Biology subjects

Barker-Haliski, M.

Publications and source records attributed to Barker-Haliski, M..

2 recordsLinked to original sources

bioRxiv2021

Continuous Seizure Emergency Evoked in Mice with Pharmacological, Electrographic, and Pathological Features Distinct from Status Epilepticus

ObjectivesBenzodiazepines are the standard of care for the management of sustained seizure emergencies, including status epilepticus (SE) and seizure clusters. Seizure clusters are a variably defined seizure emergency wherein a patient has multiple seizures above a baseline rate, with intervening periods of recovery, distinguishing clusters from SE. While phenotypically distinct, the precise pathophysiological and mechanistic differences between SE and seizure clusters are under studied. Preclinical interrogation is needed to help uncover the behavioral, physiological, and pathological mechanisms associated with seizure emergencies in order to better manage these events in the susceptible individual. MethodsHerein, we characterize a novel model of sustained seizure emergency induced in CF-1 mice through the combined administration of high-dose phenytoin (PHT; 50 mg/kg, i.p.) and pentylenetetrazol (PTZ; 100 mg/kg, s.c.). ResultsIn the present manuscript we describe a mouse model of sustained seizure emergency that is physiologically, pharmacologically, and histologically distinct from SE. Acute administration of PHT 1 hour prior to s.c.PTZ led to significantly more mice with continuous seizure activity (CSA; 73.4%) versus vehicle-pretreated mice (13.8%; p<0.0001). CSA was sensitive to lorazepam and valproic acid when administered at seizure onset, as well as 30-minutes post-seizure onset. Carbamazepine worsened seizure control and post-CSA survival. Mice in CSA exhibited EEG patterns distinct from kainic acid-induced SE and s.c.PTZ alone, clearly differentiating CSA from SE and s.c.PTZ-induced myoclonic seizures. Neuropathological assessment by FluoroJade-C staining of brains collected 24-hours later revealed no neurodegeneration in any mice with CSA, whereas there was widespread neuronal death in brains from KA-SE mice. SignificanceThis study defines a novel mouse model on which to elucidate the mechanistic differences between sustained seizure emergencies (i.e. SE and seizure clusters) to improve discovery of effective clinical interventions and define mechanisms of seizure termination. Key Points BoxO_LISeizure clusters are a variably defined seizure emergency that is sensitive to benzodiazepines, distinct from status epilepticus. C_LIO_LIThe mechanistic differences between seizure clusters and status epilepticus are not well defined. C_LIO_LIWe report a mouse seizure emergency model that is phenotypically, pathologically, and pharmacologically distinct from status epilepticus. C_LIO_LIThis mouse model provides a novel platform on which to further interrogate the mechanisms underlying seizure emergencies. C_LI

neuroscience↗

bioRxiv2020

Development of an Antiepileptogenesis Drug Screening Platform: Effects of Everolimus and Phenobarbital

ObjectiveThe kainic acid (KA)-induced status epilepticus (SE) model in rats is an etiologically-relevant animal model of epileptogenesis. Just as in patients, who develop temporal lobe epilepsy (TLE) following SE, this rat model of KA-induced SE very closely recapitulates many of the clinical and pathological characteristics of human TLE that arise following SE or another neurological insult. Spontaneous recurrent seizures (SRS) in TLE can present after a latent period following a neurological insult (TBI, SE event, viral infection, etc.). Moreover, this rat model of TLE is ideally suited for preclinical studies to evaluate the long-term process of epileptogenesis and screen putative disease-modifying/antiepileptogenic agents. This report details the pharmacological characterization and methodological refinement of a moderate-throughput drug screening program using the post KA-induced SE model of epileptogenesis in male Sprague Dawley rats to identify potential agents that may prevent or modify the onset or severity of SRS. Specifically, we sought to demonstrate whether our protocol could prevent the development of SRS, or lead to a reduced frequency/severity of SRS. MethodsRats were administered everolimus (2-3 mg/kg, P.O. commencing at 1, 2, or 24-hrs after SE onset) or phenobarbital (60 mg/kg, beginning 1 hr after SE onset). The rats in all studies (n=12/treatment dose/study) were then followed intermittently by video-EEG monitoring; i.e., 2-weeks on/2-weeks off, 2-weeks on epochs to determine latency to onset of SRS, and disease burden following SRS onset. ResultsWhile there were no adverse side effects observed in any of our studies, no treatment conferred a significant disease modifying effect, nor did any agent prevent the presentation of SRS by 6 weeks post-SE onset. ConclusionsWhile neither phenobarbital nor everolimus administered at several time points post-SE onset prevented the development of SRS, we herein demonstrate a moderate-throughput screen for potential antiepileptogenic agents in an etiologically-relevant rodent model of TLE. Key PointsO_LIDisease-modifying therapies are needed to prevent or attenuate the burden of epilepsy in at-risk individuals. C_LIO_LIWe report a moderate-throughput screening protocol to identify disease-modifying agents in a rat post-kainic acid status epilepticus model. C_LIO_LIEverolimus was administered at multiple time points post-status epilepticus with no effect on spontaneous seizures up to 6 weeks later. C_LIO_LIRepeated administration of phenobarbital also did not prevent the development of spontaneous recurrent seizures up to 6 weeks post SE. C_LIO_LIWhile we did not identify any effect of either agent, our approach provides a moderate-throughput screen for antiepileptogenesis. C_LI

neuroscience↗