechanisms of 1,5-DQA have not yet been clearly identified. The purpose of this study was to explore the protective mechanisms of 1,5-DQA on neuronal culture. METHODS: We investigated the neuroprotective effects of 1,5-DQA against amyloid ß(1-42) (Aß(42))-induced neurotoxicity in primary neuronal culture. To evaluate the neuroprotective effects of 1,5-DQA, primary cultured cortical neurons from neonate rats were pretreated with 1,5-DQA for 2 hours and then treated with 40 µmol/L Aß(42) for 6 hours. Cell counting kit-8, Hoechst staining and Western blotting were used for detecting the protective mechanism. Comparisons between two groups were evaluated by independent t test, and multiple comparisons were analyzed by one-way analysis of variance (ANOVA). RESULTS: 1,5-DQA treated neurons showed increased neuronal cell viability against Aß(42) toxicity in a concentration-dependent manner, both phosphoinositide 3-kinase (PI3K)/Akt and extracellular regulated protein kinase 1/2 (Erk1/2) were activated by 1,5-DQA with stimulating their upstream tyrosine kinase A (Trk A). However, the neuroprotective effects of 1,5-DQA were blocked by LY294002, a PI3K inhibitor, but not by PD98059, an inhibitor of mitogen-activated protein kinase kinase. Furthermore, 1,5-DQA's anti-apoptotic potential was related to the enhanced inactivating phosphorylation of glycogen synthase kinase 3ß (GSK3ß) and the modulation of expression of apoptosis-related protein Bcl-2/Bax. CONCLUSION: These results suggest that 1,5-DQA prevents Aß(42)-induced neurotoxicity through the activation of PI3K/Akt followed by the stimulation of Trk A, then the inhibition of GSK3ß as well as the modulation of Bcl-2/Bax.

Effects of immediate and delayed mild hypothermia on endogenous antioxidant enzymes and energy metabolites following global cerebral ischemia.

BACKGROUND: The optimal time window for the administration of hypothermia following cerebral ischemia has been studied for decades, with disparity outcomes. In this study, the efficacy of mild brain hypothermia beginning at different time intervals on brain endogenous antioxidant enzyme and energy metabolites was investigated in a model of global cerebral ischemia. METHODS: Forty-eight male Sprague-Dawley rats were divided into a sham-operated group, a normothermia (37°C - 38°C) ischemic group and a mild hypothermic (31°C - 32°C) ischemia groups. Rats in the last group were subdivided into four groups: 240 minutes of hypothermia, 30 minutes of normothermia plus 210 minutes of hypothermia, 60 minutes of normothermia plus 180 minutes of hypothermia and 90 minutes of normothermia plus 150 minutes of hypothermia (n = 8). Global cerebral ischemia was established using the Pulsinelli four-vessel occlusion model for 20 minutes and mild hypothermia was applied after 20 minutes of ischemia. Brain tissue was collected following 20 minutes of cerebral ischemia and 240 minutes of reperfusion, and used to measure the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), reduced glutathione (GSH) and adenosine triphosphate (ATP). RESULTS: Mild hypothermia that was started within 0 to 60 minutes delayed the consumption of SOD, GSH-Px, GSH, and ATP (P < 0.05 or P < 0.01) in ischemic tissue, as compared to a normothermic ischemia group. In contrast, mild hypothermia beginning at 90 minutes had little effect on the levels of SOD, GSH-Px, GSH, and ATP (P > 0.05). CONCLUSIONS: Postischemic mild brain hypothermia can significantly delay the consumption of endogenous antioxidant enzymes and energy metabolites, which are critical to the process of cerebral protection by mild hypothermia. These results show that mild hypothermia limits ischemic injury if started within 60 minutes, but loses its protective effects when delayed until 90 minutes following cerebral ischemia.

[Clinical rehabilitative effect of memantine on cognitive and motor disorders in patients with Parkinson's disease].

