Recently, we reported that our novel weight-bearing measurement in voluntarily walking rats is a realistic, convenient and less stressful method for measuring arthritic pain. In this study, we assessed whether our device can measure the degree of severity of pain quantitatively in the acute arthritis and even in the chronic arthritis in the rat.In the acute arthritic experiment, rats injected with carrageenan (0.1, 0.5, 1.0, 5% suspended in 50 ㎕ normal saline) and saline (50 ㎕) into their right knee joint cavity were made to walk through a pathway constructed to record the weight load by means of weight sensor(strain gauge) attached to the floor. After base line test, weight bearing test was performed at various point of time starting from 4 hours to 10 days after the carrageenan injection. In the chronic arthritic experiment, rats were injected with complete Freund’s adjuvant (50, 100 ㎕) and saline (50, 100 ㎕). Weight bearing tests were conducted at various point of time before and from 1 days to 50 days after complete Freund’s adjuvant injection. Following the carrageenan injection, the weight load on the injected side reduced in a dose dependent manner and fell to the lowest point at 4 hours in all group except for saline-treated group. In results of the complete Freund’s adjuvant injection, rats showed the lowest weight bearing by 1st day and returned to the pre-injection level by 15th day. These results suggest that our device can measure quantitatively the severity of pain in the acute arthritic model as well as chronic arthritic model in the rat.
Source: Korean J Physiol Pharmacol.2001 Dec;5(Suppl II):S95
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