Postischemic neuroprotection in the ischemia-tolerant state gerbil hippocampus is associated with increased ligand binding to inhibitory GABA(A) receptors. 2003

Clemens Sommer, and Alexander Fahrner, and Marika Kiessling
Department of Neuropathology, Ruprecht-Karls-University of Heidelberg, Germany. clemens.sommer@medizin.uni-ulm.de

Excitotoxic activation of glutamate receptors is thought to play a key role in delayed neuronal death (DND) of highly vulnerable hippocampal CA1 neurons after transient global ischemia. DND can be prevented by a short sublethal preconditioning (PC) stimulus. Recently, we demonstrated that ischemic PC, but not a single period of 5-min ischemia elicits a transient up-regulation of hippocampal [(3)H]muscimol binding to GABA(A) receptors. This indicates that activation of the GABAergic system may participate in the acquisition of neuroprotection. The present study was designed to test whether postischemic modulation of receptor binding also occurs in the ischemia-tolerant state, i.e., after a PC stimulus of 2.5-min ischemia and a subsequent normally lethal period of 5-min ischemia 4 days apart. Using receptor autoradiography, [(3)H]AMPA and [(3)H]muscimol binding to excitatory AMPA and inhibitory GABA(A) receptors was analyzed in hippocampal subfields CA1, CA3 and dentate gyrus at recirculation intervals of 30 min, 8, 24, 48, 96 h and 3 weeks. Postischemic hippocampal ligand binding to AMPA receptors remained unchanged at any time point investigated, but [(3)H]muscimol binding to GABA(A) receptors in CA1 neurons rendered tolerant to ischemia was up-regulated between 30 min and 48 h of recirculation. Our data suggest that a relative shift between excitatory and inhibitory neurotransmission may promote postischemic survival of CA1 neurons.

UI MeSH Term Description Entries
D008297 Male Males
D009118 Muscimol A neurotoxic isoxazole isolated from species of AMANITA. It is obtained by decarboxylation of IBOTENIC ACID. Muscimol is a potent agonist of GABA-A RECEPTORS and is used mainly as an experimental tool in animal and tissue studies. Agarin,Pantherine
D009474 Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM. Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D011963 Receptors, GABA-A Cell surface proteins which bind GAMMA-AMINOBUTYRIC ACID and contain an integral membrane chloride channel. Each receptor is assembled as a pentamer from a pool of at least 19 different possible subunits. The receptors belong to a superfamily that share a common CYSTEINE loop. Benzodiazepine-Gaba Receptors,GABA-A Receptors,Receptors, Benzodiazepine,Receptors, Benzodiazepine-GABA,Receptors, Diazepam,Receptors, GABA-Benzodiazepine,Receptors, Muscimol,Benzodiazepine Receptor,Benzodiazepine Receptors,Benzodiazepine-GABA Receptor,Diazepam Receptor,Diazepam Receptors,GABA(A) Receptor,GABA-A Receptor,GABA-A Receptor alpha Subunit,GABA-A Receptor beta Subunit,GABA-A Receptor delta Subunit,GABA-A Receptor epsilon Subunit,GABA-A Receptor gamma Subunit,GABA-A Receptor rho Subunit,GABA-Benzodiazepine Receptor,GABA-Benzodiazepine Receptors,Muscimol Receptor,Muscimol Receptors,delta Subunit, GABA-A Receptor,epsilon Subunit, GABA-A Receptor,gamma-Aminobutyric Acid Subtype A Receptors,Benzodiazepine GABA Receptor,Benzodiazepine Gaba Receptors,GABA A Receptor,GABA A Receptor alpha Subunit,GABA A Receptor beta Subunit,GABA A Receptor delta Subunit,GABA A Receptor epsilon Subunit,GABA A Receptor gamma Subunit,GABA A Receptor rho Subunit,GABA A Receptors,GABA Benzodiazepine Receptor,GABA Benzodiazepine Receptors,Receptor, Benzodiazepine,Receptor, Benzodiazepine-GABA,Receptor, Diazepam,Receptor, GABA-A,Receptor, GABA-Benzodiazepine,Receptor, Muscimol,Receptors, Benzodiazepine GABA,Receptors, GABA A,Receptors, GABA Benzodiazepine,delta Subunit, GABA A Receptor,epsilon Subunit, GABA A Receptor,gamma Aminobutyric Acid Subtype A Receptors
D002546 Ischemic Attack, Transient Brief reversible episodes of focal, nonconvulsive ischemic dysfunction of the brain having a duration of less than 24 hours, and usually less than one hour, caused by transient thrombotic or embolic blood vessel occlusion or stenosis. Events may be classified by arterial distribution, temporal pattern, or etiology (e.g., embolic vs. thrombotic). (From Adams et al., Principles of Neurology, 6th ed, pp814-6) Brain Stem Ischemia, Transient,Cerebral Ischemia, Transient,Crescendo Transient Ischemic Attacks,Transient Ischemic Attack,Anterior Circulation Transient Ischemic Attack,Brain Stem Transient Ischemic Attack,Brain TIA,Brainstem Ischemia, Transient,Brainstem Transient Ischemic Attack,Carotid Circulation Transient Ischemic Attack,Posterior Circulation Transient Ischemic Attack,TIA (Transient Ischemic Attack),Transient Ischemic Attack, Anterior Circulation,Transient Ischemic Attack, Brain Stem,Transient Ischemic Attack, Brainstem,Transient Ischemic Attack, Carotid Circulation,Transient Ischemic Attack, Posterior Circulation,Transient Ischemic Attack, Vertebrobasilar Circulation,Transient Ischemic Attacks, Crescendo,Vertebrobasilar Circulation Transient Ischemic Attack,Attack, Transient Ischemic,Attacks, Transient Ischemic,Brainstem Ischemias, Transient,Cerebral Ischemias, Transient,Ischemia, Transient Brainstem,Ischemia, Transient Cerebral,Ischemias, Transient Brainstem,Ischemias, Transient Cerebral,Ischemic Attacks, Transient,TIA, Brain,TIAs (Transient Ischemic Attack),Transient Brainstem Ischemia,Transient Cerebral Ischemia,Transient Cerebral Ischemias,Transient Ischemic Attacks
D005849 Gerbillinae A subfamily of the Muridae consisting of several genera including Gerbillus, Rhombomys, Tatera, Meriones, and Psammomys. Gerbils,Jird,Meriones,Psammomys,Rats, Sand,Gerbil,Jirds,Merione,Rat, Sand,Sand Rat,Sand Rats
D006624 Hippocampus A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation. Ammon Horn,Cornu Ammonis,Hippocampal Formation,Subiculum,Ammon's Horn,Hippocampus Proper,Ammons Horn,Formation, Hippocampal,Formations, Hippocampal,Hippocampal Formations,Hippocampus Propers,Horn, Ammon,Horn, Ammon's,Proper, Hippocampus,Propers, Hippocampus,Subiculums
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001345 Autoradiography The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed) Radioautography

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