Short‐term swimming exercise attenuates the sensitization of dorsal horn neurons in rats with NGF‐induced low back pain

Abstract

Physical exercise is a common treatment for low back pain. The possible mechanisms underlying the effects of exercise are probably multifold. This work shows that swimming exercise prevents sensitization of dorsal horn neurons, which may be one mechanism for the positive effects of exercise.

Spinal Mobilization Prevents NGF-Induced Trunk Mechanical Hyperalgesia and Attenuates Expression of CGRP

“…Previous studies using this NGF-induced model of LBP were limited to adult male rats and demonstrated the development of unilateral localized (trunk) mechanical hyperalgesia (Hoheisel et al, 2013;Zhang et al, 2017;de Azambuja et al, 2018). This effect began within 4 h after the second NGF injection and continued through Day 14.…”

“…Notably, SM prevented an increase in spontaneous pain immediately following the 2nd injection evidenced by no differences being found between VEH, VEH + SM, and NGF + SM groups. Electrophysiology experiments using this same NGF LBP model have demonstrated that spinal cord dorsal horn latent sensitization from the 1st NGF injection is activated very quickly (within 1-2 h) following the 2nd NGF injection and manifests itself as increased neural resting activity and evoked response, increased convergent input, and the appearance of new receptive fields (Hoheisel et al, 2013;de Azambuja et al, 2018). The acute effects of NGF's actions were enough to influence significant increases in spontaneous pain.…”

“…The onset of this NGF-induced mechanical hyperalgesia started within hours after the second NGF injection and persisted through the end of their experimental period at Day 14. While the precise neurobiological mechanisms by which NGF induces sustained mechanical trunk hyperalgesia are not completely understood, evidence indicates that sensitization of skeletal muscle nociceptors (Mann et al, 2006;Murase et al, 2010), glial-dependent latent sensitization of dorsal horn neurons (Zhang et al, 2017), and spinal dorsal horn neuron hyperexcitability immediately following the 2nd NGF injection (Hoheisel et al, 2007(Hoheisel et al, , 2013de Azambuja et al, 2018) all contribute. NGF is an endogenously produced neurotrophin involved in pain transduction that binds to tyrosine kinase receptor A in nociceptors (Klein et al, 1991;Pezet et al, 1999).…”

Exercise attenuates low back pain and alters epigenetic regulation in intervertebral discs in a mouse model

“…This is consistent with other studies in chronic LBP in animals. In one study, animals receiving swimming exercise exhibited higher pressure pain thresholds than animals in the control group [54]. In another study, running exercise alleviated the mechanical allodynia induced by intradiscal Freund's Adjuvant injection via disc repair and cell proliferation in rats [55].…”

Persistence of pain in humans and other mammals

“…B 374: 20190276 effects of exercise in neuropathic and low back pain [33,39,40]. The effects are associated with structural and functional changes in the nervous system and brain [39][40][41][42], in neuroimmune signalling [38] and in pro-and anti-inflammatory cytokine production [33,43]. Activity levels, among other environmental factors, produce epigenetic changes and, ultimately, changes in brain connectivity [44].…”