Effects of peripheral nerve injury on parvalbumin expression in adult rat dorsal root ganglion neurons

Abstract

BackgroundParvalbumin (PV) is a calcium binding protein that identifies a subpopulation of proprioceptive dorsal root ganglion (DRG) neurons. Calcitonin gene-related peptide (CGRP) is also expressed in a high proportion of muscle afferents but its relationship to PV is unclear. Little is known of the phenotypic responses of muscle afferents to nerve injury. Sciatic nerve axotomy or L5 spinal nerve ligation and section (SNL) lesions were used to explore these issues in adult rats using immunocytochemistry.ResultsIn naive animals, the mean PV expression was 25 % of L4 or L5 dorsal root ganglion (DRG) neurons, and this was unchanged 2 weeks after sciatic nerve axotomy. Colocalization studies with the injury marker activating transcription factor 3 (ATF3) showed that approximately 24 % of PV neurons expressed ATF3 after sciatic nerve axotomy suggesting that PV may show a phenotypic switch from injured to uninjured neurons. This possibility was further assessed using the spinal nerve ligation (SNL) injury model where injured and uninjured neurons are located in different DRGs. Two weeks after L5 SNL there was no change in total PV staining and essentially all L5 PV neurons expressed ATF3. Additionally, there was no increase in PV-ir in the adjacent uninjured L4 DRG cells. Co-labelling of DRG neurons revealed that less than 2 % of PV neurons normally expressed CGRP and no colocalization was seen after injury.ConclusionThese experiments clearly show that axotomy does not produce down regulation of PV protein in the DRG. Moreover, this lack of change is not due to a phenotypic switch in PV immunoreactive (ir) neurons, or de novo expression of PV-ir in uninjured neurons after nerve injury. These results further illustrate differences that occur when muscle afferents are injured as compared to cutaneous afferents.

Salidroside promotes peripheral nerve regeneration based on tissue engineering strategy using Schwann cells and PLGA: in vitro and in vivo

“…The present study also highlights the possibility of promoting nerve regeneration in cellular nerve grafts through SDS-increased NCV, SFI, neurotrophin secretion. NF200 and GAP43 are regeneration-associated markers important in the growth and functional recovery of damaged sensory and motor axons2829, which were also slightly increased by SDS administration.…”

Characterization of sensory neuronal subtypes innervating mouse tongue

“…For example, TH and vGLUT3 are primarily expressed in C-LTMRs whereas MRGRPD and MRGPRA3 are found in two separate subgroups of the unmyelinated C nociceptors, parvalbumin in proprioceptors, TrkC in Aδ LTMRs and TrkB in Aβ LTMRs. Several of these markers have also been identified on a functional level by other groups [ 4 , 24 , 48 ]. Moreover, recent study by Patil et al functionally and anatomically corroborated these results and reported additional categorization of DRG sensory neuronal subtypes [ 21 ].…”

Expression of huntingtin-associated protein 1 in adult mouse dorsal root ganglia and its neurochemical characterization in reference to sensory neuron subpopulations

“…Calbindin (CB) and nitric oxide synthase (NOS) are considered to play a vital role in the induction and transduction of nociception ( Patil et al, 2006 ; Egea et al, 2012 ), whereas transient receptor potential vanilloid 1 (TRVP1) is the receptor for capsaicin, which has been shown to be heat sensitive ( Caterina et al, 1997 ). Calretinin (CR) and parvalbumin (PV) are considered to play a vital role in proprioception ( Ren et al, 1993 ; de Nooij et al, 2013 ; Medici and Shortland, 2015 ), whereas tyrosine hydroxylase (TH) is believed to modulate light-touch sensation ( Brumovsky, 2016 ). These neurochemical markers show species or regional differences in percentage expression and distribution in DRG.…”