A novel anxiogenic role for the delta opioid receptor expressed in GABAergic forebrain neurons.

TitleA novel anxiogenic role for the delta opioid receptor expressed in GABAergic forebrain neurons.
Publication TypeJournal Article
Year of Publication2015
AuthorsChung PChu Sin, Keyworth HL, Martin-Garcia E, Charbogne P, Darcq E, Bailey A, Filliol D, Matifas A, Scherrer G, Ouagazzal A-M, Gaveriaux-Ruff C, Befort K, Maldonado R, Kitchen I, Kieffer BL
JournalBiol Psychiatry
Volume77
Issue4
Pagination404-15
Date Published2015 Feb 15
ISSN1873-2402
Abstract

BACKGROUND: The delta opioid receptor (DOR) is broadly expressed throughout the nervous system; it regulates chronic pain, emotional responses, motivation, and memory. Neural circuits underlying DOR activities have been poorly explored by genetic approaches. We used conditional mouse mutagenesis to elucidate receptor function in GABAergic neurons of the forebrain.METHODS: We characterized DOR distribution in the brain of Dlx5/6-CreXOprd1(fl/fl) (Dlx-DOR) mice and tested main central DOR functions through behavioral testing.RESULTS: The DOR proteins were strongly deleted in olfactory bulb and striatum and remained intact in cortex and basolateral amygdala. Olfactory perception, circadian activity, and despair-like behaviors were unchanged. In contrast, locomotor stimulant effects of SNC80 (DOR agonist) and SKF81297 (D1 agonist) were abolished and increased, respectively. The Dlx-DOR mice showed lower levels of anxiety in the elevated plus maze, opposing the known high anxiety in constitutive DOR knockout animals. Also, Dlx-DOR mice reached the food more rapidly in a novelty suppressed feeding task, despite their lower motivation for food reward observed in an operant paradigm. Finally, c-fos protein staining after novelty suppressed feeding was strongly reduced in amygdala, concordant with the low anxiety phenotype of Dlx-DOR mice.CONCLUSIONS: We demonstrate that DORs expressed in the forebrain mediate the described locomotor effect of SNC80 and inhibit D1-stimulated hyperactivity. Our data also reveal an unanticipated anxiogenic role for this particular DOR subpopulation, with a potential novel adaptive role. In emotional responses, DORs exert dual anxiolytic and anxiogenic roles, both of which may have implications in the area of anxiety disorders.

DOI10.1016/j.biopsych.2014.07.033
Alternate JournalBiol. Psychiatry
PubMed ID25444168
PubMed Central IDPMC4297504
Grant ListP50 DA005010 / DA / NIDA NIH HHS / United States
U01 AA016658 / AA / NIAAA NIH HHS / United States

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