OBJECTIVE: To study the effects of memantine on cognitive and motor impairment in patients with Parkinson's disease (PD). METHODS: A total of 55 PD patients complicated by varying degrees of cognitive impairment were randomly divided into two groups. The patients of experimental group (n = 28) received memantine (20 mg/d) while those in the control group (n = 27) conventional antiparkinsonian drug therapy alone. The cognitive and motor evaluations were assessed at pre-treatment and 12, 24 weeks post-treatment by clinical assessment, rating scales and neuropsychological tests. RESULTS: At week 24 the patients in the memantine group had better MMSE (22.8 ± 1.8), ADAS-cog (18.6 ± 2.3), and UPDRS-III (34.6 ± 4.2) scales scores than those taking placebo MMSE (18.5 ± 1.7), ADAS-cog (21.9 ± 2.4), and UPDRS-III (41.2 ± 4.0). Patients treated with memantine had better improvement on the MMSE (P < 0.05), ADAS-cog (P < 0.05), and UPDRS-III (P < 0.05) scales compared with the control group by the end of study week 24. CONCLUSION: Memantine may improve the cognitive and motor impairments of PD. And it is both safe and well-tolerated.

Morin exerts neuroprotective actions in Parkinson disease models in vitro and in vivo.

AIM: To investigate the neuroprotective effects of morin on 1-methyl-4-phenylpyridinium ion (MPP(+))-induced apoptosis in neuronal differentiated PC12 cells as well as in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson disease (PD). METHODS: PC12 cells were challenged with MPP(+) in the presence or absence of morin. Cell viability was determined using MTT assay. Cell apoptosis was measured using flow cytometry. Generation of reactive oxygen species (ROS) was assayed using fluorescence assay. In an MPTP mouse model of PD, behavioral deficits, striatal dopamine content, and number of dopaminergic neurons were measured. RESULTS: MPP(+) induced apoptosis and ROS formation in PC12 cells. Concomitant treatment with morin (5-50 mumol/L) significantly attenuated the loss of cell viability and apoptosis when compared with MPP(+) treatment alone. Morin also attenuated ROS formation induced by MPP(+). MPTP induced permanent behavioral deficits and nigrostriatal lesions in mice. When administered prior to MPTP, morin (20 to 100 mg/kg) attenuated behavioral deficits, dopaminergic neuronal death and striatal dopamine depletion in the MPTP mouse model. CONCLUSION: The findings suggest that morin has neuroprotective actions both in vitro and in vivo, and may provide a novel therapeutic agent for the treatment of PD and other neurodegenerative diseases.

[Magnetic resonance imaging character in chronic injury of the elbows in athletes].

OBJECTIVE: To introduce the experiences of applying MR to diagnose the imaging characters in chronic injury of the elbows in athletes. METHODS: From September 2005 to May 2008, 40 elbows of 34 athletes, included 21 males and 13 females,aged from 6 to 16 years old, averaged (12.3 +/- 3.1) years were taken axial, saggital and coronal planes MR Imaging. RESULTS: Magnetic resonance imaging showed thickening and effusion of olecranon synovial plicaes, bone marrow edema of lower humeral ossification, radial head, olecranon, ulna coronoid, ulnar collateral ligament trauma in chronic injury of the elbow joint. CONCLUSION: MRI is a susceptible method for the diagnoses of chronic injury of the elbow.

[Protective effects of doxycycline upon dopaminergic neuron in LPS-induced rat model of Parkinson's disease].

