[Effect of morphine on expression of gene of enzymes related to purine nucleotide metabolism in c6 glioma].
OBJECTIVE
To investigate the effect of morphine on catabolism and anabolism of purine nucleotide in c6 glioma cells.


METHODS
C6 glioma cells were cultured and divided into 3 groups: 1) morphine group: morphine (10 micro g/ml culture) was added for 6 h, 12 h, 24 h, 48 h, and 72 h; 2) morphine + naloxone group: naloxone (1 micro mol/L) was added for 1 hour and then morphine (10 micro g/ml) was added for 24 hours; and 3) control group: normal saline was used for 6, 12, 24, 48, and 72 hours. The C6 glioma cells were centrifuged. RT-PCR was used to examine the gene transcripts of key enzymes of purine salvage way, hypoxanthine-guanine-phosphoribosyl transferase (HGPRT) and adenylate kinase (AK). RT-PCR-Southern blotting was used to examine the gene transcripts of key enzymes of purine salvage way, xanthine dehydrogenase (XD)/xanthine oxidase (XO) mRNA.


RESULTS
Compared with that in the control group, the transcript of AK mRNA was significantly lower in the C6 cells treated with morphine for 24 hours, and began to re-increase 48 hours after morphine treatment. The transcript of AK mRNA remained at a low level after treatment of naloxone for 1 hour and treatment of morphine for 24 hours. The levels of transcript of HGPRT mRNA were lower in the morphine group than in the control group at all time points after treatment. However, the level of transcript of HGPRT mRNA 72 hours after treatment was higher in the morphine group than in the control group. The level of transcript of HGPRT mRNA 24 hours after exposure to morphine in the naloxon2 + morphine group was still lower than in the control group. The levels of transcripts of XD/XO mRNA were significantly higher after exposure to morphine in comparison with those in the control group at all time points after treatment. However, the levels of XD/XO mRNA 24 hours after exposure to morphine in the naloxone + morphine group recovered to the normal level.


CONCLUSIONS
The downregulation effect of morphine on the gene expression of AK and HGPRT may not be mediated by mu receptor. The upregulation effect of morphine on the gene expression of XD/XO may be mediated by mu receptor. Naloxone reverses the effect of morphine on enhancement of XD/XO gene expression and cannot reverse the inhibitory effect of morphine on HGPRT and AK gene expression.
Liu
Jian-kai
JK
Department of Biochemistry and Molecular Biology, Basic Medical School of Jilin University, Changchun 130021, China.
Hong
Min
M
Zhao
Xiao-dong
XD
D000248:Adenosine Kinase / Q000235:genetics / Q000378:metabolism*; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D015870:Gene Expression / Q000187:drug effects*; D005910:Glioma / Q000473:pathology; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics / Q000378:metabolism; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D011685:Purine Nucleotides / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D011685:Purine Nucleotides; D012333:RNA, Messenger; D009270:Naloxone; D009020:Morphine; D007041:Hypoxanthine Phosphoribosyltransferase; D000248:Adenosine Kinase