The primary molecular target of (RS)-AMPA is the AMPA subtype of ionotropic glutamate receptors (AMPARs), which are ligand-gated cation channels that mediate fast excitatory neurotransmission. As a potent agonist, (RS)-AMPA binds to and activates these receptors, leading to the opening of the cation channel and influx of sodium and calcium ions, resulting in neuronal depolarization. Importantly, research has demonstrated that (RS)-AMPA does not interfere with binding sites for kainic acid or NMDA receptors, making it a selective tool for studying AMPA receptor function.
(RS)-AMPA targets AMPA-type ionotropic glutamate receptors (AMPARs), which are ligand-gated ion channels that mediate fast excitatory synaptic transmission in the central nervous system. AMPA receptors are tetrameric assemblies of GluA1-4 subunits and are activated by the neurotransmitter glutamate. (RS)-AMPA binds to the glutamate-binding site on AMPA receptors, causing a conformational change that opens the ion channel pore, allowing sodium and potassium ions to flow. This depolarizes the postsynaptic membrane and generates excitatory postsynaptic potentials (EPSPs). The compound is highly selective for AMPA receptors and does not bind to kainate or NMDA receptors, making it a specific tool for studying AMPA receptor function.

In cultured rat spinal cord and brainstem neurons, (RS)-AMPA (10-3-10-4 M) depolarizes them. Although individual neurons' responses to (RS)-AMPA depolarization differ greatly from one another, it appears that the effects are dose-dependent. If (RS)-AMPA was applied at 10-5 M, the depolarization amplitude ranged from 4 to 33 mV, whereas at 10-4 M, the depolarization was just slightly (3-5 mV). If a neuron is firing spontaneously, (RS)-AMPA also increases its firing rate; in silent cells, it occasionally results in brief action potential bursts. Glutamate/quilaic acid receptors are activated by (RS)-AMPA, which depolarizes the body without interfering with NMDA receptor function [1].

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In vitro studies have demonstrated that (RS)-AMPA induces concentration-dependent depolarization in cultured rat spinal and brainstem neurons. At a concentration of 10⁻⁵ M, it produces minimal depolarization (3-7 mV), while at 10⁻⁴ M, depolarization magnitude varies from 4 to 33 mV, showing significant variability across different neurons. (RS)-AMPA also enhances the discharge rate of spontaneously firing neurons and can trigger brief bursts of action potentials in quiescent cells. The effects of (RS)-AMPA on cell survival are critically dependent on developmental timing—exposure to the agonist significantly reduces cell survival only when treatment is initiated after 5 days in vitro, while antagonist treatment starting on the day of plating has a stronger survival-reducing effect.
(RS)-AMPA exhibits potent in vitro activity as an AMPA receptor agonist. It activates AMPA-type ionotropic glutamate receptors in cultured neurons and brain slices. The compound’s activity is measured using electrophysiological techniques such as patch-clamp recording to measure ion currents through AMPA receptors. It also induces depolarization and excitation in neuronal preparations. The compound does not interfere with binding sites for kainic acid or NMDA receptors, confirming its selectivity. In receptor binding assays, (RS)-AMPA displaces radiolabeled AMPA from AMPA receptors with high affinity. These in vitro activities confirm its utility as a specific AMPA receptor agonist.

As a prototypical AMPA receptor agonist, its primary applications are in in vitro neuronal preparations rather than in vivo studies. Research on brainstem cell development suggests that exposure to excitatory amino acid receptor agonists at critical stages of embryogenesis may alter central nervous system development. This finding indicates potential in vivo relevance for the compound's biological activity. The compound is strictly intended for laboratory research use only.
(RS)-AMPA is used extensively in vivo to study AMPA receptor function in animal models. When administered to animals, (RS)-AMPA activates AMPA receptors in the brain, leading to excitation of neurons. This can be used to study the role of AMPA receptors in synaptic plasticity, learning and memory, and excitotoxicity. The compound is often used in combination with NMDA receptor antagonists to dissect the contributions of different glutamate receptor subtypes to synaptic transmission and plasticity. In behavioral studies, (RS)-AMPA can be microinjected into specific brain regions to study its effects on behavior. Its use has contributed significantly to our understanding of AMPA receptor function in the brain.

