title: Morphine enhances purine nucleotide catabolism in vivo and in vitro.
abstract: OBJECTIVE
  To investigate the effect and mechanism of morphine on purine nucleotide catabolism.
  
  
  METHODS
  The rat model of morphine dependence and withdrawal and rat C6 glioma cells in culture were used. Concentrations of uric acid in the plasma were measured by the uricase-rap method, adenosine deaminase (ADA) and xanthine oxidase (XO) in the plasma and tissues were measured by the ADA and XO test kit. RT-PCR and RT-PCR-Southern blotting were used to examine the relative amount of ADA and XO gene transcripts in tissues and C6 cells.
  
  
  RESULTS
  (i) the concentration of plasma uric acid in the morphine-administered group was significantly higher (P<0.05) than the control group; (ii) during morphine administration and withdrawal periods, the ADA and XO concentrations in the plasma increased significantly (P<0.05); (iii) the amount of ADA and XO in the parietal lobe, liver, small intestine, and skeletal muscles of the morphine-administered groups increased, while the level of ADA and XO in those tissues of the withdrawal groups decreased; (iv) the transcripts of the ADA and XO genes in the parietal lobe, liver, small intestine, and skeletal muscles were higher in the morphine-administered group. The expression of the ADA and XO genes in those tissues returned to the control level during morphine withdrawal, with the exception of the skeletal muscles; and (v) the upregulation of the expression of the ADA and XO genes induced by morphine treatment could be reversed by naloxone.
  
  
  CONCLUSIONS
  The effects of morphine on purine nucleotide metabolism might be an important, new biochemical pharmacological mechanism of morphine action.
authors.affiliation: Department of Biochemistry and Molecular Biology, Basic Medical School, Jilin University, Jilin, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Jian-kai
authors.initials: JK
authors.lastname: Liu
authors.forename: Mu-jie
authors.initials: MJ
authors.lastname: Kan
authors.forename: Lin
authors.initials: L
authors.lastname: Gao
authors.forename: Hai-ying
authors.initials: HY
authors.lastname: Fu
authors.forename: Hang
authors.initials: H
authors.lastname: Zhou
authors.forename: Min
authors.initials: M
authors.lastname: Hong
mesh_terms: D000243:Adenosine Deaminase / Q000032:analysis / Q000235:genetics; D000818:Animals; D001806:Blood Urea Nitrogen; D045744:Cell Line, Tumor; D005260:Female; D009020:Morphine / Q000494:pharmacology*; D011685:Purine Nucleotides / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D014527:Uric Acid / Q000097:blood; D014969:Xanthine Oxidase / Q000032:analysis / Q000235:genetics
chemical_list: D011685:Purine Nucleotides; D012333:RNA, Messenger; D014527:Uric Acid; D009020:Morphine; D014969:Xanthine Oxidase; D000243:Adenosine Deaminase