Corneal Kindling Seizure Test (mouse)
The pharmacological profile of the corneal kindled mouse is consistent with human focal seizures and effectively identifies the anticonvulsant potential of useful compounds for this condition, such as levetiracetam. Five- to six-week-old male C57BL/6 or CF-1 mice are kindled electrically via corneal electrodes to a criterion of 5 consecutive Stage 5 seizures (facial clonus and head nodding progressing to forelimb clonus, and finally rearing and falling accompanied by a generalized clonic seizure). C57BL/6 mice are kindled by a 1.5 mA, 60 Hz, 3 sec stimulation, whereas CF-1 mice are kindled by a 3 mA, 60 Hz, 3 sec stimulation. Prior to each stimulation corneas are treated with 0.5% tetracaine hydrochloride for local anesthesia and 0.9% saline to improve electrical conductivity. After receiving twice daily corneal stimulations, mice typically reach the first Stage 5 seizure between approximately 10-15 days. Twice daily stimulations continue for each mouse until that mouse has achieved the criterion of 5 consecutive stage 5 seizures, whereby it is considered “fully kindled”. Fully kindled mice are then stimulated every-other day until all other mice within the group reach the criterion of 5 consecutive Stage 5 seizures. Any mouse not achieving the fully kindled state is not included in any evaluation of investigational compounds.
Testing of investigational compounds commences at least 7 days after the last stimulation. Mice are stimulated on the day prior to any drug evaluation to ensure that all mice to be used in the drug study will present with a Stage 5 seizure. On the day of testing, mice are randomly assigned to groups and mice displaying a seizure score < 3 are considered protected. For identification studies, the test compound is administered to a group of 4 fully kindled mice per group at the time of peak effect (TPE) and ED50 determined in initial screening in acute models (MES and 6 HZ models). If a TPE was not determined in either of those models, then qualification studies are performed at three doses and two timepoints based on the available information about the drug. Quantification studies may also then be performed at the TPE for compounds found effective in the initial screen. At least 3 doses, sufficient to produce between 0% - 100% protection are evaluated in groups of 8 fully kindled mice. After testing, the corneal kindled animals are returned to their home cage and each corneal kindled mouse is allowed at least 3-4 days between tests to “washout” any investigational compound after testing.