Cocaine exposure at a sublethal concentration downregulates CREB functions in cultured neuroblastoma cells.
Previous studies showed that prenatal cocaine in an animal model decreased brain-derived neurotrophic factor (BDNF) activity in offspring's brain. Since BDNF is one of target genes of cAMP response element-binding protein (CREB), this study examined effects of cocaine on CREB activities in a human neuroblastoma (SK-N-AS) cell line. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazodium bromide) assay indicated that cocaine exposure at 5 microM for 24 h had no significant influences on cell viability. However, a 24-h exposure to cocaine at the same concentration significantly decreased the level of phosphorylated CREB, although no significant changes in total CREB proteins were observed. Consistent with reduced CREB phosphorylation, the electrophoretic mobility shift assay showed that exposure to 5 microM of cocaine for 24 h also inhibited CREB binding activity and significantly decreased BDNF mRNA expression. In addition, exposure to 5 microM cocaine for 24 h attenuated the glutamic acid-evoked increase in the intracellular Ca2+ concentration. Taken together, these findings suggest that cocaine exposure at the sublethal concentration downregulates CREB functions in the cultured SK-N-AS cell line, and that diminished intracellular Ca2+ responses may be associated in part with cocaine-induced downregulation of CREB activity.
Feng
Mei-Jiang
MJ
Department of Biomedical and Therapeutic Sciences, University of Illinois College of Medicine at Peoria, Peoria, IL 61656, USA.
Yan
Shu-E
SE
Yan
Qing-Shan
QS
D000704:Analysis of Variance; D019208:Brain-Derived Neurotrophic Factor / Q000187:drug effects* / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage*; D017362:Cyclic AMP Response Element-Binding Protein / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D018709:Statistics, Nonparametric
D019208:Brain-Derived Neurotrophic Factor; D017362:Cyclic AMP Response Element-Binding Protein; D012333:RNA, Messenger; D003042:Cocaine; D002118:Calcium