title: Comparison of manual and automated filaments for evaluation of neuropathic pain behavior in rats.
abstract: BACKGROUND
  The most commonly used Von Frey filaments are productive in evaluating behavioral responses of neuropathic pain in preclinical and clinical research. To reduce the potential experimenter bias, automated instruments are being developed for behavioral assessment. In preclinical research, neuropathic pain models of nerve injury with varied etiology like partial sciatic nerve ligation (PNL), chronic constricted injury (CCI) and spinal nerve ligation (SNL) are employed to screen the analgesic drugs to treat symptoms like allodynia and hyperalgesia. The current study was aimed to validate and compare conventionally used Von Frey monofilaments and automated dynamic plantar aesthesiometer using three different pain models.
  
  
  METHODS
  PNL, CCI and SNL rats were used to compare and validate the assessment of neuropathic pain using Von Frey monofilaments and automated dynamic plantar aesthesiometer.
  
  
  RESULTS
  Mechanical allodynia was assessed at various time points to mimic drug testing conditions in neuropathic pain models and anticipated to observe reliable and reproducible paw withdrawal threshold measurements across these models. Consistent paw withdrawal thresholds were observed in all the three models of neuropathic pain with Von Frey monofilaments, whereas variable paw withdrawal thresholds were noticed in PNL and CCI models but not in SNL model with dynamic plantar aesthesiometer.
  
  
  CONCLUSIONS
  Manually used Von Frey filaments can be used in assessment of mechanical allodynia in all the three models, whereas dynamic plantar aesthesiometer is suitable for assessing mechanical allodynia in SNL but not in PNL and CCI models. The reason for variable paw withdrawal thresholds during assessment of mechanical allodynia in PNL and CCI models with dynamic plantar aesthesiometer may be due to the paw deformity and change in foot posture.
authors.affiliation: Department of Pharmacology, Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Banjara Hills, Hyderabad-500034, India. nvsrk@suven.com
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Nirogi
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Goura
authors.forename: Dhanalakshmi
authors.initials: D
authors.lastname: Shanmuganathan
authors.forename: Pradeep
authors.initials: P
authors.lastname: Jayarajan
authors.forename: Renny
authors.initials: R
authors.lastname: Abraham
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002138:Calibration; D004195:Disease Models, Animal; D006614:Hindlimb; D006930:Hyperalgesia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D007091:Image Processing, Computer-Assisted; D008026:Ligation; D008297:Male; D009437:Neuralgia / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D010147:Pain Measurement / Q000295:instrumentation* / Q000379:methods*; D017288:Pain Threshold / Q000502:physiology* / Q000523:psychology; D059348:Peripheral Nerve Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000293:injuries / Q000601:surgery; D013127:Spinal Nerves / Q000293:injuries / Q000601:surgery