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Izadi A, Schedlbauer A, Ondek K, Disse G, Ekstrom AD, Cowen SL, Shahlaie K, Gurkoff GG. Early Intervention via Stimulation of the Medial Septal Nucleus Improves Cognition and Alters Markers of Epileptogenesis in Pilocarpine-Induced Epilepsy. Front Neurol 2021; 12:708957. [PMID: 34557145 PMCID: PMC8452867 DOI: 10.3389/fneur.2021.708957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/28/2021] [Indexed: 11/13/2022] Open
Abstract
Over one-third of patients with temporal lobe epilepsy are refractory to medication. In addition, anti-epileptic drugs often exacerbate cognitive comorbidities. Neuromodulation is an FDA treatment for refractory epilepsy, but patients often wait >20 years for a surgical referral for resection or neuromodulation. Using a rodent model, we test the hypothesis that 2 weeks of theta stimulation of the medial septum acutely following exposure to pilocarpine will alter the course of epileptogenesis resulting in persistent behavioral improvements. Electrodes were implanted in the medial septum, dorsal and ventral hippocampus, and the pre-frontal cortex of pilocarpine-treated rats. Rats received 30 min/day of 7.7 Hz or theta burst frequency on days 4-16 post-pilocarpine, prior to the development of spontaneous seizures. Seizure threshold, spikes, and oscillatory activity, as well as spatial and object-based learning, were assessed in the weeks following stimulation. Non-stimulated pilocarpine animals exhibited significantly decreased seizure threshold, increased spikes, and cognitive impairments as compared to vehicle controls. Furthermore, decreased ventral hippocampal power (6-10 Hz) correlated with both the development of spikes and impaired cognition. Measures of spikes, seizure threshold, and cognitive performance in both acute 7.7 Hz and theta burst stimulated animals were statistically similar to vehicle controls when tested during the chronic phase of epilepsy, weeks after stimulation was terminated. These data indicate that modulation of the septohippocampal circuit early after pilocarpine treatment alters the progression of epileptic activity, resulting in elevated seizure thresholds, fewer spikes, and improved cognitive outcome. Results from this study support that septal theta stimulation has the potential to serve in combination or as an alternative to high frequency thalamic stimulation in refractory cases and that further research into early intervention is critical.
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Affiliation(s)
- Ali Izadi
- Department of Neurological Surgery, University of California, Davis, Sacramento, CA, United States.,Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - Amber Schedlbauer
- Department of Neurological Surgery, University of California, Davis, Sacramento, CA, United States
| | - Katelynn Ondek
- Department of Neurological Surgery, University of California, Davis, Sacramento, CA, United States.,Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - Gregory Disse
- Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - Arne D Ekstrom
- Department of Psychology, University of Arizona, Tucson, AZ, United States.,McKnight Brain Institute, University of Arizona, Tucson, AZ, United States
| | - Stephen L Cowen
- Department of Psychology, University of Arizona, Tucson, AZ, United States.,McKnight Brain Institute, University of Arizona, Tucson, AZ, United States
| | - Kiarash Shahlaie
- Department of Neurological Surgery, University of California, Davis, Sacramento, CA, United States.,Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - Gene G Gurkoff
- Department of Neurological Surgery, University of California, Davis, Sacramento, CA, United States.,Center for Neuroscience, University of California, Davis, Davis, CA, United States
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Izadi A, Pevzner A, Lee DJ, Ekstrom AD, Shahlaie K, Gurkoff GG. Medial septal stimulation increases seizure threshold and improves cognition in epileptic rats. Brain Stimul 2019; 12:735-742. [PMID: 30733144 DOI: 10.1016/j.brs.2019.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 01/07/2019] [Accepted: 01/10/2019] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Temporal lobe epilepsy is most prevalent among focal epilepsies, and nearly one-third of patients are refractory to pharmacological intervention. Persistent cognitive and neurobehavioral comorbidities also occur due to the recurrent nature of seizures and medication-related side effects. HYPOTHESIS Electrical neuromodulation is an effective strategy to reduce seizures both in animal models and clinically, but its efficacy to modulate cognition remains unclear. We hypothesized that theta frequency stimulation of the medial septum would increase septohippocampal oscillations, increase seizure threshold, and improve spatial learning in a rat model of pilocarpine-induced epilepsy. METHODS Sham and pilocarpine rats were implanted with electrodes in the medial septum, hippocampus and prefrontal cortex. EEG was assessed days prior to and following stimulation. Sham and pilocarpine-treated rats received either no stimulation, continuous (throughout each behavior), or pre-task (one minute prior to each behavior) 7.7 Hz septal stimulation during the Barnes maze spatial navigation test and also during assessment of flurothyl-induced seizures. RESULTS Both continuous and pre-task stimulation prevented epilepsy-associated reductions in theta oscillations over time. Additionally, both stimulation paradigms significantly improved spatial navigation in the Barnes maze, reducing latency and improving search strategy. Moreover, stimulation led to significant increases in seizure threshold in pilocarpine-treated rats. There was no evidence of cognitive enhancement or increased seizure threshold in stimulated sham rats. CONCLUSION These findings have profound implications as theta stimulation of the septum represents a single frequency and target that has the potential to both improve cognition and reduce seizures for patients with refractory epilepsy.
