How does the ketogenic diet induce anti-seizure effects?

Intractable Generalized Epilepsy: Therapeutic Approaches

PURPOSE OF REVIEW

To summarize recent developments in therapeutic options, both medical and surgical, for patients with drug-resistant generalized epilepsy syndromes, which continue to be a multifaceted challenge for patients and physicians.

RECENT FINDINGS

Newer generation pharmaceutical options are now available, such as brivaracetam, rufinamide, lacosamide, perampanel, and cannabidiol. Less restrictive dietary options appear to be nearly as effective as classic ketogenic diet for amelioration of seizures. The latest implantable devices include responsive neurostimulation and deep brain stimulation. Corpus callosotomy is an effective treatment for some seizure types, and newer and less invasive approaches are being explored. Resective surgical options have demonstrated success in carefully selected patients despite generalized electrographic findings on electroencephalogram. The current literature reflects a widening range of clinical experience with newer anticonvulsant medications including cannabinoids, dietary therapies, surgical approaches, and neurostimulation devices for patients with intractable generalized epilepsy.

Brain Glucose Metabolism: Integration of Energetics with Function

Glucose is the long-established, obligatory fuel for brain that fulfills many critical functions, including ATP production, oxidative stress management, and synthesis of neurotransmitters, neuromodulators, and structural components. Neuronal glucose oxidation exceeds that in astrocytes, but both rates increase in direct proportion to excitatory neurotransmission; signaling and metabolism are closely coupled at the local level. Exact details of neuron-astrocyte glutamate-glutamine cycling remain to be established, and the specific roles of glucose and lactate in the cellular energetics of these processes are debated. Glycolysis is preferentially upregulated during brain activation even though oxygen availability is sufficient (aerobic glycolysis). Three major pathways, glycolysis, pentose phosphate shunt, and glycogen turnover, contribute to utilization of glucose in excess of oxygen, and adrenergic regulation of aerobic glycolysis draws attention to astrocytic metabolism, particularly glycogen turnover, which has a high impact on the oxygen-carbohydrate mismatch. Aerobic glycolysis is proposed to be predominant in young children and specific brain regions, but re-evaluation of data is necessary. Shuttling of glucose- and glycogen-derived lactate from astrocytes to neurons during activation, neurotransmission, and memory consolidation are controversial topics for which alternative mechanisms are proposed. Nutritional therapy and vagus nerve stimulation are translational bridges from metabolism to clinical treatment of diverse brain disorders.

Combating insulin resistance with the paleo diet

Lifestyle changes that include adopting a healthy diet, such as the paleo diet, can help prevent prediabetes and T2DM. This article explores the potential benefits of replacing low-calorie diets with the paleo diet. As primary care providers, NPs are positioned to help inform patients, particularly those with prediabetes and T2DM, about healthy lifestyle choices and provide them with resources to achieve weight loss success.

Ketogenic Diet and Epilepsy: What We Know So Far

The Ketogenic Diet (KD) is a modality of treatment used since the 1920s as a treatment for intractable epilepsy. It has been proposed as a dietary treatment that would produce similar benefits to fasting, which is already recorded in the Hippocratic collection. The KD has a high fat content (90%) and low protein and carbohydrate. Evidence shows that KD and its variants are a good alternative for non-surgical pharmacoresistant patients with epilepsy of any age, taking into account that the type of diet should be designed individually and that less-restrictive and more-palatable diets are usually better options for adults and adolescents. This review discusses the KD, including the possible mechanisms of action, applicability, side effects, and evidence for its efficacy, and for the more-palatable diets such as the Modified Atkins Diet (MAD) and the Low Glycemic Index Diet (LGID) in children and adults.

The Therapeutic Potential of Ketogenic Diet Throughout Life: Focus on Metabolic, Neurodevelopmental and Neurodegenerative Disorders

This chapter reviews the efficacy of the ketogenic diet in a variety of neurodegenerative, neurodevelopmental and metabolic conditions throughout different stages of life. It describes conditions affecting children, metabolic disorders in adults and disorderrs affecting the elderly. We have focused on application of the ketogenic diet in clinical studies and in preclinical models and discuss the benefits and negative aspects of the diet. Finally, we highlight the need for further research in this area with a view of discovering novel mechanistic targets of the ketogenic diet, as a means of maximising the potential benefits/risks ratio.

Reduced AMPK activation and increased HCAR activation drive anti-inflammatory response and neuroprotection in glaucoma

Background

Glaucoma is a chronic degenerative disease for which inflammation is considered to play a pivotal role in the pathogenesis and progression. In this study, we examined the impact of a ketogenic diet on the inflammation evident in glaucoma as a follow-up to a recent set of experiments in which we determined that a ketogenic diet protected retinal ganglion cell structure and function.

Methods

Both sexes of DBA/2J (D2) mice were placed on a ketogenic diet (keto) or standard rodent chow (untreated) for 8 weeks beginning at 9 months of age. DBA/2J-Gpnmb⁺ (D2G) mice were also used as a non-pathological genetic control for the D2 mice. Retina and optic nerve (ON) tissues were micro-dissected and used for the analysis of microglia activation, expression of pro- and anti-inflammatory molecules, and lactate- or ketone-mediated anti-inflammatory signaling. Data were analyzed by immunohistochemistry, quantitative RT-PCR, ELISA, western blot, and capillary tube-based electrophoresis techniques.

Results

Microglia activation was observed in D2 retina and ON as documented by intense microglial-specific Iba1 immunolabeling of rounded-up and enlarged microglia. Ketogenic diet treatment reduced Iba1 expression and the activated microglial phenotype. We detected low energy-induced AMP-activated protein kinase (AMPK) phosphorylation in D2 retina and ON that triggered NF-κB p65 signaling through its nuclear translocation. NF-κB induced pro-inflammatory TNF-α, IL-6, and NOS2 expression in D2 retina and ON. However, treatment with the ketogenic diet reduced AMPK phosphorylation, NF-κB p65 nuclear translocation, and expression of pro-inflammatory molecules. The ketogenic diet also induced expression of anti-inflammatory agents Il-4 and Arginase-1 in D2 retina and ON. Increased expression of hydroxycarboxylic acid receptor 1 (HCAR1) after ketogenic diet treatment was observed. HCAR1 stimulation by lactate or ketones from the ketogenic diet reduced inflammasome formation, as shown by reduced mRNA and protein expression of NLRP3 and IL-1β. We also detected increased levels of Arrestin β-2 protein, an adapter protein required for HCAR1 signaling.

