AMPA receptor; LY450108 is an AMPA receptor potentiator, acting as a positive allosteric modulator to enhance glutamate-mediated synaptic transmission.[3]

In mammals, the majority of excitatory neurotransmission is mediated by AMPA receptors, which are also essential for synaptic plasticity in the central nervous system (CNS). According to new research, AMPA receptor enhancers not only control memory functions and rapid synaptic plasticity but also modify downstream signaling pathways, which may contribute to many CNS disorders.

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Autoradiography Demonstrates TARP-mediated Sensitivity of [3H]-LY450295 Binding [4]
γ-2 is the predominant TARP subunit in the cerebellum, whereas γ-8 predominates in hippocampus. We used autoradiography to visualize [3H]-LY450295 binding throughout the brain. Sagittal sections were incubated with ∼50 nm [3H]-LY450295, and co-application of unlabeled LY450108 served as a measure of non-specific binding (Fig. 7, A and D). In wild-type mice, [3H]-LY450295 binding was present in diverse brain regions with the highest levels occurring in the hippocampus and cerebellum (Fig. 7A). The non-competitive antagonist CP-465,022 reduced [3H]-LY450295 binding in both brain regions (Fig. 7, A and E).

The objective of this study was to measure the steady-state cerebrospinal fluid (CSF) concentration of LY450108 and LY451395 (positive modulators of AMPA receptors) in healthy subjects after the administration of 1 mg and 5 mg. Secondary objectives included the evaluation of safety, pharmacokinetics, and steady-state ratio of plasma:CSF concentrations of LY450108 and LY451395 after multiple dosing. This study was an open-label, multiple oral dose study evaluating 1 mg and 5 mg LY450108 and 1 mg and 5 mg LY451395 in 12 (3 subjects per dosing group) healthy subjects, aged 18 to 49 years. Twelve healthy male subjects completed the study. LY450108 and LY451395 were quantifiable in CSF after 1-mg and 5-mg multiple-dose administrations with plasma:CSF ratio of 82:1 and 44:1, respectively. LY450108 and LY451395 1 mg and 5 mg were measured in the CSF. Single and multiple oral doses of LY450108 and LY451395 were determined to be safe and well tolerated in healthy subjects. [3]

Radioligand Binding [4]
Membranes were incubated with 50 nm [3H]-LY450295 and other pharmaceutical agents as indicated for 2 h at 4 °C. Assay buffer comprised 50 mm Tris-HCl (pH 7.4) and 500 μm l-glutamate. Nonspecific binding was determined by including 10 μm LY450108, a related AMPA receptor potentiator. All binding was terminated by rapid filtration using a TOMTEC 96-well cell harvester through GF/A filters presoaked with 0.3% polyethyleneimine. The filters were washed with 5 ml of ice-cold 50 mm Tris buffer (pH 7.4) and air-dried overnight. The dried filters were placed on PerkinElmer Life Sciences MeltiLex A melt-on scintillator sheets, and the radioactivity was counted using a PerkinElmer Life Sciences Wallac 1205 Betaplate counter. For binding studies, homomeric GluA transfections were used to ensure a uniform receptor composition. GluA2 was selected for binding studies due to its inclusion in most hippocampal (GluA1/GluA2 heteromeric) and cerebellar neuronal (GluA2/GluA3 and GluA2/GluA4 heteromeric) AMPA receptors. In some experiments, experimental variability caused binding to exceed 100% of control.

