Summary:Purpose: Patients with tuberous sclerosis complex (TSC) often have severe epilepsy that is intractable to available therapies. The development of novel treatments for epilepsy in TSC would benefit greatly from a suitable animal model, but most animal models of TSC to date have few reported neurological abnormalities, such as epilepsy. We previously described a novel model of TSC, due to conditional inactivation of the Tsc1 gene in glia (Tsc1 GFAP CKO mice), in which mice develop epilepsy and premature death. Here, we characterize the natural history of the epilepsy in Tsc1 GFAP CKO mice in more detail and report acute effects of treatment with standard antiepileptic drugs on seizures in these mice.Methods: Video-EEG recordings were obtained from Tsc1 GFAP CKO mice on a weekly basis, starting at 4 weeks of age until death, to monitor progression of interictal EEG abnormalities and seizures. In separate experiments, Tsc1 GFAP CKO mice were monitored for interictal EEG abnormalities and seizures before and during treatment with phenobarbital, phenytoin, or saline. Results: Tsc1GFAP CKO mice developed seizures around 4-6 weeks of age and subsequently had progressive worsening of the interictal EEG background and seizure frequency over a month, culminating in death. Treatment with phenobarbital or phenytoin caused a reduction in seizure frequency, but did not improve EEG background or prevent death.Conclusions: Tsc1 GFAP CKO mice develop progressive epilepsy. Acute treatment with standard antiepileptic drugs suppresses seizures in these mice, but does not affect long-term prognosis. Tsc1GFAP CKO mice represent a good model to test other drugs that may have true antiepileptogenic actions in TSC.

ABSTRACT: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 ␤-hydroxybutyrate (␤HB) 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. F ew treatment options exist for the 20 -30% of epileptic children whose seizures are refractory to medication. One option is the KD, a high-fat, low-carbohydrate, and adequate protein diet. The KD is remarkably effective in children with medically refractory epilepsy as 5-10% become seizure free and 30% have a Ͼ90% reduction in seizure frequency (1). Yet, its adverse effects and the parental effort involved in implementing and maintaining the diet limit its use. Thus, all epileptic children would benefit from a simpler method of attaining the diet's anticonvulsant effects, which requires elucidating its mechanism of action.Here we focus on what the impaired weight gain associated with the KD might reveal about the diet's anticonvulsant mechanism. Several studies report that children on the KD drop about 10 percentiles in weight, although appropriate weight gain is the goal (2,3). Recognizing that lowcarbohydrate diets, such as the Atkins diet, are ketogenic makes this impaired weight gain less surprising. Indeed, the Atkins diet and other low-carbohydrate KDs result in a 5% to 10% weight loss over 6 mo (4,5). Furthermore, rodents placed on a KD show slower weight gain (6,7).We hypothesized that the anticonvulsant and weight effects of the KD share a common mechanism involving a change in the serum levels of leptin, insulin, ghrelin, or cortisol. These peripherally released hormones help determine body weight because they regulate energy homeostasis (8). Importantly, leptin and insulin also modulate neuronal excitability (9,10). METHODSDietary protocols. Experimental protocols were approved by the Washington University Animal Studies Committee. Sprague-Dawley rats (Charles River Laboratories, Wilmington, MA), male ob/ob mice (Stock 000632, The Jackson Laboratory, Bar Harbor, ME), male C57BL/6J mice (Stock 000664, The Jackson Laboratory), male db/db mice (Stock 000642, The Jackson Laboratory), and male C57BLKS/J mice (Stock 0006...

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