Intra-Amygdala Kainate Model (mouse)

The intra-amygdala kainate (IAK) microinjection mouse model of mesial temporal lobe epilepsy (MTLE) recapitulates many of the features of human MTLE including injury patterns in the hippocampus. Microinjection of the chemoconvulsant kainic acid (KA) into unilateral amygdala induces a prolong status epilepticus, following which the majority of mice develop spontaneous recurrent seizures with relatively stable average frequency after a short latent period. These features make this model well suited for screening novel therapies to treat pharmacoresistant epilepsy.

Experiments are performed on C57BL/6 male mice from Jackson Laboratories. Four to five-week-old mice are implanted under isoflurane anesthesia (2-5% in O2) with a 22-gauge guide cannula over the dura matter (from Bregma: AP = -1.2 mm; ML = +3.3 mm) to deliver KA into the right basolateral amygdala, a Teflon insulated platinum iridium electrode (Plastics One Inc) in the right dorsal CA1 area of the hippocampus (from Bregma: AP = -2.3 mm; ML = 2.5 mm; DV = -1.8 mm) to record EEG, and a reference EEG electrode over the right hemisphere cerebellum. Animals are given buprenorphine for the treatment of pain 1 hour before surgery and a single dose of penicillin (60,000 units s.c.) after the surgery to prevent any infection. Mice are allowed to recover in their individual home cages for ≥ 3 days before the next experiment.

To inject KA, an injection cannula (Plastics One Inc) connected to a syringe pump is inserted into the guide cannula and slowly lowered into the basolateral amygdala at a depth of 3.7 mm below the dura and 0.39 µg of KA dissolved in 0.26 µL 0.9% saline is delivered at a rate of 50 nL/second. The injection cannula is left in place for an additional 2 minutes after KA microinjection to allow diffusion into the brain tissue and minimize movement of KA up the cannula track. The mice are continuously monitored by time synchronized video and EEG and status epilepticus (SE), as defined by continuous EEG spikes >1 Hz and concomitant stage 3-5 seizures, typically begins 10-30 minutes after KA injection. Forty minutes after the SE is confirmed, mice are detached from their tethered EEG cables, given lactated ringers, and returned to their individual home cages.

To evaluate the efficacy of an investigational drug/therapy to prevent development of epilepsy, the treatment will be initiated after the induction of SE (precipitating event) and before the appearance of spontaneous recurrent seizures (SRS). The primary outcome measured once the treatment is terminated will be occurrence/absence of SRS, but the effect on seizure frequency and sensitivity of SRS to drugs that failed to treat it in prior trials may also be examined. To determine the efficacy of a test drug/therapy to modify the disease, the treatment will be initiated after the appearance of SRS and the outcomes measured following washout period will be the same as described above for the disease prevention paradigm. The exact treatment regimen (the time of the initiation and frequency and duration of the treatment) will be based on various factors such as the effective dose identified in prior studies, pharmacokinetics and mechanism of action, and may vary between the treatments.