Parkinson Disease: Zhang W

Narayana S, Jacks A, Robin DA, Poizner H, Zhang W, Franklin C, Liotti M, Vogel D, Fox PT. · Research Imaging Center, Honors College, The University of Texas Health Science Center, San Antonio, 7703 Floyd Curl Drive MSC 6240, San Antonio, TX 78229-3900, USA. · Am J Speech Lang Pathol. · Pubmed #19029533 No free full text.

Abstract: PURPOSE: To explore the use of noninvasive functional imaging and "virtual" lesion techniques to study the neural mechanisms underlying motor speech disorders in Parkinson's disease. Here, we report the use of positron emission tomography (PET) and transcranial magnetic stimulation (TMS) to explain exacerbated speech impairment following subthalamic nucleus deep brain stimulation (STN-DBS) in a patient with Parkinson's disease. METHOD: Perceptual and acoustic speech measures, as well as cerebral blood flow during speech as measured by PET, were obtained with STN-DBS on and off. TMS was applied to a region in the speech motor network found to be abnormally active during DBS. Speech disruption by TMS was compared both perceptually and acoustically with speech produced with DBS on. RESULTS: Speech production was perceptually inferior and acoustically less contrastive during left STN stimulation compared to no stimulation. Increased neural activity in left dorsal premotor cortex (PMd) was observed during DBS on. "Virtual" lesioning of this region resulted in speech characterized by decreased speech segment duration, increased pause duration, and decreased intelligibility. CONCLUSIONS: This case report provides evidence that impaired speech production accompanying STN-DBS may result from unintended activation of PMd. Clinical application of functional imaging and TMS may lead to optimizing the delivery of STN-DBS to improve outcomes for speech production as well as general motor abilities.

Gao HM, Liu B, Zhang W, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, NC 27709, USA. · Trends Pharmacol Sci. · Pubmed #12915048 No free full text.

Abstract: Parkinson's disease (PD) is a movement disorder that is characterized by progressive degeneration of the nigrostriatal dopamine system. Although dopamine replacement can alleviate symptoms of the disorder, there is no proven therapy to halt the underlying progressive degeneration of dopamine-containing neurons. Recently, increasing evidence from human and animal studies has suggested that neuroinflammation is an important contributor to the neuronal loss in PD. Moreover, the pro-inflammatory agent lipopolysaccharide itself can directly initiate degeneration of dopamine-containing neurons or combine with other environmental factor(s), such as the pesticide rotenone, to exacerbate such neurodegeneration. These effects provide strong support for the involvement of inflammation in the pathogenesis of PD. Furthermore, growing experimental evidence demonstrates that inhibition of the inflammatory response can, in part, prevent degeneration of nigrostriatal dopamine-containing neurons in several animal models of PD, suggesting that inhibition of inflammation might become a promising therapeutic intervention for PD.

Miao J, Su C, Wang W, Lin H, Li H, Lei G, Liu Y, Liu R, Zhang W, Li Z. · Department of Neurology, Tangdu Hospital, Fourth Military Medical University, Xi'an City, Shaanxi Province 710038, China. · J Clin Neurosci. · Pubmed #19200731 No free full text.

Abstract: A 21-year-old woman, who experienced manual strangulation, developed delayed parkinsonism associated with a selective symmetric basal ganglia lesion. The patient had recovered completely one year after early combination therapy. This case emphasizes the need for greater attention in detecting early brain injuries in those afflicted with strangulation so as to provide optimal management.

Gao X, Hu X, Qian L, Yang S, Zhang W, Zhang D, Wu X, Fraser A, Wilson B, Flood PM, Block M, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA. · Environ Health Perspect. · Pubmed #18470306 links to  free full text

Abstract: BACKGROUND: Parkinson disease (PD), a chronic neurodegenerative disease, has been proposed to be a multifactorial disorder resulting from a combination of environmental mechanisms (chemical, infectious, and traumatic), aging, and genetic deficits. Microglial activation is important in the pathogenesis of PD. OBJECTIVES: We investigated dopaminergic (DA) neurotoxicity and the underlying mechanisms of formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived peptide, in relation to PD. METHODS: We measured DA neurotoxicity using a DA uptake assay and immunocytochemical staining (ICC) in primary mesencephalic cultures from rodents. Microglial activation was observed via ICC, flow cytometry, and superoxide measurement. RESULTS: fMLP can cause selective DA neuronal loss at concentrations as low as 10(-13) M. Further, fMLP (10(-13) M) led to a significant reduction in DA uptake capacity in neuron/glia (N/G) cultures, but not in microglia-depleted cultures, indicating an indispensable role of microglia in fMLP-induced neurotoxicity. Using ICC of a specific microglial marker, OX42, we observed morphologic changes in activated microglia after fMLP treatment. Microglial activation after fMLP treatment was confirmed by flow cytometry analysis of major histocompatibility antigen class II expression on a microglia HAPI cell line. Mechanistic studies revealed that fMLP (10(-13) M)-induced increase in the production of extracellular superoxide from microglia is critical in mediating fMLP-elicited neurotoxicity. Pharmacologic inhibition of NADPH oxidase (PHOX) with diphenylene-iodonium or apocynin abolished the DA neurotoxicity of fMLP. N/G cultures from PHOX-deficient (gp91PHOX-/ -) mice were also insensitive to fMLP-induced DA neurotoxicity. CONCLUSION: fMLP (10(-13) M) induces DA neurotoxicity through activation of microglial PHOX and subsequent production of superoxide, suggesting a role of fMLP in the central nervous system inflammatory process.

