title: Comparative Anatomy of Gastrin-releasing Peptide Pathways in the Trigeminal Sensory System of Mouse and the Asian House Musk ShrewSuncus murinus.
abstract: Gastrin-releasing peptide (GRP) has recently been identified as an itch-signaling molecule in the primary afferents and spinal cord of rodents. However, little information exists on the expression and localization of GRP in the trigeminal somatosensory system other than in rats. We examined the generality of the trigeminal GRP system in mammals using two distinct species, suncus as a model of specialized placental mammals known to have a well-developed trigeminal sensory system and mice as a representative small laboratory animal. We first analyzed the gross morphology of the trigeminal somatosensory system in suncus to provide a brainstem atlas on which to map GRP distribution. Immunohistochemical analyses showed that 8% of trigeminal ganglion neurons in suncus and 6% in mice expressed GRP. Expression was restricted to cells with smaller somata. The GRP-containing fibers were densely distributed in the superficial layers of the caudal part of the trigeminal spinal nucleus (Vc) but rare in the rostral parts, both in suncus and mice. Expression of GRP receptor mRNA and protein was also detected in the Vc of suncus. Taken together, these results suggest that the trigeminal GRP system mediating itch sensation is conserved in mammals.
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Takanami
authors.affiliation: Anatomy and Neurobiology, Kyoto Prefectural University of Medicine , Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Kaihei
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Anatomy and Neurobiology, Kyoto Prefectural University of Medicine , Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Mukai
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University , Ushimado, Setouchi, Okayama 701-4303, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Tamura
authors.affiliation: Laboratory of Animal Management and Resources, Department of Zoology, Okayama University of Science, Okayama 700-0005, Japan; Division of Bio-resources, Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Miyazaki 889-1692, Japan.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Jogahara
authors.affiliation: Laboratory of Animal Management and Resources, Department of Zoology, Okayama University of Science , Okayama 700-0005, Japan.
authors.forename: Sen-Ichi
authors.initials: SI
authors.lastname: Oda
authors.affiliation: Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan; School of Health Science, Bukkyo University, Higashitoganoo-cho, Nishinokyo, Nakagyo-ku, Kyoto 604-8418, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kawata
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University , Ushimado, Setouchi, Okayama 701-4303, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University , Ushimado, Setouchi, Okayama 701-4303, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sakamoto
keywords: gastrin-releasing peptide (GRP); gastrin-releasing peptide receptor (GRPR); itch; suncus; trigeminal somatosensory system