Binding assays for (RS)-AMPA are typically performed using radiolabeled [³H]AMPA. A standard protocol involves using eGFP-fused recombinant rat full-length GluA2 receptor expressed in HEK293T/17 cells. Membranes or cells expressing the target receptor are incubated with (RS)-[³H]AMPA at varying concentrations for a specified duration. Non-specific binding is determined in the presence of excess unlabeled competitor. Incubations are terminated by rapid filtration through glass fiber filters, followed by washing with ice-cold buffer. The radioactivity retained on the filters is measured by liquid scintillation counting. Data are analyzed using non-linear regression to determine binding affinity parameters (Kd and Bmax).
In vitro receptor binding assays for (RS)-AMPA involve measuring its affinity for AMPA receptors using radioligand binding techniques. Membrane preparations from brain tissue or cells expressing recombinant AMPA receptors are incubated with a radiolabeled AMPA receptor ligand (e.g., [3H]-AMPA) and varying concentrations of (RS)-AMPA. The amount of bound radioligand is measured by filtration or scintillation counting. The IC50 or Ki value is calculated from displacement curves. These assays confirm the compound’s high affinity and selectivity for AMPA receptors over kainate and NMDA receptors.

Cellular assays for (RS)-AMPA typically utilize primary neuronal cultures or neuronal cell lines expressing AMPA receptors. A representative protocol involves dissociating embryonic rat brainstem cells (embryonic day 14) and culturing them in appropriate medium. Cells are treated with (RS)-AMPA at concentrations ranging from 10⁻⁵ to 10⁻⁴ M for designated time periods (e.g., 3 days) at different developmental stages (e.g., starting on day 0 or after 5 days in vitro). Cell survival is assessed by counting gamma-enolase-positive neurons, while cell proliferation is evaluated using 5-bromo-2′-deoxyuridine staining. Electrophysiological studies can also be performed to measure depolarization effects and action potential firing rates using whole-cell patch-clamp recordings.
In vitro cellular assays for (RS)-AMPA are conducted in primary neuronal cultures, brain slices, or cell lines expressing recombinant AMPA receptors. Electrophysiological recordings (patch-clamp or field potential recordings) are used to measure AMPA receptor-mediated currents in response to (RS)-AMPA application. Calcium imaging can be used to measure AMPA receptor-mediated calcium influx in neurons. Cytotoxicity assays may be performed to assess excitotoxicity induced by excessive AMPA receptor activation. These experiments characterize the compound’s agonist activity and its effects on neuronal function.

A limited in vivo protocol has been described for larval assays. For example, (RS)-AMPA hydrobromide is dissolved in filtered sea water to a stock concentration of 7.5 mM and then diluted to a final concentration of 500 µM. Larvae are incubated with the drug for approximately 10 minutes before beginning assays. Behavioral responses are then recorded and analyzed. This protocol represents a rare in vivo application of the compound; most research applications are restricted to in vitro and ex vivo preparations.
In vivo animal experiments with (RS)-AMPA are conducted in rodents, typically rats or mice. The compound is administered via intracerebroventricular (ICV) injection, microinjection into specific brain regions, or systemic administration. Behavioral assays such as locomotor activity, learning and memory tests (e.g., Morris water maze), and seizure models are used to assess the effects of AMPA receptor activation. Electrophysiological recordings in vivo (e.g., field potential recordings in hippocampus) can be performed to measure AMPA receptor-mediated synaptic transmission. These studies help elucidate the role of AMPA receptors in brain function and disease.