Zhu W, Wang D, Zheng J, An Y, Wang Q, Zhang W, Jin L, Gao H, Lin L. · Department of Chemistry, East China Normal University, Shanghai 200062, PR China. · Clin Chem. · Pubmed #18238832 links to  free full text

Abstract: BACKGROUND: Parkinson disease (PD), a progressive neurodegenerative disease, affects at least 1% of population above the age of 65. Although the specific etiology of PD remains unclear, recently the endogenous neurotoxins such as (R)-salsolinol [(R)-Sal] and N-methyl-(R)-salsolinol [(R)-NMSal] have been thought to play a major role in PD. Much interest is focused on the degeneration of dopamine neurons induced by these neurotoxins. However, little literature is available on the impact of endogenous neurotoxins on the balance between dopamine (DA) and acetylcholine (ACh). METHODS: After injection of (R)-Sal or (R)-NMSal into the rat brain striatum, the concentrations of DA and its metabolites were detected by HPLC with electrochemical detection. We assessed the influence of neurotoxins on acetylcholinesterase (AChE) activity and developed a microdialysis-electrochemical device to measure ACh concentrations with enzyme-modified electrodes. RESULTS: (R)-Sal and (R)-NMSal led to concentration-dependent decreases in the activity of AChE. ACh concentrations in striatum treated with (R)-Sal or (R)-NMSal were increased to 131.7% and 239.8% of control, respectively. As to the dopaminergic system, (R)-NMSal caused a significant decrease in DA concentrations and (R)-Sal reduced the concentrations of DA metabolites in the striatum. CONCLUSIONS: (R)-Sal and (R)-NMSal exerted a considerable effect on the balance between DA and ACh by impairing the cholinergic system as well as the dopaminergic system. It is likely that the disruption of balance between DA and ACh plays a critical role in the pathogenesis of neurotoxin-induced PD.

Qian L, Xu Z, Zhang W, Wilson B, Hong JS, Flood PM. · Comprehensive Center for Inflammatory Disorders, University of North Carolina, Chapel Hill, North Carolina 27599, USA. · J Neuroinflammation. · Pubmed #17880684 links to  free full text

Abstract: BACKGROUND: The mechanisms involved in the induction and regulation of inflammation resulting in dopaminergic (DA) neurotoxicity in Parkinson's disease (PD) are complex and incompletely understood. Microglia-mediated inflammation has recently been implicated as a critical mechanism responsible for progressive neurodegeneration. METHODS: Mesencephalic neuron-glia cultures and reconstituted cultures were used to investigate the molecular mechanisms of sinomenine (SN)-mediated anti-inflammatory and neuroprotective effects in both the lipopolysaccharide (LPS)- and the 1-methyl-4-phenylpyridinium (MPP+)-mediated models of PD. RESULTS: SN showed equivalent efficacy in protecting against DA neuron death in rat midbrain neuron-glial cultures at both micro- and sub-picomolar concentrations, but no protection was seen at nanomolar concentrations. The neuroprotective effect of SN was attributed to inhibition of microglial activation, since SN significantly decreased tumor necrosis factor-alpha (TNF-alpha, prostaglandin E2 (PGE2) and reactive oxygen species (ROS) production by microglia. In addition, from the therapeutic point of view, we focused on sub-picomolar concentration of SN for further mechanistic studies. We found that 10(-14) M of SN failed to protect DA neurons against MPP+-induced toxicity in the absence of microglia. More importantly, SN failed to show a protective effect in neuron-glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for extracellular superoxide production in immune cells. Furthermore, we demonstrated that SN reduced LPS-induced extracellular ROS production through the inhibition of the PHOX cytosolic subunit p47phoxtranslocation to the cell membrane. CONCLUSION: Our findings strongly suggest that the protective effects of SN are most likely mediated through the inhibition of microglial PHOX activity. These findings suggest a novel therapy to treat inflammation-mediated neurodegenerative diseases.

Zhang S, Zou Z, Jiang X, Xu R, Zhang W, Zhou Y, Ke Y. · Neuromedical Institute, Zhujiang Hospital, South Medical University, Guangzhou City 510282, PR China. · Cell Mol Neurobiol. · Pubmed #17713852 No free full text.

