Anti-seizure effect of 2-deoxyglucose (2-DG) is not dependent on the presynaptic vacuole ATP pump (V-ATPase) or the somatic ATP-sensitive K+ channel (KATP)

Inhibition of glycolysis with 2-deoxyglucose (2-DG) produces anti-seizure effects in brain slices and animal models, yet the mechanisms remain elusive. Here, we examined two glycolysis-derived ATP-associated mechanisms: vacuole ATP pump (V-ATPase) and ATP-sensitive K⁺ channel (K_ATP). Epileptiform bursts were generated in the CA3 area of hippocampal slices by 0 Mg²⁺ and 4-aminopyridine. 2-DG consistently abolished epileptiform bursts in the presence of pyruvate (to sustain tricarboxylic acid cycle for oxidative ATP production) at 30-33^oC but not at room temperature (22^oC). Under physiological conditions, 2-DG did not reduce the amplitude of evoked excitatory postsynaptic currents (EPSCs) or the paired-pulse ratio in CA3 neurons. During repetitive high-frequency (20 Hz, 20-50 pulses) stimulation, 2-DG did not accelerate the decline of EPSCs (i.e., depletion of transmitter release), even when preincubated with 8 mM K⁺ to enhance activity-dependent uptake of 2-DG. In addition, in 2-DG, tetanic stimulation (200 Hz, 1 s) dramatically increased rather than diminished the occurrence of spontaneous EPSCs immediately post stimulation (i.e., no transmitter depletion). Moreover, a V-ATPase blocker, concanamycin, failed to block epileptiform bursts that were subsequently abolished by 2-DG. Furthermore, 2-DG did not induce detectable K_ATP current in hippocampal neurons. Finally, epileptiform bursts were not affected by either a K_ATP opener (diazoxide) or a K_ATP blocker (glibenclamide) but were blocked by 2-DG in the same slices. Altogether, these data suggest that 2-DG's anti-seizure action is temperature dependent and achieved exclusively by inhibition of glycolysis, and is not likely to be mediated by the two membrane-bound ATP-associated machinery mechanisms: V-ATPase or K_ATP.

Present in the Aquatic Environment, Unclear Evidence in Top Predators-The Unknown Effects of Anti-Seizure Medication on Eurasian Otters (Lutra lutra) from Northern Germany

Emerging contaminants are produced globally at high rates and often ultimately find their way into the aquatic environment. These include substances contained in anti-seizure medication (ASM), which are currently appearing in surface waters at increasing concentrations in Germany. Unintentional and sublethal, chronic exposure to pharmaceuticals such as ASMs has unknown consequences for aquatic wildlife. Adverse effects of ASMs on the brain development are documented in mammals. Top predators such as Eurasian otters (Lutra lutra) are susceptible to the bioaccumulation of environmental pollutants. Still little is known about the health status of the otter population in Germany, while the detection of various pollutants in otter tissue samples has highlighted their role as an indicator species. To investigate potential contamination with pharmaceuticals, Eurasian otter brain samples were screened for selected ASMs via high-performance liquid chromatography and mass spectrometry. Via histology, brain sections were analyzed for the presence of potential associated neuropathological changes. In addition to 20 wild otters that were found dead, a control group of 5 deceased otters in human care was studied. Even though none of the targeted ASMs were detected in the otters, unidentified substances in many otter brains were measured. No obvious pathology was observed histologically, although the sample quality limited the investigations.

Corrigendum: Improving therapy of pharmacoresistant epilepsies: The role of fenfluramine

[This corrects the article DOI: 10.3389/fphar.2022.832929.].

Replacement of Valproic Acid with New Anti-Seizure Medications in Idiopathic Generalized Epilepsy

Background: Little is known regarding the non-inferiority of new anti-seizure medications (ASMs) in terms of replacing valproic acid (VPA) in patients with idiopathic generalized epilepsy (IGE). We hypothesized that replacement of VPA with new ASMs would offer non-inferior or better control of seizure frequency. The purpose of this study was to compare epileptic seizure frequency between the subset of patients with IGE who were on VPA and the subset of patients with IGE who replaced VPA with new ASMs. Methods: Patients with IGE who were on or had been on VPA between January 2016 and March 2022 were divided into a group that replaced VPA with new ASMs (VPA-replace group) and a group that remained on VPA (VPA-continue group). We then compared the groups in terms of seizure frequency and myoclonus. Results: Of the 606 patients on VPA between January 2016 and March 2022, 156 patients with IGE were enrolled to this study (VPA-replace group, n = 68; VPA-continue group, n = 88). The VPA-replace group included significantly more females than the VPA-continue group (p < 0.001). The VPA-replace group also showed significantly higher seizure frequency before replacement (p < 0.001), but not after replacement (p = 0.074). Patients on monotherapy displayed improved seizure frequency with new ASMs (p < 0.001). Among the new ASMs, perampanel (PER) significantly improved seizure frequency (p = 0.002). Forty-two patients in the VPA-replace group who had myoclonus achieved significant improvements (p < 0.001). Among these, patients on PER monotherapy (p < 0.001) or PER + lamotrigine (0.016) showed significantly improved myoclonus scale scores. Conclusions: This study shows the non-inferiority of new ASMs compared to VPA, with better seizure control using new ASMs in subsets of patients with IGE on monotherapy.

