We provide the following two models for pain assay:

         Model for measuring thermal antinociception: Warm water tail-withdrawal assay:

         Capsaicin-induced thermal allodynia/hyperalgesia

Categories

1.       Monkey model- Warm water tail-withdrawal assay

2.       Rat pain models

Monkey Pain Model - Warm water tail-withdrawal assay

·         Model for measuring thermal antinociception: Warm water tail-withdrawal assay:

-          Adult intact male and female monkeys are adapted to sitting in primate restraint chairs during the test sessions that normally last for 2-3 hours.

-          A water bath is located in the test room, in which thermos flasks are filled with water at 42, 46, 50, and 54^oC prepared immediately before each test.

-          This procedure is able to detect an allodynic/hyperalgesic effect (a reduction in tail-withdrawal latency in 42 and 46^oC water) or antinociception (a prolonged tail-withdrawal latency in 50^oC water).

-          Tail-withdrawal latencies are recorded manually by a computerized timer. A maximum cutoff latency, 20 sec, is recorded if the monkey does not remove its tail by this time. Each experimental session begins with control determinations at each temperature.

Rat Pain Models

·         Capsaicin-induced thermal allodynia/hyperalgesia: The 46^oC water is the monkey’s thermal threshold for expressing allodynic/hyperalgesic responses following the induction of inflammation. Capsaicin is administered s.c. in the terminal of the tail. Subsequent tail-withdrawal latencies are determined at 15, 30, 60 min after injection. Experimental sessions will be conducted once per two weeks, depending on whether local injections of these irritants cause any skin infection or change the monkey’s baseline tail-withdrawal responses. In our experience, this inter-injection interval for capsaicin has not caused any changes in monkeys’ thermal nociceptive threshold.