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An automated flinch detecting system for use in the formalin nociceptive bioassay

2001; American Physiological Society; Volume: 90; Issue: 6 Linguagem: Inglês

10.1152/jappl.2001.90.6.2386

8750-7587

Tony L. Yaksh, George T. Ozaki, Damon McCumber, Michael Rathbun, Camilla I. Svensson, Shelle Malkmus, Michael C. Yaksh,

Neuroscience and Neuropharmacology Research

The biphasic display of paw-flinch behavior in the rat after injection of formalin into the dorsum of the hind paw is used for the screening of anti-hyperalgesic agents. Described and characterized here is a less labor-intensive system for counting flinch activity by detecting movement of a small metal band placed on the formalin-injected paw. A signal is generated as the band breaks the electromagnetic field of a loop antenna located under the rat and processed through an algorithm that determines flinch activity using 1) amplitude, 2) zero-voltage crossing, and 3) signal duration. Flinches are summed and stored over a selected collection interval throughout the assay for later analysis. Studies have validated the measures with respect to 1) system stability over time; 2) system-to-"practiced observer" correlation on flinch detection, r2 = 0.94; 3) system variables including time of day, sex, age, and body weight; and 4) 50% effective dose values similar to those previously reported for intrathecal morphine and the NMDA antagonist MK-801.