title: L-Histidine decarboxylase protein and activity in rat brain microvascular endothelial cells.
abstract: OBJECTIVE
  L-Histidine decarboxylase (HDC) is the primary enzyme regulating histamine biosynthesis. This study was carried out to examine whether the cultured rat brain microvascular endothelial cells (BMEC), which constitute the blood-brain barrier (BBB), have the ability to form histamine, and whether HDC mRNA is expressed in rat BMEC.
  
  
  METHODS
  Male, 3-week-old Wistar rats were used. For in vitro studies, rat BMEC were isolated from rat brains, and subculture cells were grown on collagen-coated culture flask and slide.
  
  
  METHODS
  HDC assay, immunofluorescence analysis and expression of HDC mRNA by RT-PCR were performed in rat BMEC.
  
  
  RESULTS
  The HDC activity of the BMEC was estimated to be 0.14 +/- 0.05 p mol/min/mg protein. This activity was completely inhibited by (S)-alpha-fluoromethylhistidine, a specific inhibitor of HDC. Using a polyclonal anti HDC antibody and immunofluorescence microscopy, we confirmed the presence of HDC protein in rat BMEC. RT-PCR also showed the expression of HDC mRNA in rat BMEC.
  
  
  CONCLUSIONS
  L-Histidine uptaken by rat BMEC was shown to be converted to histamine, suggesting that HDC plays an important role in BBB.
authors.affiliation: Department of Pharmaceutics I, Tohoku Pharmaceutical University, Sendai, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Yamakami
authors.forename: E
authors.initials: E
authors.lastname: Sakurai
authors.forename: A
authors.initials: A
authors.lastname: Kuramasu
authors.forename: E
authors.initials: E
authors.lastname: Sakurai
authors.forename: K
authors.initials: K
authors.lastname: Yanai
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000201:enzymology*; D002196:Capillaries / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006632:Histamine / Q000378:metabolism / Q000494:pharmacology; D006639:Histidine / Q000378:metabolism; D006640:Histidine Decarboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D004791:Enzyme Inhibitors; D008762:Methylhistidines; D012333:RNA, Messenger; D006639:Histidine; C028309:alpha-fluoromethylhistidine; D006632:Histamine; D006640:Histidine Decarboxylase