Kainic acid-induced substantia nigra seizure in rats: behavior, EEG and metabolism

Rationale: In order to clarify the role of substantia nigra pars reticulata (SNr) upon the development of epileptic seizure, kainic acid (KA) was inje cted into a unilateral SNr. Materials and methods: Wistar rats weighing 250 -350 g were used. A stainless-steel cannula and depth electrode were insert ed stereotaxically into the left substantia nigra pars reticulata (SNr). At 7 days after surgery, 1.0 pg of KA was injected into the left SNr. Experim ent 1: In eight rats, behavior and electroencephalograms (EEG) were continu ously recorded for about 30 h, and intermittently monitored following I mon th. Experiment 2: Two hours after KA injection into SNr, rats demonstrated status epilepticus. Then, 100 mu Ci/kg of [C-14]2-deoxyglucose (2-DG) was i ntravenously injected in seven rats, and the rats were processed for autora diographic study. Results: Changes in behavior and EEG: On EEG, a secondary generalized seizure status was observed at about 70 min after KA injection . In video, limbic seizure manifestations such as salivation were observed as a initial symptom and followed by rolling and generalized tonic seizures , [C-14] deoxyglucose autoradiographic study demonstrated increased local c erebral glucose metabolism in the medial and lateral septal nucleus, substa ntia nigra, hippocampus, parietal cortex, pirifonn cortex, medial and later al geniculate nucleus, anterodorsal, lateral and ventral nucleus of the tha lamus, amygdala and midbrain reticular formation. Summary: The result sugge sted that the substantia nigra played an important role in the secondary ge neralization in the substantia nigra. seizure model due to the decreased fu nction of the GABAergic projection system induced by an excessive epileptic excitation of SNr. (C) 2001 Elsevier Science B.V. All rights reserved.