Conclusion

Our data demonstrate that the AMPK activation apparent in the glaucomatous retina and ON triggers NF-κB signaling and consequently induces a pro-inflammatory response. The ketogenic diet resolves energy demand and ameliorates the inflammation by inhibition of AMPK activation and stimulation of HCAR1-ARRB2 signaling that inhibits NLRP3 inflammasome-mediated inflammation. Thus, these findings depict a neuroprotective mechanism of the ketogenic diet in controlling inflammation and suggest potential therapeutic targets for inflammatory neurodegenerative diseases, including glaucoma.

Impact of Dietary Fats on Brain Functions

BACKGROUND

Adequate dietary intake and nutritional status have important effects on brain functions and on brain health. Energy intake and specific nutrients excess or deficiency from diet differently affect cognitive processes, emotions, behaviour, neuroendocrine functions and synaptic plasticity with possible protective or detrimental effects on neuronal physiology. Lipids, in particular, play structural and functional roles in neurons. Here the importance of dietary fats and the need to understand the brain mechanisms activated by peripheral and central metabolic sensors. Thus, the manipulation of lifestyle factors such as dietary interventions may represent a successful therapeutic approach to maintain and preserve brain health along lifespan.

METHODS

This review aims at summarizing the impact of dietary fats on brain functions.

RESULTS

Starting from fat consumption, nutrient sensing and food-related reward, the impact of gut-brain communications will be discussed in brain health and disease. A specific focus will be on the impact of fats on the molecular pathways within the hypothalamus involved in the control of reproduction via the expression and the release of Gonadotropin-Releasing Hormone. Lastly, the effects of specific lipid classes such as polyunsaturated fatty acids and of the "fattest" of all diets, commonly known as "ketogenic diets", on brain functions will also be discussed.

CONCLUSION

Despite the knowledge of the molecular mechanisms is still a work in progress, the clinical relevance of the manipulation of dietary fats is well acknowledged and such manipulations are in fact currently in use for the treatment of brain diseases.

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

Traumatic brain injury (TBI) is a significant cause of disability worldwide and can lead to post-traumatic epilepsy. Multiple molecular, cellular, and network pathologies occur following injury which may contribute to epileptogenesis. Efforts to identify mechanisms of disease progression and biomarkers which predict clinical outcomes have focused heavily on metabolic changes. Advances in imaging approaches, combined with well-established biochemical methodologies, have revealed a complex landscape of metabolic changes that occur acutely after TBI and then evolve in the days to weeks after. Based on this rich clinical and preclinical data, combined with the success of metabolic therapies like the ketogenic diet in treating epilepsy, interest has grown in determining whether manipulating metabolic activity following TBI may have therapeutic value to prevent post-traumatic epileptogenesis. Here, we focus on changes in glucose utilization and glycolytic activity in the brain following TBI and during seizures. We review relevant literature and outline potential paths forward to utilize glycolytic inhibitors as a disease-modifying therapy for post-traumatic epilepsy.

Electrical Control in Neurons by the Ketogenic Diet

The ketogenic diet is used as a diet treatment for drug-resistant epilepsy, but there are no antiepileptic drugs based on the ketogenic diet. The ketogenic diet changes energy metabolites (ketone bodies, glucose and lactate) in the brain, which consequently changes electrical activities in neurons and ultimately suppresses seizures in epileptic patients. In order to elucidate the antiseizure effects of the ketogenic diet, it is important to clarify the mechanism by which these metabolic changes are converted to electrical changes in neurons. In this review, we summarize electrophysiological studies focusing on electrical control in neurons by the ketogenic diet. Recent studies have identified electrical regulators driven by the ketogenic diet: ion channels (ATP-sensitive K+ channels and voltage-dependent Ca2+ channels), synaptic receptors (AMPA-type glutamate receptors and adenosine A1 receptors), neurotransmitter transporters (vesicular glutamate transporters), and others (BCL-2-associated agonist of cell death and lactate dehydrogenase). Thus, the ketogenic diet presumably elicits neuronal inhibition via the combined actions of these molecules. From the viewpoint of drug development, these molecules are valuable as targets for the development of new antiepileptic drugs. Drug therapy to mimic the ketogenic diet may be feasible in the future, through the combination of multiple antiepileptic drugs targeting these molecules.

New insights into the mechanisms of the ketogenic diet

PURPOSE OF REVIEW

High-fat, low-carbohydrate ketogenic diets have been used for almost a century for the treatment of epilepsy. Used traditionally for the treatment of refractory pediatric epilepsies, in recent years the use of ketogenic diets has experienced a revival to include the treatment of adulthood epilepsies as well as conditions ranging from autism to chronic pain and cancer. Despite the ability of ketogenic diet therapy to suppress seizures refractory to antiepileptic drugs and reports of lasting seizure freedom, the underlying mechanisms are poorly understood. This review explores new insights into mechanisms mobilized by ketogenic diet therapies.

RECENT FINDINGS

Ketogenic diets act through a combination of mechanisms, which are linked to the effects of ketones and glucose restriction, and to interactions with receptors, channels, and metabolic enzymes. Decanoic acid, a component of medium-chain triclycerides, contributes to seizure control through direct α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor inhibition, whereas drugs targeting lactate dehydrogenase reduce seizures through inhibition of a metabolic pathway. Ketogenic diet therapy also affects DNA methylation, a novel epigenetic mechanism of the diet.

SUMMARY

Ketogenic diet therapy combines several beneficial mechanisms that provide broad benefits for the treatment of epilepsy with the potential to not only suppress seizures but also to modify the course of the epilepsy.

Small intraneuronal acidification via short-chain monocarboxylates: First evidence of an inhibitory action on over-excited human neocortical neurons

AIMS

In cortical mammalian neurons, small fluctuations of intracellular pH (pHi) play a crucial role for inter- and intracellular signaling as well as for cellular and synaptic plasticity. Yet, there have been no respective data about humans. Thus, we investigated the interrelation of pHi and excitability of human cortical neurons.

