Use of the ketogenic diet as a treatment for epilepsy refractory to drug treatment

Intracisternal administration of glibenclamide or 5-hydroxydecanoate does not reverse the neuroprotective effect of ketogenic diet against ischemic brain injury-induced neurodegeneration

PRIMARY OBJECTIVE

To investigate the role of ATP-sensitive potassium (K(ATP)) channels in the neuroprotective effects of a ketogenic diet against cardiac arrest-induced cerebral ischemic brain injury-induced neurodegeneration.

RESEARCH DESIGN

Male Sprague Dawley rats were randomly divided into three groups and were fed with a ketogenic diet for 25 days before being subjected to a cardiac arrest-induced cerebral ischemia for 8 minutes 30 seconds. Four hours before cardiac arrest-induced cerebral ischemia, one group was intracisternally injected with glibenclamide, a plasma membrane K(ATP) channel blocker. The second group was injected with 5-hydroxydecanoate, a mitochondrial K(ATP) channel blocker. The third group was without the pre-treatment with K(ATP) channel antagonist. Nine days after the cardiac arrest, rats were sacrificed. Fluoro-jade (FJ) staining was used to evaluate cerebral ischemic neurodegeneration in the rat brain sections.

MAIN OUTCOMES AND RESULTS

The number of FJ-positive degenerating neurons in the CA1 area of the hippocampus, the cerebellum and the thalamic reticular nucleus of the ketogenic diet-fed rats with or without glibenclamide or 5-hydroxydecanoate pre-treatment before cardiac arrest-induced cerebral ischemia is zero.

CONCLUSIONS

The results suggest that K(ATP) channels do not play a significant role in the neuroprotective effects of the ketogenic diet against cardiac arrest-induced cerebral ischemic injury-induced neurodegeneration.

Anticonvulsant effects of leptin in epilepsy

Secreted from adipose tissue at levels proportional to fat stores, the hormone leptin is a critical regulator of the hypothalamic machinery that controls feeding and energy metabolism. Despite the critical role of leptin in the maintenance of energy homeostasis, no leptin-based therapeutic approaches have emerged to combat metabolic disorders such as obesity or diabetes. In this issue of the JCI, Xu et al. report a robust influence of leptin, beyond its role in metabolism, on hippocampal neuronal processes implicated in the etiology of epileptic seizures, learning, and memory (see the related article beginning on page 272). They show, in two rodent seizure models, that leptin administered directly to the brain or nasal epithelium suppresses seizures via direct effects on glutamate neurotransmission in the hippocampus. These observations suggest that leptin may have therapeutic potential in the treatment of epilepsy and strengthen the notion that peripheral metabolic hormones such as leptin play important roles in the regulation of higher brain functions.

Ketogenic diet prevents seizure and reduces myoclonic jerks in rats with cardiac arrest-induced cerebral hypoxia

Although the mechanism underlying the anti-epileptic effects of a ketogenic diet (KD) is not known, KD is reported to be an effective treatment for intractable epilepsy, in particular among children. Here, we evaluated whether a KD can reduce posthypoxic seizure and myoclonic jerks in a rat model of cardiac arrest-induced cerebral hypoxia. In this study, rats were divided into two groups: one group received a normal diet while the other group was fed a KD for 25 days before being subjected to cardiac arrest-induced cerebral hypoxia. We found that rats fed a normal diet developed seizures and severe myoclonic jerks in response to auditory stimuli after the hypoxic insults, whereas the rats on the KD did not develop seizure and showed much less severe myoclonic jerks in response to auditory stimuli. The results suggested that the KD has beneficial effects against posthypoxic seizure and myoclonus.

Leptin contributes to slower weight gain in juvenile rodents on a ketogenic diet

The ketogenic diet (KD) is an efficacious therapy for medically refractory childhood epilepsy that also slows weight gain. We tested the hypothesis that the KD slows weight gain via neurohormones involved in energy homeostasis. We found that juvenile rodents fed a KD had slower weight gain than those fed a standard diet (SD). Rats fed a KD had higher serum leptin levels and lower insulin levels compared with those fed an SD. We investigated the increase in leptin further because this change was the only one consistent with slower weight gain. Although rats fed the SD experienced slower weight gain when calorie restricted, they had serum leptin levels similar to those fed the SD ad libitum. Furthermore, leptin deficient (ob/ob) and leptin receptor deficient (db/db) mice did not show slower weight gain on the KD. All animals on the KD had elevated serum beta-hydroxybutyrate (betaHB) levels. Thus, ketosis is insufficient and a functioning leptin signaling system appears necessary for the KD to slow weight gain. The increase in leptin may contribute to the anticonvulsant effects of the KD.