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Relationship between neurokinin‐1 receptor and substance P in the striatum: Light and electron microscopic immunohistochemical study in the rat
Author(s) -
Li JinLian,
Wang Dan,
Kaneko Takeshi,
Shigemoto Ryuichi,
Nomura Sakashi,
Mizuno Noboru
Publication year - 2000
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/(sici)1096-9861(20000306)418:2<156::aid-cne3>3.0.co;2-z
Subject(s) - immunolabeling , substance p , biology , tachykinin receptor 1 , striatum , axon , neurotransmitter , biophysics , neuropeptide , microbiology and biotechnology , receptor , neuroscience , immunohistochemistry , central nervous system , dopamine , biochemistry , immunology
The synaptic relationship between substance P (SP) and its receptor, i.e., neurokinin‐1 receptor (NK1R), was examined in the striatum of the rat by confocal laser‐scanning microscopy and electron microscopy. For confocal laser‐scanning microscopy, triple‐immunofluorescence histochemistry was performed to label NK1R, SP, and vesicular acetylcholine transporter (a specific marker for cholinergic neurons). In electron microscopic double‐immunolabeling study, immunoreactivity for NK1R was detected with the silver‐intensified gold method, while immunoreactivity for SP was detected with peroxidase immunohistochemistry. Simultaneous immunolabeling of NK1R and SP revealed significant mismatch at the synaptic level: although some SP‐immunopositive axon terminals were in synaptic contact with NK1R‐immunopositive sites of plasma membrane, NK1R‐immunoreactivity was observed at both synaptic and non‐synaptic sites of plasma membrane. Thus, SP released from the sites remote from NK1Rs might diffuse in the extracellular fluid to act, as a paracrine neurotransmitter, on NK1Rs distant from its releasing site. SP neurotransmission in the striatum might occur not only synaptically but also extrasynaptically. The SP‐NK1R system might constitute an association system within the striatum. J. Comp. Neurol. 418:156–163, 2000. © 2000 Wiley‐Liss, Inc.