abstract: BACKGROUND: It has recently been suggested that non-reflex behavioral readouts, such as burrowing, may be used to evaluate the efficacy of analgesics in rodent models of @entity2 . OBJECTIVE: To confirm whether intraplantar Complete Freund's Adjuvant ( @entity8 )-induced @entity2 reliably results in @entity1 which can be ameliorated by clinically efficacious analgesics as previously suggested. METHODS: Uni- or bilateral intraplantar @entity8 injections were performed in male @entity0 Han @entity0 . The time- and concentration-response of @entity1 and the ability of various analgesics to reinstate burrowing performance were studied. An anxiolytic was also tested to evaluate the motivational cue that drives this behavior. RESULTS: @entity1 were dependent on the concentration of @entity8 injected, most pronounced 24h after @entity8 injections and even more pronounced after bilateral compared with unilateral injections. @entity10 and @entity9 reversed @entity8 -induced @entity1 whereas @entity7 failed to significantly reinstate burrowing performance. @entity3 and @entity4 failed to reinstate burrowing performance, but sedation was observed in control @entity0 at doses thought to be efficacious. An antibody directed against the nerve growth factor significantly improved @entity8 -induced @entity1 . Neither @entity5 nor the anxiolytic @entity6 reinstated burrowing performance and the opportunity to find shelter did not modify burrowing performance. CONCLUSION: Burrowing is an innate behavior reliably exhibited by @entity0 . It is suppressed in a model of @entity2 and differently reinstated by clinically efficacious analgesics that lack motor impairing side effects, but not an anxiolytic, suggesting that this assay is suitable for the assessment of analgesic efficacy of novel drugs.
  