AMYGDALA-KINDLED AND ELECTROCONVULSIVE SEIZURES ALTER HIPPOCAMPAL EXPRESSION OF THE M1 AND M3 MUSCARINIC CHOLINERGIC RECEPTOR GENES

Expression of mi and m3 muscarinic cholinergic receptors mRNAs was exa mined in rat hippocampus following either: (1) kindling to five Stage 5 amygdala-kindled seizures; or (2) eight electroconvulsive shock (ECS ) seizures. Twenty-four hours after the last seizure of either type, t here was a significant decrease in both mi and m3 mRNAs in CA1, CA3 an d the dentate gyrus subfields of the hippocampus. Twenty-eight days af ter the last seizure of either type, there was a significant increase in mi mRNAs in CA1, CA3, and the dentate gyrus; for m3 mRNAs, there wa s a significant increase in CA3 28 days after the last ECS seizure, an d in CA1 and CA3 28 days after the last kindled seizure. These results suggest that seizures alter the cholinergic system in the hippocampus , and that some of the alterations are very long-lasting. (C) 1998 Els evier Science B.V. All rights reserved.