Huntington's disease (HD) is an autosomal neurodegenerative disorder, characterized by severe behavioral, cognitive, and motor deficits. Since the discovery of the huntingtin gene (HTT) mutation that causes the disease, several mouse lines have been developed using different gene constructs of Htt. Recently, a new model, the zQ175 knock-in (KI) mouse, was developed (see description by Menalled et al, [1]) in an attempt to have the Htt gene in a context and causing a phenotype that more closely mimics HD in humans. Here we confirm the behavioral phenotypes reported by Menalled et al [1], and extend the characterization to include brain volumetry, striatal metabolite concentration, and early neurophysiological changes. The overall reproducibility of the behavioral phenotype across the two independent laboratories demonstrates the utility of this new model. Further, important features reminiscent of human HD pathology are observed in zQ175 mice: compared to wild-type neurons, electrophysiological recordings from acute brain slices reveal that medium spiny neurons from zQ175 mice display a progressive hyperexcitability; glutamatergic transmission in the striatum is severely attenuated; decreased striatal and cortical volumes from 3 and 4 months of age in homo- and heterozygous mice, respectively, with whole brain volumes only decreased in homozygotes. MR spectroscopy reveals decreased concentrations of N-acetylaspartate and increased concentrations of glutamine, taurine and creatine + phosphocreatine in the striatum of 12-month old homozygotes, the latter also measured in 12-month-old heterozygotes. Motor, behavioral, and cognitive deficits in homozygotes occur concurrently with the structural and metabolic changes observed. In sum, the zQ175 KI model has robust behavioral, electrophysiological, and histopathological features that may be valuable in both furthering our understanding of HD-like pathophyisology and the evaluation of potential therapeutic strategies to slow the progression of disease.

Nitric oxide (NO) contributes to neuronal death in cerebral ischemia and other conditions. Astrocytes are anatomically well positioned to shield neurons from NO because astrocyte processes surround most neurons. In this study, the capacity of astrocytes to limit NO neurotoxicity was examined using a cortical co-culture system. Astrocyte-coated dialysis membranes were placed directly on top of neuronal cultures to provide a removable astrocyte layer between the neurons and the culture medium. The utility of this system was tested by comparing neuronal death produced by glutamate, which is rapidly cleared by astrocytes, and N-methyl-D-aspartate (NMDA), which is not. The presence of an astrocyte layer increased the LD 50 for glutamate by approximately four-fold, but had no effect on NMDA toxicity. Astrocyte effects on neuronal death produced by the NO donors S-nitroso-N-acetyl penicillamine and spermine NONOate were examined by placing these compounds into the medium of co-cultures containing either a control astrocyte layer or an astrocyte layer depleted of glutathione by prior exposure to buthionine sulfoximine. Neurons in culture with the glutathione-depleted astrocytes exhibited a two-fold increase in cell death over a range of NO donor concentrations. These ®ndings suggest that astrocytes protect neurons from NO toxicity by a glutathione-dependent mechanism.

CSF from patients with motor neurone disease (MND) has been reported to be toxic to cultured primary neurones. We found that CSF from MND patients homozygous for the D90A CuZn-superoxide dismutase (CuZn-SOD) mutation, patients with sporadic MND and patients with familial MND without CuZn-SOD mutations significantly increased apoptosis and reduced phosphorylation of neurofilaments in cultured spinal cord neurones when compared with the effects of CSF from patients with other neurological diseases. Exposure of spinal cord cultures to MND CSF also triggered microglial activation. The toxicity of MND CSF was independent of the presence of the CuZn-SOD mutation, and it did not correlate with gelatinase activity or the presence of immunoglobulin G autoantibodies in the CSF. The concentrations of glutamate, aspartate and glycine in MND CSF were not elevated. Antagonists of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid/kainate receptors prevented the toxic CSF-induced neuronal death but not microglial activation, whereas minocycline, a tetracycline derivative with anti-inflammatory potential independent of antimicrobial activity, reduced both the apoptotic neuronal death and microglial activation. We conclude that the cytotoxic action of CSF is prevalent in all MND cases and that microglia may mediate the toxicity of CSF by releasing excitotoxicity-enhancing factors.

Pyrrolidine dithiocarbamate (PDTC) is an antioxidant and inhibitor of transcription factor nuclear factor kappa-B (NFjB). Because the role of NF-jB in brain injury is controversial and another NF-jB inhibiting thiocarbamate, DDTC, was recently shown to increase ischaemic brain damage, we investigated the effect of PDTC on transient brain ischaemia. Ischaemia was induced by occlusion of the middle cerebral artery (MCAO). In Wistar rats, the PDTC treatment started even 6 h after MCAO reduced the infarction volume by 48%. PDTC protected against MCAO also in spontaneously hypertensive rats and against forebrain ischaemia in Mongolian gerbils. PDTC prevented NF-jB activation in the ischaemic brain as determined by reduced DNA binding and nuclear translocation of NF-jB in neurons. PDTC had anti-inflammatory effect by preventing induction of NF-jB-regulated proinflammatory genes. In ischaemic rats, NF-jB was localized in cyclo-oxygenase-2-immunoreactive neurons. Blood cytokine levels were not altered by ischaemia or PDTC. When cultured neurons were exposed to an excitotoxin, no production of reactive oxygen species was detected, but PDTC provided protection and prevented nuclear translocation of NF-jB. The clinically approved PDTC and its analogues may act as antiinflammatories and may be safe therapies in stroke with a wide time window. Keywords: cytokines, inflammation, neuroimmunology, rodent. Stroke is the third leading cause of death in industrialized countries and a major cause of severe disability in the elderly (Centers for Disease Control 1992; Wolf et al. 1997). There is no other acute stroke therapy than intravenous thrombolysis and it is safe and effective only for a fraction of the patients (Bednar and Gross 1999;Lindsberg and Kaste 2003). Even though animal research conducted on acute ischaemic injury has revealed several pathophysiological cascades contributing to brain infarction, no breakthroughs in developing clinically relevant stroke therapy have been achieved. One factor is that laboratory studies on a single animal species or stroke model are not sufficient for modelling more variable human strokes (STAIR 1999). Another valid reason is that the compounds, which are protective in animal models, have a limited therapeutic time window or toxic secondary effects in humans (STAIR 1999).Reactive oxygen species (ROS) and inflammation are involved in human stroke and play a crucial role in animal models of stroke during the first days after the onset of ischaemia ( Abbreviations used: COX-2, cyclo-oxygenase-2; DDTC, diethyldithiocarbamate; div, days in vitro; FBS-HI, fetal bovine serum heat inactivated; IjB, inhibitor of NF-jB; IL-1b, interleukin-1b; iNOS, inducible nitric oxide synthase; LDH, lactate dehydrogenase; MAPKs, mitogen-activated protein kinases; MCA, middle cerebral artery; MCAO, middle cerebral artery occlusion; MEM, minimal essential medium; NF-jB, nuclear factor kappa-B; NMDA, N-methyl-D-asparatate; PDTC, pyrrolidine dithiocarbamate; ROS, reactive oxygen species; SHR, spontaneously ...

Understanding the pathophysiological mechanisms underlying Alzheimer disease (AD) relies on knowledge of disease onset and the sequence of development of brain pathologies. We present a comprehensive analysis of early and progressive changes in a mouse model that demonstrates a full spectrum of characteristic AD-like pathologies. This model demonstrates an altered immune redox state reminiscent of the human disease and capitalizes on data indicating critical differences between human and mouse immune responses, particularly in nitric oxide (NO) levels produced by immune activation of the NOS2 gene. Using the APPSwDI+/+/mNos2−/− (CVN-AD) mouse strain, we show a sequence of pathological events leading to neurodegeneration that include pathologically hyperphosphorylated tau in the perforant pathway at 6 weeks of age progressing to insoluble tau, the early appearance of β-amyloid peptides in perivascular deposits around blood vessels in brain regions known to be vulnerable in AD and progression to damage and overt loss in select vulnerable neuronal populations in these regions. The role of species differences between hNOS2 and mNos2 was supported by generating mice in which the human NOS2 gene replaced mNos2. When crossed to CVN-AD mice, pathological characteristics of this new strain (APPSwDI+/−/huNOS2t +/+g/mNos2−/−) mimicked the pathological phenotypes found in the CVN-AD strain.