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Burrowing as a non‐reflex behavioural readout for analgesic action in a rat model of sub‐chronic knee joint inflammation
Author(s) -
Rutten K.,
Schiene K.,
Robens A.,
Leipelt A.,
Pasqualon T.,
Read S.J.,
Christoph T.
Publication year - 2014
Publication title -
european journal of pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.305
H-Index - 109
eISSN - 1532-2149
pISSN - 1090-3801
DOI - 10.1002/j.1532-2149.2013.00358.x
Subject(s) - ibuprofen , pregabalin , naproxen , analgesic , nociception , medicine , reflex , open field , anesthesia , pharmacology , inflammation , receptor , pathology , alternative medicine
Background Innate responses against spontaneous pain are proposed to improve the predictive validity of preclinical analgesia models. Therefore, development and validation of novel readouts is necessary. To investigate whether innate rodent burrowing is a useful alternative behavioural readout for assessment of analgesic efficacy, a complete F reund's adjuvant ( CFA )‐induced model of sub‐chronic inflammation was used to compare the effects of naproxen, ibuprofen and pregabalin in weight‐bearing ( WB ), open‐field ( OF ) and burrowing assays. Methods M ale S prague D awley rats were injected with 150 μL of CFA (2 mg/mL) into the knee (hind leg) 3 days before testing. Naproxen, ibuprofen and pregabalin were administered at different doses 30, 90 and 60 min, respectively, before testing. WB was determined using a rat incapacitance tester; horizontal distance moved and vertical rearings were recorded in an OF ; and burrowing was measured by the weight of gravel remaining in a hollow tube after 60 min. Results CFA ‐induced arthritis reduced WB , OF activity and burrowing. Naproxen, pregabalin and ibuprofen treatment normalized WB ; however, horizontal OF activity was not improved by any treatment; rearing behaviour was moderately reinstated by ibuprofen (100 mg/kg). In burrowing, naproxen (100 mg/kg), ibuprofen (31.6 and 100 mg/kg) and pregabalin (10 mg/kg) reversed CFA ‐induced deficits. Conclusions Burrowing performance is an alternative non‐reflex readout relying on innate rodent behaviour that is affected by nociceptive behaviour and can be pharmacologically manipulated. The burrowing assay appears to be more sensitive than OF assays and is as sensitive as WB assays at distinguishing between analgesic doses and doses that impair locomotion.