title: Neurokinin B- and kisspeptin-positive fibers as well as tuberoinfundibular dopaminergic neurons directly innervate periventricular hypophyseal dopaminergic neurons in rats and mice.
abstract: Neurons co-expressing kisspeptin, neurokinin B (NKB), and dynorphin in the hypothalamic arcuate nucleus, named KNDy neurons, are directly affected by sex hormones, and are well known for regulating the secretion of gonadotropin-releasing hormone. However, recent studies have shown that KNDy neurons also project and terminate to tuberoinfundibular dopaminergic (TIDA) neurons, suggesting a role in prolactin secretion. Moreover, there is a possibility that other neurosecretory dopaminergic neurons regulating prolactin secretion, such as periventricular hypophyseal dopaminergic (PHDA) neurons, may also be innervated by KNDy neurons. In the present study, by means of double immunohistochemistry and retrograde neural tracer, we examined whether KNDy neurons project directly to PHDA neurons that project to blood vessels, as well as to TIDA neurons. The results revealed that KNDy neurons are widely projecting to neurosecretory dopaminergic neurons of the PHDA and TIDA neurons in rats and mice. Secondary, presence of a major receptor for NKB, neurokinin-3 receptor (NK3R), in PHDA and TIDA neurons was examined and it appeared that most TIDA and PHDA neurons possess NK3R. These findings indicate that, in rodents, KNDy neurons widely project to neurosecretory dopaminergic neurons distributed in the hypothalamus, and may affect them via the NKB-NK3R signaling pathway.
authors.affiliation: Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. Electronic address: nsawai@gunma-u.ac.jp.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sawai
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan. Electronic address: niijima@nms.ac.jp.
authors.forename: Norio
authors.initials: N
authors.lastname: Iijima
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan. Electronic address: hozawa@nms.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ozawa
authors.affiliation: Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. Electronic address: matoshi@gunma-u.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Matsuzaki
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology*; D059290:Dopaminergic Neurons / Q000378:metabolism*; D005260:Female; D007026:Hypothalamic Area, Lateral / Q000166:cytology*; D021621:Imaging, Three-Dimensional; D059648:Kisspeptins / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009412:Nerve Fibers / Q000502:physiology*; D059906:Neuroimaging; D015287:Neurokinin B / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018042:Receptors, Neurokinin-3 / Q000378:metabolism; D013266:Stilbamidines / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D059648:Kisspeptins; D018042:Receptors, Neurokinin-3; D013266:Stilbamidines; D015287:Neurokinin B; D014446:Tyrosine 3-Monooxygenase
keywords: Kisspeptin; Neurokinin B; Neurokinin-3 receptor; Neurosecretory dopaminergic neurons; Prolactin