Summary:Purpose: Caloric restriction (CR) involves underfeeding and has long been recognized as a dietary therapy that improves health and increases longevity. In contrast to severe fasting or starvation, CR reduces total food intake without causing nutritional deficiencies. Although fasting has been recognized as an effective antiseizure therapy since the time of the ancient Greeks, the mechanism by which fasting inhibits seizures remains obscure. The influence of CR on seizure susceptibility was investigated at both juvenile (30 days) and adult (70 days) ages in the EL mouse, a genetic model of multifactorial idiopathic epilepsy.Methods: The juvenile EL mice were separated into two groups and fed standard lab chow either ad libitum (control, n ‫ס‬ 18) or with a 15% CR diet (treated, n ‫ס‬ 17). The adult EL mice were separated into three groups; control (n ‫ס‬ 15), 15% CR (n ‫ס‬ 6), and 30% CR (n ‫ס‬ 3). Body weights, seizure susceptibility, and the levels of blood glucose and ketones (␤-hydroxybutyrate) were measured over a 10-week treatment period. Simple linear regression and multiple logistic regression were used to analyze the relations among seizures, glucose, and ketones.Results: CR delayed the onset and reduced the incidence of seizures at both juvenile and adult ages and was devoid of adverse side effects. Furthermore, mild CR (15%) had a greater antiepileptogenic effect than the well-established high-fat ketogenic diet in the juvenile mice. The CR-induced changes in blood glucose levels were predictive of both blood ketone levels and seizure susceptibility.Conclusions: We propose that CR may reduce seizure susceptibility in EL mice by reducing brain glycolytic energy. Our preclinical findings suggest that CR may be an effective antiseizure dietary therapy for human seizure disorders.

Brain cells are metabolically flexible because they can derive energy from both glucose and ketone bodies (acetoacetate and b-hydroxybutyrate). Metabolic control theory applies principles of bioenergetics and genome flexibility to the management of complex phenotypic traits. Epilepsy is a complex brain disorder involving excessive, synchronous, abnormal electrical firing patterns of neurons. We propose that many epilepsies with varied etiologies may ultimately involve disruptions of brain energy homeostasis and are potentially manageable through principles of metabolic control theory. This control involves moderate shifts in the availability of brain energy metabolites (glucose and ketone bodies) that alter energy metabolism through glycolysis and the tricarboxylic acid cycle, respectively. These shifts produce adjustments in gene-linked metabolic networks that manage or control the seizure disorder despite the continued presence of the inherited or acquired factors responsible for the epilepsy. This hypothesis is supported by information on the management of seizures with diets including fasting, the ketogenic diet and caloric restriction. A better understanding of the compensatory genetic and neurochemical networks of brain energy metabolism may produce novel antiepileptic therapies that are more effective and biologically friendly than those currently available.

Summary:Purpose: The epileptic EL mouse has been studied extensively as a model of multifactorial epilepsy. Although EL mice have a seizure occasionally during routine handling associated with cage changing, most studies have used vigorous tossing or shaking procedures for seizure induction. A new seizure testing procedure was developed that involved gentle handling and simulated situations associated with emotional stress in rodents. This new testing procedure was used to identify and characterize several environmental risk factors that influence seizure predisposition in EL mice.Methods: Ten adult EL mice were monitored for 7 days under 24-h light/dark video surveillance to assess the frequency of spontaneous seizures. The development of handling-induced seizures also was studied in EL mice, in nonepileptic ABP and DDY mice, and in reciprocal ABP x EL F, hybrids from ages 30-1 80 days.Results; Seizure induction was necessary in EL mice, as spontaneous clinical seizures were not observed. Handlinginduced seizure susceptibility was strongly age and gender dependent in naive EL mice (not previously handled) and peaked -90 days, with males significantly more susceptible than females. No seizures were induced by handling in the nonepileptic mouse strains (ABP and DDY) over the testing period. Handling and seizures at young ages in EL and EL x ABP F, hybrid mice significantly enhanced their seizure susceptibility when they were tested again 1 month later. A significant "Gowers effect" was seen also in EL mice. Furthermore, susceptibility was higher in ABP x EL F, hybrids than in their reciprocal EL x ABP F, hybrids at 90-150 days.Conclusions: Seizure susceptibility in EL mice was significantly influenced by a number of environmental factors including age, gender, maternal/paternal effects, prior handling, and seizure history. The emotional stresdfear response is the likely trigger for seizure induction in EL mice. An early life experience stress-diathesis model, similar to that proposed for major depression in humans, was applicable to the development of seizure susceptibility in EL mice. The new seizure test will be useful for defining gene+nvironment interactions and in identifying susceptibility genes for multifactorial epilepsy.

