Whyment A.D.,University of Warwick |
Whyment A.D.,NeuroSolutions Ltd |
Coderre E.,Ottawa Hospital Research Institute |
Wilson J.M.M.,Ottawa Hospital Research Institute |
And 4 more authors.
Neuroscience | Year: 2011
Transient outward rectifying conductances or A-like conductances in sympathetic preganglionic neurons (SPN) are prolonged, lasting for hundreds of milliseconds to seconds and are thought to play a key role in the regulation of SPN firing frequency. Here, a multidisciplinary electrophysiological, pharmacological and molecular single-cell rt-PCR approach was used to investigate the kinetics, pharmacological profile and putative K+ channel subunits underlying the transient outward rectifying conductance expressed in SPN. SPN expressed a 4-aminopyridine (4-AP) sensitive transient outward rectification with significantly longer decay kinetics than reported for many other central neurons. The conductance and corresponding current in voltage-clamp conditions was also sensitive to the Kv4.2 and Kv4.3 blocker phrixotoxin-2 (1-10 μM) and the blocker of rapidly inactivating Kv channels, pandinotoxin-Kα (50 nM). The conductance and corresponding current was only weakly sensitive to the Kv1 channel blocker tityustoxin-Kα and insensitive to dendrotoxin I (200 nM) and the Kv3.4 channel blocker BDS-II (1 μM). Single-cell RT-PCR revealed mRNA expression for the α-subunits Kv4.1 and Kv4.3 in the majority and Kv1.5 in less than half of SPN. mRNA for accessory β-subunits was detected for Kvβ2 in all SPN with differential expression of mRNA for KChIP1, Kvβ1 and Kvβ3 and the peptidase homologue DPP6. These data together suggest that the transient outwardly rectifying conductance in SPN is mediated by members of the Kv4 subfamily (Kv4.1 and Kv4.3) in association with the β-subunit Kvβ2. Differential expression of the accessory β subunits, which may act to modulate channel density and kinetics in SPN, may underlie the prolonged and variable time-course of this conductance in these neurons. © 2011 IBRO.
Bursi R.,Clinical PK PD |
Erdemli G.,Schering |
Campbell R.,Schering |
Hutmacher M.M.,Ann Arbor Pharmacometrics Group |
And 7 more authors.
Psychopharmacology | Year: 2011
Introduction: The α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor potentiator Org 26576 represents an interesting pharmacological tool to evaluate the utility of glutamatergic enhancement towards the treatment of psychiatric disorders. In this study, a rat-human translational pharmacokinetic-pharmacodynamic (PK-PD) model of AMPA receptor modulation was used to predict human target engagement and inform dose selection in efficacy clinical trials. Methods: Modelling and simulation was applied to rat plasma and cerebrospinal fluid (CSF) pharmacokinetic and pharmacodynamic measurements to identify a target concentration (EC 80) for AMPA receptor modulation. Human plasma pharmacokinetics was determined from 33 healthy volunteers and eight major depressive disorder patients. From four out of these eight patients, CSF PK was also determined. Simulations of human CSF levels were performed for several doses of Org 26576. Results: Org 26576 (0.1-10 mg/kg, i.v.) potentiated rat hippocampal AMPA receptor responses in an exposure-dependant manner. The rat plasma and CSF PK data were fitted by one-compartment model each. The rat CSF PK-PD model yielded an EC 80 value of 593 ng/ml (90% confidence interval 406.8, 1,264.1). The human plasma and CSF PK data were simultaneously well described by a two-compartment model. Simulations showed that in humans at 100 mg QD, CSF levels of Org 26576 would exceed the EC 80 target concentration for about 2 h and that 400 mg BID would engage AMPA receptors for 24 h. Conclusion: The modelling approach provided useful insight on the likely human dose-molecular target engagement relationship for Org 26576. Based on the current analysis, 100 and 400 mg BID would be suitable to provide 'phasic' and 'continuous' AMPA receptor engagement, respectively. © 2011 Springer-Verlag.
Scopes D.I.C.,Senexis Ltd |
O'Hare E.,Queen's University of Belfast |
Jeggo R.,NeuroSolutions Ltd |
Whyment A.D.,NeuroSolutions Ltd |
And 6 more authors.