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Affiliation(s)
- Ali Izadi
- Department of Neurological Surgery, University of California, Davis, USA; Center for Neuroscience, University of California, Davis, USA
| | - Aleksandr Pevzner
- Department of Neurological Surgery, University of California, Davis, USA
| | - Darrin J Lee
- Department of Neurological Surgery, University of California, Davis, USA
| | - Arne D Ekstrom
- Center for Neuroscience, University of California, Davis, USA
| | - Kiarash Shahlaie
- Department of Neurological Surgery, University of California, Davis, USA; Center for Neuroscience, University of California, Davis, USA
| | - Gene G Gurkoff
- Department of Neurological Surgery, University of California, Davis, USA; Center for Neuroscience, University of California, Davis, USA.
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Simeone TA, Matthews SA, Simeone KA. Synergistic protection against acute flurothyl-induced seizures by adjuvant treatment of the ketogenic diet with the type 2 diabetes drug pioglitazone. Epilepsia 2017; 58:1440-1450. [PMID: 28555877 DOI: 10.1111/epi.13809] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2017] [Indexed: 12/26/2022]
Abstract
OBJECTIVE We have previously found that the transcription factor peroxisome proliferator-activated receptor γ (PPARγ) contributes to the mechanism of action of the ketogenic diet (KD), an established treatment for pediatric refractory epilepsy. We have found that the KD increases brain PPARγ and that inhibition or genetic loss of PPARγ prevents the antiseizure effects of the KD on (1) acutely induced seizures in nonepileptic mice and (2) spontaneous recurrent seizures in epileptic mice. Here, we tested the hypothesis that adjuvant treatment of KD-treated mice with a PPARγ agonist, pioglitazone, would result in an additive effect. METHODS Acute seizures were induced in three groups of C57Bl/6 mice by inhalation exposure to flurothyl gas. In Group 1, mice were weaned onto either a standard diet or KD comprised of a fat:carbohydrate/protein ratio of either 6:1, 3:1, or 1:1 for 2 weeks. In Group 2, vehicle or pioglitazone (0.1, 1, 10, 80 mg/kg) was administered 4 h prior to flurothyl exposure. In Group 3, vehicle or increasing doses of pioglitazone were administered to KD-treated mice 4 h prior to flurothyl exposure. Latency times to clonic seizures and generalized tonic-clonic (GTC) seizures were recorded, and isobolographic analysis was used to determine combinatorial interactions. RESULTS Neither KD treatment nor pioglitazone alone or in combination affected clonic seizures. However, the latency to GTC seizures was dose-dependently and significantly increased by both KD (~57%, p < 0.05) and pioglitazone (~28%, p < 0.05). Coadministration of an ineffective 1:1 KD and pioglitazone resulted in ~47-55% (p < 0.05) increase in latency to GTC. Isobolographic analysis indicated a synergistic interaction of the KD and pioglitazone. SIGNIFICANCE These results suggest coadministration may enable reduction of the KD ratio without loss of seizure protection. Such adjuvant treatment could improve quality of life and limit adverse effects of a classic KD or high-dose pioglitazone.
