Figure 1.
Prints from rats in the PawPrint walkway.
The walking pattern of a normal control rat (upper panel) and a representative monoarthritic rat (lower panel). The inflammatory induction agent was injected into the ankle joint of the left hind paw. The middle trace of each panel shows prints from the left side in red, from the right side in blue. Prints from forepaws are shown in light colour, also seen separately in the lower trace, whereas prints from the hind paws are darker, and shown separately in the upper trace. Each print detected by the PawPrint algorithm is surrounded by a white rectangle, but coloured red for the calculated median print. In places where prints would have been expected in normal gait, but not actually detected, green rectangles occur. When such a “non-print” is chosen as the median print, the rectangle is coloured orange.
Figure 2.
Visual rating scale for weight bearing during locomotion.
Illustration of typical paw prints reflecting the rating scale used. In addition to the visual print pattern, the following criteria were implemented: 0 was assigned to rats where no difference could be detected between the two hind paws, 1.5 required the animals to limp, 2.5 was assigned when each step cycle was complete, i.e. that the affected paw touched the floor at every step, 2.75 when only some of the cycles were complete, and 3 when the paw remained off the floor for the entire crossing.
Table 1.
Paw pressure visual rating scale in rats filmed in observation chambers.
Figure 3.
Correlation between ratings of weight bearing while standing and during locomotion after FCA-induced arthritis of the ankle.
The visual rating scores on the walkway (during walking) corresponding to each conventional (while standing) observation chamber score are presented as mean ± SEM. The dashed line represents an exponential curve fit based on all paired observations.
Figure 4.
FCA ankle joint injection affects weight bearing of the four paws during locomotion differently.
Time course of the weight bearing of the injected left hind paw (A), the non-injected right hind paw (B), the left forepaw (C) and the right forepaw (D), in naïve control rats and rats before and after induction of monoarthritis by injecting FCA or Freund's incomplete adjuvant into the ankle joint. For clarity, data from some concentrations (0.25, 0.50, 2.0 and 4.0 mg/mL) are omitted. Data shown as mean and SEM, n = 8–9 per group.
Figure 5.
FCA ankle joint injection increases guarding and reduces regularity during locomotion.
Time course of guarding index (upper panel) and regularity index (lower panel) in naïve control rats and rats before and after induction of monoarthritis by injecting FCA or Freund's incomplete adjuvant into the ankle joint. Bonferroni's test subsequent to ANOVA: * = p<0.05, ** = p<0.01, *** = p<0.001 compared to the naïve control group at the same time point. Data shown as mean and SEM, n = 8–9 per group.
Figure 6.
Carrageenan ankle joint injection affects weight bearing of the four paws during locomotion differently.
Time course of the weight bearing of the injected left hind paw (A), the non-injected right hind paw (B), the left forepaw (C) and the right forepaw (D), in control rats and rats before and after induction of monoarthritis by carrageenan in the ankle joint. Concentrations omitted for clarity (0.94, 3.8 and 15 mg/mL) follow the same pattern of response, in between the results of those shown. Data shown as mean and SEM, n = 10 per group.
Figure 7.
Carrageenan ankle joint injection increases guarding and reduces regularity during locomotion.
Time course of guarding index (upper panel) and regularity index (lower panel) in control rats and rats before and after induction of monoarthritis by carrageenan in the ankle joint. Bonferroni's test subsequent to ANOVA: * = p<0.05, ** = p<0.01, *** = p<0.001 compared to the control group at the same time point. Data shown as mean and SEM, n = 10 per group.
Figure 8.
Injection site of FCA plays a role for magnitude of response during locomotion.
Time course of the guarding index (upper panel) and regularity index (lower panel) for control rats and rats injected with FCA into the ankle or knee joint. Bonferroni's test subsequent to ANOVA: * = p<0.05, ** = p<0.01, *** = p<0.001 compared to the control group at the same time point and † = p<0.05 when comparing ankle to knee injection groups. Data shown as mean and SEM, n = 10 per group.
Figure 9.
Injection site of carrageenan plays a role for magnitude of response during locomotion.
Time course of guarding index (upper panel) and regularity index (lower panel) for control rats and rats injected with carrageenan into the ankle or knee joint. Bonferroni's test subsequent to ANOVA: *** = p<0.001 compared to the control group at the same time point and †† = p<0.01, ††† = p<0.001 when comparing ankle to knee injection groups. Data shown as mean and SEM, n = 10 per group.
Figure 10.
Magnitude of response depends on injection site as well as testing paradigm.
Time course of weight bearing for control rats and rats injected with carrageenan into the ankle or knee joint. Upper panel: weight bearing during locomotion in the PawPrint paradigm. Lower panel: Static weight bearing of the same animals in the Incapacitance tester. Bonferroni's test subsequent to ANOVA: * = p<0.05, ** = p<0.01, *** = p<0.001 compared to the control group at the same time point and † = p<0.05, †† = p<0.01, ††† = p<0.001 when comparing ankle to knee injection groups. Data shown as mean and SEM, n = 10 per group.
Table 2.
Effect of reference compounds on carrageenan induced monoarthritis.