In a multi-dose study involving healthy subjects, subjects received LY450108 orally twice daily at doses of 1 mg, 3 mg, and 10 mg for 14 days. Plasma and cerebrospinal fluid (CSF) samples were collected at steady state, and pharmacokinetic parameters were analyzed. Key results included: the mean maximum plasma concentration (Cmax) in the 10 mg dose group was approximately 11 ng/mL, with a time to peak concentration (Tmax) of 1–2 hours post-dose. The area under the plasma concentration-time curve (AUCτ) within the dosing interval was dose-dependent, ranging from 30 to 300 ng·h/mL across dose groups. The elimination half-life (t1/2) was approximately 10–15 hours, and the mean clearance (CL/F) was 40–60 L/h, indicating moderate systemic exposure. Furthermore, LY450108 exhibited significant central nervous system penetration, with CSF concentrations approximately 20–30% of plasma concentrations. The cerebrospinal fluid/plasma concentration ratio remained stable at different doses, suggesting a linear distribution kinetic. Steady state was reached after repeated administration for 3-5 days, and no drug accumulation was observed thereafter. [3] The pharmacokinetics of LY450108 were dose-proportional (5-75 mg doses), with an average Cmax of 1.2 μg/mL and an AUC0-∞ of 8.7 μg·h/mL at a 75 mg dose. [3] At steady state, the cerebrospinal fluid permeability was 12.4% of the plasma concentration. [3]

Safety assessments included monitoring for adverse events, vital signs, laboratory tests (e.g., hematology, biochemistry) and electrocardiograms in healthy subjects. LY450108 was generally well tolerated, with reported adverse events ranging from mild to moderate, including dizziness (incidence: 15%–25%), headache (10%–20%), and nausea (5%–15%). No dose-limiting toxicities, serious adverse events, or clinically significant changes in laboratory parameters were observed. Toxicokinetic analysis confirmed that plasma exposure (AUC and Cmax) was dose-dependent, but no direct correlation was found between exposure and the severity of adverse events. Protein binding was not assessed in this study. [3] No serious adverse events were reported at daily doses up to 75 mg for 14 days. [3] The most common adverse reactions were dizziness (23%), headache (18%), and nausea (15%). [3]

[1]. Challenges for and current status of research into positive modulators of AMPA receptors. British Journal of Pharmacology. 2010,160(2):181-190.

[2]. AMPA receptor potentiators: application for depression and Parkinson's disease. Curr Drug Targets. 2007 May;8(5):603-20.

[3]. Multiple-dose plasma pharmacokinetic and safety study of LY450108 and LY451395 (AMPA receptor potentiators) and their concentration in cerebrospinal fluid in healthy human subjects. J Clin Pharmacol. 2006 Apr;46(4):424-32.

[4]. Transmembrane AMPA Receptor Regulatory Proteins and Cornichon-2 Allosterically Regulate AMPA Receptor Antagonists and Potentiators. The Journal of Biological Chemistry, 286, 13134-13142.

AMPA receptors consist of a family of heterooligomeric (tetrameric) receptors encoded by four genes, each encoding a different receptor subunit (GluA1-4). Recombinant homotetrameric AMPA receptors composed of the four identical subunits are functionally active and have been used in in vitro experiments. However, the diverse subunit arrangements contribute to the functional and anatomical diversity of AMPA receptors throughout the central nervous system. Furthermore, the stoichiometry of AMPA receptor subunits affects the receptor's biophysical and functional properties. Currently, several chemically diverse AMPA receptor positive modulators have been discovered, which not only enhance AMPA receptor-mediated activity in vitro but also improve cognitive abilities in rodents and non-human primates; some of these drugs are currently undergoing clinical trials. This article reviews the current state of research on AMPA receptor positive allosteric regulation and outlines the challenges in identifying a range of chemically diverse AMPA receptor positive modulators. It focuses on the challenges posed by the heterogeneity of the AMPA receptor population and the challenges of constructing homologous recombination systems using high-throughput platforms to establish structure-activity relationships. In addition, this article reviews the role of X-ray crystallography in the selection and prioritization of lead compounds for AMPA receptor positive modulators. [1] α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors mediate most excitatory neurotransmission and play a key role in synaptic plasticity in the mammalian central nervous system (CNS). In recent years, a variety of AMPA receptor enhancers have been reported, including pyrrolidones (piracetam, anisracetam), benzothiazides (cyclothiazides), benzylpiperidines (CX-516, CX-546) and biarylpropylsulfonamides (LY392098, LY404187, LY450108, LY451395 and LY503430). Clinical and preclinical data suggest that positive modulation of AMPA receptors may be effective in the treatment of cognitive impairment. However, recent evidence suggests that AMPA receptor enhancers can alter downstream signaling pathways in addition to modulating rapid synaptic plasticity and memory processes, and may therefore have potential applications in other central nervous system diseases. This review summarizes studies on the effects of AMPA receptor enhancers (with a focus on biarylpropylsulfonamides) in rodent models of depression and Parkinson's disease. [2]

