title: Orexin-B-like immunoreactivity localizes in both luteinizing-hormone-containing cells and melanin-concentrating hormone-containing fibers in the red-bellied piranha (Pygocentrus nattereri) pituitary.
abstract: We examined orexin-like immunoreactivity in the pituitary of the red-bellied piranha (Pygocentrus nattereri). Orexin-B-immunoreactive (IR) cells corresponded to luteinizing hormone (LH)-containing cells in the pars distalis, and orexin-B-IR fibers corresponded to melanin-concentrating hormone (MCH)-containing fibers in the pars nervosa. In the pars distalis, orexin-B-IR puncta that were also immunoreactive for MCH were observed around the orexin-B-IR cells. In the ventral hypothalamus, orexin-B-IR and MCH-IR neurons were found in the nucleus lateralis tuberis. Immunoelectron-microscopic analysis revealed that the orexin-B-like substance co-localized with LH in secretory granules and with MCH in MCH-containing neurons. Some of the MCH secreted in the pituitary might participate in the modulation of LH secretion from the gonadotrophs, together with orexin-B, leading to food intake by the stimulation of growth hormone secretion from the somatotrophs.
authors.affiliation: Department of Biology, Fukuoka University of Education, Akamabunkyo-machi, Munakata, Fukuoka, Japan. spiderhs@fukuoka-edu.ac.jp.
authors.forename: Hirohumi
authors.initials: H
authors.lastname: Suzuki
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D060125:Characiformes / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007028:Hypothalamic Hormones / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008543:Melanins / Q000378:metabolism*; D009479:Neuropeptides / Q000276:immunology*; D000068797:Orexins; D010902:Pituitary Gland / Q000166:cytology* / Q000648:ultrastructure; D010907:Pituitary Hormones / Q000378:metabolism*
chemical_list: C000596229:HCRT protein, human; D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone; D007986:Luteinizing Hormone