OBJECTIVE: To explore the protective effect of doxycycline (DC) upon dopaminergic neuron in lipopolysaccharide (LPS)-induce rat model of Parkinson's disease (PD). METHODS: Sixty SD rats were randomly divided into three groups: control, LPS and doxycycline treatment. LPS was stereotatically injected into unilateral substantia nigra (SNc) of rats to establish the PD models. The damage to the substantia nigra DA neurons was observed by using tyrosine-hydroxylase (TH) immunohistochemical staining. Specific antibody OX6 (MHCII marker) was used to detect the changes in morphology and the numbers of microglia. The contents of dopamine and DOPAC in striatum were measured by high performance liquid chromatography (HPLC). Western blot were used to detect the expression of MHCII (Major histocompatibility complex class II) protein. RESULTS: After doxycycline treatment, the number of TH-positive cells remaining in the SNc increased from 38% +/- 5% to 79% +/- 4% (P < 0.01). The contents of dopamine and DOPAC in striatum increased from 4.89 +/- 0.27 and 0.70 +/- 0.07 to 7.00 +/- 0.34 and 1.10 +/- 0.10 respectively (P < 0.01); there was a significant decrease in rotational asymmetry in the doxycycline treatment group [(80 +/- 12) turns/30 min] when compared to the LPS group [(208 +/- 14) turns/30 min] (P < 0.01). However, the number of MHCII-positive microglia decreased significantly (LPS group: 835 +/- 82 vs doxycycline treatment group: 354 +/- 59, P < 0.01) after doxycycline treatment. Western blot were used to detect the expression of MHCII protein. The results showed that the expression of MHCII protein on microglia of LPS group increased significantly compared to the control group, but the expression of MHCII protein were inhibited significantly after doxycycline treatment in the doxycycline treatment group, as compared to the LPS group. CONCLUSIONS: Doxycycline might inhibit dopaminergic neuron degeneration by down-regulating the MHCII expression on microglia.

Does estrogen receptor gene polymorphism play a role in Parkinson's disease?

This study was designed to investigate the frequency of estrogen receptor (ER) gene polymorphism in Chinese patients with Parkinson's disease (PD). Polymerase chain reaction (PCR) method and restriction fragment length polymorphism (RFLP) were used to detect the ER gene polymorphisms in 158 PD patients and 146 healthy controls. In the PD and control groups, "x" accounted for 83.5% and 80.8%, respectively (P>0.05). "xx" was found in 77.2% of the PD group and in 69.9% of the control group (P>0.05). The frequency of "p" in the PD and control group was 67.7% and 64.0%, respectively (P>0.05). "pp" was 51.9% in the PD group and 43.8% in the control group (P>0.05). "ppxx" was found in 49.4% of the PD and 43.0% of the control subjects (P>0.05). There was no significant difference in the "x", "xx", "p", "pp" or "ppxx" between males and females within the PD or control groups. In conclusion, we found no significant differences in the genotype or allele frequencies between patients with Parkinson's disease and healthy subjects. These findings suggest that the estrogen receptor gene polymorphism may not play a key role in the pathogenesis PD in Chinese patients.

Protective effect of estrogen on apoptosis in a cell culture model of Parkinson's disease.

OBJECTIVES: The protective effect of estrogen on the neurons in Parkinson's disease (PD) is unclear. The present study aimed to investigate the effect of estrogen on the apoptosis and dopaminergic function on a cultured cell model of PD. METHODS: The PD model was established by addition of 1-methyl-4-phenylpyridinium (MPP+) to PC12 cell culture. Estrogen was added to cell groups with MPP+ (Estrogen+MPP+), and without MPP+ (Estrogen only group). Cell viability, content of tyrosine hydroxylase (TH), apoptosis ratio, expression of apoptosis-suppression protein Bcl-x and apoptosis-acceleration protein IL-1 beta converting enzyme (ICE) were measured. RESULTS: Cell viability in the Estrogen+MPP+ group was similar to the control group but was higher than in the MPP+ group (P < 0.05). The apoptosis ratios in the Estrogen+MPP+ group (33.6%), and the control group (31.3%), were also similar, but it was lower than in the MPP+ group (63.5%, P < 0.05). Concentrations of Bcl-x were higher in the Estrogen+MPP+ group, whereas ICE concentrations were lower than in the MPP+ group (P < 0.05). CONCLUSIONS: Estrogen suppresses apoptosis and improves cell viability in MPP+ induced injuries in the PC12 cells. The beneficial effects of estrogen on the PD model are due to the suppression of pro-apoptotic protein ICE, and stimulation of anti-apoptotic protein Bcl-x.

