1. Laboratory of Neuroendocrinology, Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Kashino, Ushimado, Setouchi, Okayama 701-4303, Japan
2. Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan