Morphine-induced overexpression of prepro-nociceptin/orphanin FQ in cultured astrocytes.
The effects of morphine on the gene expression of prepro-nociceptin/orphanin FQ (ppN/OFQ) in various primary cultured brain cells from embryonic day 17, rats were studied by use of real-time RT-PCR method. The basal level of ppN/OFQ mRNA in terms of ratio to the beta-actin in astrocytes was equivalent to that in neurons, but 10-times higher than that in microglia. The addition of 1 microM morphine significantly enhanced the ppN/OFQ mRNA levels in cultured astrocytes, but not neurons or microglia. The enhancement was observed as early as 1h after the addition of morphine, reached maximum at 6h. There was a concentration-dependency between 30 nM to 1 microM. The morphine-induced enhancement was abolished by naloxone, an antagonist of mu opioid peptide receptor (MOP), wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor, and PD98059, a MEK inhibitor, but not by 1,10-phenanthroline, a metalloprotease inhibitor and U73122, a phospholipase C inhibitor. These profiles contrast to the data with morphine-induced enhancement of brain-derived growth factor (BDNF) gene expression in microglia, where 1,10-phenanthroline abolished the expression. Furthermore, the ELISA analysis revealed that the immunoreactive ppN/OFQ or N/OFQ level was also increased by morphine. The present findings suggest that astrocytes could play roles in the neuronal plasticity during morphine chronic treatments by enhancing gene expression of anti-opioid peptide, N/OFQ.
Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
Naoko
N
Takayama
Hiroshi
H
Ueda
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D009020:Morphine / Q000494:pharmacology*; D018847:Opioid Peptides / Q000096:biosynthesis*; D011498:Protein Precursors / Q000096:biosynthesis*; D051381:Rats; D000097629:Nociceptin
D000701:Analgesics, Opioid; D009020:Morphine; D018847:Opioid Peptides; D011498:Protein Precursors; D000097629:Nociceptin