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Pain Research and Treatment
Volume 2012, Article ID 538739, 7 pages
http://dx.doi.org/10.1155/2012/538739
Clinical Study

Immune Biomarker Response Depends on Choice of Experimental Pain Stimulus in Healthy Adults: A Preliminary Study

1Pain Research and Intervention Center of Excellence, University of Florida, P.O. Box 103628, Gainesville, FL 32610-3628, USA
2Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, P.O. Box 103628, Gainesville, FL 32610-3628, USA
3Department of Periodontology, College of Dentistry, University of Florida, P.O. Box 103628, Gainesville, FL 32610-3628, USA
4Department of Oral Biology, College of Dentistry, University of Florida, P.O. Box 103628, Gainesville, FL 32610-3628, USA

Received 14 September 2012; Revised 15 October 2012; Accepted 17 October 2012

Academic Editor: Donald A. Simone

Copyright © 2012 Yenisel Cruz-Almeida et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Few studies in healthy subjects have examined the neuroimmune responses associated with specific experimental pain stimuli, while none has measured multiple biomarkers simultaneously. The aim of the present study was to compare the neuro-immune responses following two common experimental pain stimuli: cold pressor test (CPT) and focal heat pain (FHP). Eight adults participated in two counterbalanced experimental sessions of FHP or CPT with continuous pain ratings and blood sampling before and 30 minutes after the sessions. Despite similar pain intensity ratings (FHP = ; CPT = ; ), CPT and FHP induced different neuro-immune biomarker responses. CPT was accompanied by significant increases in cortisol ( ) and anti-inflammatory cytokine IL-10 ( ) with significant decreases in several pro-inflammatory mediators (IL-1β ( ), IL-12 ( ), TNF-α ( ), and MCP-1 ( )). There were nonsignificant biomarker changes during the FHP session. There were close to significant differences between the sessions for IL-1β ( ), IFN-γ ( ), and IL-12 ( ) with biomarkers decreasing after CPT and increasing after FHP. There were stronger associations between catastrophizing and most biomarkers after CPT compared to FHP. Our results suggest that CPT is a stressful and painful stimulus, while FHP is mostly a painful stimulus. Thus, each experimental pain stimulus can activate different neuro-immune cascades, which are likely relevant for the interpretation of studies in chronic pain conditions.