Benzodiazepine-like molecules, including diazepam and other benzodiazepines, are found in the brain and are concentrated in synaptic vesicle fractions. Training procedures cause a depletion of these molecules in medial septum, amygdala and hippocampus, suggesting a release of the substances. The intensity of the effect varies with the degree of anxiety or stress associated with the type of learning. Systemic administration of the benzodiazepine receptor antagonist, flumazenil, enhances retention of various behaviors. Post-training intrahippocampal but not intraseptal or intra-amygdala flumazenil facilitates retention of habituation learning. Post-training intrahippocampal, intraseptal or intra-amygdala flumazenil facilitates retention of inhibitory avoidance learning. The effect is counteracted by the GABAA agonist, muscimol, correlates with a reduced sensitivity to muscimol, and is shared by the indirect GABAA antagonist, Picrotoxin. The findings suggest that benzodiazepine/GABAA synapses in the hippocampus regulate memory storage of habituation, and similar synapses in septum, amygdala and hippocampus regulate memory storage of avoidance learning. Studies using localized microinjections of specific receptor agonists and antagonists suggest that GABAA synapses act by inhibiting cells excited by NMDA and muscarinic receptors which are necessary for post-training memory processing. ^-Noradrenergic synapses play a modulatory role. The neurotransmitter receptor interactions are seen in the three structures for inhibitory avoidance, and only in the hippocampus in the case of habituation. This suggests the existence of three separate mechanisms, each involved in the regulation of different aspects or components of memories, all with a similar synaptic arrangement, and all downregulated by benzodizepine/GABAA receptors, probably in response to anxiety levels.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.