Involvement of ERK1/2 and p38 MAPK in up-regulation of 14-3-3 protein induced by hydrogen peroxide preconditioning in PC12 cells.

OBJECTIVE: To investigate the protective effects of hydrogen peroxide preconditioning (HPP) on the pheochromocytoma (PC12) cells treated with 1-methyl-4-phenylpyridinium (MPP(+)) and to explore the potential mechanisms. METHODS: The viability and apoptosis of PC12 cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and 4',6'-diamidino-2-phenylindole (DAPI) staining, respectively. The expressions of 14-3-3 protein and phosphorylated p38 mitogen-activated protein kinase (MAPK) were determined by Western blot. Enzyme-linked immunosorbent assay (ELISA) was used to measure the activity of extracellular signal-regulated protein kinase 1/2 (ERK1/2). RESULTS: The cell viability decreased and the number of apoptotic cells increased dramatically in MPP(+) group compared with that in Control group. HPP induced a significant increase in cell viability and a marked decrease in population of apoptotic cells of the MPP(+)-treated PC12 cells, accompanied with up-regulation of 14-3-3 protein and increase of ERK1/2 and p38 MAPK activities. The 14-3-3 protein expression was positively correlated with the phosphorylation of ERK1/2. Furthermore, inhibition of the ERK1/2 with PD98059 abolished the 14-3-3 protein up-regulation in PC12 cells induced by HPP. CONCLUSION: HPP protects PC12 cells against MPP(+) toxicity by up-regulating 14-3-3 protein expression through the ERK1/2 and p38 MAPK signaling pathways.

Thrombin-induced microglial activation contributes to the degeneration of nigral dopaminergic neurons in vivo.

OBJECTIVE: To evaluate the role of thrombin-activated microglia in the neurodegeneration of nigral dopaminergic neurons in the rat substantia nigra (SN) in vivo. METHODS: After stereotaxic thrombin injection into unilateral SN of rats, immunostaining, reverse transcription polymerase chain reaction (RT-PCR) and biochemical methods were used to observe tyrosine hydroxylase (TH) immunoreactive positive cells, microglia activation, nitric oxide (NO) amount and inducible nitric-oxide synthase (iNOS) expression. RESULTS: (1) Selective damage to dopaminergic neurons was produced after thrombin injection, which was evidenced by loss of TH immunostaining in time-dependent manner; (2) Strong microglial activation was observed in the SN; (3) RT-PCR demonstrated the early and transient expression of neurotoxic factors iNOS mRNA in the SN. Immunofluorescence results found that thrombin induced expression of iNOS in microglia. The NO production in the thrombin-injected rats was significantly higher than that of controls (P < 0.05). CONCLUSION: Thrombin intranigral injection can injure the dopaminergic neurons in the SN. Thrombin-induced microglia activation precedes dopaminergic neuron degeneration, which suggest that activation of microglia and release of NO may play important roles in dopaminergic neuronal death in the SN.

[Proteolytic stress induced by environmental toxins in dopaminergic neurons: an experimental study].

OBJECTIVE: To explore the role of proteolytic stress induced by environmental toxins in degeneration and death of dopaminergic neurons. METHODS: Nerve growth factor-treated-rat adrenal pheochromocytoma cells of the line PC12 were co-incubated with 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenylpyridinium ion (MPP(+)), and rotenone for 24 hours. MTT assay was used to measure the cell viability induced by these neurotoxins with different concentrations. The expression levels of alpha-synuclein and ubiquited proteins in every group were observed with laser scanning confocal technique. The enzymatic activities of three main hydrolases in proteasome were measured by detection of the fluorophore of various cleft synthetic fluorogenic peptides. RESULTS: 6-OHDA, MPP(+), and rotenone decreased the activity of PC12 cells dose-dependently. Co-incubated with 100 micromol/L 6-OHDA, 75 micromol/L MPP(+), and 20 nmol/L rotenone, the activity of PC12 cells decreased by 52%, 44%, and 40% respectively. Immunofluorescence double labeling confirmed the overexpression of alpha-synuclein and ubiquitin and pellet accumulation in the cytoplasm induced by three toxins. Compared with those in the control group, the trypsin-like, chymotrypsin-like, and PgH-like activities of proteasome were markedly decreased in the MPP(+) and rotenone groups (all P < 0.05) and slightly decreased in the 6-OHDA 100 micromol/L group (all P > 0.05), but after the exposure to 6-OHDA 200 micromol/L for 24 h, the activities of the three enzymes decreased rapidly, the activities of the three enzymes were 7.2 +/- 0.6, 79.6 +/- 2.7 and 4.2 +/- 0.5 FU/100 microg respectively (vs 13.9 +/- 1.8, 99.3 +/- 5.2, and 6.9 +/- 0.6 FU/100 microg respectively in the control group, all P < 0.01). CONCLUSION: Environmental toxins induce proteolytic stress marked by dysfunction of ubiquitin proteasome and accumulation of alpha-synuclein and ubiquited proteins.

Protective effect of erythropoietin against 1-methyl-4-phenylpyridinium-induced neurodegenaration in PC12 cells.

OBJECTIVE: The neuroprotective effect of erythropoietin (EPO) against 1-methyl-4-phenylpyridinium (MPP(+))-induced oxidative stress in cultured PC12 cells, as well as the underlying mechanism, were investigated. METHODS: PC12 cells impaired by MPP(+) were used as the cell model of Parkinson's disease. Methyl thiazolyl tetrazolium (MTT) was used to assay the viability of the PC12 cells exposed to gradient concentrations of EPO, and the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay was used to analyze the apoptosis ratio of PC12 cells. The expression of Bcl-2 and Bax in PC12 cells were examined by Western blot, and the reactive oxygen species (ROS), the mitochondrial transmembrane potential and the activity of caspase-3 in each group were detected by spectrofluorometer. RESULTS: Treatment of PC12 cells with MPP(+) caused the loss of cell viability, which may be associated with the elevation in apoptotic rate, the formation of ROS and the disruption of mitochondrial transmembrane potential. It was also shown that MPP(+) significantly induced the upregulation of Bax/Bcl-2 ratio and the activation of caspase-3. In contrast, EPO significantly reversed these responses and had the maximum protective effect at 1 U/mL. CONCLUSION: The inhibitive effect of EPO on the MPP(+)-induced cytotoxicity may be ascribed to its anti-oxidative property and anti-apoptotic activity, and EPO may provide a useful therapeutic strategy for treatment of neurodegenerative diseases such as Parkinson's disease.

Favorable effects of VEGF gene transfer on a rat model of Parkinson disease using adeno-associated viral vectors.

Vascular endothelial growth factor (VEGF) is a specific angiogenic peptide, which has been identified to play a critical role in neurodegeneration, and has beneficial effects on neurons. In this study, we investigated whether neurodegeneration in a rat model of Parkinson disease could be prevented by VEGF gene transfer mediated by adeno-associated virus (AAV) vectors. Our results demonstrated that a single injection of a VEGF-expressing AAV vector into striatum improved the rotational behavior of rat Parkinson disease models, and promoted the survival of dopaminergic neurons and fibers. Meanwhile, AAV-VEGF injection significantly increased the reactive astrocytes and the levels of glial cell line-derived neurotrophic factor in striatum, but did not induce extra angiogenesis and remarkable disorder of blood-brain barrier. We thus conclude that intrastriatal delivery of VEGF gene mediated by AAV has favorable effects on the dopaminergic neurons in a rat Parkinson disease model.