The Role of ?-Endorphin in Relievable Effect of Melatonin On Morphine Withdrawal Symptoms in Rats / 中国心理卫生杂志

ABSTRACT

Objective:To explore the possible role of ? endorp hi n in effect of melatonin on morphine withdrawal symptoms in rats.Method:Acute model of morphine dependent rat was estalished by gradually increasing the dose of morphine through subcutaneous injections.CSF(cerebrospinal fluid)w a s got by push-pull perfusion and intracerebroventricular injection(icv)in a fixe d tuber.Concentration of ? endorphin in CSF was determined by radioimmunoassa y (RIA).Results:(1)The symptoms of natural morphine withdrawal were r e lieved significantly by icv ? Endorphin with a dose dependent manner.(2)The s y mptoms of natural morphine withdrawal were also relieved by ip melatonin.(3)The CSF ? endorphin level was significantly lower in morphine dependent rats than normal control,but that was higher in natural morphine withdrawal rats.That was also much more increased by ip melatonin in the withdrawal rats than in morphine dependent rats or normal control.Conclusion:The withdrawal symptom s could be relieved by icv ? endorphin or by ip melatonin in morphine dependetn rats.The mechanism may be partly due to the elevation of endogenous ? endorp hin level in brain of rats in withdrawal