title: Hepatic Met-enkephalin immunoreactivity is enhanced in primary biliary cirrhosis.
abstract: OBJECTIVE
  In contrast to the normal adult liver, the fetal human and rat livers, and the liver of rats with cholestasis secondary to bile duct resection (BDR) express the preproenkephalin (ppENK) mRNA, which codes for the endogenous opioid peptide Met-enkephalin. In addition, Met-enkephalin immunoreactivity (MEIR) is detected in hepatocytes and in proliferating bile ductules in the cholestatic rat liver. These data suggest that cholestasis is associated with the resurgence of cells that produce Met-enkephalin. To explore further the status of opioids in cholestasis, we studied the expression of MEIR in liver tissue.
  
  
  METHODS
  The MEIR was sought in paraffin-preserved liver tissues from patients with primary biliary cirrhosis (PBC) (n = 10).
  
  
  RESULTS
  The MEIR was detected in all the PBC livers. Its intensity varied from weak to strong on hepatocytes and bile ducts and the strongest expression appeared as coarse granules. The MEIR was either absent or only faintly expressed by some hepatocytes from disease and nondisease control biopsies, but absent from bile ducts.
  
  
  CONCLUSIONS
  These results suggest that the human liver in cholestasis may be a source of endogenous opioids.
authors.affiliation: Division of Gastroenterology and Liver Disease, Beth Israel Medical Center, New York, USA. nb343@columbia.edu
authors.forename: Nora V
authors.initials: NV
authors.lastname: Bergasa
authors.forename: Sally
authors.initials: S
authors.lastname: Liau
authors.forename: Peter
authors.initials: P
authors.lastname: Homel
authors.forename: Violet
authors.initials: V
authors.lastname: Ghali
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004744:Enkephalin, Methionine / Q000378:metabolism*; D005260:Female; D022781:Hepatocytes / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008105:Liver Cirrhosis, Biliary / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged
chemical_list: D004744:Enkephalin, Methionine