Inhibition by naloxone of promoter activity of the neurofilament gene in SK-N-SH cells.
Chronic administration of morphine is known to decrease the levels of neurofilaments (NFs) in the ventral tegmental area. We ligated a promoter region of the mouse 68-KDa neurofilament (NF-68) gene to the pGL3-enhancer vector containing a luciferase gene, transfected it into SK-N-SH cells and then analyzed transcriptional activity in the cells treated with agonists or antagonists of opiate receptors. The activity of the NF-68 promoter was suppressed by naloxone about 55% at 10(-5) M and 30% at 10(-7) M at 48 h, but suppressed not by morphine. Naltrexone at 10(-5) M suppressed the promoter activity about 20%, but levallorphan, DAMGO, DPDPE and U50488 did not. The inhibition by naloxone was dose-dependent and not reversed by morphine. The inhibitory effect of naloxone was not observed in N18TG-2 cells and PC12 cells. Experiments with various deletion mutants revealed that a region responsible for naloxone suppression spans from -328 to -101 in the gene. These results suggest that naloxone has the ability to suppress transcriptional activity in some neurons.
Niu
S Y
SY
Department of Pharmacology, Osaka University School of Medicine, Japan.
Kuo
C H
CH
Taira
E
E
Muraoka
O
O
Irie
Y
Y
Gan
Y H
YH
Do
E
E
Miki
N
N
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016900:Neurofilament Proteins / Q000235:genetics*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020218:Response Elements; D017557:Ventral Tegmental Area / Q000187:drug effects / Q000502:physiology
D009292:Narcotic Antagonists; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; C066858:neurofilament protein NF 68; D009270:Naloxone; D009020:Morphine; D002118:Calcium