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Affiliation(s)
- Timothy A Simeone
- Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska, U.S.A
| | - Stephanie A Matthews
- Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska, U.S.A
| | - Kristina A Simeone
- Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska, U.S.A
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Simeone TA, Matthews SA, Samson KK, Simeone KA. Regulation of brain PPARgamma2 contributes to ketogenic diet anti-seizure efficacy. Exp Neurol 2016; 287:54-64. [PMID: 27527983 DOI: 10.1016/j.expneurol.2016.08.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 08/05/2016] [Accepted: 08/11/2016] [Indexed: 12/23/2022]
Abstract
The ketogenic diet (KD) is an effective therapy primarily used in pediatric patients whom are refractory to current anti-seizure medications. The mechanism of the KD is not completely understood, but is thought to involve anti-inflammatory and anti-oxidant processes. The nutritionally-regulated transcription factor peroxisome proliferator activated receptor gamma, PPARγ, regulates genes involved in anti-inflammatory and anti-oxidant pathways. Moreover, endogenous ligands of PPARγ include fatty acids suggesting a potential role in the effects of the KD. Here, we tested the hypothesis that PPARγ contributes to the anti-seizure efficacy of the KD. We found that the KD increased nuclear protein content of the PPARγ2 splice variant by 2-4 fold (P<0.05) in brain homogenates from wild-type (WT) and epileptic Kv1.1 knockout (KO) mice, while not affecting PPARγ1. The KD reduced the frequency of seizures in Kv1.1KO mice by ~70% (P<0.01). GW9662, a PPARγ antagonist, prevented KD-mediated changes in PPARγ2 expression and prevented the anti-seizure efficacy of the KD in Kv1.1KO mice. Further supporting the association of PPARγ2 in mediating KD actions, the KD significantly prolonged the latency to flurothyl-induced seizure in WT mice by ~20-35% (P<0.01), but was ineffective in PPARγ2KO mice and neuron-specific PPARγKO mice. Finally, administering the PPARγ agonist pioglitazone increased PPARγ2 expression by 2-fold (P<0.01) and reduced seizures in Kv1.1KO mice by ~80% (P<0.01). Our findings implicate brain PPARγ2 among the mechanisms by which the KD reduces seizures and strongly support the development of PPARγ2 as a therapeutic target for severe, refractory epilepsy.
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Affiliation(s)
- Timothy A Simeone
- Creighton University, School of Medicine, Department of Pharmacology, Omaha, NE 68174, USA.
| | - Stephanie A Matthews
- Creighton University, School of Medicine, Department of Pharmacology, Omaha, NE 68174, USA
| | - Kaeli K Samson
- Creighton University, School of Medicine, Department of Pharmacology, Omaha, NE 68174, USA
| | - Kristina A Simeone
- Creighton University, School of Medicine, Department of Pharmacology, Omaha, NE 68174, USA
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Hashimoto Y, Araki H, Suemaru K, Gomita Y. Effects of drugs acting on the GABA-benzodiazepine receptor complex on flurothyl-induced seizures in Mongolian gerbils. Eur J Pharmacol 2006; 536:241-7. [PMID: 16581068 DOI: 10.1016/j.ejphar.2006.02.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 02/15/2006] [Accepted: 02/21/2006] [Indexed: 11/19/2022]
Abstract
In the present study, the mechanism behind flurothyl-induced seizures was examined using drugs acting on the GABA-benzodiazepine receptor complex in Mongolian gerbils. In addition, amino acid concentrations in the brain were also investigated. In behavioral experiments, the incidence of tonic extensor was 83.3% in both the control and picrotoxin (0.5 mg/kg)-treated groups, 0% in the valproate (200 mg/kg)-treated group, and 50% in the picrotoxin plus valproate-treated group. However, picrotoxin did not antagonize the effect of valproate on clonic seizure latency at all. Flumazenil, a benzodiazepine receptor antagonist, was found to have an inhibitory effect on the anticonvulsant action of diazepam (0.5 mg/kg). The incidence of tonic extensor was 83.3% in flumazenil (10 mg/kg)-treated group, 0% in the diazepam (0.5 mg/kg)-treated group, and 83% in the flumazenil plus diazepam-treated group as well as the control group. Flumazenil also completely reversed the effect of diazepam on clonic seizure latency. In biochemical experiments, the concentration of the inhibitory amino acid, GABA, was significantly increased in the hippocampus (P<0.05) and cerebellum (P<0.01) in diazepam-treated animals. The increase of GABA in the hippocampus and cerebellum was antagonized by the administration of flumazenil. These results suggested that the anticonvulsant action of diazepam may be linked to increase in hippocampus and cerebellum GABA concentrations. The findings suggest that the mechanism of flurothyl-induced seizures, in part, is related to the highly sensitive benzodiazepine site of the GABA-benzodiazepine receptor complex.
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Affiliation(s)
- Yasuhiko Hashimoto
- Department of Hospital Pharmacy, Okayama University Medical School, 2-5-1, Shikata-cho, Okayama 700-8558, Japan.
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