title: Estrogen upregulates nitric oxide synthase expression in cultured rat hepatic sinusoidal endothelial cells.
abstract: OBJECTIVE
  Estrogen receptor (ER) is present in vascular endothelial cells and estrogen promotes nitric oxide (NO) synthesis, which relaxes smooth muscle cells. It is also speculated that NO is synthesized by estrogen in hepatic sinusoidal endothelial cells (SECs). Here we investigated the localization of ER and endothelial cell nitric oxide synthase (ecNOS), and determined 17beta-estradiol (E2)-induced ecNOS expression in normal rat SECs.
  
  
  METHODS
  Cultured SECs were used. Fluorescence intensities of ecNOS were measured by immunofluorescence using a confocal laser-scanning microscope. E2 was added (100 pg/ml) to the culture medium, and the expressions of ecNOS mRNA and protein were analyzed by reverse-transcription polymerase chain reaction and Western blotting. NO production in cultured SECs was examined using diaminofluorescein-2 diacetate as a fluorescent indicator for NO.
  
  
  RESULTS
  Immunolocalization of ER and ecNOS in normal liver was demonstrated in endothelial cells lining the hepatic sinusoids. ER and ecNOS were localized in the nuclei and cytoplasm of cultured SECs, respectively. The mRNA expression of ecNOS in cultured SECs was increased after 6 h, and the protein expression of ecNOS was increased 24 h after E2 stimulation. The fluorescence intensity of NO in cultured SECs was increased by E2 stimulation compared with untreated control cells.
  
  
  CONCLUSIONS
  These results suggested that ER is present in SECs, and estrogen upregulates NO production in SECs. E2 may be involved in the regulation of the hepatic sinusoidal microcirculation.
authors.affiliation: Second Department of Medicine, Kurume University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Sakamoto
authors.forename: T
authors.initials: T
authors.lastname: Uen
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: O
authors.initials: O
authors.lastname: Hashimoto
authors.forename: R
authors.initials: R
authors.lastname: Sakata
authors.forename: M
authors.initials: M
authors.lastname: Kin
authors.forename: R
authors.initials: R
authors.lastname: Ogata
authors.forename: T
authors.initials: T
authors.lastname: Kawaguch
authors.forename: T
authors.initials: T
authors.lastname: Torimura
authors.forename: M
authors.initials: M
authors.lastname: Sata
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology; D004958:Estradiol / Q000494:pharmacology*; D007150:Immunohistochemistry; D008099:Liver / Q000098:blood supply / Q000187:drug effects / Q000201:enzymology*; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000235:genetics* / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D011960:Receptors, Estrogen; D009569:Nitric Oxide; D004958:Estradiol; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat