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Effects of coexisting neurochemicals on the release of serotonin from the intermediate area of rat thoracic spinal cord
Author(s) -
Yang Ling,
Helke Cinda J.
Publication year - 1995
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.890210406
Subject(s) - agonist , medicine , endocrinology , substance p , autoreceptor , serotonin , chemistry , serotonergic , spinal cord , neurokinin b , neurokinin a , tachykinin receptor , receptor , neuropeptide , biology , neuroscience
Serotonin (5‐HT), substance P (SP), neurokinin A (NKA), and thyrotropin‐releasing hormone (TRH) coexist in the nerve terminals of the intermediolateral cell column (IML) of the thoracic spinal cord. The Ca2 + ‐dependent release of 5‐HT from the microdissected intermediate area (including the IML) of the rat thoracic spinal cord, and the 5‐HT 1B autoreceptor regulator of 5‐HT release, were previously demonstrated. In this paper, the effects of SP, NKA, TRH, and/or their analogs on the release of [ 3 H]5‐HT from the intermediate area were investigated using an in vitro superfusion system. Both SP (the endogenous ligand for neurokinin‐1 (NK 1 ) receptor) and an NK 1 , agonist (GR 73632) significantly increased the basal release of [ 3 3H]5‐HT. SP and GR 73632 did not change the K + ‐stimulated release of [ 3 H]5‐HT. The effect of the NK 1 agonist on the basal release of [ 3 H]5‐HT was dose‐dependent, was reduced by an NK 1 antagonist (GR 82334), and was not dependent on extracellular Ca 2+ . Neither NKA, an NK 2 , agonist (GR 64349), nor a TRH analog (MK‐771) altered the basal or stimulated release of [ 3 H]5‐HT. These data suggest that basal release of 5‐HT from the intermediate area of the rat thoracic spinal cord is regulated by SP (acting through an NK 1 receptor), but not by NKA or TRH. These results provide evidence for the role of SP as a modulator of serotoninergic neurons in the intermediate area of the thoracic spinal cord, and may help to clarify the role of coexisting neurochemicals in the spinal regulation of the sympathetic nervous system. © 1995 Wiley‐Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.