US EPA

1514791 

Journal Article 

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

Yaksh, TL; Ozaki, G; Mccumber, D; Rathbun, M; Svensson, C; Malkmus, S; Yaksh, MC 

2001 

Yes 

Journal of Applied Physiology (1985)
ISSN: 8750-7587
EISSN: 1522-1601 

90 

6 

2386-2402 

English 

11356806 

10.1152/jappl.2001.90.6.2386 

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. 

Analgesics/pharmacology; Animals; Automation; Behavior, Animal/drug effects; Body Weight/drug effects; Data Collection; Dose-Response Relationship, Drug; Electromagnetic Fields; Electromyography; Formaldehyde/ diagnostic use; Injections; Injections, Spinal; Models, Biological; Pain Measurement/ instrumentation; Rats, Sprague-Dawley; Signal Processing, Computer-Assisted