Abstract: AIMS: To investigate the therapeutic effects of tyrosine hydroxylase (TH)-transfected neuronal stem cells derived from bone marrow stem cells (NdSCs-D-BMSCs) on Parkinson's disease (PD) through different transplantation protocols, including microinjection into the cerebral ventricles (CV) and the striatum (ST). METHODS: After identification by enzyme digestion, the constructed plasmid pEGFP-C2-TH was transfected into 8-day-cultured NdSCs-D-BMSCs by electroporation resulting in the coexpression of green fluorescent protein (GFP) and TH. The TH-transfected cells were injected into either the right ST or CV of PD rats. The changes in locomotor activity of PD rats and the migration of transplanted cells in cerebral tissue were monitored and cerebral DA levels were assayed by high performance liquid chromatography (HPLC). RESULTS: Five days after plasmid pEGFP-C2-TH transfection into NdSCs-D-BMSCs GFP was expressed in 62.1% of the cells and the rate of co-expression with TH was 83.5%. Ten weeks following transplantation, the symptoms of PD rats in both groups were significantly improved and DA levels were restored to 46.6% and 33% of control. The transferred cells showed excellent survival rates in PD rat brains and distant migration was observed. CONCLUSION: Both CV and ST transplantation of TH-transfected NDSCs-D-BMSCs has obvious therapeutic effects on PD rats. This study could provide evidence for future transplantation route selection, possibly leading to stem cell transplantation through lumbar puncture.

Zhang W, Shin EJ, Wang T, Lee PH, Pang H, Wie MB, Kim WK, Kim SJ, Huang WH, Wang Y, Zhang W, Hong JS, Kim HC. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Science/National Institutes of Health, Research Triangle Park, North Carolina, USA. · FASEB J. · Pubmed #17142799 links to  free full text

Abstract: We investigated the neuroprotective property of analogs of dextromethorphan (DM) in lipopolysaccharide (LPS) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models to identify neuroprotective drugs for Parkinson's disease (PD). In vivo studies showed that daily injections with DM analogs protected dopamine (DA) neurons in substantia nigra pars compacta and restored DA levels in striatum using two different models for PD. Of the five analogs studied, 3-hydroxymorphinan (3-HM), a metabolite of DM, was the most potent, and restored DA neuronal loss and DA depletion up to 90% of the controls. Behavioral studies showed an excellent correlation between potency for preventing toxin-induced decrease in motor activities and neuroprotective effects among the DM analogs studied, of which 3-HM was the most potent in attenuating behavioral damage. In vitro studies revealed two glia-dependent mechanisms for the neuroprotection by 3-HM. First, astroglia mediated the 3-HM-induced neurotrophic effect by increasing the gene expression of neurotrophic factors, which was associated with the increased acetylation of histone H3. Second, microglia participated in 3-HM-mediated neuroprotection by reducing MPTP-elicited reactive microgliosis as evidenced by the decreased production of reactive oxygen species. In summary, we show the potent neuroprotection by 3-HM in LPS and MPTP PD models investigated. With its high efficacy and low toxicity, 3-HM may be a novel therapy for PD.

Zhang W, Shin EJ, Wang T, Lee PH, Pang H, Wie MB, Kim WK, Kim SJ, Huang WH, Wang Y, Zhang W, Hong JS, Kim HC. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Science/National Institutes of Health, Research Triangle Park, North Carolina, USA. · FASEB J. · Pubmed #17142799 links to  free full text

Abstract: We investigated the neuroprotective property of analogs of dextromethorphan (DM) in lipopolysaccharide (LPS) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models to identify neuroprotective drugs for Parkinson's disease (PD). In vivo studies showed that daily injections with DM analogs protected dopamine (DA) neurons in substantia nigra pars compacta and restored DA levels in striatum using two different models for PD. Of the five analogs studied, 3-hydroxymorphinan (3-HM), a metabolite of DM, was the most potent, and restored DA neuronal loss and DA depletion up to 90% of the controls. Behavioral studies showed an excellent correlation between potency for preventing toxin-induced decrease in motor activities and neuroprotective effects among the DM analogs studied, of which 3-HM was the most potent in attenuating behavioral damage. In vitro studies revealed two glia-dependent mechanisms for the neuroprotection by 3-HM. First, astroglia mediated the 3-HM-induced neurotrophic effect by increasing the gene expression of neurotrophic factors, which was associated with the increased acetylation of histone H3. Second, microglia participated in 3-HM-mediated neuroprotection by reducing MPTP-elicited reactive microgliosis as evidenced by the decreased production of reactive oxygen species. In summary, we show the potent neuroprotection by 3-HM in LPS and MPTP PD models investigated. With its high efficacy and low toxicity, 3-HM may be a novel therapy for PD.

Wang T, Zhang W, Pei Z, Block M, Wilson B, Reece JM, Miller DS, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park,North Carolina, USA. · FASEB J. · Pubmed #16675848 links to  free full text

