title: Neuronal nitric oxide synthase immunoreactivity in the guinea-pig liver: distribution and colocalization with neuropeptide Y and calcitonin gene-related peptide.
abstract: OBJECTIVE
  The innervation pattern of the guinea-pig liver is similar to that of the human liver. However, many aspects of the distribution of the neuronal isoform of the enzyme nitric oxide synthase (nNOS) in the guinea-pig liver and its colocalization with neuropeptides remain to be elucidated.
  
  
  METHODS
  The distribution of nNOS was studied in fixed guinea-pig liver by light microscopic immunohistochemistry. Confocal analysis was used to determine its colocalization with neuropeptide Y (NPY) or calcitonin gene-related peptide (CGRP).
  
  
  RESULTS
  nNOS-immunoreactive (nNOS-IR) nerves were observed in relation to hilar and interlobar vessels and in Glisson's capsule. A few nNOS-IR ganglia were observed in the extrahepatic bile duct and close to the interlobar portal triads. In addition, nNOS-IR fibers were located in the interlobular portal triads and pervading the parenchyma. Moreover, nNOS-IR nerves were demonstrated for the first time in the larger central veins and in the hepatic vein. nNOS-NPY and nNOS-CGRP colocalizations were detected in the fibromuscular layer of the bile duct and periductal plexus, respectively.
  
  
  CONCLUSIONS
  These results support the phylogenetic conservation of the nNOS-IR hepatic innervation and its possible contribution to the regulation of hepatic blood flow and certain hepatic functions.
authors.affiliation: Area de Biología Celular, Unidad Asociada C.S.I.C.-Universidad de Jaén, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Esteban
authors.forename: A
authors.initials: A
authors.lastname: Jiménez
authors.forename: A P
authors.initials: AP
authors.lastname: Fernández
authors.forename: M L
authors.initials: ML
authors.lastname: del Moral
authors.forename: A M
authors.initials: AM
authors.lastname: Sánchez-López
authors.forename: R
authors.initials: R
authors.lastname: Hernández
authors.forename: M
authors.initials: M
authors.lastname: Garrosa
authors.forename: J A
authors.initials: JA
authors.lastname: Pedrosa
authors.forename: J
authors.initials: J
authors.lastname: Rodrigo
authors.forename: M A
authors.initials: MA
authors.lastname: Peinado
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006168:Guinea Pigs; D008099:Liver / Q000294:innervation*; D008297:Male; D018613:Microscopy, Confocal; D009478:Neuropeptide Y / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D017933:Peripheral Nervous System / Q000201:enzymology*
chemical_list: D009478:Neuropeptide Y; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D015740:Calcitonin Gene-Related Peptide