The team built their study around a phenomenon called immediate postictal potentiation, or PIP, which they regard as a unique experimental model of the enhanced excitability that characterizes the developing nervous system. In adult animals, an electrical seizure is followed by several minutes of postictal depression, during which a second stimulus elicits either no seizure at all or a shorter one. In immature animals, the opposite occurs: after an electrical seizure, the brain enters a state of enhanced excitability in which a second stimulus elicits a longer seizure. The researchers exploited this reversal using a technique they developed in previous work. They applied pairs of identical stimuli to the sensorimotor cortex of 12-day-old rats, an age whose neocortical development is considered comparable to that of a full-term human newborn. The first, conditioning stimulus elicits an electrical seizure, known as an afterdischarge, which is recorded in the contralateral cortex. One minute later, a test stimulus assesses neuronal excitability following the initial seizure. If the test afterdischarge is longer than the conditioning one, that indicates postictal potentiation; if it is shorter, that indicates the adult-like postictal depression.

The experimental protocol was elegant in its simplicity. Each animal received two pairs of cortical stimuli separated by 10 minutes. The first pair served as a control and showed the typical PIP of immature animals, with the test afterdischarge longer than the conditioning one. Immediately after the end of the first test afterdischarge, a glutamate receptor antagonist was administered. Ten minutes later, the second pair of stimuli was applied. If PIP was absent in the second pair, meaning the test afterdischarge was either not present or shorter than the conditioning one, the researchers took that as evidence that the receptor targeted by the antagonist was involved in mediating PIP and, by extension, was an important factor in the hyperexcitability of the immature brain. The 12-day-old male Wistar rats were implanted with epidural electrodes under brief ether anesthesia, kept on a heating pad at 34 degrees Celsius throughout, and only animals demonstrating intact righting, placing, and suckling reflexes were used. Each animal was studied only once.

The most dramatic result came from ifenprodil, a selective antagonist of NMDA receptors that contain the GluN2B subunit. This drug did not merely suppress immediate PIP; it converted the condition to an adult-like postictal depression, with the test afterdischarge significantly shorter than the conditioning one after drug administration. The effect was even more pronounced than that of dizocilpine, also known as MK-801, a potent non-competitive NMDA receptor antagonist, which also abolished PIP and produced postictal depression in the second stimulus pair. Memantine, a low-affinity NMDA receptor antagonist, showed a similar but smaller effect, with only a tendency for the test afterdischarge to be shorter than the conditioning one at the higher dose, most likely reflecting its lower affinity and dwell time at the receptor. By contrast, PEAQX, an antagonist that preferentially targets NMDA receptors containing the GluN2A subunit, the dominant form in adult animals, was ineffective at abolishing PIP. MTEP, an antagonist of metabotropic glutamate receptor 5 used to indirectly probe the NMDA system, also had no effect.

This subunit-specific pattern makes biological sense given the developmental progression of NMDA receptors. NMDA receptors are tetramers composed of two obligatory GluN1 subunits plus two additional subunits drawn from a set that most often consists of GluN2A or GluN2B. In immature animals, GluN2B subunits predominate, but during the third postnatal week there is a progressive increase in GluN2A subunits, which predominate in adults. The two subunit types confer different functional properties. GluN2B-containing receptors have longer channel opening times, stronger calcium influx currents, and slower deactivation than GluN2A-containing receptors. These characteristics very likely contribute to the enhanced neuronal excitability of the immature brain. When ifenprodil blocked the GluN2B-containing receptors, only GluN2A-containing receptors remained active, mimicking the adult situation. As a consequence, PIP disappeared and was replaced by the postictal depression characteristic of mature animals.

The role of AMPA receptors proved more complicated but revealed an unexpected second layer of the phenomenon. Neither of the two AMPA receptor antagonists tested, the competitive antagonist NBQX or IEM 1460, had a significant effect on immediate PIP. In fact, after IEM 1460 administration, the second stimulus pair showed dramatic PIP similar to that seen in the first pair. However, the AMPA antagonists demonstrated an effect not seen with any of the NMDA antagonists. In control animals, the potentiation following the first stimulus pair lingers: 10 minutes after the first test afterdischarge, the second conditioning afterdischarge has not returned to baseline and is sometimes even longer than the first test one. This prolonged potentiation was selectively abolished by the AMPA antagonists. IEM 1460 was particularly effective, returning the second conditioning afterdischarge to baseline excitability while the immediate potentiation 1 minute after the second conditioning stimulus was preserved. NBQX showed a similar effect at the low dose of 7.5 mg/kg, while higher doses of 15 and 30 mg/kg profoundly depressed all afterdischarges, essentially eliminating all forms of potentiation.

The selectivity of IEM 1460 is significant because it targets AMPA receptors that lack a functional GluA2 subunit, a form that predominates in immature animals. Like NMDA receptors, AMPA receptors are heteromeric tetramers composed of combinations of four subunits, GluA1 through GluA4, and their subunit composition varies during development. The absence of a GluA2 subunit markedly alters the functional characteristics of the AMPA receptor, most significantly making it permeable to calcium ions, which may contribute to increased neuronal excitability in the immature brain. The authors note that their data are consistent with the established role of AMPA receptors in status epilepticus, and that prolonged postictal potentiation may underlie the increased susceptibility of neonates to recurrent seizures and status epilepticus.

The findings carry therapeutic implications that extend beyond the acute treatment of neonatal seizures. It is well established that neonatal seizures lead to a greater incidence of epilepsy and cognitive deficits later in life. Previous work on models of hypoxic seizures in 10-day-old rats, which mimic many long-term postictal sequelae, has implicated AMPA receptors in those lasting changes. Developing drugs that target AMPA receptors lacking the GluA2 subunit may therefore be useful not only for treating acute neonatal seizures, especially recurrent ones, but also for attenuating some of the detrimental long-term consequences of neonatal seizures. On the NMDA side, the GluN2B subunit, being uniquely predominant in the neonatal period, should be considered an attractive target for the design of drugs to treat neonatal seizures.

The path to the clinic is complicated by the serious side effects that have blocked the therapeutic potential of NMDA and AMPA receptor antagonists, including effects on memory and cognition. The only NMDA receptor antagonist currently used in patients is the low-affinity antagonist memantine, prescribed for Alzheimer’s disease, which does not exhibit serious side effects. The authors argue that their results demonstrate the importance of both NMDA and AMPA receptors in the high seizure susceptibility of the immature brain and underscore the necessity of finding new antagonists of these receptors without severe side effects. Because PIP appears to be a function of the unique structure of glutamate receptors in the immature nervous system, particularly NMDA receptors containing the GluN2B subunit, understanding its mechanisms could provide valuable insights into designing more effective treatments for the seizures of newborns, a population for whom current therapies remain largely ineffective.

Subject of Research: NMDA receptors play an important role in postictal potentiation in immature rats

Article Title: NMDA receptors play an important role in postictal potentiation in immature rats

Article References: Mares, P., Burchfiel, J. L., & Kubova, H. (2026). NMDA receptors play an important role in postictal potentiation in immature rats. Frontiers in Synaptic Neuroscience, 18, Article 1742164. https://doi.org/10.3389/fnsyn.2026.1742164

Image Credits: AI Generated

DOI: 10.3389/fnsyn.2026.1742164

Keywords: neonatal seizures, NMDA receptors, AMPA receptors, GluN2B subunit, postictal potentiation, epilepsy, developing brain, glutamate receptors, status epilepticus, synaptic neuroscience, NMDA, receptors

The focal point of the investigation was PSD-95, or postsynaptic density protein-95, a scaffold protein that anchors NMDA and AMPA glutamate receptors and organizes the signaling cascades responsible for synaptic plasticity. Because PSD-95 physically links receptor localization with calcium/calmodulin-dependent protein kinase II (CaMKII), a central regulator of activity-dependent plasticity, changes in its expression and clustering translate into changes in how excitatory synapses are built and maintained. Disruption of PSD-95 has been implicated in a striking range of conditions, including DLG4-related synaptopathy, a rare genetic disorder caused by pathogenic variants in the gene encoding PSD-95, as well as autism spectrum disorder, schizophrenia, Alzheimer’s disease, and Fragile X syndrome. This makes PSD-95 a high-value target for any intervention claiming to support synaptic health.

The experimental design was deliberately symmetric and composition-controlled. The team used differentiated human SH-SY5Y neuroblastoma cells, a widely employed neuronal-like model, matured over 14 days with retinoic acid and BrainPhys neuronal medium. After differentiation, cultures were treated for 24 hours with DHA alone (50 micromolar), EPA alone (50 micromolar), or defined DHA:EPA molar mixtures of 2:1, 1:1, and 1:2, with the total fatty acid concentration held constant at 50 micromolar across all conditions. This five-point series spanned the full compositional range from pure DHA to pure EPA, allowing the researchers to isolate the effect of the DHA:EPA ratio rather than simply total omega-3 exposure. Vehicle-treated and untreated controls confirmed that the ethanol carrier, kept at or below 0.04 percent, had no detectable influence.

