Elevated Galanin Receptor Type 2 Primarily Contributes to Mechanical Hypersensitivity After Median Nerve Injury
Overview
Authors
Affiliations
In this study, we investigated temporal changes in galanin receptor type 2 (GalR2) expression in NF200-, galanin-, neuropeptide Y (NPY)-, and neuronal nitric oxide synthase (nNOS)-like immunoreactive (LI) dorsal root ganglion (DRG) neurons after median nerve chronic constriction injury (CCI), and the effects of GalR2 on c-Fos expression in the cuneate nucleus (CN). Double immunofluorescence labeling methods were used to appraise changes in GalR2 expression in NF200-LI, galanin-LI, NPY-LI, and nNOS-LI DRG neurons after CCI. The von Frey assay was used to assess the efficiency of intraplantar administration of saline, M871 (a GalR2 antagonist), or AR-M1896 (a GalR2 agonist) on neuropathic signs of rats with CCI. The effects of alterations in c-Fos expression were assessed in all treatments. The percentage of GalR2-LI neurons in lesioned DRGs increased and peaked at 1 week after CCI. We further detected that percentages of GalR2-LI neurons labeled for NF200, galanin, NPY, and nNOS significantly increased following CCI. Furthermore, M871 remarkably attenuated tactile allodynia, but the sensation was slightly aggravated by AR-M1896 after CCI. Consequentially, after electrical stimulation of the CCI-treated median nerve, the number of c-Fos-LI neurons in the cuneate nucleus (CN) was significantly reduced in the M871 group, whereas it increased in the AR-M1896 group. These results suggest that activation of GalR2, probably through NPY or nitric oxide, induces c-Fos expression in the CN and transmits mechanical allodynia sensations to the thalamus.
Yang S, Zhong S, Jin X, Fan G, Liao X, Yang X Int Wound J. 2023; 21(4):e14511.
PMID: 38084069 PMC: 10958100. DOI: 10.1111/iwj.14511.
Fonseca-Rodrigues D, Almeida A, Pinto-Ribeiro F Cells. 2022; 11(5).
PMID: 35269462 PMC: 8909084. DOI: 10.3390/cells11050839.
Dong Y, Li C, Zhang X, Liu Y, Yang S, Li M J Physiol Sci. 2021; 71(1):6.
PMID: 33546583 PMC: 10717428. DOI: 10.1186/s12576-021-00790-5.
Ronchi G, Morano M, Fregnan F, Pugliese P, Crosio A, Tos P Front Cell Neurosci. 2019; 13:288.
PMID: 31316355 PMC: 6609919. DOI: 10.3389/fncel.2019.00288.