title: Benzodiazepine-induced hippocampal CA1 neuron alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid (AMPA) receptor plasticity linked to severity of withdrawal anxiety: differential role of voltage-gated calcium channels and N-methyl-D-aspartic acid receptors.
abstract: Withdrawal from 1-week oral administration of the benzodiazepine, flurazepam (FZP) is associated with increased alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid (AMPA) receptor (AMPAR) miniature excitatory postsynaptic currents (mEPSCs) but reduction of N-methyl-D-aspartic acid (NMDA) receptor (NMDAR)-evoked (e)EPSCs in hippocampal CA1 neurons. A positive correlation was observed between increased AMPAR-mediated mEPSC amplitude and anxiety-like behavior in 1-day FZP-withdrawn rats. These effects were disrupted by systemic AMPAR antagonist administration (GYKI-52466, 0.5 mg/kg, intraperitoneal) at withdrawal onset, strengthening the hypothesis that CA1 neuron AMPAR-mediated hyperexcitability is a central component of a functional anatomic circuit associated with the expression of withdrawal anxiety. Abolition of AMPAR current upregulation in 2-day FZP withdrawn rats by GYKI-52466 injection also reversed the reduction in NMDAR-mediated eEPSC amplitude in CA1 neurons from the same rats, suggesting that downregulation of NMDAR function may serve a protective, negative-feedback role to prevent AMPAR-mediated neuronal overexcitation. NMDAR antagonist administration (MK-801, 0.25 mg/kg intraperitoneally) had no effect on modifying increased glutamatergic strength or on withdrawal anxiety, whereas injection of an L-type voltage-gated calcium channel antagonist, nimodipine (10 mg/kg, intraperitoneally) averted AMPAR current enhancement and anxiety-like behavior, suggesting that these manifestations may be initiated by a voltage-gated calcium channel-dependent signal transduction pathway. An evidence-based model of likely cellular mechanisms in the hippocampus contributing to benzodiazepine withdrawal anxiety was proposed implicating regulation of multiple CA1 neuron ion channels.
authors.affiliation: Department of Physiology and Pharmacology, University of Toledo College of Medicine, Health Science Campus, Toledo, Ohio 43614, USA.
authors.forename: Kun
authors.initials: K
authors.lastname: Xiang
authors.forename: Elizabeth I
authors.initials: EI
authors.lastname: Tietz
mesh_terms: D000818:Animals; D001007:Anxiety / Q000139:chemically induced / Q000503:physiopathology*; D001569:Benzodiazepines / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D004195:Disease Models, Animal; D016291:Dizocilpine Maleate / Q000494:pharmacology; D015536:Down-Regulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005479:Flurazepam / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009473:Neuronal Plasticity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000187:drug effects* / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000378:metabolism; D012720:Severity of Illness Index; D015398:Signal Transduction; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*
chemical_list: D020746:Calcium Channels, L-Type; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; C061950:GYKI 52466; D001569:Benzodiazepines; D016291:Dizocilpine Maleate; D005479:Flurazepam