1. Intracallosal neuronal nitric oxide synthase neurons colocalize with neurokinin 1 substance P receptor in the rat.
- Author
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Barbaresi P, Mensà E, Lariccia V, Desiato G, Fabri M, and Gratteri S
- Subjects
- Animals, Cell Count, Fluorescent Antibody Technique, Male, Microscopy, Confocal, Photomicrography, Rats, Sprague-Dawley, Corpus Callosum cytology, Corpus Callosum metabolism, Neurons cytology, Neurons metabolism, Nitric Oxide Synthase Type I metabolism, Receptors, Neurokinin-1 metabolism
- Abstract
The corpus callosum (cc) contains nitric oxide (NO)-producing neurons. Because NO is a potent vasodilator, these neurons could translate neuronal signals into vascular responses that can be detected by functional brain imaging. Substance P (SP), one of the most widely expressed peptides in the CNS, also produces vasomotor responses by inducing calcium release from intracellular stores through its preferred neurokinin 1 (NK1) receptor, thus inducing NO production via activation of neuronal NO synthase (nNOS). Single- and double-labeling experiments were performed to establish whether NK1-immunopositive neurons (NK1IP -n) are found in the rat cc and the extent of NK1 colocalization with nNOS. NK1IP -n were seen to constitute a large neuronal population in the cc and had a distribution similar to that of nNOSIP neurons (nNOSIP -n). NK1IP -n were numerous in the lateral cc and gradually decreased in the more medial portions, where they were few or absent. Intracallosal NK1IP -n and their dendritic trees were intensely labeled, allowing classification into four morphological types: bipolar, round, polygonal, and pyramidal. Confocal microscopic examination demonstrated that nearly all NK1IP -n contained nNOS (96.43%) and that 84.59% of nNOSIP -n co-expressed NK1. These data suggest that the majority of intracallosal neurons can release NO as a result of the action of SP. A small proportion of nNOSIP -n does not contain NK1 and is not activated by SP; these neurons may release NO via alternative mechanisms. The possible mechanisms by which intracallosal neurons release NO are also reviewed., (© 2014 Wiley Periodicals, Inc.)
- Published
- 2015
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