Search

Apoptosis of dopaminergic neurons in the nigrostriatal projection plays a crucial role in the pathogenesis of Parkinson's disease (PD). Although the detailed mechanisms responsible for dopaminergic neuron loss are still under investigation, oxidative stress is identified as a major contributor for neuronal apoptosis. In the current study, we studied the effects of MPP, a substrate that mimics oxidative stress, on neuron-like PC12 cells and the underlying mechanisms. PC12 cells were cultured and treated by 100 μmol/L MPP for 4, 8, 16, 24 and 48 h, respectively. For drug pretreatment, the PC12 cells were incubated with N-acetyl-l-cysteine (NAC, 5 mmol/L), an antioxidant, SP600125 (20 μmol/L) or PD98059 (100 μmol/L), two pharmacological inhibitors of JNK and ERK1/2, for 1 h before addition of MPP. Cell apoptosis was measured by flow cytometry. The mRNA expression of Cu/Zn-SOD, GSH-Px, Bcl-2 and Bax was detected by RT-PCR. The protein expression of p-ERK1/2 and p-JNK was determined by Western blotting. Our results showed that MPP exposure could induce substantial PC12 cell apoptosis. The pretreatment of SP600125 or PD98059 could effectively reduce the apoptosis rate by reducing the ratio of Bax/Bcl-2 mRNA levels. MPP exposure also induced high level of reactive oxygen species (ROS), marked by dramatic increase of Cu/Zn-SOD and GSH-Px mRNA levels. The elevated ROS was strongly associated with the activation of JNK and ERK1/2 signal pathways after MPP exposure, since the pretreatment of NAC significantly reduced the upregulation of p-JNK and p-ERK1/2. Finally, the pretreatment of SP600125, but not PD98059, alleviated the increase of Cu/Zn-SOD and GSH-Px mRNAs induced by MPP, suggesting that the activation of the JNK signal pathway, but not the ERK1/2 signal pathway, could, in some degree, antagonize the generation of ROS induced by oxidative stress. In conclusion, our results suggest that JNK and ERK1/2 signal pathways, which are activated via ROS, play a crucial role in neuronal apoptosis induced by oxidative stress. [ABSTRACT FROM AUTHOR]

Neural stem/progenitor cells (NSCs) can spontaneously differentiate into neurons and glial cells in the absence of mitogen fibroblast growth factor-2 (FGF-2) or epidermal growth factor (EGF) in medium and the spontaneous differentiation of NSCs is mediated partially by endogenous ciliary neurotrophic factor (CNTF). This study examined the relationship of FGF-2 and CNTF in the spontaneous differentiation of adult hippocampal progenitor cells (AHPs). AHPs were cultured in the medium containing different concentration of FGF-2 (1-100 ng/mL). Western blotting and immunofluorescence staining were applied to detect the expression of the astrocytic marker GFAP, the neuronal marker Tuj1, the oligodendrocytic marker CNPase and, Nestin, the marker of AHPs. The expression of endogenous CNTF in AHPs at early (passage 4) and late stage (passage 22) was also measured by Western blotting. The results showed that FGF-2 increased the expression of Nestin, dramatically inhibited the expression of GFAP and Tuj1 and slightly suppressed the expression of CNPase. FGF-2 down-regulated the expression of endogenous CNTF in AHPs at both early (passage 4) and late stage (passage 22). These results suggested that FGF-2 could inhibit the spontaneous differentiation of cultured AHPs by negatively regulating the expression of endogenous CNTF in AHPs. [ABSTRACT FROM AUTHOR]

Previous studies have suggested that glutathione-S-transferase π (GST-π) over-expression in the brain tissue is associated with refractory epilepsy. However, whether the change in GST-π level in the peripheral blood is in line with that in brain tissue remains unknown. This study examined the correlation between GST-π in brain tissue and that in peripheral blood in rat models of pilocarpine-induced refractory epilepsy. The animals were divided into drug-resistant group and drug-responsive group according to the response to anti-epileptic drugs. GST-π expression in brain tissue was immunohistochemically determined, while the expression of GST-π in peripheral blood was analyzed by Western blotting. In the hippocampus and cortex, GST-π was mainly found in the cytoplasm and membrane of neurons, and the GST-π expression level was higher in drug-resistant group than in the drug-responsive group and saline control group ( P<0.05). Moreover, there was no significant difference between responders and saline control animals ( P>0.05). The change in expression of GST-π in peripheral blood showed the same pattern as that in brain tissues, suggesting GST-π might contribute to drug resistance in epilepsy. Importantly, the GST-π over-expression in peripheral blood could be used as a marker for resistance to anti-epileptic agents. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the clinical evidence for or against mood stabilizers as a treatment for Alzheimer's disease (AD). We searched 5 databases from their inception to January 2010. Five randomized clinical trials of mood stabilizers to treat human patients suffering from AD were included. These trials assessed the effectiveness of mood stabilizers as an adjunct treatment to conventional anti-dementia drugs on behavioral and psychological symptoms, especially on agitation. Methodological quality was assessed using the Jadad score. The results suggested a significant effect in favor of placebo on the Mini-Mental Status Examination [ n=270, weight mean difference (WMD), −0.89; 95% confidence intervals (CIs) −1.69 to −0.09, P=0.03] and on the Neuropsychiatric Inventory total (NPI total) ( n=51, WMD, 3.71; 95% CIs 0.15 to 7.26, P=0.04). There were no significant differences in change scores on total Brief Psychiatric Rating Scale (BPRS total), NPI/BPRS agitation, Cohen-Mansfield Agitation Inventory total and Physical Self Maintenance Scale between mood stabilizers and placebo. Only one of these studies was free of methodological limitations (Jadad score=5). In conclusion, based on the existing evidence, mood stabilizers are ineffective or even harmful as a treatment for AD. [ABSTRACT FROM AUTHOR]