MATERIALS AND METHODS

Intracellular electrophysiological and pH-recordings were made in neurons in slices taken from brain tissue resected from the middle temporal gyrus of two male children (26 months and 35 months old) who suffered from pharmacotherapy-resistant temporal lobe epilepsy. To excite the tissue (n = 13), we used the 0-Mg2+/high-K+-in vitro epilepsy model producing robust epileptiform discharges (ED). To evoke an intracellular acidification (n = 12), we used the well-established propionate-model and applied 10 mM propionate to the bath solutions. In addition, we recorded the effects of other strongly related short-chain monocarboxylates (l-lactate (10 mM) and the ketone body DL-β-hydroxybutyrate (10 mM)) on ED and pHi.

KEY FINDINGS

The ED-frequency was reversibly reduced by propionate (n = 5), l-lactate (n = 5), or DL-β-hydroxybutyrate (n = 3), while the durations of EDs and their after-depolarizations increased. In parallel experiments, all three short-chain monocarboxylates (each n = 4) lowered the pHi of the neurons (n = 12) by 0.05-0.07 pH units which was temporally related to the reported changes in bioelectric activity.

SIGNIFICANCE

A mild drop of the intraneuronal pH was associated with the control of even over-excited human neocortical tissue. This is identical with prior observations in non-human mammalian cortical neurons. Possible implications for neuroplasticity and the treatment of neuropsychiatric disorders are discussed.

ATP1A3-related epileptic encephalopathy responding to ketogenic diet

BACKGROUND

Alternating Hemiplegia of Childhood (AHC) is a rare neurological disease caused by mutations in ATP1A3 gene codifying for alpha3 subunit of Na⁺-K⁺ ATPase pump. Repeated and transient attacks of hemiplegia, usually affecting one side of the body or the other, or both sides of the body at once, are the core features of AHC. Monocular nystagmus, other abnormalities in ocular movements, dystonic posturing and epilepsy are commonly associated to AHC. However, the spectrum of ATP1A3 related diseases is still expanding and new phenotypes have been reported.

CASE REPORT

Here, we described a patient who developed a severe early onset drug-resistant epileptic encephalopathy and months later, he presented episodes of hemiplegic attacks and monocular nystagmus. Thus, AHC was hypothesized and a novel mutation in ATP1A3 gene was found. Interestingly, ketogenic diet (KD) was started and both epileptic seizures and classical AHC paroxysmal episodes stopped. Long-term follow-up shows a global improvement of neurological development.

CONCLUSIONS

Our case reinforces the role of KD as a novel therapeutic option for ATP1A3-related conditions. However, proper dedicated confirmatory trials on KD are necessary.

Opposing effects of 2-deoxy-d-glucose on interictal- and ictal-like activity when K+ currents and GABAA receptors are blocked in rat hippocampus in vitro

The ketogenic diet (KD), a high-fat, carbohydrate-restricted diet, is used as an alternative treatment for drug-resistant epileptic patients. Evidence suggests that compromised glucose metabolism has a significant role in the anticonvulsant action of the KD; however, it is unclear what part of the glucose metabolism that is important. The present study investigates how selective alterations in glycolysis and oxidative phosphorylation influence epileptiform activity induced by blocking K+ currents and GABAA and NMDA receptors in the hippocampal slice preparation. Blocking glycolysis with the glucose derivative 2-deoxy-d-glucose (2-DG; 10 mM) gave a fast reduction of the frequency of interictal discharge (IED) consistent with findings in other in vitro models. However, this was followed by the induction of seizure-like discharges in area CA1 and CA3. Substituting glucose with sucrose (glucopenia) had effects similar to those of 2-DG, whereas substitution with l-lactate or pyruvate reduced the IED but had a less proconvulsant effect. Blockade of ATP-sensitive K+ channels, glycine or adenosine 1 receptors, or depletion of the endogenous anticonvulsant compound glutathione did not prevent the actions of 2-DG. Baclofen (2 μM) reproduced the effect of 2-DG on IED activity. The proconvulsant effect of 2-DG could be reproduced by blocking the oxidative phosphorylation with the complex I toxin rotenone (4 μM). The data suggest that inhibition of IED, induced by 2-DG and glucopenia, is a direct consequence of impairment of glycolysis, likely exerted via a decreased recurrent excitatory synaptic transmission in area CA3. The accompanying proconvulsant effect is caused by an excitatory mechanism, depending on impairment of oxidative phosphorylation.

NEW & NOTEWORTHY This study reveals two opposing effects of 2-deoxy-d-glucose (2-DG) and glucopenia on in vitro epileptiform discharge observed during combined blockade of K+ currents and GABAA receptors. Interictal-like activity is inhibited by a mechanism that selectively depends on impairment of glycolysis and that results from a decrease in the strength of excitatory recurrent synaptic transmission in area CA3. In contrast, 2-DG and glucopenia facilitate ictal-like activity by an excitatory mechanism, depending on impairment of mitochondrial oxidative phosphorylation.

Pharmacotherapy for Refractory and Super-Refractory Status Epilepticus in Adults

Patients with prolonged seizures that do not respond to intravenous benzodiazepines and a second-line anticonvulsant suffer from refractory status epilepticus and those with seizures that do not respond to continuous intravenous anesthetic anticonvulsants suffer from super-refractory status epilepticus. Both conditions are associated with significant morbidity and mortality. A strict pharmacological treatment regimen is urgently required, but the level of evidence for the available drugs is very low. Refractory complex focal status epilepticus generally does not require anesthetics, but all intravenous non-anesthetizing anticonvulsants may be used. Most descriptive data are available for levetiracetam, phenytoin and valproate. Refractory generalized convulsive status epilepticus is a life-threatening emergency, and long-term clinical consequences are eminent. Administration of intravenous anesthetics is mandatory, and drugs acting at the inhibitory gamma-aminobutyric acid (GABA)A receptor such as midazolam, propofol and thiopental/pentobarbital are recommended without preference for one of those. One in five patients with anesthetic treatment does not respond and has super-refractory status epilepticus. With sustained seizure activity, excitatory N-methyl-d-aspartate (NMDA) receptors are increasingly expressed post-synaptically. Ketamine is an antagonist at this receptor and may prove efficient in some patients at later stages. Neurosteroids such as allopregnanolone increase sensitivity at GABAA receptors; a Phase 1/2 trial demonstrated safety and tolerability, but randomized controlled data failed to demonstrate efficacy. Adjunct ketogenic diet may contribute to termination of difficult-to-treat status epilepticus. Randomized controlled trials are needed to increase evidence for treatment of refractory and super-refractory status epilepticus, but there are multiple obstacles for realization. Hitherto, prospective multicenter registries for pharmacological treatment may help to improve our knowledge.

