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Fig. 1 | Arthritis Research & Therapy

Fig. 1

From: Selective inhibition of tropomyosin-receptor-kinase A (TrkA) reduces pain and joint damage in two rat models of inflammatory arthritis

Fig. 1

Effects of the selective tropomyosin-receptor-kinase A (TrkA) inhibitor AR786 on carrageenan-induced pain behaviour. Rat knees were injected with either 2 % carrageenan (triangles and diamonds) or saline (circles) on day 0 (dotted line). Twice-daily oral dose of 30 mg/kg AR786 (diamonds) or 5 % Gelucire vehicle (triangles) control was given 1 h prior to and 8 h after the carrageenan injection and then twice daily (each pair of doses separated by 6 h) through day 4. Vehicle-treated carrageenan-injected animals (triangles) had increased pain behaviour measured as increased difference in weight-bearing (a) and reduced paw withdrawal thresholds (b) through 4 days after carrageenan injection compared with saline-injected controls (circles). Administration AR786 was associated with reduced pain behaviour, with reduced weight-bearing asymmetry from day 1 and increased paw withdrawal thresholds from day 2. Paw withdrawal thresholds were similar in AR786-treated, carrageenan-injected animals to those in saline-injected (non-synovitic) control levels by day 4. Paw withdrawal threshold was not evoked on the contralateral side. *p < 0.05, **p < 0.01 and ***P < 0.001 compared with saline-injected controls; + p < 0.05, ++ p < 0.01, +++ p < 0.001 compared with vehicle-treated, carrageenan-injected animals

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