Abstract: It has been reported that extracellular matrix (ECM) molecules regulate monocyte activation by binding with a 67 kDa nonintegrin laminin receptor (LR). As microgliosis is a pivotal factor in propelling the progress of chronic neurodegeneration in the brain, we hypothesized that LR may regulate the microgliosis and subsequent neurotoxicity. Using 1-methyl-4-phenylpyridinium (MPP+) -treated C57 mice primary mesencephalic neuron-glia cultures as an in vitro Parkinson's disease (PD) model, we observed that MPP+ treatment increased LR expression only in the mixed neuron-glia but not in microglia-enriched or microglia-depleted cultures, indicating that MPP+-induced increase of LR expression is associated with neuron-microglia interaction. Using confocal microscopic examination, we found that LR was localized in the microglia, which were F4/80 positive. Treatment with the antibody (Ab) against LR (LR-Ab) or YIGSR, a synthetic pentapeptide inhibitor for LR, significantly attenuated the MPP+-increased F4/80 immunoreactivity (24 h) and dopaminergic (DA) neurotoxicity. LR-Ab also attenuated MPP+-increased microglial phagocytotic activity (48 h) and the superoxide production (4 days). Further study demonstrated that exogenous laminin (1-10 microg/ml) treatment induced microglial activation and DA neurotoxicity, in a dose-dependent manner, which was partially attenuated by the LR-Ab. We concluded that by regulating cell-ECM interaction, LR plays important roles in mediating microgliosis and subsequent DA neurotoxicity. Laminin is a potential ligand for activating this LR receptor. This study also suggests that laminin/LR is a potential target for developing new therapeutic drugs against neurodegenerative disorders such as PD.

McLaughlin P, Zhou Y, Ma T, Liu J, Zhang W, Hong JS, Kovacs M, Zhang J. · Department of Pathology, University of Washington School of Medicine, Seattle, 98104, USA. · Glia. · Pubmed #16419087 No free full text.

Abstract: Although the pathogenesis of Parkinson's disease (PD) remains unknown, it appears that microglial activation is associated with enhanced neurodegeneration in animal models of PD as well as in PD patients. Experimentally, C57BL/6 and SWR/J mice demonstrate striking differences in the extent of dopaminergic (DAergic) neurodegeneration induced by a parkinsonian toxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The purpose of this study was to determine whether differences in microglial activation between these two strains of mice could provide insight into the variability seen in toxicant induced neuronal death, and subsequently to use a high-throughput proteomic method, combining stable isotope labeling with amino acids in cell culture (SILAC) with liquid chromatography and tandem mass spectrometry, to compare the microglial proteomes of C57BL/6 and SWR/J mice after stimulation with a classical microglial activator, lipopolysaccharide (LPS). We found that DAergic neurotoxicity induced by LPS in a primary neuron-microglia coculture was twofold greater with microglia isolated from the brains of C57BL/6 mice compared with that of SWR/J mice. Upon proteomic analysis we found that, out of over 1,000 proteins identified and quantified, 400 displayed a significant difference in their relative abundance between these two murine strains. Several proteins, which had relatively higher levels in C57BL/6 mice, have previously been implicated in LPS-mediated microglial activation, including those involved in the COX-2 pathway and in prostaglandin E-2 (PGE(2)) production. To validate our proteomic results we confirmed the increased expression level of iNOS in C57BL/6 vs. SWR/J microglia with semiquantitative Western blot. Further analysis of our proteomic discovery data will likely reveal numerous novel proteins involved in inflammation-mediated neurotoxicity in PD.

Zhang W, Wang T, Pei Z, Miller DS, Wu X, Block ML, Wilson B, Zhang W, Zhou Y, Hong JS, Zhang J. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, North Carolina, USA. · FASEB J. · Pubmed #15791003 links to  free full text

Abstract: A growing body of evidence indicates that an inflammatory process in the substantia nigra, characterized by activation of resident microglia, likely either initiates or aggravates nigral neurodegeneration in Parkinson's disease (PD). To study the mechanisms by which nigral microglia are activated in PD, the potential role of alpha-synuclein (a major component of Lewy bodies that can cause neurodegeneration when aggregated) in microglial activation was investigated. The results demonstrated that in a primary mesencephalic neuron-glia culture system, extracellular aggregated human alpha-synuclein indeed activated microglia; microglial activation enhanced dopaminergic neurodegeneration induced by aggregated alpha-synuclein. Furthermore, microglial enhancement of alpha-synuclein-mediated neurotoxicity depended on phagocytosis of alpha-synuclein and activation of NADPH oxidase with production of reactive oxygen species. These results suggest that nigral neuronal damage, regardless of etiology, may release aggregated alpha-synuclein into substantia nigra, which activates microglia with production of proinflammatory mediators, thereby leading to persistent and progressive nigral neurodegeneration in PD. Finally, NADPH oxidase could be an ideal target for potential pharmaceutical intervention, given that it plays a critical role in alpha-synuclein-mediated microglial activation and associated neurotoxicity.

