title: Neurochemical organization of the nucleus paramedianus dorsalis in the human.
abstract: We have characterized the neurochemical organization of a small brainstem nucleus in the human brain, the nucleus paramedianus dorsalis (PMD). PMD is located adjacent and medial to the nucleus prepositus hypoglossi (PH) in the dorsal medulla and is distinguished by the pattern of immunoreactivity of cells and fibers to several markers including calcium-binding proteins, a synthetic enzyme for nitric oxide (neuronal nitric oxide synthase, nNOS) and a nonphosphorylated neurofilament protein (antibody SMI-32). In transverse sections, PMD is oval with its long axis aligned with the dorsal border of the brainstem. We identified PMD in eight human brainstems, but found some variability both in its cross-sectional area and in its A-P extent among cases. It includes calretinin immunoreactive large cells with oval or polygonal cell bodies. Cells in PMD are not immunoreactive for either calbindin or parvalbumin, but a few fibers immunoreactive to each protein are found within its central region. Cells in PMD are also immunoreactive to nNOS, and immunoreactivity to a neurofilament protein shows many labeled cells and fibers. No similar region is identified in atlases of the cat, mouse, rat or monkey brain, nor does immunoreactivity to any of the markers that delineate it in the human reveal a comparable region in those species. The territory that PMD occupies is included in PH in other species. Since anatomical and physiological data in animals suggest that PH may have multiple subregions, we suggest that the PMD in human may be a further differentiation of PH and may have functions related to the vestibular control of eye movements.
authors.affiliation: Department of Physiology and Biophysics, 123 Sherman Hall, University at Buffalo, State University of New York, Buffalo, NY 14214, USA. baizer@buffalo.edu
authors.forename: Joan S
authors.initials: JS
authors.lastname: Baizer
authors.forename: James F
authors.initials: JF
authors.lastname: Baker
authors.forename: Kristin
authors.initials: K
authors.lastname: Haas
authors.forename: Raquel
authors.initials: R
authors.lastname: Lima
mesh_terms: D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D015415:Biomarkers / Q000032:analysis; D001931:Brain Mapping; D064032:Calbindin 2; D002135:Calcium-Binding Proteins / Q000378:metabolism; D048430:Cell Shape / Q000502:physiology; D005133:Eye Movements / Q000502:physiology; D006801:Humans; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology; D012249:Rhombencephalon / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D014726:Vestibular Nuclei / Q000502:physiology
chemical_list: D015415:Biomarkers; C576764:CALB2 protein, human; C576511:Calb2 protein, mouse; C576512:Calb2 protein, rat; D064032:Calbindin 2; D002135:Calcium-Binding Proteins; D016900:Neurofilament Proteins; D064030:S100 Calcium Binding Protein G; D052248:Nitric Oxide Synthase Type I