Quantification combined high-content immunofluorescence imaging with Western blot densitometry. Using an Opera Phenix High Content Screening System and a standardized segmentation pipeline in Columbus software, the team measured PSD-95 fluorescence intensity, PSD-95 puncta density within MAP2-positive neurites, and the pixel-wise overlap of PSD-95 with synaptophysin, a presynaptic marker, to approximate Manders’ colocalization coefficients. Protein abundance was assessed by Western blot with stain-free total-protein normalization, a method chosen over single housekeeping proteins because it accounts for lane-to-lane loading variability. An MTT assay confirmed that none of the treatments reduced cellular metabolic activity, meaning the molecular changes could not be attributed to toxicity.

The results were unambiguous. DHA alone produced the largest increase in PSD-95 protein abundance by immunoblot, the strongest increase in PSD-95 puncta density (adjusted p = 0.0005), and the greatest total colocalization with synaptophysin (adjusted p < 0.0001). The proportion of PSD-95 apposed to synaptophysin-positive regions also rose with DHA (adjusted p = 0.0214), whereas EPA actually reduced this proportion relative to control (adjusted p = 0.0079). Among the mixed formulations, the DHA-dominant 2:1 ratio most closely resembled pure DHA, while the equimolar and EPA-dominant compositions showed progressively attenuated responses. Critically, the PSD-95 puncta increases extended into neuronal processes: puncta density normalized to neurite length was significantly elevated by DHA, 2:1, and 1:1 DHA:EPA, indicating that the effect is not confined to the cell body.

The glutamatergic signaling proteins told a consistent story. DHA produced the strongest increase in NMDA receptor expression (adjusted p < 0.0001), with the 2:1 mixture mirroring that response, the 1:1 mixture showing a smaller rise, and the 1:2 mixture failing to differ from control. AMPA receptor expression followed a similar but less pronounced pattern, with DHA again the strongest inducer (adjusted p = 0.0008). CaMKII levels increased across every treatment, though DHA remained the most potent. EPA alone, however, stood out for the wrong reason: it significantly reduced NMDA receptor levels relative to control (adjusted p = 0.0056), demonstrating that EPA is not biologically inert at the synapse but can actively work against the postsynaptic receptor profile that DHA supports.

Why would two structurally similar fatty acids, differing only in two carbons and one double bond, behave so differently? The answer lies in their divergent fates in the brain. DHA is the most abundant long-chain omega-3 in the central nervous system, comprising 10 to 20 percent of neuronal membrane phospholipids and exceeding 30 percent in some synaptic and retinal membranes. It is preferentially esterified into phosphatidylserine and phosphatidylethanolamine, where its six double bonds promote membrane curvature and acyl chain disorder, shaping the lateral organization of membrane microdomains that host glutamate receptors. EPA, by contrast, normally accounts for less than 0.5 percent of brain fatty acids and is rapidly turned over, consistent with a signaling role rather than a structural one. Enzymes such as long-chain acyl-CoA synthetase 6, lysophosphatidylethanolamine acyltransferase 2, and phosphatidylserine synthase 2 preferentially channel DHA into synaptic phospholipids, providing a plausible mechanistic basis for the differential retention the study observed, though these pathways were not directly measured.

The findings carry immediate implications for how omega-3 research and supplementation should be interpreted. Clinical omega-3 formulations vary enormously in DHA:EPA ratio, and prior clinical literature hints that this matters: EPA-predominant preparations have shown greater efficacy in depression, while DHA-containing formulations dominate cognitive and neurodegenerative studies. The new data suggest that when the goal is postsynaptic scaffold stability and glutamatergic signaling, diluting DHA with EPA may attenuate the benefit. The authors are careful to note a key design limitation: because total fatty acid concentration was fixed, increasing the EPA share necessarily decreased the absolute DHA dose, so the study cannot distinguish a true DHA-EPA interaction from a simple reduction in DHA exposure. Other caveats include the acute 24-hour exposure, the use of an immortalized cell line that cannot capture the cellular diversity of the human cortex, and the absence of electrophysiological measurements, meaning the protein changes should be read as evidence of molecular reorganization rather than proven functional enhancement.

