Effects of Morphine on μOpioid Receptor-mediated ERK Phosphorylation / 医药导报

ABSTRACT

Objective To study the phosphorylation mode of extracellular regulated kinase( ERK)induced by acute and chronic morphine treatment on Chinese hamster ovary( CHO)cells expressed withμopioid receptors. Methods The time course of ERK phosphorylation 1 h and 36 h after morphine exposure as well as naloxone-precipitated withdrawal was detected by immunobloting. Results A transient enhancement of ERK phosphorylation was induced by 1 μmol · L-1 morphine with the peak effect at 5 min(P〈0. 01),and the effect was dose-dependent. No difference in ERK phosphorylation was found after 36h of treatment with 10 μmol · L-1 morphine compared with the control. However,5 or 10 min-naloxone precipitation induced remarkable decrease in ERK phosphorylation compared with the control(P〈0. 01). Conclusion Different changes of ERK phosphorylation were found under acute and chronic morphine treatment and naloxone precipitation,indicating a compensation of ERK related pathway induced byμ opioid receptors.