The role of KCNQ channels in the thalamus

Der ventrobasale thalamische Komplex (VB) spielt eine entscheidende Rolle bei der somatosensorischen Informationsverarbeitung und ist insbesondere wichtig für die diskriminativen und räumlichen Aspekte der akuten Schmerzverarbeitung. Wir schlagen einen neuen antinozizeptiven Mechanismus vor, der auf der Aktivierung von KCNQ-Kanälen in diesem Hirngebiet beruht. Die Wirkung von Retigabin, einem K+-Kanalöffner, beruht auf der spezifischen Aktivierung von KCNQ-Kanälen, welche den M-Strom (IM) herbeiführt. Dies gilt im Besonderen für die Untereinheiten KCNQ2 und KCNQ3, die durch Retigabin aktiviert und durch den spezifischen KCNQ-Kanalblocker XE991 inhibiert werden. In vitro induziert die Applikation von Retigabin eine Hyperpolarisation des Membranruhepotentials, die mit der Verringerung tonischer Aktivität und einer Förderung von Salvenaktivität einhergeht. Dies führt in vivo zu einer Schmerzhemmung. The thalamic ventrobasal complex (VB) plays a crucial role in somatosensory information processing, and it is particularly important for the discriminative and spatial aspects of acute pain processing. We propose a new antinociceptive mechanism based on the activation of KCNQ channels in the brain. Here, the channels formed by the co-assembly of the subunits KCNQ2 and KCNQ3 mediates the M current (IM). In vitro, the application of the specific opener retigabine induced hyperpolarization of the resting membrane potential, associated with the reduction in tonic activity and promotion of burst-like activity. This shift in the firing pattern is associated to reduction of pain sensation at supraspinal level. Thus, the possible role of thalamic KCNQ channels in pain sensation was the tested in an animal model of acute pain, suggesting a novel target for pain therapy

NOX4-derived ROS are neuroprotective by balancing intracellular calcium stores

Hyperexcitability is associated with neuronal dysfunction, cellular death, and consequently neurodegeneration. Redox disbalance can contribute to hyperexcitation and increased reactive oxygen species (ROS) levels are observed in various neurological diseases. NOX4 is an NADPH oxidase known to produce ROS and might have a regulating function during oxidative stress. We, therefore, aimed to determine the role of NOX4 on neuronal firing, hyperexcitability, and hyperexcitability-induced changes in neural network function. Using a multidimensional approach of an in vivo model of hyperexcitability, proteomic analysis, and cellular function analysis of ROS, mitochondrial integrity, and calcium levels, we demonstrate that NOX4 is neuroprotective by regulating ROS and calcium homeostasis and thereby preventing hyperexcitability and consequently neuronal death. These results implicate NOX4 as a potential redox regulator that is beneficial in hyperexcitability and thereby might have an important role in neurodegeneration.</p

The quality of cortical network function recovery depends on localization and degree of axonal demyelination

AbstractMyelin loss is a severe pathological hallmark common to a number of neurodegenerative diseases, including multiple sclerosis (MS). Demyelination in the central nervous system appears in the form of lesions affecting both white and gray matter structures. The functional consequences of demyelination on neuronal network and brain function are not well understood. Current therapeutic strategies for ameliorating the course of such diseases usually focus on promoting remyelination, but the effectiveness of these approaches strongly depends on the timing in relation to the disease state. In this study, we sought to characterize the time course of sensory and behavioral alterations induced by de- and remyelination to establish a rational for the use of remyelination strategies. By taking advantage of animal models of general and focal demyelination, we tested the consequences of myelin loss on the functionality of the auditory thalamocortical system: a well-studied neuronal network consisting of both white and gray matter regions. We found that general demyelination was associated with a permanent loss of the tonotopic cortical organization in vivo, and the inability to induce tone-frequency-dependent conditioned behaviors, a status persisting after remyelination. Targeted, focal lysolecithin-induced lesions in the white matter fiber tract, but not in the gray matter regions of cortex, were fully reversible at the morphological, functional and behavioral level. These findings indicate that remyelination of white and gray matter lesions have a different functional regeneration potential, with the white matter being able to regain full functionality while cortical gray matter lesions suffer from permanently altered network function. Therefore therapeutic interventions aiming for remyelination have to consider both region- and time-dependent strategies

Additional file 1 of Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Additional file 1: Figure S1. Experimental scheme. Active MOG EAE was induced as previously described by immunization (day 0) of C57BL/6J mice with MOG35–55 peptide, followed by pertussis toxin (PTX) injections (day 0 and day 2) (15). Mice were divided into two experimental groups: Group 1 received cladribine via oral gavage (10 mg/kg from day 5 to day 9), while group 2 received only the vehicle for the same period of time. On day 10 post-EAE induction, focal EAE lesions were generated by stereotactic injection of proinflammatory cytokines (interferon gamma (INF-γ) and tumor necrosis factor alpha (TNF-α) into the auditory cortex to induce cortical grey matter lesions. Experimental read-out (electrophysiological recordings, flow cytometric immunophenotyping, histology) was performed either on dmax (defining the day of maximal clinical deterioration) or on day 27 post-EAE induction (to assess the chronical EAE state)

