AREA-DEPENDENT CNS MEMBRANE RESPONSE OF MUSCARINIC RECEPTOR TO CONVULSANT 3-MERCAPTOPROPIONIC ACID

It has already been shown that the administration of convulsant 3-merc aptopropionic acid at 150 mg/kg enhances binding affinity of muscarini c antagonist [H-3]quinuclidinyl benzilate ([H-3]QNB) to certain rat CN S membranes without affecting site number. Herein we employed a 100 mg /kg dose and tested [3H]QNB binding to cerebellar, hippocampal, and st riatal membranes obtained from rats killed at preseizure, seizure, and postseizure stages. In cerebellum, binding increased 24, 65, and 19% at preseizure, seizure, and postseizure stages, respectively; in hippo campus, values were 12 and 20% higher at pre-and seizure stages, but f ailed to differ from controls at postseizure; in striatum, increases o f 10 and 18% were recorded at seizure and postseizure, with no changes at preseizure. Neither a subconvulsant dose (20 mg/kg) nor in vitro d rug addition had any effect on binding. Results indicate a differentia l response to the convulsant, with reversible changes in cerebellum an d hippocampus, and a delayed response in striatum, supporting the conc ept of area-dependent neuronal plasticity.