Publications by authors named "Laura Aldegheri"

7 Publications

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Pharmacological characterisation of MDI-222, a novel AMPA receptor positive allosteric modulator with an improved safety profile.

J Psychopharmacol 2020 01 26;34(1):93-102. Epub 2019 Nov 26.

Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow, UK.

Purpose: There is considerable interest in positive allosteric modulators (PAMs) of the α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) subtype of ionotropic glutamate receptors as therapeutic agents for a range of cognitive and mood disorders. However, the challenge is to increase AMPA receptor (AMPAR) function sufficient to enhance cognitive function but not to the extent that there are mechanism-related pro-convulsant or convulsant side effects. In this present study, we report the preclinical pharmacology data for MDI-222, an AMPAR PAM which enhances cognition but has a much reduced side-effect (i.e. convulsant) liability relative to other molecules of this mechanism.

Methods: The pharmacological effects of MDI-222 were characterised in in vitro and in vivo preclinical electrophysiology, efficacy (cognition), side-effect (pro-convulsant/convulsant), tolerability and toxicity assays.

Results: We demonstrate that MDI-222 is an AMPAR PAM, since it enhanced AMPAR function in vitro at human (hGluA1-4) and rat (rGluA2) homomeric receptors, and potentiated hetero-oligomeric AMPARs in rat neurons. MDI-222 enhanced electrically evoked AMPAR-mediated synaptic transmission in the anaesthetised rat at 10 mg/kg (administered intravenously) and did not significantly lower the seizure threshold in the pro-convulsant maximal electroshock threshold test (MEST) at any dose tested up to a maximum of 30 mg/kg (administered by oral gavage (p.o.)). MDI-222 reversed a delay-induced deficit in novel object recognition (NOR) in rats with a minimum effective dose (MED) of 0.3 mg/kg (p.o.) following acute administration, which was reduced to 0.1 mg/kg following sub-chronic administration, and improved passive avoidance performance in scopolamine-impaired rats with a MED of 10 mg/kg p.o. On the other hand, MDI-222 was not pro-convulsant in the MEST, resulting in a therapeutic window between plasma concentrations that enhanced cognitive performance and those associated with mechanism-related side effects of ⩾1000-fold. Unfortunately, despite the excellent preclinical profile of this compound, further development had to be halted due to non-mechanism-related issues.

Conclusions: We conclude that MDI-222 is an AMPAR PAM which enhances cognitive performance in rats and has a significantly improved safety profile in preclinical species.
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http://dx.doi.org/10.1177/0269881119872198DOI Listing
January 2020

A Novel Modulator of Kv3 Potassium Channels Regulates the Firing of Parvalbumin-Positive Cortical Interneurons.

J Pharmacol Exp Ther 2015 Sep 17;354(3):251-60. Epub 2015 Jun 17.

Autifony s.r.l., Verona, Italy (M.D.R.-S., G.A.); Aptuit s.r.l., Verona, Italy (E.Z., C.M., N.G., R.B., L.A., C.V.); Medicines Research Centre, GlaxoSmithKline S.p.A., Verona, Italy (F.G.); and Autifony Therapeutics Limited, Imperial College Incubator, London, United Kingdom (C.H.L.)

Kv3.1 and Kv3.2 high voltage-activated potassium channels, which display fast activation and deactivation kinetics, are known to make a crucial contribution to the fast-spiking phenotype of certain neurons. Pharmacological experiments show that the blockade of native Kv3 currents with low concentrations of tetraethylammonium or 4-aminopyridine impairs the expression of this firing phenotype. In particular, Kv3 channels are highly expressed by fast-spiking, parvalbumin-positive interneurons in corticolimbic brain circuits, which modulate the synchronization of cortical circuits and the generation of brain rhythms. Here, we describe a novel small molecule, (5R)-5-ethyl-3-(6-{[4-methyl-3-(methyloxy)phenyl]oxy}-3-pyridinyl)-2,4-imidazolidinedione (AUT1), which modulates Kv3.1 and Kv3.2 channels in human recombinant and rodent native neurons. AUT1 increased whole currents mediated by human Kv3.1b and Kv3.2a channels, with a concomitant leftward shift in the voltage dependence of activation. A less potent effect was observed on hKv3.3 currents. In mouse somatosensory cortex slices in vitro, AUT1 rescued the fast-spiking phenotype of parvalbumin-positive-fast-spiking interneurons following an impairment of their firing capacity by blocking a proportion of Kv3 channels with a low concentration of tetraethylammonium. Notably, AUT1 had no effect on interneuron firing when applied alone. Together, these data confirm the role played by Kv3 channels in the regulation of the firing phenotype of somatosensory interneurons and suggest that AUT1 and other Kv3 modulators could represent a new and promising therapeutic approach to the treatment of disorders associated with dysfunction of inhibitory feedback in corticolimbic circuits, such as schizophrenia.
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http://dx.doi.org/10.1124/jpet.115.225748DOI Listing
September 2015

Integration of lead optimization with crystallography for a membrane-bound ion channel target: discovery of a new class of AMPA receptor positive allosteric modulators.

