Dysregulated Glucose Metabolism as a Therapeutic Target to Reduce Post-traumatic Epilepsy

Tracing the path of disruption: 13C isotope applications in traumatic brain injury-induced metabolic dysfunction

Cerebral metabolic dysfunction is a critical pathological hallmark observed in the aftermath of traumatic brain injury (TBI), as extensively documented in clinical investigations and experimental models. An in-depth understanding of the bioenergetic disturbances that occur following TBI promises to reveal novel therapeutic targets, paving the way for the timely development of interventions to improve patient outcomes. The 13C isotope tracing technique represents a robust methodological advance, harnessing biochemical quantification to delineate the metabolic trajectories of isotopically labeled substrates. This nuanced approach enables real-time mapping of metabolic fluxes, providing a window into the cellular energetic state and elucidating the perturbations in key metabolic circuits. By applying this sophisticated tool, researchers can dissect the complexities of bioenergetic networks within the central nervous system, offering insights into the metabolic derangements specific to TBI pathology. Embraced by both animal studies and clinical research, 13C isotope tracing has bolstered our understanding of TBI-induced metabolic dysregulation. This review synthesizes current applications of isotope tracing and its transformative potential in evaluating and addressing the metabolic sequelae of TBI.

The "Curious Case of Postictal Oxygen Dissipation": Could ROS Be the Culprit?

Postictal Hypoxia Involves Reactive Oxygen Species and Is Ameliorated by Chronic Mitochondrial Uncoupling Villa BR, George AG, Shutt TE, Sullivan PG, Rho JM, Teskey GC. Neuropharmacology . 2023;238:109653. doi:10.1016/j.neuropharm.2023.109653 Prolonged severe hypoxia follows brief seizures and represents a mechanism underlying several negative postictal manifestations without interventions. Approximately 50% of the postictal hypoxia phenomenon can be accounted for by arteriole vasoconstriction. What accounts for the rest of the drop in unbound oxygen is unclear. Here, we determined the effect of pharmacological modulation of mitochondrial function on tissue oxygenation in the hippocampus of rats after repeatedly evoked seizures. Rats were treated with mitochondrial uncoupler 2,4 dinitrophenol (DNP) or antioxidants. Oxygen profiles were recorded using a chronically implanted oxygen-sensing probe, before, during, and after seizure induction. Mitochondrial function and redox tone were measured using in vitro mitochondrial assays and immunohistochemistry. Postictal cognitive impairment was assessed using the novel object recognition task. Mild mitochondrial uncoupling by DNP raised hippocampal oxygen tension and ameliorated postictal hypoxia. Chronic DNP also lowered mitochondrial oxygen-derived reactive species and oxidative stress in the hippocampus during postictal hypoxia. Uncoupling the mitochondria exerts therapeutic benefits on postictal cognitive dysfunction. Finally, antioxidants do not affect postictal hypoxia, but protect the brain from associated cognitive deficits. We provided evidence for a metabolic component of the prolonged oxygen deprivation that follow seizures and its pathological sequelae. Furthermore, we identified a molecular underpinning of this metabolic component, which involves excessive oxygen conversion into reactive species. Mild mitochondrial uncoupling may be a potential therapeutic strategy to treat the postictal state where seizure control is absent or poor.

Risk of Epilepsy Following Traumatic Brain Injury: A Systematic Review and Meta-analysis

BACKGROUND

Limited evidence has explored the impact of traumatic brain injury (TBI) on posttraumatic epilepsy with control cohort for comparison. In addition, we could not find any review to identify the effect of TBI on the outcomes. Thus, we conducted this study to compare the risk of epilepsy between individuals with TBI and without TBI.

METHODS

Systematic and comprehensive search was carried out in the following databases and search engines: EMBASE, Cochrane, MEDLINE, ScienceDirect, and Google Scholar from 1954 until January 2022. The Newcastle Ottawa (NO) Scale was utilized to assess the risk of bias. Meta-analysis was carried out using the random-effects model, and pooled odds ratio (OR) along with 95% CI was reported.

RESULTS

In total, we included 10 studies satisfying inclusion criteria. Most studies had good to satisfactory quality. The pooled OR was 4.25 (95% CI, 1.77-10.25; I2 = 100%), indicating that the individuals with TBI had 4.25 times higher risk of having epilepsy than individuals without TBI, and this association was statistically significant ( P = .001). Subgroup analysis based on the years of follow-up revealed that the patients within 5 years post-TBI had the highest risk of epilepsy (pooled OR = 7.27; 95% CI, 3.61-14.64).

CONCLUSION

Individuals with TBI had a significantly higher risk of epilepsy than the individuals without TBI, irrespective of the duration of the injury. Hence, long-term follow-up of the individuals with TBI is necessary to prevent any adverse consequences.

CircRNA SRRM4 affects glucose metabolism by regulating PKM alternative splicing via SRSF3 deubiquitination in epilepsy

OBJECTIVES

Several reports suggest that epigenetic therapy may be a potential method for treating epilepsy, and circular RNAs (circRNAs) play important roles in mediating the epigenetic mechanisms associated with epilepsy; however, currently there are no effective treatment methods to prevent the progression of epileptogenesis. The circRNA serine/arginine repetitive matrix 4 (circSRRM4) was found to exert regulatory effects in temporal lobe epilepsy (TLE); however, the mechanisms involved are still unknown.