Zhang W, Wang T, Pei Z, Miller DS, Wu X, Block ML, Wilson B, Zhang W, Zhou Y, Hong JS, Zhang J. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, North Carolina, USA. · FASEB J. · Pubmed #15791003 links to  free full text

Abstract: A growing body of evidence indicates that an inflammatory process in the substantia nigra, characterized by activation of resident microglia, likely either initiates or aggravates nigral neurodegeneration in Parkinson's disease (PD). To study the mechanisms by which nigral microglia are activated in PD, the potential role of alpha-synuclein (a major component of Lewy bodies that can cause neurodegeneration when aggregated) in microglial activation was investigated. The results demonstrated that in a primary mesencephalic neuron-glia culture system, extracellular aggregated human alpha-synuclein indeed activated microglia; microglial activation enhanced dopaminergic neurodegeneration induced by aggregated alpha-synuclein. Furthermore, microglial enhancement of alpha-synuclein-mediated neurotoxicity depended on phagocytosis of alpha-synuclein and activation of NADPH oxidase with production of reactive oxygen species. These results suggest that nigral neuronal damage, regardless of etiology, may release aggregated alpha-synuclein into substantia nigra, which activates microglia with production of proinflammatory mediators, thereby leading to persistent and progressive nigral neurodegeneration in PD. Finally, NADPH oxidase could be an ideal target for potential pharmaceutical intervention, given that it plays a critical role in alpha-synuclein-mediated microglial activation and associated neurotoxicity.

Zhang W, Qin L, Wang T, Wei SJ, Gao HM, Liu J, Wilson B, Liu B, Zhang W, Kim HC, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, P.O. Box 12233, NC, USA. · FASEB J. · Pubmed #15596482 links to  free full text

Abstract: The purpose of this study was to develop a novel therapy for Parkinson's disease (PD). We recently reported that dextromethorphan (DM), an active ingredient in a variety of widely used anticough remedies, protected dopaminergic neurons in rat primary mesencephalic neuron-glia cultures against lipopolysaccharide (LPS)-mediated degeneration and provided potent protection for dopaminergic neurons in a MPTP mouse model. The underlying mechanism for the protective effect of DM was attributed to its anti-inflammatory activity through inhibition of microglia activation. In an effort to develop more potent compounds for the treatment of PD, we have screened a series of analogs of DM, and 3-hydroxymorphinan (3-HM) emerged as a promising candidate for this purpose. Our study using primary mesencephalic neuron-glia cultures showed that 3-HM provided more potent neuroprotection against LPS-induced dopaminergic neurotoxicity than its parent compound. The higher potency of 3-HM was attributed to its neurotrophic effect in addition to the anti-inflammatory effect shared by both DM and 3-HM. First, we showed that 3-HM exerted potent neuroprotective and neurotrophic effects on dopaminergic neurons in rat primary mesencephalic neuron-glia cultures treated with LPS. The neurotrophic effect of 3-HM was glia-dependent since 3-HM failed to show any protective effect in the neuron-enriched cultures. We subsequently demonstrated that it was the astroglia, not the microglia, that contributed to the neurotrophic effect of 3-HM. This conclusion was based on the reconstitution studies, in which we added different percentages of microglia (10-20%) or astroglia (40-50%) back to the neuron-enriched cultures and found that 3-HM was neurotrophic after the addition of astroglia, but not microglia. Furthermore, 3-HM-treated astroglia-derived conditioned media exerted a significant neurotrophic effect on dopaminergic neurons. It appeared likely that 3-HM caused the release of neurotrophic factor(s) from astroglia, which in turn was responsible for the neurotrophic effect. Second, the anti-inflammatory mechanism was also important for the neuroprotective activity of 3-HM because the more microglia were added back to the neuron-enriched cultures, the more significant neuroprotective effect was observed. The anti-inflammatory mechanism of 3-HM was attributed to its inhibition of LPS-induced production of an array of pro-inflammatory and neurotoxic factors, including nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2) and reactive oxygen species (ROS). In conclusion, this study showed that 3-HM exerted potent neuroprotection by acting on two different targets: a neurotrophic effect mediated by astroglia and an anti-inflammatory effect mediated by the inhibition of microglial activation. 3-HM thus possesses these two important features necessary for an effective neuroprotective agent. In view of the well-documented very low toxicity of DM and its analogs, this report may provide an important new direction for the development of therapeutic interventions for inflammation-related diseases such as PD.

Zhang W, Qin L, Wang T, Wei SJ, Gao HM, Liu J, Wilson B, Liu B, Zhang W, Kim HC, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, P.O. Box 12233, NC, USA. · FASEB J. · Pubmed #15596482 links to  free full text

