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The metabotropic glutamate receptor 2 (mGluR2) has emerged as a potential therapeutic target for the treatment of various neurological diseases, prompting substantial interest in the development of mGluR2-targeted drug candidates. As part of our medicinal chemistry program, we synthesized a series of isoindolone derivatives and assessed their potential as mGluR2 positive allosteric modulators (PAMs). Notably, AZ12559322 exhibited high affinity (K i mGluR2 = 1.31 nM) and an excellent in vitro binding specificity of 89% while demonstrating selectivity over other mGluR subtypes (>4000-fold). Autoradiography with the radiolabeled counterpart, [3H]AZ12559322, revealed a heterogeneous accumulation with the highest binding in mGluR2-rich brain regions. Radioligand binding was significantly reduced by pretreatment with nonradioactive mGluR2 PAMs in brains of rats and nonhuman primates. Although positron emission tomography imaging of [11C]AZ12559322 (6a) revealed low brain uptake in a nonhuman primate, this study provides valuable guidance to further design novel isoindolone-based mGluR2 PAMs with improved brain exposure.
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Numerous methods have been reported for detecting ROS/RNS in vitro and in vivo; however, detecting methods for the secondary products of the ROS/RNS reactions, particularly quasi-stable oxidized products, have been much less explored. In this report, we observed that half-curcumins could generate chemiluminescence. In contrast to other chemiluminescence scaffolds, the distinguishing feature of a half-curcumin is the formation of a carbanion intermediate of its acetylacetone moiety, opening unique avenues for applications. In this study, we designed a series of half-curcumins CRANAD-Xs and found that CRANAD-164 could be used to detect quasi-stable oxidized proteins (QSOP) in vivo and in patient serum samples. We illustrated that CRANAD-164 could be used to monitor the responses of taurine, an amino acid with newly reported anti-aging capacity, in an inflammatory mouse model. Remarkably, we further demonstrated that the QSOP levels were much higher in the disease serum samples, including Alzheimer's disease, compared to the samples from healthy controls. Moreover, our results revealed that the sera chemiluminescence intensities were higher in aged healthy controls compared to young healthy subjects, suggesting that CRANAD-164 can be used to monitor the increase of QSOP during aging.
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To quantitatively evaluate the effect of the process parameters and the material properties on the temperature in laser powder bed fusion (LPBF), this paper proposed a sensitivity analysis of the temperature based on the validated prediction model. First, three different heat source modes-point heat source, Gaussian surface heat source, and Gaussian body heat source-were introduced. Then, a case study of Ti6Al4V is conducted to determine the suitable range of heat source density for the three different heat source models. Based on this, the effects of laser processing parameters and material thermophysical parameters on the temperature field and molten pool size are quantitatively discussed based on the Gaussian surface heat source. The results indicate that the Gaussian surface heat source and the Gaussian body heat source offer higher prediction accuracy for molten pool width compared to the point heat source under similar processing parameters. When the laser energy density is between 40 and 70 J/mm3, the prediction accuracy of the Gaussian surface heat source and the body heat source is similar, and the average prediction errors are 4.427% and 2.613%, respectively. When the laser energy density is between 70 and 90 J/mm3, the prediction accuracy of the Gaussian body heat source is superior to that of the Gaussian surface heat source. Among the influencing factors, laser power exerts the greatest influence on the temperature field and molten pool size, followed by scanning speed. In particular, laser power and scan speed contribute 38.9% and 23.5% to the width of the molten pool, 39.1% and 19.6% to the depth of the molten pool, and 38.9% and 21.5% to the maximum temperature, respectively.
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The strategic installation of a [18F]fluorine atom at the specific position of the lead molecule is a never-ending challenge for radiochemists in their endeavour to develop novel positron emission tomography (PET) imaging applications. Although the radiosynthesis of [18F]CF2H-containing molecules has been explored in the past decade, more methods need to be explored for various well-functionalized compounds. Recently, two novel strategies of radiodifluoromethylation were reported, namely the utilization of [18F]difluorocarbene building block and frustrated Lewis pair-mediated C-18F bond formation, respectively. These methods provide an efficient radiofunctionalization of complex CF2H-containing molecules for drug discovery and PET ligand development.