Anxiolytic Effect of Exogenous Ketone Supplementation Is Abolished by Adenosine A1 Receptor Inhibition in Wistar Albino Glaxo/Rijswijk Rats

Anxiety disorders are one of the most common mental health problems worldwide, but the exact pathophysiology remains largely unknown. It has been demonstrated previously that administration of exogenous ketone supplement KSMCT (ketone salt/KS + medium chain triglyceride/MCT oil) by intragastric gavage for 7 days decreased the anxiety level in genetically absence epileptic Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. To investigate the potential role of the adenosinergic system in the pathomechanism of anxiety we tested whether the inhibition of adenosine A₁ receptors (A₁Rs) influence the anxiolytic effect of the exogenous ketone supplement. As A₁Rs may mediate such an effect, in the present study we used a specific A₁R antagonist, DPCPX (1,3-dipropyl-8-cyclopentylxanthine) to test whether it modulates the anxiolytic effect of sub-chronically (7 days) applied KSMCT in the previously tested animal model by using elevated plus maze (EPM) test. We administered KSMCT (2.5 g/kg/day) alone by intragastric gavage and in combination with intraperitoneally (i.p.) injected of DPCPX in two doses (lower: 0.15 mg/kg, higher: 0.25 mg/kg). Control groups represented i.p saline and water gavage with or without i.p. DPCPX administration (2.5 g/kg/day). After treatments, the level of blood glucose and beta-hydroxybutyrate (βHB), as well as body weight were recorded. KSMCT alone significantly increased the time spent in the open arms and decreased the time spent in the closed arms, supporting our previous results. Injection of lower dose of DPCPX decreased, while higher dose of DPCPX abolished the effect of KSMCT administration on EPM. Blood βHB levels were significantly increased after administration of KSMCT, while DPCPX did not change the KSMCT induced increase in blood βHB levels. These results demonstrate that A₁R inhibition modified (decreased) the anti-anxiety effect of KSMCT administration implying that the adenosinergic system, likely via A₁Rs, may modulate the exogenous ketone supplement induced anxiolytic influence.

Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health

Impaired mitochondrial function often results in excessive production of reactive oxygen species (ROS) and is involved in the etiology of many chronic diseases, including cardiovascular disease, diabetes, neurodegenerative disorders, and cancer. Moderate levels of mitochondrial ROS, however, can protect against chronic disease by inducing upregulation of mitochondrial capacity and endogenous antioxidant defense. This phenomenon, referred to as mitohormesis, is induced through increased reliance on mitochondrial respiration, which can occur through diet or exercise. Nutritional ketosis is a safe and physiological metabolic state induced through a ketogenic diet low in carbohydrate and moderate in protein. Such a diet increases reliance on mitochondrial respiration and may, therefore, induce mitohormesis. Furthermore, the ketone β-hydroxybutyrate (BHB), which is elevated during nutritional ketosis to levels no greater than those resulting from fasting, acts as a signaling molecule in addition to its traditionally known role as an energy substrate. BHB signaling induces adaptations similar to mitohormesis, thereby expanding the potential benefit of nutritional ketosis beyond carbohydrate restriction. This review describes the evidence supporting enhancement of mitochondrial function and endogenous antioxidant defense in response to nutritional ketosis, as well as the potential mechanisms leading to these adaptations.

Safety and tolerability of the ketogenic diet used for the treatment of refractory childhood epilepsy: a systematic review of published prospective studies

BACKGROUND

To review the available evidence from prospective studies on the safety and tolerability of the ketogenic diet (KD) for the treatment of refractory childhood epilepsy.

METHODS

A comprehensive bibliographic search was performed with the aim of retrieving prospective studies that monitored adverse effects (AEs) in children after receiving the classic or medium-chain triglyceride KD therapy for refractory epilepsy.

RESULTS

A total of 45 studies were retrieved, including 7 randomized controlled trials. More than 40 categories of AEs were reported. The most common AEs included gastrointestinal disturbances (40.6%), hyperlipidemia (12.8%), hyperuricemia (4.4%), lethargy (4.1%), infectious diseases (3.8%) and hypoproteinemia (3.8%). Severe AEs, such as respiratory failure and pancreatitis, occurred in no more than 0.5% of children. Specifically, patients receiving KD therapy should be monitored for osteopenia, urological stones, right ventricular diastolic dysfunction, and growth disturbance. The total retention rates of the diet for 1 year and 2 years were 45.7% and 29.2%, respectively. Nearly half of the patients discontinued the diet because of lack of efficacy. AEs were not the main reason for the KD discontinuation. None of the 24 deaths reported after initiation of the diet was attributed to the KD.

CONCLUSIONS

KD is a relatively safe dietary therapy. However, because the KD can cause various AEs, it should be implemented under careful medical supervision. Continuous follow-up is needed to address the long-term impact of the diet on the overall health of children.

BAD knockout provides metabolic seizure resistance in a genetic model of epilepsy with sudden unexplained death in epilepsy

Metabolic alteration, either through the ketogenic diet (KD) or by genetic alteration of the BAD protein, can produce seizure protection in acute chemoconvulsant models of epilepsy. To assess the seizure-protective role of knocking out (KO) the Bad gene in a chronic epilepsy model, we used the Kcna1^-/- model of epilepsy, which displays progressively increased seizure severity and recapitulates the early death seen in sudden unexplained death in epilepsy (SUDEP). Beginning on postnatal day 24 (P24), we continuously video monitored Kcna1^-/- and Kcna1^-/- Bad^-/- double knockout mice to assess survival and seizure severity. We found that Kcna1^-/- Bad^-/- mice outlived Kcna1^-/- mice by approximately 2 weeks. Kcna1^-/- Bad^-/- mice also spent significantly less time in seizure than Kcna1^-/- mice on P24 and the day of death, showing that BadKO provides seizure resistance in a genetic model of chronic epilepsy.

