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Activation of endogenous opioid gene expression in human keratinocytes and fibroblasts by pulsed radiofrequency energy fields

Authors Moffett J, Fray L, Kubat N

Received 16 June 2012

Accepted for publication 28 July 2012

Published 19 September 2012 Volume 2012:5 Pages 347—357


Review by Single anonymous peer review

Peer reviewer comments 4

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John Moffett,1 Linley M Fray,1 Nicole J Kubat2

1Life Science Department, 2Independent Consultant, Regenesis Biomedical Inc, Scottsdale, AZ, USA

Background: Pulsed radiofrequency energy (PRFE) fields are being used increasingly for the treatment of pain arising from dermal trauma. However, despite their increased use, little is known about the biological and molecular mechanism(s) responsible for PRFE-mediated analgesia. In general, current therapeutics used for analgesia target either endogenous factors involved in inflammation, or act on endogenous opioid pathways.
Methods and Results: Using cultured human dermal fibroblasts (HDF) and human epidermal keratinocytes (HEK), we investigated the effect of PRFE treatment on factors, which are involved in modulating peripheral analgesia in vivo. We found that PRFE treatment did not inhibit cyclooxygenase enzyme activity, but instead had a positive effect on levels of endogenous opioid precursor mRNA (proenkephalin, pro-opiomelanocortin, prodynorphin) and corresponding opioid peptide. In HEK cells, increases in opioid mRNA were dependent, at least in part, on endothelin-1. In HDF cells, additional pathways also appear to be involved. PRFE treatment was also followed by changes in endogenous expression of several cytokines, including increased levels of interleukin-10 mRNA and decreased levels of interleukin-1β mRNA in both cell types.
Conclusion: These findings provide a new insight into the molecular mechanism underlying PRFE-mediated analgesia reported in the clinical setting.

Keywords: peripheral analgesia, endogenous opioids, endothelin-1, endothelin receptor A, endothelin receptor B, pulsed radiofrequency energy field, cyclooxygenase

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