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Poly(ADP-ribose) polymerase (PARP) activation often indicates a disruptive signal to lipid metabolism, the physiological alteration of which may be implicated in the development of non-alcoholic fatty liver disease. The objective of this study was to evaluate the capability of [68Ga]DOTA-PARPi PET to detect hepatic PARP expression in a non-alcoholic steatohepatitis (NASH) mouse model. In this study, male C57BL/6 mice were subjected to a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) for a 12-week period to establish preclinical NASH models. [68Ga]DOTA-PARPi PET imaging of the liver was conducted at the 12-week mark after CDAHFD feeding. Comprehensive histopathological analysis, covering hepatic steatosis, inflammation, fibrosis, along with blood biochemistry, was performed in both NASH models and control groups. Despite the induction of severe inflammation, steatosis and fibrosis in the liver of mice with the CDAHFD-NASH model, PET imaging of NASH with [68Ga]-DOTA-PARPi did not reveal a significantly higher uptake in NASH models compared to the control. This underscores the necessity for further development of new chelator-based PARP1 tracers with high binding affinity to enable the visualization of PARP1 changes in NASH pathology.
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Aggregated α-synuclein (α-syn) protein is a pathological hallmark of Parkinson's disease (PD) and Lewy body dementia (LBD). Development of positron emission tomography (PET) radiotracers to image α-syn aggregates has been a longstanding goal. This work explores the suitability of a pyridothiophene scaffold for α-syn PET radiotracers, where 47 derivatives of a potent pyridothiophene (asyn-44; Kd=1.85â nM) were synthesized and screened against [3H]asyn-44 in competitive binding assays using post-mortem PD brain homogenates. Equilibrium inhibition constant (Ki) values of the most potent compounds were determined, of which three had Ki's in the lower nanomolar range (12-15â nM). An autoradiography study confirmed that [3H]asyn-44 is promising for imaging brain sections from multiple system atrophy and PD donors. Fluorine-18 labelled asyn-44 was synthesized in 6±2 % radiochemical yield (decay-corrected, n=5) with a molar activity of 263±121 GBq/µmol. Preliminary PET imaging of [18F]asyn-44 in rats showed high initial brain uptake (>1.5 standardized uptake value (SUV)), moderate washout (~0.4 SUV at 60â min), and low variability. Radiometabolite analysis showed 60-80 % parent tracer in the brain after 30 and 60â mins. While [18F]asyn-44 displayed good inâ vitro properties and acceptable brain uptake, troublesome radiometabolites precluded further PET imaging studies. The synthesis and inâ vitro evaluation of additional pyridothiophene derivatives are underway, with the goal of attaining improved affinity and metabolic stability.
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Parkinson's disease (PD) is one of the most highly debilitating neurodegenerative disorders, which affects millions of people worldwide, and leucine-rich repeat kinase 2 (LRRK2) mutations have been involved in the pathogenesis of PD. Developing a potent LRRK2 positron emission tomography (PET) tracer would allow for in vivo visualization of LRRK2 distribution and expression in PD patients. In this work, we present the facile synthesis of two potent and selective LRRK2 radioligands [11C]3 ([11C]PF-06447475) and [18F]4 ([18F]PF-06455943). Both radioligands exhibited favorable brain uptake and specific bindings in rodent autoradiography and PET imaging studies. More importantly, [18F]4 demonstrated significantly higher brain uptake in the transgenic LRRK2-G2019S mutant and lipopolysaccharide (LPS)-injected mouse models. This work may serve as a roadmap for the future design of potent LRRK2 PET tracers.
