The changes of monoamine neurotransmitters in two rat models of morphine dependence and the effects of sinomenine on morphine dependence

Abstract

Objective To investigate the changes of monoamine neurotransmitters of the brain in two tat models of morphine dependence,and to explore the effects of sinomenine on morphine dependence.Methods A physical dependent rat model was established with morphine at a gradually increasing dosage and the withdrawal syndrome was scored after naloxone precipitation.The conditioned place preference(CPP)in rats induced by morphine was used to investigate psychic dependence in rots.Contents of norepinephrine(NE),dopamine(DA)and serotonin(5-HT)in hypothalamus of rats were assayed with a fluorescent method.Results 1.In naloxone precipitated withdrawal test of in morphine-dependent rats,after morphine withdrawal,the rats presented marked with drawal symptoms and signs,their withdrawal scores were significantly increased,and the levels of NE and 5-HT in hypothalamus of the rats were significantly increased than the control group Ⅰ(7.07±1.406μg/g wet tissue and 1.15±0.346 μg/g wet tissue,respectively,P 0.05).Sinomenine could significantly inhibit the withdrawal syndrome and development of CPP induced by morphine in rats,and could suppress the rising of monoamine neurotransmitters of the brain in two morphine dependent models in rats.Conclusion In the physical dependent model induced by morphine in rats,the rising of NE and 5-HT in the rat brain were significant,but in CPP model induced by morphine in rats,the levels of DA in the rat brain were enhanced predominately.Sinomenine could inhibit the withdrawal syndrome and development of CPP in rats,and regulate and improve the function of monoamine nerve system. Key words: Morphine; Sinomenine; Monoamine neurotransmitters Withdrawal syndrome; Conditional place preference