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Subcellular targeting of kappa‐opioid receptors in the rat nucleus locus coeruleus
Author(s) -
Reyes B.A.S.,
Chavkin Charles,
van Bockstaele E.J.
Publication year - 2008
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21880
Subject(s) - locus coeruleus , axon , postsynaptic potential , dynorphin , tyrosine hydroxylase , nucleus , neuroscience , κ opioid receptor , microbiology and biotechnology , galanin , immunofluorescence , chemistry , colocalization , receptor , synapse , biology , opioid peptide , opioid , dopamine , neuropeptide , biochemistry , antibody , immunology
The dynorphin (DYN)‐kappa opioid receptor (κOR) system has been implicated in stress modulation, depression, and relapse to drug‐seeking behaviors. Previous anatomical and physiological data have indicated that the noradrenergic nucleus locus coeruleus (LC) is one site at which DYN may contribute to these effects. Using light microscopy, immunofluorescence, and electron microscopy, the present study investigated the cellular substrates for pre‐ and postsynaptic interactions of κOR in the LC. Dual immunocytochemical labeling for κOR and tyrosine hydroxylase (TH) or κOR and preprodynorphin (ppDYN) was examined in the same section of tissue. Light microscopic analysis revealed prominent κOR immunoreactivity in the nuclear core of the LC and in the peri‐coerulear region where noradrenergic dendrites extend. Fluorescence and electron microscopy revealed κOR immunoreactivity within TH‐immunoreactive somata and dendrites in the LC as well as localized to ppDYN‐immunoreactive processes. In sections processed for κOR and TH, ≈29% (200/688) of the κOR‐containing axon terminals identified targeted TH‐containing profiles. Approximately 49% (98/200) of the κOR‐labeled axon terminals formed asymmetric synapses with TH‐labeled dendrites. Sections processed for κOR and ppDYN showed that, of the axon terminals exhibiting κOR, 47% (223/477) also exhibited ppDYN. These findings indicate that κORs are poised to modulate LC activity by their localization to somata and dendrites. Furthermore, κORs are strategically localized to presynaptically modulate DYN afferent input to catecholamine‐containing neurons in the LC. These data add to the growing literature showing that κORs can modulate diverse afferent signaling to the LC. J. Comp. Neurol. 512:419–431, 2009. © 2008 Wiley‐Liss, Inc.