Abstract: The purpose of this study was to develop a novel therapy for Parkinson's disease (PD). We recently reported that dextromethorphan (DM), an active ingredient in a variety of widely used anticough remedies, protected dopaminergic neurons in rat primary mesencephalic neuron-glia cultures against lipopolysaccharide (LPS)-mediated degeneration and provided potent protection for dopaminergic neurons in a MPTP mouse model. The underlying mechanism for the protective effect of DM was attributed to its anti-inflammatory activity through inhibition of microglia activation. In an effort to develop more potent compounds for the treatment of PD, we have screened a series of analogs of DM, and 3-hydroxymorphinan (3-HM) emerged as a promising candidate for this purpose. Our study using primary mesencephalic neuron-glia cultures showed that 3-HM provided more potent neuroprotection against LPS-induced dopaminergic neurotoxicity than its parent compound. The higher potency of 3-HM was attributed to its neurotrophic effect in addition to the anti-inflammatory effect shared by both DM and 3-HM. First, we showed that 3-HM exerted potent neuroprotective and neurotrophic effects on dopaminergic neurons in rat primary mesencephalic neuron-glia cultures treated with LPS. The neurotrophic effect of 3-HM was glia-dependent since 3-HM failed to show any protective effect in the neuron-enriched cultures. We subsequently demonstrated that it was the astroglia, not the microglia, that contributed to the neurotrophic effect of 3-HM. This conclusion was based on the reconstitution studies, in which we added different percentages of microglia (10-20%) or astroglia (40-50%) back to the neuron-enriched cultures and found that 3-HM was neurotrophic after the addition of astroglia, but not microglia. Furthermore, 3-HM-treated astroglia-derived conditioned media exerted a significant neurotrophic effect on dopaminergic neurons. It appeared likely that 3-HM caused the release of neurotrophic factor(s) from astroglia, which in turn was responsible for the neurotrophic effect. Second, the anti-inflammatory mechanism was also important for the neuroprotective activity of 3-HM because the more microglia were added back to the neuron-enriched cultures, the more significant neuroprotective effect was observed. The anti-inflammatory mechanism of 3-HM was attributed to its inhibition of LPS-induced production of an array of pro-inflammatory and neurotoxic factors, including nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2) and reactive oxygen species (ROS). In conclusion, this study showed that 3-HM exerted potent neuroprotection by acting on two different targets: a neurotrophic effect mediated by astroglia and an anti-inflammatory effect mediated by the inhibition of microglial activation. 3-HM thus possesses these two important features necessary for an effective neuroprotective agent. In view of the well-documented very low toxicity of DM and its analogs, this report may provide an important new direction for the development of therapeutic interventions for inflammation-related diseases such as PD.

Gao HM, Liu B, Zhang W, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. · FASEB J. · Pubmed #12923073 links to  free full text

Abstract: Parkinson's disease (PD) is a profound movement disorder resulting from progressive degeneration of the nigrostriatal dopaminergic pathway. Although its etiology remains unknown, increasing evidence suggests the involvement of multiple factors such as environmental toxins and genetic susceptibilities in the pathogenesis of PD. In this study using mesencephalic neuron-glia cultures as an in vitro PD model, we demonstrated that the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 0.1-0.5 microM) and an inflammogen lipopolysaccharide (LPS, 0.5 ng/ml) synergistically induced a progressive and selective degeneration of dopaminergic neurons. The synergistic neurotoxicity was observed when both agents were applied either simultaneously or in tandem. The synergistic neurotoxicity was more prominent when lower doses of both agents were applied for a longer period of time. Mechanistically, microglial NADPH oxidase-mediated generation of reactive oxygen species played a pivotal role in the synergistic neurotoxicity: MPTP and LPS synergistically stimulated the NADPH oxidase-mediated release of superoxide free radical; pharmacological inhibition and genetic inactivation of NADPH oxidase prevented superoxide production and the synergistic neurotoxicity. Additionally, inhibition of nitric oxide synthase afforded significant neuroprotection, suggesting the involvement of nitric oxide in the synergistic neurotoxicity. This study lends strong support for a multifactorial etiology of PD and provides clues for therapeutic interventions.

Gao HM, Liu B, Zhang W, Hong JS. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, North Carolina, USA. · FASEB J. · Pubmed #12897068 links to  free full text

Abstract: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) damages dopaminergic neurons as seen in Parkinson's disease. Although increasing evidence suggests an involvement of glia in MPTP neurotoxicity, the nature of this involvement remains unclear. Exploiting the advantage of cell culture systems, we demonstrated that microglia, but not astroglia, significantly enhanced the progression of MPTP-induced dopaminergic neurodegeneration. Characterization of the temporal relationship between neurodegeneration and microglial activation demonstrates that reactive microgliosis resulting from MPTP-initiated neuronal injury, but not direct activation, underlies the microglia-enhanced MPTP neurotoxicity. Mechanistically, through the release of NADPH oxidase-derived reactive oxygen species, microglia contribute to the progressive neuronal damage. Among the factors measured, the production of extracellular superoxide was the most prominent. NADPH oxidase inhibitor, apocynin, attenuated MPTP-induced dopaminergic neurodegeneration only in the presence of glia. More importantly, dopaminergic neurons from mice lacking NADPH oxidase, a key enzyme for superoxide production in immune cells, are significantly more resistant to MPTP neurotoxicity than those from wild-type controls, and microglia dictate the resistance. This study demonstrates that reactive microgliosis triggered by MPTP-induced neuronal injury and NADPH oxidase-mediated superoxide production in microglia constitute an integral component of MPTP neurotoxicity. This study also suggests that NADPH oxidase may be a promising target for therapeutic interventions in Parkinson's disease.

Zhang W, Xie Y, Ai S, Wan F, Wang J, Jin L, Jin J. · Department of Chemistry, East China Normal University, ZhingShan Road North 3663, Shanghai 200062, China. · J Chromatogr B Analyt Technol Biomed Life Sci. · Pubmed #12798181 No free full text.

