Assessing the impact of non-steroidal antiinflammatory drugs in the hot plate test: An alternative model

The current paradigm for the hot plate pain test is problematic in several ways. It uses very limited behavioral criteria to define pain; traditionally, the hot plate pain test measures rats' latencies to performing a specified behavior (hind paw mouthing or jumping) when placed on a warm surface. Also, the hot plate test yields significant results for only certain analgesics. Non-steroidal antiinflammatory drugs (NSAIDs) have an analgesic effect in humans. They do not, however, affect hot plate latencies in rats, unlike opioid analgesics, such as morphine. This study was intended to develop a new paradigm for using the hot plate to determine the effectiveness of different analgesics. This study had two main components; first, an inventory of morphine and saline treated rats' behavior on the hot plate was compiled. Videotaped sessions of rats being placed on the hot plate were used to operationally define several behaviors not commonly employed in hot plate analysis. Then the frequencies of these behaviors were determined from the tapes and used to develop a paradigm intended to yield significant results for rats treated with NSAIDs. In the second component of this study, rats treated with ibuprofen, an NSAID, were subjected to the new paradigm. These rats displayed certain behaviors at a significantly different frequency than control rats suggesting that there are in fact behavioral changes on the hot plate in response to NSAIDs, and they are detectable with the new paradigm.