• Liron S Duraku, Sjoerd P Niehof, Yesim Misirli, Marco Everaers, Sieske Hoendervangers, Joan Holstege, Henk-Jan J Boele, Sebastiaan K E Koekkoek, Ernst S Smits, Ruud W Selles, and Erik T Walbeehm.
• Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, The Netherlands; Department of Plastic, Reconstructive and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, The Netherlands. Electronic address: l.duraku@erasmusmc.nl.
• J. Neurosci. Methods. 2014 Mar 15; 224: 1-12.

BackgroundTo investigate the pathophysiology of temperature hypersensitivity in neuropathic pain rodent models, it is essential to be able to quantify the phenotype as objective as possible. Current temperature sensitivity measuring paradigms are performed during exposure to external factors, i.e. light, sound and smell, which modulate behavior significantly. In addition the present outcome measure for temperature hypersensitivity in rodents is the examination of the hind paw lift upon exposure to a certain temperature, which reflects more a reflex-flexion than an experience of pain.New MethodTherefore the Rotterdam Advanced Multiple Plate (RAMP) was developed to assess cold hyperalgesia and allodynia objectively in freely behaving neuropathic pain rats, which measures the avoidance for certain temperatures and monitoring the location of the rat with an infrared camera while excluding external environmental influences such as light and sound.ResultsCompared to sham rats, the spared nerve injury (SNI) rats demonstrated a higher preference for the comfortable plate (27 °C) when the other three plates were set at 5 °C, 14 °C, 17 °C and 19 °C. We were unable to detect heat hyperalgesia and allodynia with the RAMP.Comparison With Existing MethodThe paw withdrawal method displays similar results during cold hypersensitivity measurements as observed with the RAMP. The SNI group did display heat hypersensitivity during the paw withdrawal test.ConclusionsThe results indicate that the RAMP is able to quantify cold hyperalgesia and allodynia in neuropathic pain rats while resolves some of the problems of conventional temperature sensitivity measuring paradigms in rodents.Copyright © 2013 Elsevier B.V. All rights reserved.

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