Even with those limitations, the study delivers a clear and potentially consequential message: omega-3 effects on synaptic biology depend on fatty acid identity and relative composition, not merely total omega-3 intake. DHA and EPA are not interchangeable, and the DHA:EPA ratio is a modifiable variable that shapes postsynaptic scaffold organization. The research team suggests that future work in human iPSC-derived neurons, lipidomic profiling of membrane remodeling, pathway-inhibition experiments targeting candidates such as PI3K/Akt and MAPK/ERK, and electrophysiological recordings will be needed to determine whether DHA-dominant formulations can translate their molecular signature into genuine synaptic and network benefits. For conditions marked by disrupted PSD-95 organization, from rare genetic synaptopathies to Alzheimer’s disease, the possibility that a carefully tuned lipid composition could stabilize the postsynaptic apparatus offers a compelling, testable direction for lipid-based therapeutics.

Subject of Research: Effects of DHA and EPA omega-3 fatty acid ratios on PSD-95 scaffold organization and glutamatergic signaling in human neuronal cells

Article Title: DHA-dominant Omega-3 compositions enhance PSD-95 organization and glutamatergic protein expression

Article References: Medina, G., Baird, S. D., Rodriguez-Alcocer, L. A., & MacKenzie, A. E. (2026). DHA-dominant Omega-3 compositions enhance PSD-95 organization and glutamatergic protein expression. Frontiers in Synaptic Neuroscience, 18, Article 1947075. https://doi.org/10.3389/fnsyn.2026.1947075

Image Credits: AI Generated

DOI: 10.3389/fnsyn.2026.1947075

Keywords: DHA, EPA, omega-3 fatty acids, PSD-95, synaptic plasticity, glutamate receptors, NMDA receptor, AMPA receptor, CaMKII, SH-SY5Y neurons, postsynaptic density, synaptophysin

The research, led by Sylvain Gourier and Marwan Bouras of Brest University Hospital Centre in France, together with colleagues in Quebec and Nantes, set out to answer a deceptively simple question: when AMPA receptor antagonists are administered after a traumatic brain injury in mammals, do they actually make things better? The team searched three major biomedical databases, MEDLINE, Embase and Web of Science, and screened 410 records to arrive at a final set of eleven studies that met their strict inclusion criteria. Only mammalian in vivo experiments in which an AMPA receptor antagonist was given after the injury and compared against a vehicle control, no treatment, or an alternative intervention were eligible, a design intended to mirror as closely as possible the clinical scenario in which a patient arrives at a hospital after the insult has already occurred.

The biological rationale behind this line of investigation runs deep. When the brain is subjected to mechanical trauma, damaged and dying cells flood the extracellular space with glutamate, the principal excitatory neurotransmitter of the central nervous system. Under normal conditions, glutamate transmission is tightly regulated, but after injury the excess glutamate overstimulates its receptors, provoking a cascade known as excitotoxicity. Calcium floods into neurons through ion channels, mitochondrial function collapses, free radicals accumulate, and cells that survived the initial blow die a slow secondary death over hours to days. Because this secondary injury unfolds on a timescale that leaves a therapeutic window, interrupting it with receptor blockers has long been an attractive strategy. Previous attempts targeting the related NMDA receptor ultimately failed in human trials, but the AMPA receptor, which mediates the fast component of excitatory synaptic transmission and can become calcium-permeable after injury, has re-emerged as a distinct and possibly more tractable target.

To conduct the meta-analysis, two reviewers independently screened the candidate studies, extracted the data and appraised methodological quality and risk of bias using two established instruments: the CAMARADES checklist, developed specifically for pooling animal data from experimental studies, and the SYRCLE tool, which probes sources of bias in laboratory animal research. The primary outcome was neurobehavioural performance, assessed across three distinct domains: neurological deficit, cognition and memory, and motor coordination. Secondary outcomes included the severity of brain lesions, mortality, and inflammatory biomarkers. The team applied random-effects meta-analysis, expressing treatment effects as standardized mean differences, a statistical approach that allows results measured on different behavioural scales in different laboratories to be combined into a single estimate.

The headline result is striking for cognition. Across five studies, AMPA receptor antagonists produced a large improvement in cognition and memory, with a standardized mean difference of 1.53 and a tight 95 percent confidence interval running from 1.06 to 2.01. Perhaps more importantly for the credibility of the finding, the statistical heterogeneity across these studies was almost nonexistent, with an I-squared value of just 3 percent, meaning the effect was remarkably consistent from one experiment to the next. In a field where preclinical results often vary wildly between laboratories, this kind of uniformity is rare and lends considerable weight to the conclusion that AMPA blockade genuinely protects the injured, memory-forming circuits of the hippocampus and surrounding structures.

