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Lamotrigine‐resistant corneal‐kindled mice: A model of pharmacoresistant partial epilepsy for moderate‐throughput drug discovery
Author(s) -
Koneval Zachery,
Knox Kevin M.,
White H. Steve,
BarkerHaliski Melissa
Publication year - 2018
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.14190
Subject(s) - lamotrigine , epilepsy , kindling model , kindling , epileptogenesis , pharmacology , medicine , anticonvulsant , carbamazepine , phenytoin , valproic acid , pentylenetetrazol , seizure threshold , anesthesia , psychiatry
Summary Objective Despite numerous treatments for epilepsy, over 30% of patients remain resistant to available antiseizure drugs ( ASD s). Thus, there is a strong need for more effective ASD s for these individuals. Early ASD discovery has historically relied on acute in vivo seizure models (maximal electroshock, subcutaneous pentylenetetrazol, 6 Hz), which lack the pathophysiology that defines chronic epilepsy. Etiologically relevant rodent models of pharmacoresistant epilepsy exist (eg, phenytoin ( PHT )‐ and lamotrigine ( LTG )‐resistant amygdala‐kindled rat and focal kainic acid mouse), but these models are resource‐ and labor‐intensive and thus unsuitable for frontline ASD discovery. Methods We adapted the LTG ‐resistant amygdala‐kindled rat protocol to the 60 Hz corneal‐kindled mouse ( CKM ) to develop a medium‐throughput model of pharmacoresistant chronic seizures. Male CF ‐1 mice were administered either vehicle ( VEH ; 0.5% methylcellulose) or LTG (8.5 mg/kg, ip) 30 minutes prior to each twice‐daily corneal stimulation until mice achieved kindling criterion. Prototype ASD s were then evaluated in fully kindled mice. Compounds with specific mechanisms of action of interest to epilepsy (fluoxetine, minocycline, and celecoxib) were also evaluated. Results LTG did not modify kindling acquisition. A challenge dose of 17 mg/kg (ip) LTG did not block the secondarily generalized kindled seizure in LTG ‐kindled mice (mean seizure score [ MSS ] ± standard error of the mean: 5.67 ± 0.14), whereas VEH ‐treated mice were sensitive ( MSS : 2.25 ± 0.30); confirming LTG ‐resistance. LTG ‐resistant CKM were also resistant to carbamazepine, retigabine, and valproic acid at doses that significantly reduced MSS in VEH ‐treated kindled mice. Fluoxetine, minocycline, and celecoxib were ineffective at the doses tested in either kindled cohort. Finally, the behavioral phenotype of LTG ‐resistant CKM was also characterized. CKM demonstrated exacerbated hyperexcitability and increased anxiety‐like behavior in an open field relative to sham‐kindled mice regardless of LTG sensitivity. Significance The pharmacoresistant LTG ‐resistant CKM provides an etiologically relevant moderate‐throughput platform that is suitable for early compound discovery before advancing to more resource‐intensive models of epilepsy.