Journal article
Increased neuronal expression of neurokinin‐1 receptor and stimulus‐evoked internalization of the receptor in the rostral ventromedial medulla of the rat after peripheral inflammatory injury
Journal of comparative neurology (1911), Vol.522(13), pp.3037-3051
09/01/2014
DOI: 10.1002/cne.23564
PMID: 24639151
Abstract
ABSTRACT
This study examined possible mechanisms by which Substance P (Sub P) assumes a pronociceptive role in the rostral ventromedial medulla (RVM) under conditions of peripheral inflammatory injury, in this case produced by intraplantar (ipl) injection of complete Freund's adjuvant (CFA). In saline‐ and CFA‐treated rats, neurokinin‐1 receptor (NK1R) immunoreactivity was localized to neurons in the RVM. Four days after ipl injection of CFA, the number of NK1R‐immunoreactive neurons in the RVM was increased by 30%, and there was a concomitant increase in NK1R‐immunoreactive processes in CFA‐treated rats. Although NK1R immunoreactivity was increased, tachykinin‐1 receptor (Tacr1) mRNA was not increased in the RVM of CFA‐treated rats. To assess changes in Sub P release, the number of RVM neurons that exhibited NK1R internalization was examined in saline‐ and CFA‐treated rats following noxious heat stimulation of the hind paws. Only CFA‐treated rats that experienced noxious heat stimulation exhibited a significant increase in the number of neurons showing NK1R internalization. These data suggest that tonic Sub P release is not increased as a simple consequence of peripheral inflammation, but that phasic or evoked release of Sub P in the RVM is increased in response to noxious peripheral stimulation in a persistent inflammatory state. These data support the proposal that an upregulation of the NK1R in the RVM, as well as enhanced release of Sub P following noxious stimulation, underlie the pronociceptive role of Sub P under conditions of persistent inflammatory injury. J. Comp. Neurol. 522:3037–3051, 2014. © 2014 Wiley Periodicals, Inc.
Following peripheral inflammatory injury, substance P assumes a pronociceptive role in the brainstem. Mechanisms that underlie this transition include an increase in neurokinin‐1 receptor expressing neurons, determined using stereology, and facilitated release of substance P in response to heat stimulation, as evidenced by an increase in neurons exhibiting receptor internalization.
Details
- Title: Subtitle
- Increased neuronal expression of neurokinin‐1 receptor and stimulus‐evoked internalization of the receptor in the rostral ventromedial medulla of the rat after peripheral inflammatory injury
- Creators
- Marta V Hamity - University of IowaRoxanne Y Walder - University of IowaDonna L Hammond - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of comparative neurology (1911), Vol.522(13), pp.3037-3051
- DOI
- 10.1002/cne.23564
- PMID
- 24639151
- ISSN
- 0021-9967
- eISSN
- 1096-9861
- Number of pages
- 16
- Grant note
- DOI: 10.13039/100000026, name: National Institute on Drug Abuse, award: R01DA023576
- Language
- English
- Date published
- 09/01/2014
- Academic Unit
- Iowa Neuroscience Institute; Nursing; Anesthesia; Neuroscience and Pharmacology
- Record Identifier
- 9984007170602771
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