2000). In contrast to most other main nerve trunks, the first and second trigeminal branches are purely sensory, and the motor (masticatory) component of the third branch is distinctly separated from the sensory component by a thick perineurial sheath, from the trigeminal root to the proximal part of the branch. Moreover, there are several human pain conditions that affect specifically the trigeminal nerves and a differential
Inhibitors,research,lifescience,medical sensitivity to certain drugs in neuropathic pain in the trigeminal versus other territories has been observed (Idanpaan-Heikkila and Guilbaud 1999; Watson 2004). It is therefore valuable to develop specific animal models for the Protein Tyrosine Kinase inhibitor orofacial area. This review presents an overview of the rodent models developed for the trigeminal area over the last 20 years, with the emphasis on behavioral tests. To date, most reviews have overviewed the mechanistic
components of trigeminal Inhibitors,research,lifescience,medical pain but none have focused specifically on the various behavioral testing methods available in rodents. For reviews which specifically elucidate the mechanisms of orofacial pain, see for example Sessle (2005), Inhibitors,research,lifescience,medical Hargreaves (2011), Takeda et al. (2011), Iwata et al. (2011). The scope of this review will span basic research on the rodent skin and mucosa, and muscular and articular sensory territories of the trigeminal Inhibitors,research,lifescience,medical nerve that has been published in the last few decades. For reasons of simplicity, and because these topics have already been broadly discussed in the literature, models that involve specific target organs such as teeth, the eye, and salivary glands will be omitted. Useful reviews and reports are available on dental pain (Cooper
and Desjardins 2010; Tarsa et al. 2010; Hargreaves 2011), eye pain (Tashiro et al. 2010; Marquart 2011), and salivary gland pain (Ogawa et al. 2003). Cancer pain has certain inflammatory components and sometimes some neuropathic pain aspects (Mantyh et al. 2002; Benoliel et al. Inhibitors,research,lifescience,medical 2007). The behavioral evaluation methods used in animal models of orofacial cancer pain are similar to those used in other orofacial pain models (Nagamine et al. 2006; Ono et al. 2009; Harano check et al. 2010) and this topic will also not be explored in this review. Finally, chronic primary headaches, including migraines, fall into craniofacial disorders but are not usually considered “orofacial” conditions1 (Zakrzewska 2009) and thus will not be discussed. Of particular interest will be models of TN, TMD, and facial muscle pain and other models of cutaneous nociception in rodent orofacial pain. While several recent reviews have summarized some of the techniques used to induce neuropathic or inflammatory pain in the facial region (Khan and Hargreaves 2010; Iwata et al.