The study was aimed to examine the prevalence of depression in patients with Parkinson’s disease (PD) and identify its features. A total of 131 out-patients, diagnosed as having idiopathic PD in accordance with the United Kingdom Parkinson’s Disease Society Brain Bank criteria, were interviewed with questionnaire and evaluated by Mini-Mental State Examination (MMSE), Unified Parkinson’s Disease Rating Scale (UPDRS), Hohen &Yahr staging (H&Y staging) and Hamilton Rating Scale for Depression (HRSD). Patients were divided into three groups in terms of HRSD score: depression group, sub-threshold depression group and non-depression group. The clinical variables and symptom profiles were obtained and compared among the three groups. The results showed that 27 patients (20.6%) fell into the depression group, 71 (54.2%) into the sub-threshold depression group, and 33 (25.2%) into the non-depression group. There were no differences in age, gender or tremor score among the groups ( P>0.05). Significant differences were found in duration of PD, UPDRS score, rigidity score and H&Y stage between the sub-threshold depression group (or the depression group) and the non-depression group ( P<0.05). Moreover, the clinical variables in the subthreshold depression group had the trend of increasing with the severity of PD and their values were similar to those in the depression group. Anhedonia, feeling of incapability, sleep disturbance, gastrointestinal symptoms and depressive moods were most common in the depression group. And these symptoms also were more common in the other two groups. It is concluded that depression and sub-threshold depression are common in PD and share similar clinical features. Furthermore, subthreshold depression might be the prodrome of depression and may develop into depression as the condition progresses. [ABSTRACT FROM AUTHOR]

This study investigated the effect and mechanism of cell cycle reentry induced by 6-hydrodopamine (6-OHDA) in PC12 cells. By using neural differentiated PC12 cells treated with 6-OHDA, the apoptosis model of dopaminergic neurons was established. Cell viability was measured by MTT. Cell apoptosis and the distribution of cell cycle were assessed by flow cytometry. Western blot was used to detect the activation of extracellular regulator kinase1/2 (ERK1/2) pathway and the phosphorylation of retinoblastoma protein (RB). Our results showed that after PC12 cells were treated wtih 6-OHDA, the viability of PC12 cells was declined in a concentration-dependent manner. Flow cytometry revealed that 6-OHDA could increase the apoptosis ratio of PC12 cells in a time-dependent manner. The percentage of cells in G0/G1 phase of cell cycle was decreased and that in S phase and G2/M phase increased. Simultaneously, ERK1/2 pathway was activated and phosphorylated RB increased. It was concluded that 6-OHDA could induce cell cycle reentry of dopaminergic neurons through the activation of ERK1/2 pathway and RB phosphorylation. The aberrant cell cycle reentry contributes to the apoptosis of dopaminergic neurons. [ABSTRACT FROM AUTHOR]

To examine the ability of intrastriatal gene transfer of vascular endothelial growth factor 165 mediated by adenoviral vector to rescue dopaminergic neurons in a rat model of Parkinson’s disease (PD), we constructed recombinant replication-deficent adenoviral vectors carrying the gene of VEGF165 (Ad-VEGF), and injected Ad-VEGF (or Ad-LacZ and PBS as controls) into the striatum of rats 7 days after the lesion by 6-hydroxydopamine. The rat rotational behavior analysis and tyrosine hydroxylase (TH) immunohistochemistry were performed to assess the change of dopaminergic neurons. Our results showed that the rats receiving Ad-VEGF injection displayed a significant improvement in apomorphine-induced rotational behavior and a significant preservation of TH-positive neurons and fibers compared with control animals. It is concluded that intrastriatal gene transfer by Ad-VEGF may rescue the dopaminergic neurons from degeneration in a rat model of PD. [ABSTRACT FROM AUTHOR]