Summary: Purpose: The ketogenic diet (KD) is a high-fat, low-carbohydratc and -protein diet that has been used to treat refractory seizures in children for more than 75 years. However, little is known about how the KD inhibits seizures or its el'fects on epilcptogcnesis. Several animal models of epilepsy have responded favorably to KD treatment, but the KD has not been studied in animals with a genetic predisposition to seizures. Here we studied the antiepileptogenic effect of the KD in EL mice, an animal model for human idiopathic epilepsy.M&ods: Young male EL mice (postnatal day 30) were randomly separated into two groups fed ad libitum with either the KD (treated, n = 21) or Agway chow (control, n = 19). The mice werc wcighcd and tested for seizures once per week for a total of 10 weeks. The effects of the KD on plasma levels of ketone bodies and glucose were analyzed at several time points throughout the study. Associative learning was compared between treated and control animals using a water maze.Results: KD treatment delayed seizure onset in young male EL mice by 1 month; however, seizure protection was transient, inasmuch as the treated and control mice experienced a similar number and intensity of seizures after 6 wccks on the diet. Plasma glucose levels and associativc learning were similar in the treated and control groups, but the plasma P-hydroxybutyrate levels were significantly highcr in mice on the KD. The level of ketosis, however, was not predictive of seizure protection in EL mice.Conclusion: The KD delayed seizure onset in EL mice, suggesting a transient protection against epileptogcnesis. The KD did not influence plasma glucose levels or learning. Therefore, the EL mousc may serve as a good model to study the antiepileptogenic mechanisms of the KD.

The influence of local circuit interneurons is thought to play an important role in adjusting synaptic strength via endogenous cannabinoid type 1 (CB1) receptors. Using paired whole-cell recordings, combined with double immunofluorescence and biocytin labelling in acute slices of rat CA1 at postnatal day 18-23, we investigated the properties of Cholecystokinin (CCK)-positive stratum radiatum local circuit interneuron connections that utilised CB1 receptors. Three types of synaptic connections were studied, lacunosum-moleculare-radiatum perforant path-associated (LM-R PPA) to Shaffer collateral-associated (SCA) interneurons, SCA-SCA interneurons and SCA-pyramidal cells. These three synapses were differentially under tonic reduction of inhibition that was blocked by the CB1 receptor inverse agonist AM-251 (10 lm), which enhanced IPSPs. The strength of tonic reduction of inhibition was correlated with asynchronous release which was apparent at connections among interneurons. AM-251 increased the ratio of synchronous to asynchronous release (synchronicity ratio), while the CB receptor agonist anandamide (14 lm) decreased the synchronicity ratio. Fast and slow calcium chelators (BAPTA-AM and EGTA-AM) also increased the synchronicity ratio, accelerated inhibitory time courses and reduced IPSP amplitudes. These data suggest that CB1 receptors at connections among interneuron synapses play a role in tonic suppression of inhibition and govern the asynchronous release of GABA, modulating the time windows of inhibition. Effects of calcium chelators suggest that asynchronous release is a result of a long-lasting presynaptic calcium transients and ⁄ or a large distance between calcium source and sensor of exocytosis. These properties of specialised inhibitory neurons may have important modulatory roles in controlling spike timing among local circuit interneurons.