Neuronal nitric oxide synthase immunoreactivity in the guinea-pig liver: distribution and colocalization with neuropeptide Y and calcitonin gene-related peptide.
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.
Esteban
F J
FJ
Area de Biología Celular, Unidad Asociada C.S.I.C.-Universidad de Jaén, Spain.
Jiménez
A
A
Fernández
A P
AP
del Moral
M L
ML
Sánchez-López
A M
AM
Hernández
R
R
Garrosa
M
M
Pedrosa
J A
JA
Rodrigo
J
J
Peinado
M A
MA
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*
D009478:Neuropeptide Y; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D015740:Calcitonin Gene-Related Peptide