chapter  13
12 Pages

Pain Relief by Local Peripheral Injection of Beta-Caryophyllene through Cannabinoid 2 Receptor

Aromatherapy usually uses aromatic essential oils, which are highly volatile organic compounds extracted by distillation from plants to achieve physical and psychological health. Plants are used for various purposes, including their cosmetic, nutritive, and biomedical properties. Plant-derived drugs have played an important role in health and wellness benets. Plant essential oils are typically composed of volatile aromatic terpenes and phenylpropanoids. The natural sesquiterpene beta-caryophyllene (BCP) is a major plant volatile found in large amounts in the essential oils of many different spice and food plants, such as clove, oregano, thyme, black pepper, and cinnamon (Legault and Pichette, 2007), all of which have been used as natural remedies and fragrances. BCP has been shown to

13.1 Introduction ..................................................................................................269 13.2 Cannabinoid 2 Receptor ............................................................................... 270 13.3 Beta-Caryophyllene ...................................................................................... 270 13.4 Local Peripheral Antinociceptive Effects of Beta-Caryophyllene ............... 272

13.4.1 Antinociceptive Effect of Local Intraplantar Injection of BCP Was Assayed by the Capsaicin Tests in Mice ...................... 272

13.4.2 Antiallodynic Effect of Local Intraplantar Injection of BCP Was Assayed by the PSNL-Induced Mechanical Allodynia Model in Mice ............................................. 274

References .............................................................................................................. 276

produce marked anti-inammatory activity against carrageenan-and prostaglandin E1-induced edema in rats as well as antiarthritic activity (Martin et al., 1993; Baricevic et al., 2001; Agarwal and Rangari, 2003). There is evidence that oral administration of BCP is sufcient to display anti-inammatory effects on dextran sulfate sodium-induced colitis in mice (Beltramo, 2009 for review). Moreover, BCP is known to be a major component in the essential oil of the marijuana plant Cannabis sativa L. (Hendriks et al., 1975), while Δ9-tetrahydrocannabinol, the active constituent of marijuana, binds with high afnity to cannabinoid (CB) receptors, cloned and determined as the CB1 and CB2 receptor subtypes (Matsuda et al., 1990; Munro et al., 1993). There is accumulated evidence that the activation of both CB1 and CB2 receptors elicits antinociception in mice and rats through not only central, but also peripheral mechanisms involving CB1 and CB2 receptors (for review, Hohmann, 2002; Malan et al., 2002; Anand et al., 2009). Further studies show that the activation of CB2 receptors stimulates the release from keratinocytes of β-endorphin, an endogenous opioid (Ibrahim et al., 2005). In addition, there is evidence that the activation of peripheral μ-opioid receptors in local tissue is effective at attenuating neuropathic pain (Obara et al., 2004; Guan et al., 2008). This review will focus on elucidating the pain relief functions of beta-caryophyllene and peripheral CB2 receptor.