The septum and amygdala differentially mediate the anxiolytic effects of benzodiazepines.
Microinfusions of a benzodiazepine anxiolytic (midazolam) into the septum or the amygdala suppressed different fear reactions in two tests of rat "anxiety". Septal infusions increased open-arm activity in the plus-maze test and decreased burying behavior in the shock-probe test whereas amygdaloid infusions produced neither of these antianxiety effects. Amygdaloid infusions, however, dramatically impaired shock-probe avoidance, an antianxiety effect not produced by the septal infusions. Infusions of the benzodiazepine receptor antagonist Ro 15-1788 (flumazenil) blocked each of these specific, anti-fear effects of midazolam without producing intrinsic effects by itself. These results suggest that benzodiazepine receptor systems within the amygdala and the septum differentially mediate specific fear reactions.
Pesold
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C
Department of Psychology, University of Alberta, Edmonton, Canada.
Treit
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D
D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001007:Anxiety; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D005442:Flumazenil / Q000494:pharmacology*; D007263:Infusions, Parenteral; D007858:Learning / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008874:Midazolam / Q000008:administration & dosage / Q000494:pharmacology*; D009928:Organ Specificity; D051381:Rats; D017207:Rats, Sprague-Dawley
D005442:Flumazenil; D008874:Midazolam