title: Co-expression of endothelial and neuronal nitric oxide synthases in the developing vasculatures of the human fetal eye.
abstract: BACKGROUND
  Nitric oxide (NO) is a multifunctional gaseous molecule that regulates various physiological functions in both neuronal and non-neuronal cells. NO is synthesized by nitric oxide synthases (NOSs), of which three isoforms have been identified. Neuronal NOS (nNOS) and endothelial NOS (eNOS) constitutively produce low levels of NO as a cell-signaling molecule in response to an increase in intracellular calcium concentration. Recent data have revealed a predominant role of eNOS in both angiogenesis and vasculogenesis.
  
  
  METHODS
  The immunohistochemical localization of nNOS and eNOS was investigated during embryonic and fetal ocular vascular development from 7 to 21 weeks gestation (WG) on sections of cryopreserved tissue.
  
  
  RESULTS
  eNOS was confined to endothelial cells of developing vessels at all ages studied. nNOS was prominent in nuclei of vascular endothelial and smooth muscle cells in the fetal vasculature of vitreous and choriocapillaris. nNOS was also prominent in the nuclei of CXCR4(+) progenitors in the inner retina and inner neuroblastic layer.
  
  
  CONCLUSIONS
  These findings demonstrate co-expression of n- and eNOS isoforms in different compartments of vasoformative cells during development. Nuclear nNOS was present in vascular and nonvascular progenitors as well as endothelial cells and pericytes. This suggests that nNOS may play a role in the transcription regulatory systems in endothelial cells and pericytes during ocular hemo-vasculogenesis, vasculogenesis, and angiogenesis.
authors.affiliation: Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, M041 Smith Research Building, 400 North Broadway, Baltimore, MD 21287, USA.
authors.forename: D Scott
authors.initials: DS
authors.lastname: McLeod
authors.forename: Takayuki
authors.initials: T
authors.lastname: Baba
authors.forename: Imran A
authors.initials: IA
authors.lastname: Bhutto
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Lutty
mesh_terms: D002829:Choroid / Q000098:blood supply / Q000196:embryology; D003238:Connective Tissue / Q000196:embryology* / Q000201:enzymology; D047108:Embryonic Development; D004730:Endothelium, Vascular / Q000196:embryology* / Q000201:enzymology; D005123:Eye / Q000098:blood supply / Q000196:embryology*; D047109:Fetal Development; D005865:Gestational Age; D006801:Humans; D007124:Immunoenzyme Techniques; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009131:Muscle, Smooth, Vascular / Q000196:embryology* / Q000201:enzymology; D018919:Neovascularization, Physiologic; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D012171:Retinal Vessels / Q000196:embryology / Q000201:enzymology; D014822:Vitreous Body / Q000098:blood supply / Q000196:embryology
chemical_list: C496320:NOS1 protein, human; C496314:NOS3 protein, human; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III