5. Experimental models for screening of analgesic substances

The animal models employed for screening of analgesic agents include

#### 5.1. Pain-state models using thermal stimuli

For the activation of cutaneous receptors, heat is a suitable stimulus. Nociceptive stimulation origin can be far apart from its target, for example radiant heat from a lamp in a direct touch with the skin. Comparatively, radiant heat comprises a selective stimulus for nociceptors; moreover, it has an advantage of producing no tactile stimulus over the other ways of thermal stimulation.