MATERIALS AND METHODS

To elucidate the molecular mechanism of circSRRM4, we investigated human epileptic brain tissue, epileptic rats, neuron and astrocyte cell lines using RT-qPCR, western blot, fluorescence in situ hybridisation, immunofluorescence staining, Nissl stain, micro-PET-CT, RNA-pulldown, liquid chromatography-mass spectrometry, and RBP immunoprecipitation techniques. Furthermore, we evaluated the pyruvate kinase M1/2 (PKM) expression patterns in the human and rat models of TLE.

RESULTS

We detected the increased circSRRM4 expression in the hypometabolic lesions of patients with TLE and discovered that circSrrm4 has specific spatiotemporal characteristics in rats with kainic acid-induced epilepsy. The decreased PKM1 expression and increased PKM2 expression were similar to the Warburg effect in tumours. Notably, circSrrm4 silencing reduced the incidence and frequency of epilepsy, improved local hypometabolism, and prevented neuronal loss and astrocyte activation.

CONCLUSION

PKM2 promotes lactic acid production in the astrocytes by inducing glycolysis, thereby contributing to the energy source for epileptic seizures. Notably, circSRRM4 combines with and inhibits serine and arginine rich splicing factor 3 (SRSF3) from joining the ubiquitin-proteasome pathway, improving the SRSF3-regulated alternative splicing of PKM, and consequently stimulating glycolysis in cells.

Broadband-NIRS System Identifies Epileptic Focus in a Child with Focal Cortical Dysplasia—A Case Study

Epileptic seizures are transiently occurring symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Previous functional near-infrared spectroscopy (fNIRS) studies during seizures have focused in only monitoring the brain oxygenation and haemodynamic changes. However, few tools are available to measure actual cellular metabolism during seizures, especially at the bedside. Here we use an in-house developed multichannel broadband NIRS (or bNIRS) system, that, alongside the changes in oxy-, deoxy- haemoglobin concentration (HbO₂, HHb), also quantifies the changes in oxidised cytochrome-c-oxidase Δ(oxCCO), a marker of cellular oxygen metabolism, simultaneously over 16 different brain locations. We used bNIRS to measure metabolic activity alongside brain tissue haemodynamics/oxygenation during 17 epileptic seizures at the bedside of a 3-year-old girl with seizures due to an extensive malformation of cortical development in the left posterior quadrant. Simultaneously Video-EEG data was recorded from 12 channels. Whilst we did observe the expected increase in brain tissue oxygenation (HbD) during seizures, it was almost diminished in the area of the focal cortical dysplasia. Furthermore, in the area of seizure origination (epileptic focus) ΔoxCCO decreased significantly at the time of seizure generalization when compared to the mean change in all other channels. We hypothesize that this indicates an incapacity to sustain and increase brain tissue metabolism during seizures in the region of the epileptic focus.

Choice of anesthesia and data analysis method strongly increases sensitivity of 18F-FDG PET imaging during experimental epileptogenesis

Purpose

Alterations in brain glucose metabolism detected by 2-deoxy-2-[¹⁸F]-fluoro-D-glucose (¹⁸F-FDG) positron emission tomography (PET) may serve as an early predictive biomarker and treatment target for epileptogenesis. Here, we aimed to investigate changes in cerebral glucose metabolism before induction of epileptogenesis, during epileptogenesis as well as during chronic epilepsy. As anesthesia is usually unavoidable for preclinical PET imaging and influences the distribution of the radiotracer, four different protocols were compared.

Procedures

We investigated ¹⁸F-FDG uptake phase in conscious rats followed by a static scan as well as dynamic scans under continuous isoflurane, medetomidine-midazolam-fentanyl (MMF), or propofol anesthesia. Furthermore, we applied different analysis approaches: atlas-based regional analysis, statistical parametric mapping, and kinetic analysis.

Results

At baseline and compared to uptake in conscious rats, isoflurane and propofol anesthesia resulted in decreased cortical ¹⁸F-FDG uptake while MMF anesthesia led to a globally decreased tracer uptake. During epileptogenesis, MMF anesthesia was clearly best distinctive for visualization of prominently increased glucometabolism in epilepsy-related brain areas. Kinetic modeling further increased sensitivity, particularly for continuous isoflurane anesthesia. During chronic epilepsy, hypometabolism affecting more or less the whole brain was detectable with all protocols.

Conclusion

This study reveals evaluation of anesthesia protocols for preclinical ¹⁸F-FDG PET imaging as a critical step in the study design. Together with an appropriate data analysis workflow, the chosen anesthesia protocol may uncover otherwise concealed disease-associated regional glucometabolic changes.

