Kainic acid-induced substantia nigra seizure in rats: behavior, EEG and metabolism.
BACKGROUND
In order to clarify the role of substantia nigra pars reticulata (SNr) upon the development of epileptic seizure, kainic acid (KA) was injected into a unilateral SNr.


METHODS
Wistar rats weighing 250-350 g were used. A stainless-steel cannula and depth electrode were inserted stereotaxically into the left substantia nigra pars reticulata (SNr). At 7 days after surgery, 1.0 microg of KA was injected into the left SNr. Experiment 1: In eight rats, behavior and electroencephalograms (EEG) were continuously recorded for about 30 h, and intermittently monitored following 1 month. Experiment 2: Two hours after KA injection into SNr, rats demonstrated status epilepticus. Then, 100 microCi/kg of [(14)C]2-deoxyglucose (2-DG) was intravenously injected in seven rats, and the rats were processed for autoradiographic 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. [(14)C]deoxyglucose autoradiographic study demonstrated increased local cerebral glucose metabolism in the medial and lateral septal nucleus, substantia nigra, hippocampus, parietal cortex, piriform cortex, medial and lateral geniculate nucleus, anterodorsal, lateral and ventral nucleus of the thalamus, amygdala and midbrain reticular formation.


CONCLUSIONS
The result suggested that the substantia nigra played an important role in the secondary generalization in the substantia nigra seizure model due to the decreased function of the GABAergic projection system induced by an excessive epileptic excitation of SNr.
Sawamura
A
A
Department of Neurosurgery, Asahikawa Medical College, 2-1, Midorigaoka-Higashi, Asahikawa 078-8510, Japan. tanakat@asahikawa-med.ac.jp
Hashizume
K
K
Yoshida
K
K
Tanaka
T
T
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004569:Electroencephalography / Q000187:drug effects*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D004827:Epilepsy / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D007608:Kainic Acid / Q000494:pharmacology; D009410:Nerve Degeneration / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013378:Substantia Nigra / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*
D002250:Carbon Radioisotopes; D018690:Excitatory Amino Acid Agonists; D003847:Deoxyglucose; D005947:Glucose; D007608:Kainic Acid