Abstract: The fabrication and application of a novel electrochemical detection (ED) method with the functionalized multi-wall carbon nanotubes (MWNTs) chemically modified electrode (CME) for liquid chromatography (LC) were described. The electrochemical behaviors of dopamine (DA) and other monoamine neurotransmitters at the CME were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results indicated that the CME exhibited efficient electrocatalytic effects on the current responses of monoamine neurotransmitters and their metabolites with high sensitivity, high stability and long-life activity. In LC-ED, DA, norepinephrine (NE), 3-methoxy-4-hydroxyphenylglycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) had good and stable current responses at the CME. The linear ranges of seven analytes were over four orders of magnitude and the detection limits were 2.5 x 10(-10) mol/l for DA, 2.5 x 10(-10) mol/l for NE, 5.0 x 10(-10) mol/l for MHPG, 3.0 x 10(-10) mol/l for DOPAC, 3.5 x 10(-10) mol/l for 5-HT, 6.0 x 10(-10) mol/l for 5-HIAA, 1.25 x 10(-9) mol/l for HVA. The application of this method coupled with microdialysis sampling for the determination of monoamine neurotransmitters and their metabolites in Parkinsonian patients' cerebrospinal fluid was satisfactory.

Sun M, Zhang GR, Kong L, Holmes C, Wang X, Zhang W, Goldstein DS, Geller AI. · Department of Neurology, West Roxbury VA Hospital/Harvard Medical School, 1400 VFW Parkway, West Roxbury, MA 02132, USA. · Hum Gene Ther. · Pubmed #12691607 links to  free full text

Abstract: We previously reported long-term biochemical and behavioral correction of the 6-hydroxydopamine (6-OHDA) rat model of Parkinson's disease (PD) by expression of tyrosine hydroxylase (TH) in the partially denervated striatum, using a herpes simplex virus type 1 (HSV-1) vector. This study had a number of limitations, including the use of a helper virus packaging system, limited long-term expression, and expression of only TH. To address these issues, we developed a helper virus-free packaging system, a modified neurofilament gene promoter that supports long-term expression in forebrain neurons, and a vector that coexpresses TH and aromatic amino acid decarboxylase (AADC). Coexpression of TH and AADC supported high-level (80%), behavioral correction of the 6-OHDA rat model of PD for 5 weeks. Biochemical correction included increases in extracellular dopamine and DOPAC concentrations between 2 and 4 months after gene transfer. Histologic analyses demonstrated neuronal-specific coexpression of TH and AADC at 4 days to 7 months after gene transfer, and cell counts revealed 1000 to 10,000 TH positive cells per rat at 2 months after gene transfer. This improved system efficiently corrects the rat model of PD.

Gao HM, Hong JS, Zhang W, Liu B. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. · J Neurosci. · Pubmed #12598611 links to  free full text

Abstract: Parkinson's disease (PD) is characterized by a progressive degeneration of the nigrostriatal dopaminergic pathway resulting in movement disorders. Although its etiology remains unknown, PD may be the final outcome of interactions among multiple factors, including exposure to environmental toxins and the occurrence of inflammation in the brain. In this study, using primary mesencephalic cultures, we observed that nontoxic or minimally toxic concentrations of the pesticide rotenone (0.5 nm) and the inflammogen lipopolysaccharide (LPS) (0.5 ng/ml) synergistically induced dopaminergic neurodegeneration. The synergistic neurotoxicity of rotenone and LPS was observed when the two agents were applied either simultaneously or in tandem. Mechanistically, microglial NADPH oxidase-mediated generation of reactive oxygen species appeared to be a key contributor to the synergistic dopaminergic neurotoxicity. This conclusion was based on the following observations. First, inhibition of NADPH oxidase or scavenging of free radicals afforded significant neuroprotection. Second, rotenone and LPS synergistically stimulated the NADPH oxidase-mediated release of the superoxide free radical. Third and most importantly, rotenone and LPS failed to induce the synergistic neurotoxicity as well as the production of superoxide in cultures from NADPH oxidase-deficient animals. This is the first demonstration that low concentrations of a pesticide and an inflammogen work in synergy to induce a selective degeneration of dopaminergic neurons. Findings from this study may be highly relevant to the elucidation of the multifactorial etiology of PD and the discovery of effective therapeutic agents for the treatment of the disease.

Gao HM, Jiang J, Wilson B, Zhang W, Hong JS, Liu B. · Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences/National Institutes of Health, North Carolina, USA. · J Neurochem. · Pubmed #12068076 No free full text.

Abstract: The etiology of sporadic Parkinson's disease (PD) remains unknown. Increasing evidence has suggested a role for inflammation in the brain in the pathogenesis of PD. However, it has not been clearly demonstrated whether microglial activation, the most integral part of the brain inflammatory process, will result in a delayed and progressive degeneration of dopaminergic neurons in substantia nigra, a hallmark of PD. We report here that chronic infusion of an inflammagen lipopolysaccharide at 5 ng/h for 2 weeks into rat brain triggered a rapid activation of microglia that reached a plateau in 2 weeks, followed by a delayed and gradual loss of nigral dopaminergic neurons that began at between 4 and 6 weeks and reached 70% by 10 weeks. Further investigation of the underlying mechanism of action of microglia-mediated neurotoxicity using rat mesencephalic neuron-glia cultures demonstrated that low concentrations of lipopolysaccharide (0.1-10 ng/mL)-induced microglial activation and production of neurotoxic factors preceded the progressive and selective degeneration of dopaminergic neurons. Among the factors produced by activated microglia, the NADPH oxidase-mediated release of superoxide appeared to be a predominant effector of neurodegeneration, consistent with the notion that dopaminergic neurons are particularly vulnerable to oxidative insults. This is the first report that microglial activation induced by chronic exposure to inflammagen was capable of inducing a delayed and selective degeneration of nigral dopaminergic neurons and that microglia-originated free radicals play a pivotal role in dopaminergic neurotoxicity in this inflammation-mediated model of PD.