Additional file 3 of Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Additional file 3: Figure S3. Gating strategy for flow cytometry. Single immune cells from the periphery (A, here exemplary shown with spleen tissue) and the central nervous system (CNS; B, here exemplary shown with spinal cord tissue) were simultaneously analyzed by flow cytometry. Total leukocytes were identified by forward scatter (FSC) and sideward scatter (SSC) and cell-doublets were removed by FSC width and FSC height gating. From these cells, we identified leukocytes subsets based on their surface marker expression: CD45R+ B cells; CD3+CD4+ T-helper cells, CD3+CD8+ cytotoxic T cells and CD4+CD8+ double positive T cells; CD3−NK1.1+ natural killer (NK) cells; CD11b+CD11c− monocytes and macrophages (M/M) and CD11b+CD11c+ dendritic cells. Regarding the CNS tissue, prior to discrimination of leukocyte subsets, we differentiated microglia cells (CD45med) from infiltrated leukocytes (CD45high)

Additional file 4 of Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Additional file 4: Figure S4. Gating strategy for sorting of macrophages. CD11b+ cells were isolated from murine CNS and spinal cord via magnetic beads. Subsequently, CD11b+ cells were simultaneously analyzed and sorted by flow cytometry. Total CD11b+ cells were identified by forward scatter (FSC) and sideward scatter (SSC) (A), and cell-doublets were removed by SSC width and SSC height gating (B). From these cells, we discriminated macrophages based on their surface marker expression of CD45highCD11bhigh (C). Macrophages were sorted for downstream experiments (D). Plots (E)-(F) show the distribution of microglia (CD45intermCD11bhigh) in comparison to macrophages

Additional file 6 of Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Additional file 6: Figure S6. Migration assay of leukocytes in organ cultures of spleens from naïve wild-type mice, with and without cladribine treatment in vitro. A: Migration ratios (number of migrated cells: total cell count) of viable (live), CD4+ or CD8+ T cells and B cells upon cladribine treatment (vehicle (migration) versus cladribine 0.1 µM (migration)) (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs, p-values > 0.05). B: Flow cytometric analysis of the immune cell distribution in % in spleens (vehicle or cladribine (organ)) and the migrated immune cells (vehicle or cladribine (migration)) (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs). C: Mean fluorescence intensities (MFIs) of migration and activation markers in viable CD4+ cells still located in the respective spleen (vehicle or cladribine (organ)) compared to those after egress (vehicle or cladribine ((migration)) (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs). D: MFIs of migration and activation markers in viable CD8+ cells still located in the respective spleen (vehicle or cladribine (organ)) compared to those after egress (vehicle or cladribine ((migration)) (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs, p-values > 0.05). E: MFIs of migration and activation markers in viable B cells still located in the respective spleen (vehicle or cladribine (organ)) compared to those after egress (vehicle or cladribine ((migration)) (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs). p > 0.05 = ns, p < 0.05 = *, p < 0.01 = **, p < 0.001 = ***, p < 0.0001 = ****

Additional file 2 of Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Additional file 2: Figure S2. Titration curves of oral cladribine treatment in mice. In preliminary experiments, we analyzed the plasma [ng/ml] and brain concentrations [ng/g] of oral cladribine treatment with different doses (3.25, 5 and 10 mg/kg bodyweight) over a time period of 2.5 h. Every 30 min blood was drawn and a proportion of animals was killed to obtain brain tissue for titration analyses. Curves show the maximal concentration of cladribine in blood and brain tissue (Cmax [ng/ml or ng/g]), the time to maximal concentration (tmax [hours]) and the area under the curve (AUC [ng*h/ml or ng*h/g])

Additional file 7 of Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Additional file 7: Figure S7. Proliferation assay of splenocytes from naïve wild-type mice, with and without cladribine treatment in vitro. A: Proliferated cells in % after cladribine treatment (with 0.1 or 1 μM cladribine) versus vehicle-treated cells. We compared the unstimulated to the stimulated setting (stimulated with 1 μg/mL anti-CD3 and 2 μg/mL anti-CD28 for 3 days) (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs). B: Mean fluorescence intensities (MFIs) of migration and activation markers in all viable stimulated cells upon vehicle- compared to cladribine-treatment (n = 6 for both vehicle and cladribine treatment, two-way ANOVAs). p > 0.05 = ns, p < 0.05 = *, p < 0.001 = ***, p < 0.0001 = ****