title: Immunohistochemical localization of a GnRH-like peptide in the brain of the cephalopod spear-squid, Loligo bleekeri.
abstract: We examined whether a gonadotropin-releasing hormone (GnRH)-like peptide exists in the brain of the cephalopod spear-squid, Loligo bleekeri, by performing a time-resolved fluoroimmunoassay and immunohistochemistry. The displacement curve obtained for serially diluted extracts of the spear-squid brain paralleled the chicken GnRH-II (cGnRH-II) standard curve, indicating the existence of a cGnRH-II-like peptide in the brain. For immunohistochemistry, a mouse monoclonal antibody raised against the common amino acid sequence of GnRH (LRH13) and a rabbit polyclonal antibody raised against cGnRH-II were used. GnRH-like-immunoreactive (ir) cell bodies (that reacted with LRH13) were mainly detected in the central part of the ventral magnocellular lobe (vmL), and a few cell bodies were also detected in the olfactory lobe and palliovisceral lobe (pvL). Bundles of GnRH-like-ir axons were observed running from the vmL to the internal brain regions. GnRH-like-ir fibers were widely distributed in almost all the brain regions. cGnRH-II-ir cell bodies were localized in the optic gland, outer region of the vmL, and pvL. Further, cGnRH-II-ir fibers were distributed in the wide areas of the brain. These results suggest that at least two forms of GnRH-like peptidergic neuronal systems exist in the spear-squid brain.
authors.affiliation: School of Fisheries Sciences, Kitasato University, Ofunato, Iwate, Japan. amanoma@kitasato-u.ac.jp
authors.forename: Masafumi
authors.initials: M
authors.lastname: Amano
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Oka
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nagai
authors.forename: Noriko
authors.initials: N
authors.lastname: Amiya
authors.forename: Kunio
authors.initials: K
authors.lastname: Yamamori
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001369:Axons / Q000378:metabolism; D001921:Brain / Q000166:cytology; D001923:Brain Chemistry / Q000502:physiology*; D002645:Chickens; D005455:Fluorescent Antibody Technique; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007150:Immunohistochemistry; D049834:Loligo / Q000502:physiology*; D051379:Mice; D012487:Salmonidae; D012694:Serine / Q000378:metabolism; D013045:Species Specificity; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D007987:Gonadotropin-Releasing Hormone; D014443:Tyrosine; D012694:Serine