Post-Traumatic Seizures: A Deep-Dive Into Pathogenesis

Post-traumatic seizures (PTS) have become an emerging challenge for neurologists worldwide with the rise of brain injuries. Trauma can lead to various outcomes, ranging from naive spasms to debilitating post-traumatic epilepsy (PTE). In this article, we will explore the pathogenesis of convulsions following a concussion. We will look at multiple studies to explain the various structural, metabolic, and inflammatory changes leading to seizures. Additionally, we will explore the association between severity and location of injury and PTE. PTE's pathophysiology is not entirely implicit, and we are still in the dark as to which anti-epileptic drugs will be useful in circumventing these attacks. The purpose of this narrative review is to explain the post-traumatic brain changes in detail so that such attacks can be either thwarted or treated more resourcefully in the future.

In Vivo Imaging of Neuroinflammatory Targets in Treatment-Resistant Epilepsy

PURPOSE OF REVIEW

Recent evidence indicates that chronic, low-level neuroinflammation underlies epileptogenesis. Targeted imaging of key neuroinflammatory cells, receptors, and tissues may enable localizing epileptogenic onset zone, especially in those patients who are treatment-resistant and considered MRI-negative. Finding a specific, sensitive neuroimaging-based biomarker could aid surgical planning and improve overall prognosis in eligible patients. This article reviews recent research on in vivo imaging of neuroinflammatory targets in patients with treatment-resistant, non-lesional epilepsy.

RECENT FINDINGS

A number of advanced approaches based on imaging neuroinflammation are being implemented in order to assist localization of epileptogenic onset zone. The most exciting tools are based on radioligand-based nuclear imaging or revisiting of existing technology in novel ways. The greatest limitations stem from gaps in knowledge about the exact function of neuroinflammatory targets (e.g., neurotoxic or neuroprotective). Further, lingering questions about each approach's specificity, reliability, and sensitivity must be addressed, and clinical utility must be validated before any novel method is incorporated into mainstream clinical practice. Current applications of imaging neuroinflammation in humans are limited and underutilized, but offer hope for finding sensitive and specific neuroimaging-based biomarker(s). Future work necessitates appreciation of investigations to date, significant findings, and neuroinflammatory targets worth exploring further.

Epilepsy Benchmarks Area II: Prevent Epilepsy and Its Progression

Area II of the 2014 Epilepsy Research Benchmarks aims to establish goals for preventing the development and progression of epilepsy. In this review, we will highlight key advances in Area II since the last summary of research progress and opportunities was published in 2016. We also highlight areas of investigation that began to develop before 2016 and in which additional progress has been made more recently.

The 'epileptic diet'- ketogenic and/or slow release of glucose intervention: A review

BACKGROUND & AIMS

The ketogenic diet is high in fat content, adequate with respect to protein but low in carbohydrate and designed to provide brain energy as ketone bodies rather than glucose. The consequence is that epilepsy can be managed and endurance (sport) related energy be derived from fat rather than ingested or stored (glycogen) carbohydrate. This review aims to set the diet in context for seizure related intervention, sport and potential modern variants with respect to glucose management - which have many medical (including epilepsy potentially) and activity related applications.

METHODS

The literature was reviewed using relevant data bases (e.g. Pubmed, Science Direct, Web of Science, Wiley on Line Library) and relevant articles were selected to provide historic and contemporary data for the text and associated Tables.

RESULTS

It is clear great health related benefits have been achieved by feeding the ketogenic to individuals subject to seizures where it helps manage the malaise. Sports applications are evident to. Glucose control diets provide health benefits of the ketogenic diet potentially and there is some evidence they are/can be very effective.

CONCLUSIONS

Key to epilepsy and sport performance is the control of blood glucose. The ketogenic diet has proven to be very effective in this regard but now other approaches to control blood glucose ae being evaluated which have advantages over the ketogenic diet. This therapeutic approach of clinical nutrition will undoubtedly move forwards over the next few years in view of the negative aspects of the ketogenic diet.

Glycolytic inhibitor 2-deoxyglucose prevents cortical hyperexcitability after traumatic brain injury

Traumatic brain injury (TBI) causes cortical dysfunction and can lead to post-traumatic epilepsy. Multiple studies demonstrate that GABAergic inhibitory network function is compromised following TBI, which may contribute to hyperexcitability and motor, behavioral, and cognitive deficits. Preserving the function of GABAergic interneurons, therefore, is a rational therapeutic strategy to preserve cortical function after TBI and prevent long-term clinical complications. Here, we explored an approach based on the ketogenic diet, a neuroprotective and anticonvulsant dietary therapy which results in reduced glycolysis and increased ketosis. Utilizing a pharmacologic inhibitor of glycolysis (2-deoxyglucose, or 2-DG), we found that acute in vitro application of 2-DG decreased the excitability of excitatory neurons, but not inhibitory interneurons, in cortical slices from naïve mice. Employing the controlled cortical impact (CCI) model of TBI in mice, we found that in vitro 2-DG treatment rapidly attenuated epileptiform activity seen in acute cortical slices 3 to 5 weeks after TBI. One week of in vivo 2-DG treatment immediately after TBI prevented the development of epileptiform activity, restored excitatory and inhibitory synaptic activity, and attenuated the loss of parvalbumin-expressing inhibitory interneurons. In summary, 2-DG may have therapeutic potential to restore network function following TBI.