title: Expression of gamma-aminobutyric acid and glutamic acid decarboxylases in rat descending colon and their relation to epithelial differentiation.
abstract: OBJECTIVE
  To detect the expression of gamma-aminobutyric acid (GABA) and glutamic acid decarboxylases (GADs; including two isoforms GAD65 and GAD67) in the epithelial growth zones of the descending colon in rats, and to investigate their relation to epithelial differentiation and proliferation.
  
  
  METHODS
  The expression of GABA and GADs in rat descending colon was investigated by immunofluorescent staining and confocal laser scanning techniques, and goblet cells were further investigated by wheat-germ agglutinin histochemistry. In addition, GAD65 and GAD67 mRNAs were also detected by reverse transcription-polymerase chain reaction. Furthermore, evaluation of cell kinetics in colonic epithelia was conducted by ABC immunostaining using a monoclonal antibody against proliferating cell nuclear antigen (PCNA).
  
  
  RESULTS
  Immunoreactive GABA and GADs were distributed in the upper third of the crypts and at the luminal surface in the rat descending colon. Strong staining for GABA and GADs was localized mainly in the cytoplasm of epithelial cells near the neck of the crypts and along the luminal surface. In addition, GABA and GAD65 were also detected at the lamina propria in colonic mucosa. No staining for GABA or GADs was found in goblet cells. GAD65 and GAD67 mRNAs were identified in homogenates of rat descending colon. PCNA labeled nuclei were found in the lower two-thirds of the crypts.
  
  
  CONCLUSIONS
  The expression of GABA and GADs in the maturation and function zones of rat descending colon suggests that GABA may be involved in the differentiation of colonic epithelial cells.
authors.affiliation: Department of Gastroenterology, Nanjing General Hospital of Nanjing Military Command, PLA, Nanjing, China. wangf65@yahoo.com
authors.forename: Fang Yu
authors.initials: FY
authors.lastname: Wang
authors.forename: Ren Min
authors.initials: RM
authors.lastname: Zhu
authors.forename: Kentaro
authors.initials: K
authors.lastname: Maemura
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hirata
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Katsu
authors.forename: Masahito
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D044683:Colon, Descending / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000096:biosynthesis*; D007150:Immunohistochemistry / Q000379:methods; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D037102:Lectins; D008297:Male; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013194:Staining and Labeling; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
chemical_list: D037102:Lectins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase