title: Automated assessment of pain in rats using a voluntarily accessed static weight-bearing test.
abstract: The weight-bearing test is one method to assess pain in rodent animal models; however, the acceptance of this convenient method is limited by the low throughput data acquisition and necessity of confining the rodents to a small chamber.
  
  
  METHODS
  We developed novel data acquisition hardware and software, data analysis software, and a conditioning protocol for an automated high throughput static weight-bearing assessment of pain. With this device, the rats voluntarily enter the weighing chamber, precluding the necessity to restrain the animals and thereby removing the potential stress-induced confounds as well as operator selection bias during data collection. We name this device the Voluntarily Accessed Static Incapacitance Chamber (VASIC).
  
  
  RESULTS
  Control rats subjected to the VASIC device provided hundreds of weight-bearing data points in a single behavioral assay. Chronic constriction injury (CCI) surgery and paw pad injection of complete Freund's adjuvant (CFA) or carrageenan in rats generated hundreds of weight-bearing data during a 30 minute recording session. Rats subjected to CCI, CFA, or carrageenan demonstrated the expected bias in weight distribution favoring the un-operated leg, and the analgesic effect of i.p. morphine was demonstrated. In comparison with existing methods, brief water restriction encouraged the rats to enter the weighing chamber to access water, and an infrared detector confirmed the rat position with feet properly positioned on the footplates, triggering data collection. This allowed hands-off measurement of weight distribution data reducing operator selection bias.
  
  
  CONCLUSIONS
  The VASIC device should enhance the hands-free parallel collection of unbiased weight-bearing data in a high throughput manner, allowing further testing of this behavioral measure as an effective assessment of pain in rodents.
authors.affiliation: Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
authors.forename: Hung Tae
authors.initials: HT
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Uchimoto
authors.affiliation: Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Duellman
authors.affiliation: Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA. Electronic address: Jyang75@wisc.edu.
authors.forename: Jay
authors.initials: J
authors.lastname: Yang
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D057205:Automation, Laboratory / Q000379:methods*; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D004327:Drinking Behavior; D004867:Equipment Design; D005620:Freund's Adjuvant; D006614:Hindlimb / Q000187:drug effects / Q000293:injuries / Q000503:physiopathology; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010146:Pain / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome; D014868:Water Deprivation; D016474:Weight-Bearing
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine; D005620:Freund's Adjuvant
keywords: Automation; Behavior; Chronic constriction injury; Inflammation; Neuropathy; Pain; Rodents; Unbiased data; Weight-bearing