Efficacy of a ketogenic diet with concomitant intranasal perillyl alcohol as a novel strategy for the therapy of recurrent glioblastoma

It has been hypothesized that persistent ketotic hypoglycemia represents a potential therapeutic strategy against high-grade gliomas. Perillyl alcohol (POH) is a non-toxic, naturally-occurring, hydroxylated monoterpene that exhibits cytotoxicity against temozolomide-resistant glioma cells, regardless of O6-methylguanine-methyltransferase promoter methylation status. The present study aimed to evaluate the toxicity and therapeutic efficacy of intranasal POH when administered in combination with a ketogenic diet (KD) program for the treatment of patients with recurrent glioblastoma. The 32 enrolled patients were divided into two groups, KD or standard diet, with intranasal POH treatment (n=17 and n=15, respectively). The nutritional status and anthropometric parameters of the patients were measured. Patients that adhered to the KD maintained a strict dietary regimen, in addition to receiving 55 mg POH four times daily, in an uninterrupted administration schedule for three months. Neurological examination and magnetic resonance imaging analysis were used to monitor disease progression. A total of 9/17 patients in the KD group survived and maintained compliance with the KD. After three months of well-tolerated treatment, a partial response (PR) was observed for 77.8% (7/9) of the patients, stable disease (SD) in 11.1% (1/9) and 11.1% (1/9) presented with progressive disease (PD). Among the patients assigned to the standard diet group, the PR rate was 25% (2/8 patients), SD 25% (2/8) and PD 50% (4/8 patients). The patients assigned to the KD group presented with reduced serum lipid levels and decreased low-density lipoprotein cholesterol levels. These results are encouraging and suggest that KD associated with intranasal POH may represent a viable option as an adjunct therapy for recurrent GBM.

Short-term and long-term efficacy of classical ketogenic diet and modified Atkins diet in children and adolescents with epilepsy: A systematic review and meta-analysis

OBJECTIVES

Classical ketogenic diet (KD) and modified Atkins diet (MAD) are two types of KD commonly used for the treatment of intractable epilepsy throughout the world. Studies have shown the efficacy of these diets. However, no systematic review and meta-analysis study has to date compared the efficacy of KD and MAD in a time trend. Therefore, the objectives of the present study were to compare the short-term and long-term efficacy of classical KD and MAD in children and adolescents with epilepsy and to determine the efficacy of classical KD and MAD at multiple time points and in a time trend.

METHODS

Main electronic literature databases, including MEDLINE/PubMed, Web of Science, Scopus, and EMBASE, were searched in November 2016. Rate difference and random effects model were used to compare the efficacy of the classical KD and MAD.

RESULTS

Overall, 70 studies were eligible for inclusion. Meta-analysis revealed a non-significant trend toward a higher efficacy of MAD at month-3 and month-6 (P > 0.05). In the classical KD group, the percentage of responder patients achieving ≥50% seizure reduction was 62, 60, 52, 42, and 46% at month-1, 3, 6, 12 and 24 and for the MAD group was 55, 47, 42, and 29% at month-1, 3, 6, and 12, respectively.

DISCUSSION

Classical KD does not differ substantially from MAD in ≥50% and ≥90% reduction of seizure frequency at month-3 and month-6. Overall, the number of patients achieving seizure freedom increases over time.

Epilepsy and astrocyte energy metabolism

Epilepsy is a complex neurological syndrome characterized by neuronal hyperexcitability and sudden, synchronized electrical discharges that can manifest as seizures. It is now increasingly recognized that impaired astrocyte function and energy homeostasis play key roles in the pathogenesis of epilepsy. Excessive neuronal discharges can only happen, if adequate energy sources are made available to neurons. Conversely, energy depletion during seizures is an endogenous mechanism of seizure termination. Astrocytes control neuronal energy homeostasis through neurometabolic coupling. In this review, we will discuss how astrocyte dysfunction in epilepsy leads to distortion of key metabolic and biochemical mechanisms. Dysfunctional glutamate metabolism in astrocytes can directly contribute to neuronal hyperexcitability. Closure of astrocyte intercellular gap junction coupling as observed early during epileptogenesis limits activity-dependent trafficking of energy metabolites, but also impairs clearance of the extracellular space from accumulation of K⁺ and glutamate. Dysfunctional astrocytes also increase the metabolism of adenosine, a metabolic product of ATP degradation that broadly inhibits energy-consuming processes as an evolutionary adaptation to conserve energy. Due to the critical role of astroglial energy homeostasis in the control of neuronal excitability, metabolic therapeutic approaches that prevent the utilization of glucose might represent a potent antiepileptic strategy. In particular, high fat low carbohydrate "ketogenic diets" as well as inhibitors of glycolysis and lactate metabolism are of growing interest for the therapy of epilepsy.

Metabolic and Homeostatic Changes in Seizures and Acquired Epilepsy-Mitochondria, Calcium Dynamics and Reactive Oxygen Species

Acquired epilepsies can arise as a consequence of brain injury and result in unprovoked seizures that emerge after a latent period of epileptogenesis. These epilepsies pose a major challenge to clinicians as they are present in the majority of patients seen in a common outpatient epilepsy clinic and are prone to pharmacoresistance, highlighting an unmet need for new treatment strategies. Metabolic and homeostatic changes are closely linked to seizures and epilepsy, although, surprisingly, no potential treatment targets to date have been translated into clinical practice. We summarize here the current knowledge about metabolic and homeostatic changes in seizures and acquired epilepsy, maintaining a particular focus on mitochondria, calcium dynamics, reactive oxygen species and key regulators of cellular metabolism such as the Nrf2 pathway. Finally, we highlight research gaps that will need to be addressed in the future which may help to translate these findings into clinical practice.

Metabolomics As a Tool for the Characterization of Drug-Resistant Epilepsy

Purpose

Drug resistance is a critical issue in the treatment of epilepsy, contributing to clinical emergencies and increasing both serious social and economic burdens on the health system. The wide variety of potential drug combinations followed by often failed consecutive attempts to match drugs to an individual patient may mean that this treatment stage may last for years with suboptimal benefit to the patient. Given these challenges, it is valuable to explore the availability of new methodologies able to shorten the period of determining a rationale pharmacologic treatment. Metabolomics could provide such a tool to investigate possible markers of drug resistance in subjects with epilepsy.

