title: Characterization of a novel high-potency positive modulator of K(v)7 channels.
abstract: K(v)7 channel activators decrease neuronal excitability and might potentially treat neuronal hyperexcitability disorders like epilepsy and mania. Here we introduce NS15370 ((2-(3,5-difluorophenyl)-N-[6-[(4-fluorophenyl)methylamino]-2-morpholino-3-pyridyl]acetamide)hydrochloride, an in vitro high-potency chemical analogue of retigabine, without effects on GABA(A) receptors. NS15370 activates recombinant homo- and heteromeric K(v)7.2-K(v)7.5 channels in HEK293 cells at sub-micromolar concentrations (EC₅₀~100 nM, as quantified by a fluorescence based Tl⁺-influx assay). In voltage clamp experiments NS15370 exhibits a complex, concentration-dependent mode-of-action: At low concentrations it accelerates voltage-dependent activation rates, slows deactivations, and increases steady-state current amplitudes. Quantified by the peak-tail current method, the V½ value of the steady-state activation curve is shifted towards hyperpolarized potentials at concentrations ~100 times lower than retigabine. However, in contrast to retigabine, NS15370 also introduces a distinct time-dependent current decrease, which eventually, at higher concentrations, causes suppression of the current at depolarized potentials, and an apparent "cross-over" of the voltage-activation curve. In brain slices, NS15370 hyperpolarizes and increases spike frequency adaptation of hippocampal CA1 neurons and the compound reduces the autonomous firing of dopaminergic neurons in the substantia-nigra pars compacta. NS15370 is effective in rodent models of hyperexcitability: (i) it yields full protection against mouse 6 Hz seizures and rat amygdala kindling discharges, two models of partial epilepsia; (ii) it reduces (+)-MK-801 hydrogen maleate (MK-801)-induced hyperactivity as well as chlordiazepoxide (CDP)+d-amphetamine (AMP)-induced hyperactivity, models sensitive to classic anti-psychotic and anti-manic treatments, respectively. Our findings with NS15370 consolidate neuronal K(v)7 channels as targets for anti-epileptic and psychiatric drug development.
authors.affiliation: NeuroSearch A/S, Pederstrupvej 93, DK-2750 Ballerup, Denmark.
authors.forename: William
authors.initials: W
authors.lastname: Dalby-Brown
authors.forename: Carsten
authors.initials: C
authors.lastname: Jessen
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hougaard
authors.forename: Marianne L
authors.initials: ML
authors.lastname: Jensen
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Jacobsen
authors.forename: Karin S
authors.initials: KS
authors.lastname: Nielsen
authors.forename: Helle K
authors.initials: HK
authors.lastname: Erichsen
authors.forename: Morten
authors.initials: M
authors.lastname: Grunnet
authors.forename: Philip K
authors.initials: PK
authors.lastname: Ahring
authors.forename: Palle
authors.initials: P
authors.lastname: Christophersen
authors.forename: Dorte
authors.initials: D
authors.lastname: Strøbæk
authors.forename: Susanne
authors.initials: S
authors.lastname: Jørgensen
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology / Q000627:therapeutic use*; D018692:Antimanic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D014150:Antipsychotic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D044482:Benzeneacetamides / Q000494:pharmacology / Q000627:therapeutic use*; D001714:Bipolar Disorder / Q000188:drug therapy / Q000378:metabolism; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000378:metabolism; D004828:Epilepsies, Partial / Q000188:drug therapy / Q000378:metabolism; D005260:Female; D059330:GABAergic Neurons / Q000187:drug effects* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D066298:In Vitro Techniques; D051657:KCNQ1 Potassium Channel / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D008297:Male; D049990:Membrane Transport Modulators / Q000494:pharmacology / Q000627:therapeutic use; D051379:Mice; D009419:Nerve Tissue Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D011618:Psychotic Disorders / Q000188:drug therapy / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism
chemical_list: C584425:2-(3,5-difluorophenyl)-N-(6-((4-fluorophenyl)methylamino)-2-morpholino-3-pyridyl)acetamide; D000631:Aminopyridines; D000927:Anticonvulsants; D018692:Antimanic Agents; D014150:Antipsychotic Agents; D044482:Benzeneacetamides; D051657:KCNQ1 Potassium Channel; D049990:Membrane Transport Modulators; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins