title: Transcutaneous electrical nerve stimulation on Yongquan acupoint reduces CFA-induced thermal hyperalgesia of rats via down-regulation of ERK2 phosphorylation and c-Fos expression.
abstract: Activation of extracellular signal-regulated kinase-1/2 (ERK1/2) and its involvement in regulating gene expression in spinal dorsal horn, cortical and subcortical neurons by peripheral noxious stimulation contribute to pain hypersensitivity. Transcutaneous electrical nerve stimulation (TENS) is a treatment used in physiotherapy practice to promote analgesia in acute and chronic inflammatory conditions. In this study, a total number of 114 rats were used for three experiments. Effects of complete Freund's adjuvant (CFA)-induced inflammatory pain hypersensitivity and TENS analgesia on ERK1/2 phosphorylation and c-Fos protein expression were examined by using behavioral test, Western blot, and immunostaining methods. We found that CFA injection caused an area of localized swelling, erythema, hypersensitivity to thermal stimuli, the decreased response time of hind paw licking (HPL), as well as upregulation of c-Fos protein expression and ERK2 phosphorylation in the ipsilateral spinal dorsal horn and the contralateral primary somatosensory area of cortex and the amygdala of rats. TENS on Yongquan acupoint for 20 min produced obvious analgesic effects as demonstrated with increased HPL to thermal stimuli of CFA-treated rats. In addition, TENS application suppressed the CFA-induced ERK2 activation and c-Fos protein expression. These results suggest that down-regulation of ERK2 phosphorylation and c-Fos expression were involved in TENS inhibition on CFA-induced thermal hyperalgesia of rats.
authors.affiliation: Department of Anatomy, Histology and Embryology, Capital Medical University, Beijing, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Lianxue
authors.initials: L
authors.lastname: Yang
authors.forename: Xiulai
authors.initials: X
authors.lastname: Gao
mesh_terms: D015669:Acupuncture Points; D000698:Analgesia; D000818:Animals; D015536:Down-Regulation; D005528:Foot; D005620:Freund's Adjuvant; D006930:Hyperalgesia / Q000139:chemically induced / Q000378:metabolism* / Q000628:therapy*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D010766:Phosphorylation; D020671:Posterior Horn Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D004561:Transcutaneous Electric Nerve Stimulation
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D005620:Freund's Adjuvant; D019950:Mitogen-Activated Protein Kinase 1