British Journal of Pharmacology | Year: 2012
BACKGROUND AND PURPOSE Amyloid-β (Aβ) aggregation into synaptotoxic, prefibrillar oligomers is a major pathogenic event underlying the neuropathology of Alzheimer's disease (AD). The pharmacological and neuroprotective properties of a novel Aβ aggregation inhibitor, SEN1269, were investigated on aggregation and cell viability and in test systems relevant to synaptic function and memory, using both synthetic Aβ1-42 and cell-derived Aβ oligomers. EXPERIMENTAL APPROACH Surface plasmon resonance studies measured binding of SEN1269 to Aβ1-42. Thioflavin-T fluorescence and MTT assays were used to measure its ability to block Aβ1-42-induced aggregation and reduction in cell viability. In vitro and in vivo long-term potentiation (LTP) experiments measured the effect of SEN1269 on deficits induced by synthetic Aβ1-42 and cell-derived Aβ oligomers. Following i.c.v. administration of the latter, a complex (alternating-lever cyclic ratio) schedule of operant responding measured effects on memory in freely moving rats. KEY RESULTS SEN1269 demonstrated direct binding to monomeric Aβ1-42, produced a concentration-related blockade of Aβ1-42 aggregation and protected neuronal cell lines exposed to Aβ1-42. In vitro, SEN1269 alleviated deficits in hippocampal LTP induced by Aβ1-42 and cell-derived Aβ oligomers. In vivo, SEN1269 reduced the deficits in LTP and memory induced by i.c.v. administration of cell-derived Aβ oligomers. CONCLUSIONS AND IMPLICATIONS SEN1269 protected cells exposed to Aβ1-42, displayed central activity with respect to reducing Aβ-induced neurotoxicity and was neuroprotective in electrophysiological and behavioural models of memory relevant to Aβ-induced neurodegeneration. It represents a promising lead for designing inhibitors of Aβ-mediated synaptic toxicity as potential neuroprotective agents for treating AD. © 2012 The Authors. British Journal of Pharmacology.
Hebeisen S.,BSys GmbH Analytics |
Pires N.,BIAL |
Loureiro A.I.,BIAL |
Bonifacio M.J.,BIAL |
And 6 more authors.
Neuropharmacology | Year: 2015
This study aimed at evaluating the effects of eslicarbazepine, carbamazepine (CBZ), oxcarbazepine (OXC) and lacosamide (LCM) on the fast and slow inactivated states of voltage-gated sodium channels (VGSC). The anti-epileptiform activity was evaluated in mouse isolated hippocampal slices. The anticonvulsant effects were evaluated in MES and the 6-Hz psychomotor tests. The whole-cell patch-clamp technique was used to investigate the effects of eslicarbazepine, CBZ, OXC and LCM on sodium channels endogenously expressed in N1E-115 mouse neuroblastoma cells. CBZ and eslicarbazepine exhibit similar concentration dependent suppression of epileptiform activity in hippocampal slices. In N1E-115 mouse neuroblastoma cells, at a concentration of 250 μM, the voltage dependence of the fast inactivation was not influenced by eslicarbazepine, whereas LCM, CBZ and OXC shifted the V0.5 value (mV) by -4.8, -12.0 and -16.6, respectively. Eslicarbazepine- and LCM-treated fast-inactivated channels recovered similarly to control conditions, whereas CBZ- and OXC-treated channels required longer pulses to recover. CBZ, eslicarbazepine and LCM shifted the voltage dependence of the slow inactivation (V0.5, mV) by -4.6, -31.2 and -53.3, respectively. For eslicarbazepine, LCM, CBZ and OXC, the affinity to the slow inactivated state was 5.9, 10.4, 1.7 and 1.8 times higher than to the channels in the resting state, respectively. In conclusion, eslicarbazepine did not share with CBZ and OXC the ability to alter fast inactivation of VGSC. Both eslicarbazepine and LCM reduce VGSC availability through enhancement of slow inactivation, but LCM demonstrated higher interaction with VGSC in the resting state and with fast inactivation gating. © 2014 Elsevier Ltd.
O'Hare E.,Queen's University of Belfast |
Scopes D.I.C.,Senexis Ltd |
Kim E.-M.,University of Ulster |
Palmer P.,Queen's University of Belfast |
And 9 more authors.