Methods

Blood samples were collected from (1) controls (C) (n = 35), (2) patients with epilepsy “responder” (R) (n = 18), and (3) patients with epilepsy “non-responder” (NR) (n = 17) to the drug therapy. The samples were analyzed using nuclear magnetic resonance spectroscopy, followed by multivariate statistical analysis.

Key findings

A different metabolic profile based on metabolomics analysis of the serum was observed between C and patients with epilepsy and also between R and NR patients. It was possible to identify the discriminant metabolites for the three classes under investigation. Serum from patients with epilepsy were characterized by increased levels of 3-OH-butyrate, 2-OH-valerate, 2-OH-butyrate, acetoacetate, acetone, acetate, choline, alanine, glutamate, scyllo-inositol (C < R < NR), and decreased concentration of glucose, lactate, and citrate compared to C (C > R > NR).

Significance

In conclusion, metabolomics may represent an important tool for discovery of differences between subjects affected by epilepsy responding or resistant to therapies and for the study of its pathophysiology, optimizing the therapeutic resources and the quality of life of patients.

β-Hydroxybutyrate: A Signaling Metabolite

Various mechanisms in the mammalian body provide resilience against food deprivation and dietary stress. The ketone body β-hydroxybutyrate (BHB) is synthesized in the liver from fatty acids and represents an essential carrier of energy from the liver to peripheral tissues when the supply of glucose is too low for the body's energetic needs, such as during periods of prolonged exercise, starvation, or absence of dietary carbohydrates. In addition to its activity as an energetic metabolite, BHB is increasingly understood to have cellular signaling functions. These signaling functions of BHB broadly link the outside environment to epigenetic gene regulation and cellular function, and their actions may be relevant to a variety of human diseases as well as human aging.

Adenosine A1 Receptor Antagonism Abolished the Anti-seizure Effects of Exogenous Ketone Supplementation in Wistar Albino Glaxo Rijswijk Rats

The state of therapeutic ketosis can be achieved by using the ketogenic diet (KD) or exogenous ketone supplementation. It was suggested previously that the adenosinergic system may be involved in the mediating effect of KD on suppressing seizure activity in different types of epilepsies, likely by means of adenosine A1 receptors (A1Rs). Thus, we tested in the present study whether exogenous ketone supplements (ketone ester: KE, 2.5 g/kg/day; ketone salt/KS + medium chain triglyceride/MCT: KSMCT, 2.5 g/kg/day) applied sub-chronically (for 7 days) by intragastric gavage can modulate absence epileptic activity in genetically absence epileptic Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. The number of spike-wave discharges (SWDs) significantly and similarly decreased after both KE and KSMCT treatment between 3rd and 7th days of gavage. Moreover, blood beta-hydroxybutyrate (βHB) levels were significantly increased alike after KE and KSMCT gavage, compared to control levels. The SWD number and βHB levels returned to the baseline levels on the first day without ketone supplementation. To determine whether A1Rs can modify ketone supplement-evoked changes in absence epileptic activity, we applied a non-pro-epileptic dose of a specific A1R antagonist DPCPX (1,3-dipropyl-8-cyclopentylxanthine) (intraperitoneal/i.p. 0.2 mg/kg) in combination with KSMCT (2.5 g/kg/day, gavage). As expected, DPCPX abolished the KSMCT-evoked decrease in SWD number. Thus, we concluded that application of exogenous ketone supplements may decrease absence epileptic activity in WAG/Rij rats. Moreover, our results suggest that among others the adenosinergic system, likely via A1Rs, may modulate the exogenous ketone supplements-evoked anti-seizure effects.

Reduction of epileptiform activity in ketogenic mice: The role of monocarboxylate transporters

Epilepsy is a chronic neurological disorder that affects approximately 50 million people worldwide. Ketogenic diet (KD) can be a very effective treatment for intractable epilepsy. Potential mechanisms of action for KD have been proposed, including the re-balance among excitatory and inhibitory neurotransmission and decrease in the glycolytic rate in brain cells. KD has been shown to have an effect on the expression pattern of monocarboxylate transporters (MCT), however, it is unknown whether MCT transport activity is affected by KD and linked to the reduction of seizures during KD. Therefore, we studied the influence of KD on MCT transport activity and the role of MCTs during epileptiform activity. Our results showed a decrease in the epileptiform activity in cortical slices from mice fed on KD and in the presence of beta-hydroxybutyrate. KD increased transport capacity for ketone bodies and lactate in cortical astrocytes by raising the MCT1 expression level. Inhibition of MCT1 and MCT2 in control conditions decreases epileptiform activity, while in KD it induced an increase in epileptiform activity. Our results suggest that MCTs not only play an important role in the transport of ketone bodies, but also in the modulation of brain energy metabolism under normal and ketogenic conditions.

The vicious circle of hypometabolism in neurodegenerative diseases: Ways and mechanisms of metabolic correction

Hypometabolism, characterized by decreased brain glucose consumption, is a common feature of many neurodegenerative diseases. Initial hypometabolic brain state, created by characteristic risk factors, may predispose the brain to acquired epilepsy and sporadic Alzheimer's and Parkinson's diseases, which are the focus of this review. Analysis of available data suggests that deficient glucose metabolism is likely a primary initiating factor for these diseases, and that resulting neuronal dysfunction further promotes the metabolic imbalance, establishing an effective positive feedback loop and a downward spiral of disease progression. Therefore, metabolic correction leading to the normalization of abnormalities in glucose metabolism may be an efficient tool to treat the neurological disorders by counteracting their primary pathological mechanisms. Published and preliminary experimental results on this approach for treating Alzheimer's disease and epilepsy models support the efficacy of metabolic correction, confirming the highly promising nature of the strategy. © 2017 Wiley Periodicals, Inc.

