Table of Contents
ISRN Pharmacology
Volume 2012, Article ID 439860, 6 pages
http://dx.doi.org/10.5402/2012/439860
Research Article

Capsaicin, a TRPV1 Ligand, Suppresses Bone Resorption by Inhibiting the Prostaglandin E Production of Osteoblasts, and Attenuates the Inflammatory Bone Loss Induced by Lipopolysaccharide

1Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan
2Cooperative Major in Advanced Health Science, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan

Received 14 December 2011; Accepted 18 January 2012

Academic Editors: M. Brunner, M. L. Ferrandiz, G. Froldi, and T. W. Stone

Copyright © 2012 Megumi Kobayashi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Capsaicin, a transient receptor potential vanilloid type 1 (TRPV1) ligand, regulates nerve-related pain-sensitive signals, inflammation, and cancer growth. Capsaicin suppresses interleukin-1-induced osteoclast differentiation, but its roles in bone tissues and bone diseases are not known. This study examined the effects of capsaicin on inflammatory bone resorption and prostaglandin E (PGE) production induced by lipopolysaccharide (LPS) in vitro and on bone mass in LPS-treated mice in vivo. Capsaicin suppressed osteoclast formation, bone resorption, and PGE production induced by LPS in vitro. Capsaicin suppressed the expression of cyclooxygenase-2 (COX-2) and membrane-bound PGE synthase-1 (mPGES-1) mRNAs and PGE production induced by LPS in osteoblasts. Capsaicin may suppress PGE production by inhibiting the expression of COX-2 and mPGES-1 in osteoblasts and LPS-induced bone resorption by TRPV1 signals because osteoblasts express TRPV1. LPS treatment markedly induced bone loss in the femur in mice, and capsaicin significantly restored the inflammatory bone loss induced by LPS in mice. TRPV1 ligands like capsaicin may therefore be potentially useful as clinical drugs targeting bone diseases associated with inflammatory bone resorption.