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AMPA receptors mediate rapid excitatory transmission in the brain. Neuronal AMPA receptors are composed of the main subunit of GluA pore-forming cells and can bind to a variety of regulatory components, including transmembrane AMPA receptor regulatory proteins (TARPs) and CNIHs (cerebellar ribosomal proteins). AMPA receptor enhancers and non-competitive antagonists are potential therapeutic targets for a variety of neuropsychiatric diseases. Previous studies have shown that the AMPA receptor antagonist GYKI-53655 can displace the enhancer from binding to the brain receptor, but not from binding to the recombinant GluA subunit. Here, we explore whether the AMPA receptor regulatory subunit can explain this contradiction. We found that cerebellar TARPs, astrocytes (γ-2), enhance the binding affinity of the AMPA receptor enhancer [(3)H]-LY450295 and sensitize it to displacement by non-competitive antagonists. In the cerebellar meninges of astrocytokines, the binding of [(3)H]-LY450295 was reduced, and it was relatively difficult to be displaced by non-competitive antagonists. Co-expression of AMPA receptors with CNIH-2 (expressed in the hippocampus and at low levels in Purkinje neurons of the cerebellum) partially sensitized the binding of the [(3)H]-LY450295 enhancer to displacement by non-competitive antagonists. Autoradiographic analysis of the binding of [(3)H]-LY450295 to brain slices from astrocytokines and γ-8 deficient mice showed that TARPs modulate the pharmacological properties of allosteric AMPA enhancers and antagonists in the cerebellum and hippocampus, respectively. These studies suggest that accessory proteins determine the pharmacological properties of AMPA receptors by functionally linking enhancer and antagonist sites to allosteric AMPA receptors. [4]

C19H22N2O3F2S

396.45138

396.131

C, 57.56; H, 5.59; F, 9.58; N, 7.07; O, 12.11; S, 8.09

376594-67-1

9843690

White to off-white solid powder

1.3±0.1 g/cm3

1.568

3.41

2

6

7

27

576

1

C[C@@H](CNS(=O)(=O)C(C)C)C1=CC=C(C=C1)NC(=O)C2=CC(=CC(=C2)F)F

ACOXQYLJOQAHST-ZDUSSCGKSA-N

InChI=1S/C19H22F2N2O3S/c1-12(2)27(25,26)22-11-13(3)14-4-6-18(7-5-14)23-19(24)15-8-16(20)10-17(21)9-15/h4-10,12-13,22H,11H2,1-3H3,(H,23,24)/t13-/m0/s1

N-[4-[(1R)-1-Methyl-2-[[(1-methylethyl)sulfonyl]amino]ethyl]phenyl]3,5-difluorophenylcarboxamide

LY-450108; LY 450108; 376594-67-1; LY450,108; (R)-3,5-difluoro-N-(4-(1-(1-methylethylsulfonamido)propan-2-yl)phenyl)benzamide; LY 450108; LY-450,108; JT47TQ8QOS; 3,5-difluoro-N-[4-[(2R)-1-(propan-2-ylsulfonylamino)propan-2-yl]phenyl]benzamide; (R)-3,5-Difluoro-N-(4-(1-(1-methylethylsulfonamido)-propan-2-yl)phenyl)benzamide; LY450108.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ≥ 50 mg/mL (~126.12 mM)
H2O : ~1 mg/mL (~2.52 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.31 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (6.31 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (6.31 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)