Neurobiology of Aging | Year: 2013
Oligomers of beta-amyloid (Aβ) are implicated in the early memory impairment seen in Alzheimer's disease before to the onset of discernable neurodegeneration. Here, the capacity of a novel orally bioavailable, central nervous system-penetrating small molecule 5-aryloxypyrimidine, SEN1500, to prevent cell-derived (7PA2 [conditioned medium] CM) Aβ-induced deficits in synaptic plasticity and learned behavior was assessed. Biochemically, SEN1500 bound to Aβ monomer and oligomers, produced a reduction in thioflavin-T fluorescence, and protected a neuronal cell line and primary cortical neurons exposed to synthetic soluble oligomeric Aβ1-42. Electrophysiologically, SEN1500 alleviated the in vitro depression of long-term potentiation induced by both synthetic Aβ1-42 and 7PA2 CM, and alleviated the in vivo depression of long-term potentiation induced by 7PA2 CM, after systemic administration. Behaviorally, oral administration of SEN1500 significantly reduced memory-related deficits in operant responding induced after intracerebroventricular injection of 7PA2 CM. SEN1500 reduced cytotoxicity, acute synaptotoxicity, and behavioral deterioration after in vitro and in vivo exposure to synthetic Aβ and 7PA2 CM, and shows promise for development as a clinically viable disease-modifying Alzheimer's disease treatment. © 2013 Elsevier Inc.
Hopkins S.C.,Sunovion Pharmaceuticals |
Zhao F.-Y.,Neurosolutions Ltd. |
Bowen C.A.,Sunovion Pharmaceuticals |
Fang X.,Neurosolutions Ltd. |
And 8 more authors.
Journal of Pharmacology and Experimental Therapeutics | Year: 2013
Inhibition of D-amino acid oxidase (DAAO) activity is a potential target for the treatment of chronic pain. Here we characterized the effects of systemic administration of the DAAO inhibitor 4Hfuro[ 3,2-b]pyrrole-5-carboxylic acid (SUN) in rat models of neuropathic and inflammatory pain. Oral administration of SUN dose dependently attenuated tactile allodynia induced by ligation of the L5 spinal nerve (SNL) and similarly reversed thermal hyperalgesia produced by chronic constriction injury. In addition, SUN was efficacious against complete Freund's adjuvant-induced thermal hyperalgesia. In these models, maximal reversal of pain-related behaviors corresponded with maximum rates of increase in brain and plasma D-serine concentrations, indicative of full inhibition of DAAO activity. To investigate the possible site(s) of action, we recorded spontaneous nerve activity and mechanically evoked responses of central spinal cord dorsal horn neurons and compared these with spontaneous activity of peripheral dorsal root filaments in anesthetized SNL model animals. Oral SUN reduced spontaneous activity in both central and peripheral recordings at doses and pretreatment times that corresponded to reduced mechanical allodynia in behavioral experiments. After intravenous administration of SUN, the onset of action for this central effect was rapid (maximal effects within 30 minutes), but was abolished by severing afferent inputs to the dorsal horn. Overall, these results indicate that inhibition of DAAO in peripheral afferent spinal circuits reduced spontaneous neuronal activity to attenuate painrelated behaviors in rat models of neuropathic and inflammatory pain. Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics.
Simonds S.E.,Monash University |
Pryor J.T.,University of Warwick |
Pryor J.T.,Neurosolutions Ltd. |
Ravussin E.,Pennington Biomedical Research Center |
And 18 more authors.
Cell | Year: 2014
Obesity is associated with increased blood pressure (BP), which in turn increases the risk of cardiovascular diseases. We found that the increase in leptin levels seen in diet-induced obesity (DIO) drives an increase in BP in rodents, an effect that was not seen in animals deficient in leptin or leptin receptors (LepR). Furthermore, humans with loss-of-function mutations in leptin and the LepR have low BP despite severe obesity. Leptin's effects on BP are mediated by neuronal circuits in the dorsomedial hypothalamus (DMH), as blocking leptin with a specific antibody, antagonist, or inhibition of the activity of LepR-expressing neurons in the DMH caused a rapid reduction of BP in DIO mice, independent of changes in weight. Re-expression of LepRs in the DMH of DIO LepR-deficient mice caused an increase in BP. These studies demonstrate that leptin couples changes in weight to changes in BP in mammalian species. © 2014 The Authors.
PubMed | Clinical and Biological Research Unit, Lohocla Research Corporation, Colorado State University, Neurosolutions Ltd. and 3 more.