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Morfolinas , Nitrilas , Doença de Parkinson , Pirimidinas , Camundongos , Animais , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Leucina , Tomografia por Emissão de Pósitrons/métodos , Doença de Parkinson/metabolismo , MutaçãoRESUMO
The hydrofluorination of alkenes represents an attractive strategy for the synthesis of aliphatic fluorides. This approach provides a direct means to form C(sp3)-F bonds selectively from readily available alkenes. Nonetheless, conducting hydrofluorination using nucleophilic fluorine sources poses significant challenges due to the low acidity and high toxicity associated with HF and the poor nucleophilicity of fluoride. In this study, we present a new Co(salen)-catalyzed hydrofluorination of simple alkenes utilizing Et3N·3HF as the sole source of both hydrogen and fluorine. This process operates via a photoredox-mediated polar-radical-polar crossover mechanism. We also demonstrated the versatility of this method by effectively converting a diverse array of simple and activated alkenes with varying degrees of substitution into hydrofluorinated products. Furthermore, we successfully applied this methodology to 18F-hydrofluorination reactions, enabling the introduction of 18F into potential radiopharmaceuticals. Our mechanistic investigations, conducted using rotating disk electrode voltammetry and DFT calculations, unveiled the involvement of both carbocation and CoIV-alkyl species as viable intermediates during the fluorination step, and the contribution of each pathway depends on the structure of the starting alkene.
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Cholesterol homeostasis is impaired in Alzheimer's disease; however, attempts to modulate brain cholesterol biology have not translated into tangible clinical benefits for patients to date. Several recent milestone developments have substantially improved our understanding of how excess neuronal cholesterol contributes to the pathophysiology of Alzheimer's disease. Indeed, neuronal cholesterol was linked to the formation of amyloid-ß and neurofibrillary tangles through molecular pathways that were recently delineated in mechanistic studies. Furthermore, remarkable advances in translational molecular imaging have now made it possible to probe cholesterol metabolism in the living human brain with PET, which is an important prerequisite for future clinical trials that target the brain cholesterol machinery in Alzheimer's disease patients-with the ultimate aim being to develop disease-modifying treatments. This work summarizes current concepts of how the biosynthesis, transport and clearance of brain cholesterol are affected in Alzheimer's disease. Further, current strategies to reverse these alterations by pharmacotherapy are critically discussed in the wake of emerging translational research tools that support the assessment of brain cholesterol biology not only in animal models but also in patients with Alzheimer's disease.
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Doença de Alzheimer , Encéfalo , Colesterol , Desenvolvimento de Medicamentos , Doença de Alzheimer/metabolismo , Doença de Alzheimer/tratamento farmacológico , Humanos , Colesterol/metabolismo , Encéfalo/metabolismo , Animais , Desenvolvimento de Medicamentos/métodosRESUMO
AMPA glutamate receptors (AMPARs) play a pivotal role in excitatory neurotransmission, particularly in the hippocampus where the TARP γ-8 subunit is enriched and serves as a target for emerging anti-epileptic drugs. To enable inâ vivo visualization of TARP γ-8 distribution and expression by positron emission tomography (PET), this study focuses on the development of novel 18 F-labeled TARP γ-8 inhibitors and their corresponding precursors, stemming from the azabenzimidazole scaffold. The resulting radioligands [18 F]TARP-2204 and [18 F]TARP-2205 were successfully synthesized with acceptable radiochemical yield, high molar activity, and excellent radiochemical purity. In vitro autoradiography demonstrates high level of specific binding of [18 F]TARP-2205 to TARP γ-8 in both rat and nonhuman primate brain tissues. However, unexpected radiodefluorination in PET imaging studies of rodents emphasizes the need for further structural refinement. This work serves as an excellent starting point for the development of future 18 F-labeled TARP γ-8 PET tracers, offering valuable insights into medicinal chemistry design, radiosynthesis and subsequent PET evaluation.
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Tomografia por Emissão de Pósitrons , Receptores de AMPA , Ratos , Animais , Receptores de AMPA/metabolismo , Tomografia por Emissão de Pósitrons/métodos , HipocampoRESUMO
This study aimed to develop a template-based attenuation correction (AC) for the nonhuman primate (NHP) brain. We evaluated the effects of AC on positron emission tomography (PET) data quantification with two experimental paradigms by comparing the quantitative outcomes obtained using a segmentation-based AC versus template-based AC. Population-based atlas was generated from ten adult rhesus macaques. Bolus experiments using [18F]PF-06455943 and a bolus-infusion experiment using [11C]OMAR were performed on a 3T Siemens PET/magnetic resonance-imaging (MRI). PET data were reconstructed with either µ map obtained from the segmentation-based AC or template-based AC. The standard uptake value (SUV), volume of distribution (VT), or percentage occupancy of rimonabant were calculated for [18F]PF-06455943 and [11C]OMAR PET, respectively. The leave-one-out cross-validation showed that the absolute percentage differences were 2.54 ± 2.86% for all region of interests. The segmentation-based AC had a lower SUV and VT (â¼10%) of [18F]PF-06455943 than the template-based method. The estimated occupancy was higher in the template-based method compared to the segmentation-based AC in the bolus-infusion study. However, future studies may be needed if a different reference tissue is selected for data quantification. Our template-based AC approach was successfully developed and applied to the NHP brain. One limitation of this study was that validation was performed by comparing two different MR-based AC approaches without validating against AC methods based on computed tomography (CT).