DEPDC5 as a potential therapeutic target for epilepsy

INTRODUCTION

Dishevelled, Egl-10 and Pleckstrin (DEP) domain-containing protein 5 (DEPDC5) is a protein subunit of the GTPase-activating proteins towards Rags 1 (GATOR1) complex. GATOR1 is a recently identified modulator of mechanistic target of rapamycin (mTOR) activity. mTOR is a key regulator of cell proliferation and metabolism; disruption of the mTOR pathway is implicated in focal epilepsy, both acquired and genetic. Tuberous sclerosis is the prototypic mTOR genetic syndrome with epilepsy, however GATOR1 gene mutations have recently been shown to cause lesional and non-lesional focal epilepsy. Areas covered: This review summarizes the mTOR pathway, including regulators and downstream effectors, emphasizing recent developments in the understanding of the complex role of the GATOR1 complex. We review the epilepsy types associated with mTOR overactivity, including tuberous sclerosis, polyhydramnios megalencephaly symptomatic epilepsy, cortical dysplasia, non-lesional focal epilepsy and post-traumatic epilepsy. Currently available mTOR inhibitors are discussed, primarily rapamycin analogs and ATP competitive mTOR inhibitors. Expert opinion: DEPDC5 is an attractive therapeutic target in focal epilepsy, as effects of DEPDC5 agonists would likely be anti-epileptogenic and more selective than currently available mTOR inhibitors. Therapeutic effects might be synergistic with certain existing dietary therapies, including the ketogenic diet.

The use of a formula-based ketogenic diet in children with refractory epilepsy

ABSTRACT The ketogenic diet (KD) is a nonpharmacologic treatment that has been used for refractory epilepsy since 1921. The KD is a high-fat, low-carbohydrate, and restricted protein diet, which is calculated and weighed for each individual patient. Introducing and maintaining the diet for a long time remains a challenge. In this study, we evaluated the acceptability, tolerance, and efficacy of a formula-based KD in 10 children with refractory epilepsy. The ketogenic formula tested herein caused only mild KD-related adverse events and adequate adherence. Moreover, 60% of patients had more than 50% seizure frequency reduction and 10% were seizure-free.

Multi-dimensional Roles of Ketone Bodies in Fuel Metabolism, Signaling, and Therapeutics

Ketone body metabolism is a central node in physiological homeostasis. In this review, we discuss how ketones serve discrete fine-tuning metabolic roles that optimize organ and organism performance in varying nutrient states and protect from inflammation and injury in multiple organ systems. Traditionally viewed as metabolic substrates enlisted only in carbohydrate restriction, observations underscore the importance of ketone bodies as vital metabolic and signaling mediators when carbohydrates are abundant. Complementing a repertoire of known therapeutic options for diseases of the nervous system, prospective roles for ketone bodies in cancer have arisen, as have intriguing protective roles in heart and liver, opening therapeutic options in obesity-related and cardiovascular disease. Controversies in ketone metabolism and signaling are discussed to reconcile classical dogma with contemporary observations.

Chronic inhibition of brain glycolysis initiates epileptogenesis

Metabolic abnormalities found in epileptogenic tissue provide considerable evidence of brain hypometabolism, while major risk factors for acquired epilepsy all share brain hypometabolism as one common outcome, suggesting that a breakdown of brain energy homeostasis may actually precede epileptogenesis. However, a causal link between deficient brain energy metabolism and epilepsy initiation has not been yet established. To address this issue we developed an in vivo model of chronic energy hypometabolism by daily intracerebroventricular (i.c.v.) injection of the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DG) and also investigated acute effects of 2-DG on the cellular level. In hippocampal slices, acute glycolysis inhibition by 2-DG (by about 35%) led to contrasting effects on the network: a downregulation of excitatory synaptic transmission together with a depolarization of neuronal resting potential and a decreased drive of inhibitory transmission. Therefore, the potential acute effect of 2-DG on network excitability depends on the balance between these opposing pre- and postsynaptic changes. In vivo, we found that chronic 2-DG i.c.v. application (estimated transient inhibition of brain glycolysis under 14%) for a period of 4 weeks induced epileptiform activity in initially healthy male rats. Our results suggest that chronic inhibition of brain energy metabolism, characteristics of the well-established risk factors of acquired epilepsy, and specifically a reduction in glucose utilization (typically observed in epileptic patients) can initiate epileptogenesis. © 2017 Wiley Periodicals, Inc.

The Role of Sirt1 in Epileptogenesis

The mechanisms by which brain insults lead to subsequent epilepsy remain unclear. Insults, including trauma, stroke, tumors, infections, and long seizures [status epilepticus (SE)], create a neuronal state of increased metabolic demand or decreased energy supply. Neurons express molecules that monitor their metabolic state, including sirtuins (Sirts). Sirtuins deacetylate cytoplasmic proteins and nuclear histones, and their epigenetic modulation of the chromatin governs the expression of many genes, influencing neuronal properties. Thus, sirtuins are poised to enduringly modulate neuronal properties following SE, potentially contributing to epileptogenesis, a hypothesis supported by the epilepsy-attenuating effects of blocking a downstream target of Sirt1, Neuron-Restrictive Silencer Factor (NRSF) also know as REST (RE1-Silencing Transcription factor). Here we used an adult male rat model of epileptogenesis provoked by kainic acid-induced SE (KA-SE). We assessed KA-SE-provoked Sirt1 activity, infused a Sirt1 inhibitor (EX-527) after KA-SE, and examined for epileptogenesis using continuous digital video-EEG. Sirt1 activity, measured using chromatin immunoprecipitation for Sirt1 binding at a target gene, increased rapidly after SE. Post hoc infusion of the Sirt1 inhibitor prevented Sirt1-mediated repression of a target gene. Blocking Sirt1 activity transiently after KA-SE did not significantly influence the time- course and all of the parameters of epilepsy development. Specifically, latency to first seizure and seizure number, duration, and severity (using the Racine scale and EEG measures) as well as the frequency and duration of interictal spike series, were all unchanged. KA-SE provoked a robust inflammatory response and modest cell loss, yet neither was altered by blocking Sirt1. In conclusion, blocking Sirt1 activity after KA-SE does not abrogate epilepsy development, suggesting that the mechanisms of such acquired epileptogenesis are independent of Sirt1 function.