Type: | Journal: European journal of pharmacology | Year: 2016
Recent understanding of the systems that mediate complex disease states, has generated a search for molecules that simultaneously modulate more than one component of a pathologic pathway. Chronic pain syndromes are etiologically connected to functional changes (sensitization) in both peripheral sensory neurons and in the central nervous system (CNS). These functional changes involve modifications of a significant number of components of signal generating, signal transducing and signal propagating pathways. Our analysis of disease-related changes which take place in sensory neurons during sensitization led to the design of a molecule that would simultaneously inhibit peripheral NMDA receptors and voltage sensitive sodium channels. In the current report, we detail the selectivity of N,N-(diphenyl)-4-ureido-5,7-dichloro-2-carboxy-quinoline (DCUKA) for action at NMDA receptors composed of different subunit combinations and voltage sensitive sodium channels having different subunits. We show that DCUKA is restricted to the periphery after oral administration, and that circulating blood levels are compatible with its necessary concentrations for effects at the peripheral cognate receptors/channels that were assayed in vitro. Our results demonstrate that DCUKA, at concentrations circulating in the blood after oral administration, can modulate systems which are upregulated during peripheral sensitization, and are important for generating and conducting pain information to the CNS. Furthermore, we demonstrate that DCUKA ameliorates the hyperalgesia of chronic pain without affecting normal pain responses in neuropathic and inflammation-induced chronic pain models.
Amijee H.,Senexis Ltd |
Amijee H.,University of Manchester |
Bate C.,Lane College |
Williams A.,Lane College |
And 9 more authors.
Biochemistry | Year: 2012
Oligomeric forms of β-amyloid (Aβ) have potent neurotoxic activity and are the primary cause of neuronal injury and cell death in Alzheimer's disease (AD). Compounds that perturb oligomer formation or structure may therefore be therapeutic for AD. We previously reported that d-[(chGly)-(Tyr)-(chGly)-(chGly)-(mLeu)]-NH2 (SEN304) is able to inhibit Aβ aggregation and toxicity, shown primarily by thioflavin T fluorescence and MTT (Kokkoni, N. et al. (2006) N-Methylated peptide inhibitors of β-amyloid aggregation and toxicity. Optimisation of inhibitor structure. Biochemistry45, 9906-9918). Here we extensively characterize how SEN304 affects Aβ(1-42) aggregation and toxicity, using biophysical assays (thioflavin T, circular dichroism, SDS-PAGE, size exclusion chromatography, surface plasmon resonance, traveling wave ion mobility mass spectrometry, electron microscopy, ELISA), toxicity assays in cell culture (MTT and lactate dehydrogenase in human SH-SHY5Y cells, mouse neuronal cell death and synaptophysin) and long-term potentiation in a rat hippocampal brain slice. These data, with dose response curves, show that SEN304 is a powerful inhibitor of Aβ(1-42) toxicity, particularly effective at preventing Aβ inhibition of long-term potentiation. It can bind directly to Aβ(1-42), delay β-sheet formation and promote aggregation of toxic oligomers into a nontoxic form, with a different morphology that cannot bind thioflavin T. SEN304 appears to work by inducing aggregation, and hence removal, of Aβ oligomers. It is therefore a promising lead compound for Alzheimer's disease. © 2012 American Chemical Society.
PubMed | NeuroSolutions Ltd, University College Birmingham, Glaxosmithkline and University of Melbourne
Type: Journal Article | Journal: British journal of pharmacology | Year: 2016
The 5-HT7 receptor is a GPCR that is the target of a broad range of antidepressant and antipsychotic drugs. Various studies have demonstrated an ability of the 5-HT7 receptor to modulate glutamatergic neurotransmission and cognitive processes although the potential impact upon AMPA receptors has not been investigated directly. The purposes of the present study were to investigate a direct modulation of the GluA1 AMPA receptor subunit and determine how this might influence AMPA receptor function.The influence of pharmacological manipulation of the 5-HT7 receptor system upon phosphorylation of GluA1 subunits was assessed by Western blotting of fractionated proteins from hippocampal neurones in culture (or proteins resident at the neurone surface) and the functional impact assessed by electrophysiological recordings in rat hippocampus in vitro and in vivo.5-HT7 receptor activation increased cAMP and relative pCREB levels in cultures of rat hippocampal neurones along with an increase in phosphorylation (Ser845) of the GluA1 AMPA receptor subunit evident in whole neurone extracts and within the neurone surface compartment. Electrophysiological recordings in rat hippocampus demonstrated a 5-HT7 receptor-mediated increase in AMPA receptor-mediated neurotransmission in vitro and in vivo.The 5-HT7 receptor-mediated phosphorylation of the GluA1 AMPA receptor provides a molecular mechanism consistent with the 5-HT7 receptor-mediated increase in AMPA receptor-mediated neurotransmission.