Improving Therapy of Pharmacoresistant Epilepsies: The Role of Fenfluramine

Epilepsy is among the most common neurological chronic disorders, with a prevalence of 0.5-1%. Despite the introduction of new antiepileptic drugs during recent years, about one third of the epileptic population remain drug-resistant. Hence, especially in the pediatric population limited by different pharmacokinetics and pharmacodynamics and by ethical and regulatory issues it is needed to identify new therapeutic resources. New molecules initially used with other therapeutic indications, such as fenfluramine, are being considered for the treatment of pharmacoresistant epilepsies, including Dravet Syndrome (DS) and Lennox-Gastaut Syndrome (LGS). Drug-refractory seizures are a hallmark of both these conditions and their treatment remains a major challenge. Fenfluramine is an amphetamine derivative that was previously approved as a weight loss drug and later withdrawn when major cardiac adverse events were reported. However, a new role of fenfluramine has emerged in recent years. Indeed, fenfluramine has proved to be a promising antiepileptic drug with a favorable risk-benefit profile for the treatment of DS, LGS and possibly other drug-resistant epileptic syndromes. The mechanism by which fenfluramine provide an antiepileptic action is not fully understood but it seems to go beyond its pro-serotoninergic activity. This review aims to provide a comprehensive analysis of the literature, including ongoing trials, regarding the efficacy and safety of fenfluramine as adjunctive treatment of pharmacoresistant epilepsies.

Anti-Seizure Medication Treatment of Benign Childhood Epilepsy With Centrotemporal Spikes: A Systematic Review and Meta-analysis

Background: This study aimed to evaluate the efficacy and tolerability of Anti-Seizure medication (ASM) treatment in patients with BECTS. Method: We searched PubMed, Cochrane Library, Embase, MEDLINE, Web of Science, China National Knowledge Infrastructure (CNKI), WANFANG DATA, and China Science and Technology Journal Database (VIP) between 1 Jan 1990, and 1 Sep 2021, for randomized controlled studies. Data on seizure freedom rate, rate of treatment withdrawal due to serious adverse events, rate of any adverse events and dropout, 50% remission rate, the proportion of patients whose EEG to be normalized, and improvement in cognitive function were extracted by two authors independently. The pooled data were meta-analyzed using a random effects model. Results: A total of 27 studies evaluating 9 ASMs were included, 19 of which were suitable for meta-analysis. Compared with sulthiame (STM), levetiracetam (LEV) was associated with a higher probability of treatment withdrawal due to serious adverse events [RR = 5.12, 95% CI (1.19, 22.01), I ² = 0.0%], experiencing any adverse events [RR = 5.12, 95% CI (1.19, 22.01)], and dropping out for any reason [RR = 3.17, 95% CI (1.36, 10.11)], while it did not affect the seizure freedom rate [RR = 0.90, 95% CI (0.75, 1.06)]. LEV significantly improved cognitive performance relative to carbamazepine (CBZ) but had no effect on the proportion of any adverse events [RR = 0.62, 95% CI (0.25, 1.59)] and EEG to be normalized [RR = 1.27, 95% CI (0.94, 1.71)]. There was no higher probability of a 50% remission rate when comparing valproic acid (VPA) to LEV [RR = 0.96, 95% CI (0.57, 1.61)] and oxcarbazepine (OXC) [RR = 0.61, 95% CI (0.31, 1.20)]. In addition, STM was related to a higher probability of EEG normalization than placebo [RR = 4.61, 95% CI (2.12, 10.01)]. The included single studies also provided some evidence for the efficacy and/or tolerability of other ASMs in BECTS, including topiramate, lamotrigine, clobazam, and clonazepam. The risk of bias of the included studies was frequently low or unclear. Conclusion: This study indicated some discrepancies in efficacy and tolerability among ASMs used in patients with BECTS. More randomized controlled trials (RCTs) comparing ASMs with larger populations are required to ascertain the optimum antiepileptic drug treatment to guide clinicians.

Role of Common Genetic Variants for Drug-Resistance to Specific Anti-Seizure Medications

Objective: Resistance to anti-seizure medications (ASMs) presents a significant hurdle in the treatment of people with epilepsy. Genetic markers for resistance to individual ASMs could support clinicians to make better-informed choices for their patients. In this study, we aimed to elucidate whether the response to individual ASMs was associated with common genetic variation. Methods: A cohort of 3,649 individuals of European descent with epilepsy was deeply phenotyped and underwent single nucleotide polymorphism (SNP)-genotyping. We conducted genome-wide association analyses (GWASs) on responders to specific ASMs or groups of functionally related ASMs, using non-responders as controls. We performed a polygenic risk score (PRS) analyses based on risk variants for epilepsy and neuropsychiatric disorders and ASM resistance itself to delineate the polygenic burden of ASM-specific drug resistance. Results: We identified several potential regions of interest but did not detect genome-wide significant loci for ASM-specific response. We did not find polygenic risk for epilepsy, neuropsychiatric disorders, and drug-resistance associated with drug response to specific ASMs or mechanistically related groups of ASMs. Significance: This study could not ascertain the predictive value of common genetic variants for ASM responder status. The identified suggestive loci will need replication in future studies of a larger scale.