To examine the changes in erythropoietin (Epo) protein and its mRNA expression in rat brain subjected to focal ischemia and possible mechanism of the preconditioning of mitochondrial toxin 3-nitropropionic acid (3-NPA), rats were administrated either vehicle or 3-NPA at a dose of 20 mg/kg, intraperitoneally (ip), 3 days prior to a 2-h middle cerebral artery occlusion followed by 24-h reperfusion. Infarct volumes were measured by using 2, 3, 5 triphenylte trazolinm chloride (TTC) staining, and Epo protein and its mRNA levels were assessed by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR), respectively. Our results showed that after reperfusion, Epo was found to be expressed extensively in the rat brain. It was most apparent in the basal nuclei and hippocampus, and was, to some extent, present in cortex. Preconditioning with 3-NPA caused a reduction in infarct volume. The expression of both Epo protein and mRNA increased significantly in the different brain areas in the 3-NPA pretreated group as compared with the non-pretreated ischemia model group. These results suggested that preconditioning with low dose 3-NPA could induce ischemic tolerance and neuro-protective effects by increasing the Epo expression in the ischemic and ischemia-related areas. [ABSTRACT FROM AUTHOR]

To study the effects of 6-hydroxydopamine (6-OHDA) and reduced glutathione (GSH) on the nigral dopaminergic neurons in brain slices in vitro, immolunohistochemical technique was used to observe the changes of TH-stained neurons, including cell bodies and the dendrites, in the substantia nigra (SN) of midbrain slices of rats after incubation for 1 h in the presence of GSH 15 min before and during the period of incubation with 6-OHDA. The results showed that cell bodies remained intact but dendrites were fragmented and truncated after treatment with 6-OHDA. The antioxidant GSH alone did not significantly affect the dendrites of SN neurons but prevented 6-OHDA-induced damage of dendrites. It was concluded that glutathione may prevent 6-OHDA-induced dopaminergic neurodegeneration and play a protective role in dopaminergic neurons. [ABSTRACT FROM AUTHOR]

To study the protective effect of rosuvastatin on ischemic brain injury and its mechanism, focal cerebral ischemia/reperfusion was induced by occlusion of the middle cerebral artery (MCA) using the intra-luminal filament technique. The cerebral blood flow was monitored with laser-Doppler flowmetry (LDF). The slices of brain tissue were stained with cresyl-violet. The cerebral volume of infarction and edema were quantified with ImageJ software. The expressions of endothelial NO synthase (eNOS) and activated caspase-3 were detected with Western blot. The inducible NO synthase (iNOS) positive cells were immunohistochemically observed. The results demonstrated that rosuvastatin (20 mg/kg) could remarkably decrease infarct volume and cerebral edema after MCAO 90 min/reperfusion 24 h. Western blots showed that the expression of eNOS in cerebral cortex before and after ischemia was (100±43.3) %, (1668.9±112.2) % respectively ( P<0.001), rosuvastatin significantly up-regulated the expression of eNOS in non-ischemic cortex ( P<0.001), whereas in ischemic cortex of rosuvastatin group the expression of eNOS was (1678.8±121.3) %. There was no expression of activated caspase-3 in non-ischemic cortex, nonetheless the expression of activated caspase-3 increased after ischemia, and rosuvastatin significantly diminished it ( P<0.01). Immunohistochemistry revealed no iNOS-positive cells in non-ischemic brain area, while in ischemic brain area the number of iNOS positive cells went up, and rosuvastatin could significantly reduced them. Consequently, the mechanisms of rosuvastatin’s neural protection on ischemic brain injury are to enhance expression of eNOS, to inhibit expression of iNOS and activated caspase-3. [ABSTRACT FROM AUTHOR]

The effects of antisense FosB and CREB intra-striatum injection on the expression of prodynorphin (PDyn) gene in striatal neurons of Levodopa-induced dyskinesias (LID) rats with Parkinson disease (PD) were explored. PD model in rats was established by 6-OHDA microinjection stereotaxically. The rats were treated with chronic intermittent Levodopa celiac injection for 28 days to get the LID rats. Antisense FosB and cAMP response element-binding protein (CREB) were injected into striatum of all rats respectively. In situ hybridization was used to measure the changes in the expression of PDyn mRNA in striatum and behavior changes were observed. The results showed after administration of antisense FosB, abnormal involuntary movement (AIM) was decreased and the expression of PDyn mRNA in striatum was increased in LID rats as compared with sense FosB group ( P<0.01, respectively). As compared with the control group, the expression of PDyn mRNA in striatum was decreased by antisense CREB-treated LID group ( P<0.01) and compared with sense CREB treated LID group, antisense CREB-treated LID group showed no changes in AIM scores and the expressions of PDyn mRNA (both P>0.05). In conclusion, FosB protein, which replaced the CREG, could regulate the expression of PDyn mRNA and play critical role in the pathogenesis of LID. [ABSTRACT FROM AUTHOR]