Using in vivo calcium imaging and home cage behavioural analysis to study pain in mouse models of rheumatoid- and osteo-arthritis

Abstract

AbstractObjectiveThe purpose of this study was to evaluate the use ofin vivocalcium imaging to monitor activity in joint afferents and group-housed home cage monitoring for the assessment of pain-like behaviors in mouse models of rheumatoid- and osteo-arthritis.MethodsAntigen induced arthritis (AIA) was used to model rheumatoid arthritis and partial medial meniscectomy (PMX) was used to model osteoarthritis. Group-housed home cage monitoring was used to assess behaviour in all mice, and weight bearing was performed in PMX mice.In vivocalcium with GCaMP6s was used to monitor spontaneous activity in L4 ganglion joint neurons retrogradely labelled with fast blue 2 days following AIA and 13-15 weeks following PMX. Cartilage degradation was assessed in knee joint sections stained with Safranin O and Fast Green in PMX mice.ResultsAntigen induced arthritis produced knee joint swelling and PMX caused degeneration of articular cartilage in the knee. In the first 46 hours following AIA, mice travelled less distance and were less mobile compared to their control cage mates. In contrast, these parameters were similar between PMX and sham mice between 4-12 weeks post-surgery. Joint neurons had increased spontaneous activity in AIA but not PMX mice. Spontaneous activity was mostly localized to medium-sized neurons in AIA mice and was not correlated with any of the home cage behaviors.ConclusionWe conclude that group-housed home cage monitoring is a suitable technique for assessing joint pain behaviour in AIA mice.In vivoimaging of joint afferents revealed increased spontaneous activity in AIA but not PMX mice.