1. Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
2. Department of Orthopaedic Surgery, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan
3. Department of Physiology, School of Dentistry, Nihon University, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
4. Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing 100069, P.R. China