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The N-methyl-d-aspartate receptor (NMDAR) subtype 2B (GluN1/2B) is implicated in various neuropathologies. Given the lack of a validated radiofluorinated positron emission tomography (PET) probe for the imaging of GluN1/2B receptors, we comprehensively investigated the enantiomers of [18F]OF-NB1 in rodents. Particularly, the (R)- and (S)- enantiomers were evaluated using in silico docking, in vitro autoradiography, in vivo PET imaging, and ex vivo biodistribution studies. A select panel of GluN1/2B antagonists (CP-101,606, CERC-301, and eliprodil) and the off-target sigma-1 receptor ligands (fluspidine and SA4503) were used to determine the specificity and selectivity of the tested enantiomers. Additionally, a nonmetal-mediated radiofluorination strategy was devised that harnesses the potential of diaryliodoniums in the nucleophilic radiofluorination of nonactivated aromatic compounds. Both enantiomers exhibited known GluN1/2B binding patterns; however, the R-enantiomer showed higher GluN1/2B-specific accumulation in rodent autoradiography and higher brain uptake in PET imaging experiments compared to the S-enantiomer. Molecular simulation studies provided further insights with respect to the difference in binding, whereby a reduced ligand-receptor interaction was observed for the S-enantiomer. Nonetheless, both enantiomers showed dose dependency when two different doses (1 and 5 mg/kg) of the GluN1/2B antagonist, CP-101,606, were used in the PET imaging study. Taken together, (R)-[18F]OF-NB1 appears to exhibit the characteristics of a suitable PET probe for imaging of GluN2B-containing NMDARs in clinical studies.
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Receptores de N-Metil-D-Aspartato , Roedores , Animais , Roedores/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Distribuição Tecidual , Tomografia por Emissão de Pósitrons/métodos , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismoRESUMO
As a subclass of ionotropic glutamate receptors (iGluRs), α-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic acid (AMPA) receptors have been implicated in various neurological disorders and neurodegenerative diseases. To further our understanding of AMPA receptor-related disorders in the central nervous system (CNS), it is important to be able to image and quantify AMPA receptors in vivo. In this study, we identified a novel F-containing AMPA positive allosteric modulator (PAM) 6 as a potential lead compound. Molecular docking studies and CNS PET multi-parameter optimization (MPO) analysis were used to predict the absorption, distribution, metabolism, and excretion (ADME) characteristics of 6 as a PET probe. The resulting PET probe, [18F]6 (codename [18F]AMPA-2109), was successfully radiolabeled and demonstrated excellent blood-brain barrier (BBB) permeability and high brain uptake in rodents and non-human primates. However, [18F]6 did not show substantial specific binding in the rodent or non-human primate brain. Further medicinal chemistry efforts are necessary to improve specific binding, and our work may serve as a starting point for the design of novel 18F-labeled AMPA receptor-targeted PET radioligands aimed for clinical translation.
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Receptores de AMPA , Tiadiazinas , Animais , Receptores de AMPA/metabolismo , Tiadiazinas/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico , Simulação de Acoplamento Molecular , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Roedores/metabolismoRESUMO
GluN2B subunit-containing N-methyl-d-aspartate (NMDA) receptors have been implicated in various neurological disorders. Nonetheless, a validated fluorine-18 labeled positron emission tomography (PET) ligand for GluN2B imaging in the living human brain is currently lacking. The aim of this study was to develop a novel synthetic approach that allows an enantiomerically pure radiosynthesis of the previously reported PET radioligands (R)-[18F]OF-NB1 and (S)-[18F]OF-NB1 as well as to assess their in vitro and in vivo performance characteristics for imaging the GluN2B subunit-containing NMDA receptor in rodents. A novel synthetic approach was successfully developed, which allows for the enantiomerically pure radiosynthesis of (R)-[18F]OF-NB1 and (S)-[18F]OF-NB1 and the translation of the probe to the clinic. While both enantiomers were selective over sigma2 receptors in vitro and in vivo, (R)-[18F]OF-NB1 showed superior GluN2B subunit specificity by in vitro autoradiography and higher volumes of distribution in the rodent brain by small animal PET studies.
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Tomografia por Emissão de Pósitrons , Receptores de N-Metil-D-Aspartato , Animais , Humanos , Receptores de N-Metil-D-Aspartato/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Radioisótopos de FlúorRESUMO
The cannabinoid type 2 receptor (CB2) has been implicated in a variety of central and peripheral inflammatory diseases, prompting significant interest in the development of CB2-targeted diagnostic and therapeutic agents. A validated positron emission tomography (PET) radioligand for imaging CB2 in the living human brain as well as in peripheral tissues is currently lacking. As part of our research program, we have recently identified the trisubstituted pyridine, [18F]RoSMA-18-d6, which proved to be highly suitable for in vitro and in vivo mapping of CB2 in rodents. The aim of this study was to assess the performance characteristics of [18F]RoSMA-18-d6 in nonhuman primates (NHPs) to pave the way for clinical translation. [18F]RoSMA-18-d6 was synthesized from the respective tosylate precursor according to previously reported procedures. In vitro autoradiograms with NHP spleen tissue sections revealed a high binding of [18F]RoSMA-18-d6 to the CB2-rich NHP spleen, which was significantly blocked by coincubation with the commercially available CB2 ligand, GW405833 (10 µM). In contrast, no specific binding was observed by in vitro autoradiography with NHP brain sections, which was in agreement with the notion of a CB2-deficient healthy mammalian brain. In vitro findings were corroborated by PET imaging experiments in NHPs, where [18F]RoSMA-18-d6 uptake in the spleen was dose-dependently attenuated with 1 and 5 mg/kg GW405833, while no specific brain signal was observed. Remarkably, we observed tracer uptake and retention in the NHP spinal cord, which was reduced by GW405833 blockade, pointing toward a potential utility of [18F]RoSMA-18-d6 in probing CB2-expressing cells in the bone marrow. If these observations are substantiated in NHP models of enhanced leukocyte proliferation in the bone marrow, [18F]RoSMA-18-d6 may serve as a valuable marker for hematopoietic activity in various pathologies. In conclusion, [18F]RoSMA-18-d6 proved to be a suitable PET radioligand for imaging CB2 in NHPs, supporting its translation to humans.
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Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Animais , Humanos , Compostos Radiofarmacêuticos/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Ligantes , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Primatas/metabolismo , Receptor CB2 de Canabinoide/metabolismo , Radioisótopos de Flúor/metabolismo , Mamíferos/metabolismoRESUMO
Orexin 2 receptors (OX2R) represent a vital subtype of orexin receptors intricately involved in the regulation of wakefulness, arousal, and sleep-wake cycles. Despite their importance, there are currently no positron emission tomography (PET) tracers available for imaging the OX2R in vivo. Herein, we report [11C]1 ([11C]OX2-2201) and [11C]2 ([11C]OX2-2202) as novel PET ligands. Both compounds 1 (Ki = 3.6 nM) and 2 (Ki = 2.2 nM) have excellent binding affinity activities toward OX2R and target selectivity (OX2/OX1 > 600 folds). In vitro autoradiography in the rat brain suggested good to excellent in vitro binding specificity for [11C]1 and [11C]2. PET imaging in rat brains indicated that the low brain uptake of [11C]2 may be due to P-glycoprotein and/or breast cancer resistance protein efflux interaction and/or low passive permeability. Continuous effort in medicinal chemistry optimization is necessary to improve the brain permeability of this scaffold.
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Despite the success of Sonogashira coupling for the synthesis of arylalkynes and conjugated enynes, the engagement of unactivated alkyl halides in such reactions remains historically challenging. We report herein a strategy that merges Cu-catalyzed alkyne transfer with the aryl radical activation of carbon-halide bonds to enable a general approach for the coupling of alkyl iodides with terminal alkynes. This unprecedented Sonogashira-type cross-coupling reaction tolerates a broad range of functional groups and has been applied to the late-stage cross-coupling of densely functionalized pharmaceutical agents as well as the synthesis of positron emission tomography tracers.
