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Substance P and nitric oxide signaling in cerebral cortex: Anatomical evidence for reciprocal signaling between two classes of interneurons
Author(s) -
Vruwink Megan,
Schmidt Harald H.H.W.,
Weinberg Richard J.,
Burette Alain
Publication year - 2001
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.1413
Subject(s) - parvalbumin , biology , interneuron , neuroscience , neocortex , inhibitory postsynaptic potential , somatostatin , neuropil , calretinin , neuropeptide , nitric oxide , gamma aminobutyric acid , receptor , endocrinology , biochemistry , central nervous system , immunohistochemistry , immunology
Parvalbumin‐containing fast‐spiking interneurons in the cerebral cortex exhibit widespread electrical coupling, as do somatostatin‐containing low‐threshold spiking interneurons. Besides the classical neurotransmitter γ‐aminobutyric acid, these cortical interneurons may also release various neuropeptides including substance P (SP), as well as the freely diffusible messenger nitric oxide (NO). To investigate whether these two networks of interneurons might interact via these nonclassical messengers, we performed immunocytochemistry for SP and NO signaling pathways in rat somatic sensory cortex. SP was found in a subset of parvalbumin‐positive cells concentrated in layers IV and V, whereas its receptor, NK1, was found in a subset of somatostatin‐containing neurons (and also, at much lower levels, in a disjoint subset of parvalbumin‐containing neurons). Only 4% of SP‐containing axon terminals were apposed to NK1‐positive dendrites, suggesting that in the cerebral cortex, SP may act predominantly as a paracrine neuromediator. Nitric oxide synthase‐I (NOS‐I), the synthetic enzyme for NO, was found almost exclusively in NK1‐positive neurons; 95% of intensely somatostatin/NK1‐positive neurons were also positive for NOS‐I, and 94% of NOS‐positive neurons were also positive for NK1. Immunoreactivity for soluble guanylyl cyclase (the NO receptor) was at high levels in the apical dendrites of layer V pyramidal neurons and in parvalbumin/SP‐positive neurons. These data point to a novel reciprocal chemical interaction between two inhibitory networks in the rat neocortex. J. Comp. Neurol. 441:288–301, 2001. © 2001 Wiley‐Liss, Inc.