title: Mouse δ opioid receptors are located on presynaptic afferents to hippocampal pyramidal cells.
abstract: Delta opioid receptors participate in the control of chronic pain and emotional responses. Recent data have also identified their implication in drug-context associations pointing to a modulatory role on hippocampal activity. We used fluorescent knock-in mice that express a functional delta opioid receptor fused at its carboxy terminus with the green fluorescent protein in place of the native receptor to investigate the receptor neuroanatomical distribution in this structure. Fine mapping of the pyramidal layer was performed in hippocampal acute brain slices and organotypic cultures using fluorescence confocal imaging, co-localization with pre- and postsynaptic markers and correlative light-electron microscopy. The different approaches concurred to identify delta opioid receptors on presynaptic afferents to glutamatergic principal cells. In the latter, only scarce receptors were detected that were confined within the Golgi or vesicular intracellular compartments with no receptor present at the cell surface. In the mouse hippocampus, expression of functional delta opioid receptors is therefore mostly associated with interneurons emphasizing a presynaptic modulatory effect on the pyramidal cell firing rate.
authors.affiliation: Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC) CNRS/INSERM/UdS, Illkirch, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Rezaï
authors.forename: Lauren
authors.initials: L
authors.lastname: Faget
authors.forename: Ewa
authors.initials: E
authors.lastname: Bednarek
authors.forename: Yannick
authors.initials: Y
authors.lastname: Schwab
authors.forename: Brigitte L
authors.initials: BL
authors.lastname: Kieffer
authors.forename: Dominique
authors.initials: D
authors.lastname: Massotte
mesh_terms: D000344:Afferent Pathways / Q000166:cytology / Q000378:metabolism; D000818:Animals; D005260:Female; D055879:Gene Knock-In Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D007395:Interneurons / Q000166:cytology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants; D009924:Organ Culture Techniques; D010146:Pain / Q000378:metabolism / Q000473:pathology; D017729:Presynaptic Terminals / Q000378:metabolism*; D017966:Pyramidal Cells / Q000166:cytology / Q000378:metabolism*; D017465:Receptors, Opioid, delta / Q000235:genetics / Q000378:metabolism*
chemical_list: D017465:Receptors, Opioid, delta; D049452:Green Fluorescent Proteins