Neurological deficit scores also favoured the drug-treated animals, with a standardized mean difference of 1.28 across four studies, although the confidence interval here, stretching from 0.05 to 2.50, barely excludes zero and the heterogeneity was high at 78 percent, signalling that study designs, drug choices or injury models differed in ways that materially affected the results. Motor coordination told a different story altogether: pooling two studies yielded a standardized mean difference of minus 1.00 with a confidence interval spanning from minus 2.96 to 0.96 and extreme heterogeneity of 83 percent, which the authors interpret as no reliable benefit for motor function. This dissociation between cognitive and motor outcomes is biologically plausible, since AMPA receptor signalling is central to synaptic plasticity in memory circuits, while motor recovery after trauma may depend on mechanisms that pharmacological receptor blockade cannot rescue, or may even require intact AMPA-mediated signalling for compensatory plasticity to occur.

Beyond behaviour, the drugs left visible marks on the injured brain itself. In seven studies measuring lesion severity, AMPA receptor antagonists significantly reduced the extent of tissue damage, with a standardized mean difference of minus 1.39 and moderate heterogeneity of 53 percent. The included experiments spanned several generations of compounds, from early competitive antagonists such as NBQX and the quinoxalinediones ZK200775 and YM872 to the noncompetitive agent talampanel and, more recently, perampanel, the first AMPA antagonist approved for clinical use as an antiepileptic drug. Several of the newer studies also documented consistent reductions in inflammatory biomarkers, aligning with work showing that perampanel dampens oxidative stress, pyroptosis and neuroinflammation through pathways involving molecules such as Sirt3, and protects the neurovascular unit that maintains the blood-brain barrier. Mortality, by contrast, showed no significant effect, a reminder that preventing cellular cascades of damage does not necessarily translate into survival advantages in these models.

The authors are careful to frame their conclusions within the limits of the evidence. Some results, particularly those for neurological deficit and motor coordination, rest on small numbers of studies with substantial statistical heterogeneity and should be interpreted with caution. Publication bias, a chronic problem in animal research in which positive results are more likely to be published than negative ones, may also inflate the apparent effect sizes. The protocol was prospectively registered on the Open Science Framework in April 2025, and the team followed PRISMA reporting guidelines, measures that improve transparency but cannot conjure data that were never collected. The related clinical picture remains sobering: an earlier systematic review by the same senior group found that excitatory amino acid inhibitors have not demonstrated clear benefit in human trials of acute traumatic brain injury, and the field’s history with NMDA antagonists, which failed despite promising animal data, haunts every new preclinical success.

Yet the timing of this analysis is propitious, because the preclinical evidence now intersects with a genuinely new clinical opportunity. Perampanel is already approved and in widespread use for epilepsy, with a growing literature documenting its safety, tolerability, brain penetration and even intravenous formulations suitable for critically ill patients. A phase-two multicentre randomised clinical trial, known as PEACE-TBI, has been designed in Japan to test whether perampanel can alleviate secondary injury after traumatic brain injury in humans. Against that backdrop, the present meta-analysis provides exactly the kind of rigorous synthesis of the animal evidence that trial designers and funders need, confirming biological plausibility for the neurobehavioural and lesion-reducing effects while honestly flagging the outcomes, motor recovery and mortality, where the signal is weak or absent. Whether AMPA receptor antagonists can finally break the decades-long cycle of failed neuroprotection in traumatic brain injury will be decided in patients, but the laboratory evidence assembled here suggests the hypothesis deserves its day in the clinic.

Subject of Research: Efficacy of AMPA receptor antagonists in preclinical animal models of traumatic brain injury

Article Title: AMPA Receptor Antagonists in Preclinical Models of Traumatic Brain Injury: A Systematic Review and Meta-analysis of Animal Studies

Article References: Gourier, S., Morin, C., Gargadennec, T., Turgeon, A. F., Poulain, C., Roquilly, A., Caillard, A., Langeron, O., & Bouras, M. (2026). AMPA Receptor Antagonists in Preclinical Models of Traumatic Brain Injury: A Systematic Review and Meta-analysis of Animal Studies. Neurocritical Care. https://doi.org/10.1007/s12028-026-02640-x

Image Credits: AI Generated

DOI: 10.1007/s12028-026-02640-x

Keywords: traumatic brain injury, AMPA receptor antagonists, excitotoxicity, neuroprotection, perampanel, systematic review, meta-analysis, preclinical models, neurobehavioural outcomes, brain lesion severity, neuroinflammation, glutamate receptors