title: Changes in rat brain muscarinic receptors after inhibitory avoidance learning.
abstract: It is widely accepted that cerebral acetylcholine is necessary for learning and memory, but little is known about the type of muscarinic receptors involved in these functions. To investigate this problem, [3H]-N-methyl-scopolamine which binds to different types of muscarinic receptors, [3H]-Pirenzepine an M1 receptor antagonist, and [3H]-Oxotremorine-M which binds mainly to M2 receptors, were used as ligands to look for possible changes in muscarinic receptor density in neostriatum (NEO), hippocampus (HIP), amygdala (AMY), and temporo-parietal neocortex (CTX), after testing for retention of inhibitory avoidance, trained with high or low footshock intensities. After low reinforcement there was an M1 postsynaptic receptor up-regulation in NEO, HIP, and CTX, and an M2 presynaptic receptor down-regulation in HIP, which suggests a concerted pre- and postsynaptic cholinergic activation in this area. An up-regulation of both M1 and M2 receptors was detected in CTX of low and high footshocked animals, which indicates the presence of a cortical postsynaptic M2 receptor.
authors.affiliation: Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV, IPN, México.
authors.forename: A
authors.initials: A
authors.lastname: Ortega
authors.forename: M A
authors.initials: MA
authors.lastname: del Guante
authors.forename: R A
authors.initials: RA
authors.lastname: Prado-Alcalá
authors.forename: V
authors.initials: V
authors.lastname: Alemán
mesh_terms: D000679:Amygdala / Q000378:metabolism; D000818:Animals; D001362:Avoidance Learning; D001921:Brain / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism; D004192:Discrimination, Psychological; D006624:Hippocampus / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008568:Memory; D019832:N-Methylscopolamine; D017072:Neostriatum / Q000378:metabolism; D009928:Organ Specificity; D010095:Oxotremorine / Q000378:metabolism; D010890:Pirenzepine / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012054:Reinforcement, Psychology; D012602:Scopolamine Derivatives / Q000378:metabolism
chemical_list: D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D010890:Pirenzepine; D010095:Oxotremorine; D019832:N-Methylscopolamine