Differential Effects of Acute and Repeated Electrically and Chemically Induced Seizures on [H]Nimodipine and [125I]Omega-Conotoxin GVIA Binding in Rat Brain

[3H]Nimodipine and high-affinity [125I]omega-conotoxin GVIA (CgTX) binding were investigated in membranes from rat cerebral cortex, cerebellum, and hippocampus after electrically and chemically induced seizures. Animals were decapitated 30 min after a single electroconvulsive shock (ECS) or lidocaine-induced seizure and 24 h after the last of 10 once-daily ECS or six once-daily lidocaine-induced seizures. After a single ECS, [3H]nimodipine and [125I]CgTX binding sites decreased in cerebral cortex (by 10% and 17%, respectively). A downregulation of [3H]nimodipine binding sites in hippocampus occurred after single and repeated lidocaine-induced seizures (by 24% and 11%, respectively), whereas [125I]CgTX binding remained unaltered. An earlier report on changes in [3H]nitrendipine binding after chronic ECS in cortex and hippocampus was not confirmed.