Zhang W, Wang X, Yang Y. · Neuroscience Research Institute, Peking University, Beijing 100083, China. · Zhonghua Yi Xue Za Zhi. · Pubmed #11930634 No free full text.

Abstract: OBJECTIVE: To construct a kind of engineered cell secreting human GDNF and study its possible effects on gene therapy of Parkinson's disease. METHOD: Human GDNF cDNA with Kozak sequence was cloned by RT-PCR, and then was transfected into SH-SY5Y cell line of human neuroblastoma. These engineered cells were co-cultured with primary mesencephalic cells of rats. Dopaminergic neurons were examined by immunohistochemistry. RESULTS: The number of dopaminergic neurons protected by engineered cells increased at least by 95.4% in comparison with the control cells (P < 0.01). The number of dopaminergic neurons protected by engineered cells against MPP+ toxicity increased 9.5-10.8 times (P < 0.01). CONCLUSION: A kind of engineered SH-SY5Y cells secreting human GDNF has been constructed successfully. These cells obviously protect dopaminergic neurons against degeneration and MPP+ toxication and may play an important role in gene therapy of Parkinson's disease.

Xu R, Zhang W, Zhang S, Li Y, Yang Z, Huang R, Ye Y. · Department of Neurosurgery, Zhujiang Hospital, First Military Medical University, Guangzhou 510282. · Zhonghua Wai Ke Za Zhi. · Pubmed #11829895 No free full text.

Abstract: OBJECTIVE: To introduce the methods and effects of microelectrode-guided posteroventral pallidotomy (PVP) for Parkinson's disease. METHODS: 109 patients underwent PVP by microelectrode electrophysiological recording for intraoperative target localization. 45 patients underwent unilateral PVP, 21 patients simultaneous bilateral PVP, 43 patients combined thalamotomy and PVP. Modified Webster Scale was used for objective assessments before and after operation. Postoperative CT scan or MRI was performed to localise lesions. RESULTS: Microelectrode recording usually led to a final pallidotomy lesion position that deviated from the CT stereotactically defined target point. The change rate of targets was 84.7%. PVP significantly and immediately improved all Parkinsonian motor signs and reduced drug-induced motor fluctuations and dyskinesia. The mean Webster Scale was improved by (72.7 +/- 11.3)% in the "on"" state, and (89.3 +/- 8.1)% in the "off" state. No patient showed permanent complications. CONCLUSIONS: Microelectrode-guided PVP was proved to be safe and effective. Bilateral PVP and combined PVP can significantly and immediately abolish all Parkinsonian motor signs. Physiological methods of microelectrode recording can significantly improve the safety and efficacy of PVP, and decrease the rate of complication.

Gao HM, Hong JS, Zhang W, Liu B. · Neuropharmacology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. · J Neurosci. · Pubmed #11826108 links to  free full text

Abstract: Increasing evidence has suggested an important role for environmental factors such as exposure to pesticides in the pathogenesis of Parkinson's disease. In experimental animals the exposure to a common herbicide, rotenone, induces features of parkinsonism; mechanistically, rotenone-induced destruction of dopaminergic neurons has been attributed to its inhibition of the activity of neuronal mitochondrial complex I. However, the role of microglia, the resident brain immune cells in rotenone-induced neurodegeneration, has not been reported. Using primary neuron-enriched and neuron/glia cultures from the rat mesencephalon, we discovered an extraordinary feature for rotenone-induced degeneration of cultured dopaminergic neurons. Although little neurotoxicity was detected in neuron-enriched cultures after treatment for 8 d with up to 20 nm rotenone, significant and selective dopaminergic neurodegeneration was observed in neuron/glia cultures 2 d after treatment with 20 nm rotenone or 8 d after treatment with 1 nm rotenone. The greatly enhanced neurodegenerative ability of rotenone was attributed to the presence of glia, especially microglia, because the addition of microglia to neuron-enriched cultures markedly increased their susceptibility to rotenone. Mechanistically, rotenone stimulated the release of superoxide from microglia that was attenuated by inhibitors of NADPH oxidase. Furthermore, inhibition of NADPH oxidase or scavenging of superoxide significantly reduced the rotenone-induced neurotoxicity. This is the first report demonstrating that microglia play a pivotal role in rotenone-induced degeneration of dopaminergic neurons. The results of this study should advance our understanding of the mechanism of action for pesticides in the pathogenesis of Parkinson's disease.