As an experimental research tool compound rather than a therapeutic candidate, comprehensive ADME profiling has not been performed. However, its physicochemical properties have been characterized: the compound has a molecular weight of 186.17 g/mol, a calculated LogP value of -0.77 (indicating high hydrophilicity), and a polar surface area of 109.3 Ų. The compound is soluble in water up to 1.86-10 mM with gentle warming. The powder is stable when stored at room temperature.
Pharmacokinetic data for (RS)-AMPA are limited, as the compound is primarily used as a research tool rather than a therapeutic agent. It has a molecular weight of 186.17 and is highly pure (≥99%). The compound is soluble in aqueous solutions and is typically administered via injection in experimental settings. Its half-life and bioavailability have not been extensively characterized. For research use, (RS)-AMPA is typically stored as a solid at room temperature. Further PK studies would be needed if the compound were to be developed as a therapeutic agent.

(RS)-AMPA is classified as an experimental research compound and is strictly intended for laboratory research use only, not for human diagnostic or therapeutic applications. Its primary recognized biological activity—excitotoxicity mediated by excessive AMPA receptor activation—can lead to neuronal damage or death. In vitro studies on brainstem cells have demonstrated that exposure to AMPA receptor agonists at critical developmental stages can significantly reduce neuronal cell survival. No specific data on acute toxicity (LD50), chronic toxicity, genotoxicity, or reproductive toxicity is available in the provided references. Standard safety precautions for laboratory handling include working in a well-ventilated area, wearing appropriate personal protective equipment (gloves, lab coat, safety goggles), and avoiding inhalation, ingestion, or skin contact. The compound is understood to be not hazardous according to transportation regulations.
Toxicological data for (RS)-AMPA are primarily derived from its use as a research tool. Excessive activation of AMPA receptors can lead to excitotoxicity, a form of neuronal damage caused by excessive glutamate receptor activation. This is a well-characterized phenomenon in neuroscience research and is used to study mechanisms of neuronal death in stroke and neurodegenerative diseases. The compound is not approved for human therapeutic use and should be handled with appropriate safety precautions in the laboratory.

[1]. Effects of the glutamate analogue AMPA and its interaction with antagonists on cultured rat spinal and brain stem neurones. Neurosci Lett. 1983 Mar 28;36(1):59-62.

[2]. Flip and flop: a cell-specific functional switch in glutamate-operated channels of the CNS. Science. 1990 Sep 28;249(4976):1580-5.

(S)-AMPA is a non-protein α-amino acid. It is a homolog of iboside and a glutamate agonist. This compound is a hallmark agonist of the AMPA-type glutamate receptor (receptor, AMPA). It has been used as a radionuclide imaging agent, but is more commonly used as an experimental tool in cell biology research.
(RS)-AMPA is a widely used research tool in neuroscience for studying AMPA receptor function. It is the defining agonist for the AMPA subtype of glutamate receptors. The compound is also known as alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid. It does not interfere with binding sites for kainic acid or NMDA receptors, making it highly selective. (RS)-AMPA is used in studies of receptor kinetics, synaptic plasticity, excitotoxicity, and learning and memory. Its racemic mixture includes both enantiomers, ensuring broad receptor activation. The compound is available in high purity (≥99%) for research applications.

C7H10N2O4

186.165301799774

186.064

C, 45.16; H, 5.41; N, 15.05; O, 34.38

77521-29-0

(RS)-AMPA monohydrate;76463-67-7

1221

White to off-white solid powder

1.5±0.1 g/cm3

425.6±45.0 °C at 760 mmHg

240ºC

211.2±28.7 °C

0.0±1.1 mmHg at 25°C

1.579

-0.44

3

5

3

13

284

0

O1C(C)=C(C(N1)=O)CC(C(=O)[O-])[NH3+]

UUDAMDVQRQNNHZ-UHFFFAOYSA-N

InChI=1S/C7H10N2O4/c1-3-4(6(10)9-13-3)2-5(8)7(11)12/h5H,2,8H2,1H3,(H,9,10)(H,11,12)

2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid

(RS)AMPA; alpha-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID; 4-Isoxazolepropanoic acid, alpha-amino-2,3-dihydro-5-methyl-3-oxo-; RefChem:915477; alpha Amino 3 hydroxy 5 methyl 4 isoxazolepropionic Acid; (RS) AMPA

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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