J Med Chem 2011 Jan 3;54(1):78-94. Epub 2010 Dec 3.

School of Life Sciences, University of Sussex, Brighton, United Kingdom.

A novel series of AMPAR positive modulators is described that were identified by high throughput screening. The molecules of the series have been optimized from a high quality starting point hit to afford excellent developability, tolerability, and efficacy profiles, leading to identification of a clinical candidate. Unusually for an ion channel target, this optimization was integrated with regular generation of ligand-bound crystal structures and uncovered a novel chemotype with a unique and highly conserved mode of interaction via a trifluoromethyl group.
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http://dx.doi.org/10.1021/jm100679eDOI Listing
January 2011

N-substituted pyrrolidines and tetrahydrofurans as novel AMPAR positive modulators.

Bioorg Med Chem Lett 2010 Dec 17;20(23):7116-9. Epub 2010 Sep 17.

Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow, Essex, United Kingdom.

A series of novel AMPA receptor positive modulators displaying CNS penetration have been discovered with sub-micromolar activity and good selectivity over the cardiac channel receptor, hERG. We describe here the synthesis of these compounds which are biaryl pyrrolidine and tetrahydrofuran sulfonamides and disclose their activities against the human GluA2 flip isoform homotetrameric receptor.
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http://dx.doi.org/10.1016/j.bmcl.2010.09.062DOI Listing
December 2010

Discovery of N-[(2S)-5-(6-fluoro-3-pyridinyl)-2,3-dihydro-1H-inden-2-yl]-2-propanesulfonamide, a novel clinical AMPA receptor positive modulator.

J Med Chem 2010 Aug;53(15):5801-12

Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow, Essex, UK.

A series of AMPA receptor positive allosteric modulators has been optimized from poorly penetrant leads to identify molecules with excellent preclinical pharmacokinetics and CNS penetration. These discoveries led to 17i, a potent, efficacious CNS penetrant molecule with an excellent pharmacokinetic profile across preclinical species, which is well tolerated and is also orally bioavailable in humans.
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http://dx.doi.org/10.1021/jm1005429DOI Listing
August 2010

The antidepressant fluoxetine blocks the human small conductance calcium-activated potassium channels SK1, SK2 and SK3.

Neurosci Lett 2003 Jul;346(1-2):85-8

GlaxoSmithKline, Medicines Research Centre, Via A Fleming 4, 37135 Verona, Italy.

The effects of fluoxetine (Prozac) on the activity of human small-conductance calcium-activated potassium (SK) channels were investigated utilizing a functional fluorescence assay with bis-(1,3-dibutylbarbituric acid)trimethine oxonol (DiBAC(4)(3)). Fluoxetine blocked SK channels stably expressed in HEK 293 cells in a concentration-dependent manner displaying half-maximal inhibitory concentrations (IC(50)) of 9 microM for hSK1, 7 microM for hSK2 and 20 microM for hSK3. The block of hSK3 channels was confirmed by whole cell patch-clamp recordings of the recombinant cells and human TE 671 cells. Fluoxetine also inhibited [(125)I]apamin binding in a concentration-dependent manner displaying IC(50) values of 63 microM for hSK1, 148 microM for hSK2 and 295 microM for hSK3. These results provide new information concerning the mechanism of therapeutic and/or side effects of one of the most widely used antidepressant drugs.
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http://dx.doi.org/10.1016/s0304-3940(03)00574-3DOI Listing
July 2003

Pharmacological properties of rat alpha 7 nicotinic receptors expressed in native and recombinant cell systems.

Eur J Pharmacol 2002 Jun;445(3):153-61

Systems Research, GlaxoSmithKline Medicines Research Centre, Via A. Fleming 4, 37135, Verona, Italy.

The pharmacological properties of the rat alpha7 nicotinic acetylcholine receptor endogenously expressed in PC12 cells and recombinantly expressed in GH4C1 cells (alpha7-GH4C1 cells) were characterized and compared. Patch-clamp recordings demonstrated that activation by choline and block by methyllycaconitine and dihydro-beta-erythroidine were similar, but block by mecamylamine was different. Whereas in alpha7-GH4C1 cells the inhibition curve for mecamylamine was monophasic (IC(50) of 1.6 microM), it was biphasic in PC12 cells (IC(50) values of 341 nM and 9.6 microM). The same rank order of potency was obtained for various nicotinic agonists, while acetylcholine was 3.7-fold less potent and 1.5-fold more effective in PC12 cells. Dihydro-beta-erythroidine differentially blocked acetylcholine-evoked currents in both systems. Since reverse transcriptase polymerase chain reaction (RT-PCR) experiments revealed expression of alpha3, alpha4, alpha5, alpha7 and beta4 subunits in PC12 cells, whereas GH4C1 cells express only the beta4 subunit, our results suggest that more than one form of alpha7 containing heteromeric nicotinic receptors might be functionally expressed in PC12 cells.
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http://dx.doi.org/10.1016/s0014-2999(02)01750-8DOI Listing
June 2002