EXPERIMENTAL SEIZURES IN THE FROG (RANA-PIPIENS)

We investigated the effects of chemical convulsants in the leopard fro g. Systemic kainic acid (5-20 mg/kg) caused limbic-like seizures, with staring, catatonia, fasciculations, and severe motor seizures, which were almost always lethal. Intracerebral electroencephalographic (EEG) recordings showed spike or spike-and-wave patterns at 6-8 Hz that dec reased in frequency and increased in amplitude, maximal at an electrod e in the midline olfactory/telencephalic (OLF-M) region. With time, an interictal pattern of 100-200 mu V periodic spikes developed, followe d by diffuse suppression of all brain activity. Seizures induced by pe ntylenetetrazole (150-450 mg/kg) and bicuculline (5-10 mg/kg) were cha racterized by the abrupt onset of motor activity, which continued inte rmittently for several hours, followed by recovery. EEG recordings in animals treated with pentylenetetrazole showed rhythmic spike-and-wave bursts at 1.5-3 Hz that were maximal at OLF-M. Recordings from frogs treated with bicuculline showed repetitive 3-6 Hz spike-and-wave disch arges maximal at OLF-M that were nearly constant in amplitude and at t imes became continuous. Strychnine (1-5 mg/kg) caused reversible seizu res characterized by tonic extensions of the extremities, that seemed to originate in the spinal cord. Frogs with recurrent seizures from sy stemic cis-diamminedichloroplatinum II showed 4-8 Hz rhythmic spike-an d-wave activity that gradually slowed in frequency and increased in am plitude. Thus, the frog's reactivity to convulsive agents is similar t o that of mammals.