Tissue Specific Impacts of a Ketogenic Diet on Mitochondrial Dynamics in the BTBRT+tf/j Mouse

The ketogenic diet (KD) has been utilized as a dietary therapeutic for nearly a century. One experimental model particularly responsive to the KD is the BTBR^T+tf/j (BTBR) mouse, which displays phenotypic characteristics of autism spectrum disorder (ASD) and insulin resistance. Recently, the study of impaired mitochondrial function has become a focal point of research investigating the pathophysiology of ASD. As highly dynamic organelles, mitochondria undergo constant fluctuations in morphology, biogenesis, and quality control in order to maintain cellular homeostasis. An important modifier of mitochondrial dynamics is energy availability. Therefore, the aim of this study was to examine the impact of a KD on mitochondrial dynamics in the liver and brain (prefrontal cortex) of the BTBR mouse model of ASD. Juvenile male C57Bl/6 (B6) and BTBR mice were age-matched to 5 weeks of age before being fed standard chow (CD, 13% kcal fat) or a KD (75% kcal fat) for 10–14 days. Analysis of brain tissue identified differences in mitochondrial gene expression but no correlation with protein levels. Unlike in the brain, KD led to decreased levels of mitochondrial proteins in the liver, despite increased gene expression. Consistent with decreased mitochondrial proteins, we also observed decreased mtDNA for all mice on the KD, demonstrating that the KD reduces the total amount of mitochondria in the liver. In order to explain the discrepancy between protein levels and gene expression, we investigated whether mitochondrial turnover via mitophagy was increased. To this end, we examined expression levels of the mitophagy regulator BNIP3 (BCL2/adenovirus E1B 19 kd-interacting protein 3). BNIP3 gene and protein expression were significantly elevated in liver of KD animals (p < 0.05), indicating the potential activation of mitophagy. Therefore, consumption of a KD exerts highly tissue-specific effects, ultimately increasing mitochondrial turnover in the liver, while gene and protein expression in the brain remaining tightly regulated.

Exogenous Ketone Supplements Reduce Anxiety-Related Behavior in Sprague-Dawley and Wistar Albino Glaxo/Rijswijk Rats

Nutritional ketosis has been proven effective for seizure disorders and other neurological disorders. The focus of this study was to determine the effects of ketone supplementation on anxiety-related behavior in Sprague-Dawley (SPD) and Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. We tested exogenous ketone supplements added to food and fed chronically for 83 days in SPD rats and administered sub-chronically for 7 days in both rat models by daily intragastric gavage bolus followed by assessment of anxiety measures on elevated plus maze (EPM). The groups included standard diet (SD) or SD + ketone supplementation. Low-dose ketone ester (LKE; 1,3-butanediol-acetoacetate diester, ~10 g/kg/day, LKE), high dose ketone ester (HKE; ~25 g/kg/day, HKE), beta-hydroxybutyrate-mineral salt (βHB-S; ~25 g/kg/day, KS) and βHB-S + medium chain triglyceride (MCT; ~25 g/kg/day, KSMCT) were used as ketone supplementation for chronic administration. To extend our results, exogenous ketone supplements were also tested sub-chronically on SPD rats (KE, KS and KSMCT; 5 g/kg/day) and on WAG/Rij rats (KE, KS and KSMCT; 2.5 g/kg/day). At the end of treatments behavioral data collection was conducted manually by a blinded observer and with a video-tracking system, after which blood βHB and glucose levels were measured. Ketone supplementation reduced anxiety on EPM as measured by less entries to closed arms (sub-chronic KE and KS: SPD rats and KSMCT: WAG/Rij rats), more time spent in open arms (sub-chronic KE: SPD and KSMCT: WAG/Rij rats; chronic KSMCT: SPD rats), more distance traveled in open arms (chronic KS and KSMCT: SPD rats) and by delayed latency to entrance to closed arms (chronic KSMCT: SPD rats), when compared to control. Our data indicates that chronic and sub-chronic ketone supplementation not only elevated blood βHB levels in both animal models, but reduced anxiety-related behavior. We conclude that ketone supplementation may represent a promising anxiolytic strategy through a novel means of inducing nutritional ketosis.

SLC6A1 Mutation and Ketogenic Diet in Epilepsy With Myoclonic-Atonic Seizures

BACKGROUND

Epilepsy with myoclonic-atonic seizures, also known as myoclonic-astatic epilepsy or Doose syndrome, has been recently linked to variants in the SLC6A1 gene. Epilepsy with myoclonic-atonic seizures is often refractory to antiepileptic drugs, and the ketogenic diet is known for treating medically intractable seizures, although the mechanism of action is largely unknown. We report a novel SLC6A1 variant in a patient with epilepsy with myoclonic-atonic seizures, analyze its effects, and suggest a mechanism of action for the ketogenic diet.

METHODS

We describe a ten-year-old girl with epilepsy with myoclonic-atonic seizures and a de novo SLC6A1 mutation who responded well to the ketogenic diet. She carried a c.491G>A mutation predicted to cause p.Cys164Tyr amino acid change, which was identified using whole exome sequencing and confirmed by Sanger sequencing. High-resolution structural modeling was used to analyze the likely effects of the mutation.

RESULTS

The SLC6A1 gene encodes a transporter that removes gamma-aminobutyric acid from the synaptic cleft. Mutations in SLC6A1 are known to disrupt the gamma-aminobutyric acid transporter protein 1, affecting gamma-aminobutyric acid levels and causing seizures. The p.Cys164Tyr variant found in our study has not been previously reported, expanding on the variants linked to epilepsy with myoclonic-atonic seizures.

CONCLUSION

A 10-year-old girl with a novel SLC6A1 mutation and epilepsy with myoclonic-atonic seizures had an excellent clinical response to the ketogenic diet. An effect of the diet on gamma-aminobutyric acid reuptake mediated by gamma-aminobutyric acid transporter protein 1 is suggested. A personalized approach to epilepsy with myoclonic-atonic seizures patients carrying SLC6A1 mutation and a relationship between epilepsy with myoclonic-atonic seizures due to SLC6A1 mutations, GABAergic drugs, and the ketogenic diet warrants further exploration.

Ketogenic diet - A novel treatment for early epileptic encephalopathy due to PIGA deficiency

We describe the presentation and workup of two brothers with early-onset epileptic encephalopathy who became seizure-free on a ketogenic diet. Extensive testing culminated in whole exome sequencing, which led to the diagnosis of phosphatidyl inositol glycan biosynthesis class A protein (PIGA) deficiency. This familial case highlights the importance of genetic testing for early-onset epileptic encephalopathies and underscores the potential value of a ketogenic diet in the treatment of this condition.