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Due to the characteristics of high brittleness and low fracture toughness of monocrystalline silicon, its high precision and high-quality cutting have great challenges. Aiming at the urgent need of wafer cutting with high efficiency, this paper investigates the influence law of different laser processes on the size of the groove and the machining affected zone of laser cutting. The experimental results show that when laser cutting monocrystalline silicon, in addition to generating a groove, there will also be a machining affected zone on both sides of the groove and the size of both will directly affect the cutting quality. After wiping the thermal products generated by cutting on the material surface, the machining affected zone and the recast layer in the cutting seam can basically be eliminated to generate a wider cutting seam and the surface after wiping is basically the same as that before cutting. Increasing the laser cutting times will increase the width of the material's machining affected zone and the groove width after chip removal. When the cutting times are less than 80, increasing the cutting times will increase the groove width at the same time; but, after the cutting times exceed 80, the groove width abruptly decreases and then slowly increases. In addition, the lower the laser scanning speed, the larger the width of the material's machining affected zone and the width of the groove after chip removal. The increase in laser frequency will increase the crack width and the crack width after chip removal but decrease the machining affected zone width. The laser pulse width has a certain effect on the cutting quality but it does not show regularity. When the pulse width is 0.3 ns the cutting quality is the best and when the pulse width is 0.15 ns the cutting quality is the worst.
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Cholinergic receptors represent a promising class of diagnostic and therapeutic targets due to their significant involvement in cognitive decline associated with neurological disorders and neurodegenerative diseases as well as cardiovascular impairment. Positron emission tomography (PET) is a noninvasive molecular imaging tool that has helped to shed light on the roles these receptors play in disease development and their diverse functions throughout the central nervous system (CNS). In recent years, there has been a notable advancement in the development of PET probes targeting cholinergic receptors. The purpose of this review is to provide a comprehensive overview of the recent progress in the development of these PET probes for cholinergic receptors with a specific focus on ligand structure, radiochemistry, and pharmacology as well as in vivo performance and applications in neuroimaging. The review covers the structural design, pharmacological properties, radiosynthesis approaches, and preclinical and clinical evaluations of current state-of-the-art PET probes for cholinergic receptors.
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Compostos Radiofarmacêuticos , Receptores Colinérgicos , Compostos Radiofarmacêuticos/química , Tomografia por Emissão de Pósitrons/métodos , Encéfalo/diagnóstico por imagem , Sistema Nervoso CentralRESUMO
N-methyl-D-aspartate receptors (NMDAR), ionotropic glutamate receptors, mediate a slow component of excitatory synaptic transmission in the central nervous system and play a key role in normal brain function and development. Genetic variations in GRIN genes encoding NMDAR subunits that alter the receptor's functional characteristics are associated with a wide range of neurological and neuropsychiatric conditions. Pathological GRIN variants located in the M2 re-entrant loop lining the channel pore cause significant functional changes, the most consequential alteration being a reduction in voltage-dependent Mg2+ inhibition. Voltage-dependent Mg2+ block is a unique feature of NMDAR biology whereby channel activation requires both ligand binding and postsynaptic membrane depolarization. Thus, loss of NMDAR Mg2+ block will have a profound impact on synaptic function and plasticity. Here, we choose 11 missense variants within the GRIN1, GRIN2A, and GRIN2B genes that alter residues located in the M2 loop and significantly reduce Mg2+ inhibition. Each variant was evaluated for tolerance to genetic variation using the 3-dimensional structure and assessed for functional rescue pharmacology via electrophysiological recordings. Three FDA-approved NMDAR drugs-memantine, dextromethorphan, and ketamine-were chosen based on their ability to bind near the M2 re-entrant loop, potentially rectifying dysregulated NMDAR function by supplementing the reduced voltage-dependent Mg2+ block. These results provide insight of structural determinants of FDA-approved NMDAR drugs at their binding sites in the channel pore and may further define conditions necessary for the use of such agents as potential rescue pharmacology.