The Effects And Its Mechanisms Of Cedemex On Morphine Dependence In Rats

The development of morphine dependence is a very complicated procedures which involves many aspects such as opiate receptors,neurotransmitter,neuropeptide,signal transduction inside the cells,ion channel,nucleus,neural circuit,learning and memory,and the rewarding mechanism etc.Present studies about the morphine dependence mainly focus on the opiate receptors,opiate system and their modulated effects to the neurotransmitter through complicated neurohumour mechanism.The changes in the post-receptor signal transduction system has become a heated point nowadays.Cedemex is a Chinese drugs preparation which has clinically favourable herapeutic action for drug dependence.This study focus on the effect and its action mechanism of Cedemex against rat morphine dependence in the entire body,organ,cell and molecular levels,so that we can provide some theoretical basis for the exploitation and clinical therapy of Cedemex.Objective:To investigate the effects and its mechanisms of the Cedemex against drug dependence.Methods:(1)Morphine dependent rat model with withdrawal syndrome induced by naloxone was established to study the ethological effects of Cedemex against the model,including the intervention and therapeutic action of Cedemex to the morphine dependent rats.(2)Morphine dependent guinea pig ileum(GPI)model in vitro was used to study the effects of the Cedemex on the model.(3)The morphological changes of different brain sections(VTA,Hth,HIP)in morphine dependence rats were observed by light microscope and electron microscope after the treatment with Cedemex.(4)The contents of the neurotransmitters of monoamines in different brain sections(four areas as Acc,VTA,HIP,CC)in morphine dependent rats treated by Cedemex were checked through reversed phase high-performance liquid chromatography(RP-HPLC).(5)The contents of the endorphine,cAMP and cGMP in different brain sections(hypothalamus and pituitary)in morphine dependent rats treated by Cedemex were determined through radioimmunity assay(RIA).(6)The mRNA expressions of POMC,D₂R and CREB in different brain sections(hypothalamus and pituitary)in morphine dependent rats treated by Cedemex were observed using the methods of RT-PCR and fluorescent quantitation PCR.Results.(1)Cedemex could decrease the abstinent symptom scores of morphine dependent rat model in both conditions such as the natural withdrawal syndrome and the withdrawal syndrome induced by naloxone(P＜0.05),(the scores were 70.25±10.27 in N group, 51.63±3.33 in high dose of Cedemex group,52.25±5.33 in middle dose of Cedemex group, 53.00±10.39 in low dose of Cedemex group,51.355±0.483 in positive drug control group). Cedemex could also reduce the loss of the body weight of the morphine dependent rats with withdrawal syndrome participated(P＜0.05),(the percentages of the loss of body weight were 2.834±0.588 in N group,1.309±1.305 in high dose of Cedemex group,1.646±0.379 in middle dose of Cedemex group,1.855±2.482 in low dose of Cedemex group,1.3554±0.483 in positive drug control group).(2)Cedemex could inhibit the contraction force of GPI induced by naloxone(p＜0.01), (the tension was 2.45±0.53 in N group,0.89±0.18 in high dose of Cedemex group,0.97±0.18 in middle dose of Cedemex group,2.13±0.33 in low dose of Cedemex group,0.96±0.11 in positive drug control group),and refrain the contraction tension of the normal GPI induced by Ach.(3)Mild edema could be seen in hippocampus in all morphine dependent models,but no other obvious abnormality could be founded.The apoptosis of neuron was obvious in morphine group and saline group under electron microscope.Apoptosis of neuron could hardly be seen in high dose of Cedemex group,and be seen a small percentage in middle and low dose of Cedemex group.(4)Dopamine contents were decreased in high dose and middle doseof Cedemex groups, and positive drug control group,compared with that of N group(p＜0.01),(dopamine contents in N group were 3914.96±80.65 in VTA area of rat brain,4032.07±77.21 in HIP field, 4941.90±82.92 in cortical field,4716.03±85.87 in NA;dopamine contents in high dose of Cedemex group were 2426.17±75.49 in VTA area of rat brain,3453.27±78.80 in HIP field, 3782.134±61.72 in cortical field,3252.08±78.97 in NA;dopamine contents in middle dose of Cedemex group were 3312.61±66.21 in VTA area of rat brain,3569.064±76.11 in HIP field, 3806.63±85.01 in cortical field,2613.09±77.12 in NA;dopamine contents in positive drug control group were 2298.66±77.12 in VTA area of rat brain,3010.02±71.33 in HIP field, 3611.914±83.61 in cortical field,3009.44±80.56 in NA);Norepinephrine contents were decreased in high dose of Cedemex group and positive drug control group,compared with that of N group(p＜0.05),(norepinephrine contents in N group were 3571.10±73.01 in VTA area of rat brain,3949.31±97.20 in HIP field,3844.89±46.11 in cortical field,4846.90±74.80 in NA;norepinephrine contents in high dose of Cedemex group were 4672.83±82.43 in VTA area of rat brain,3809.46±77.30 in HIP field,3554.914±74.72 in cortical field,3868.41±56.96 in NA;norepinephrine contents in positive drug control group were 3747.35±73.51 in VTA area of rat brain,3771.20±65.35 in HIP field,3441.92±51.02 in cortical field,4557.26±73.11 in NA;5-HT contents were decreased in high dose of Cedemex group and positive drug control group,compared with that of N group(p＜0.01),(5-HT contents in N group were 30.62±0.54 in VTA area of rat brain,10.25±0.62 in HIP field,13.41±0.31 in cortical field, 30.62±0.54 in NA;5-HT contents in high dose of Cedemex group were 22.53±0.75 in VTA area of rat brain,6.43±0.42 in HIP field,8.75±0.39 in cortical field,7.81±0.43 in NA;5-HT contents in positive drug control group were 7.67±0.42 in VTA area of rat brain,5.86±0.37 in HIP field,8.76±0.42 in cortical field,22.31±0.65 in NA).(5)cAMP contents were decreased in high dose,middle dose and low dose of Cedemex groups,compared with that of N group(p＜0.05),(cAMP contents in N group were 12332.17±122.75 in VTA area of rat brain,16062.25±754.86 in HIP field,16427.39±667.07 in cortical field),cGMP contents were increased evidently(P＜0.05),(cGMP contents in N group were 728.71±11.55 in VTA area of rat brain,706.67±16.28 in HIP field,600.43±11.24 in cortical field).The changes of cAMP and cGMP were dose-dependent,after the treatment with Cedemex.(6)Compared with that of N group,the expressions of D₂ RmRNA were increased in high dose and middle dose of Cedemex(p＜0.01),(the expressions of D₂ RmRNA were (4.9±0.8)×10⁶ in N group,(8.4±0.9)×10⁵ in high dose of Cedemex group,(7.1±1.1)×10⁶ in middle dose of Cedemex group,(3.2±0.9)×10⁶ in low dose of Cedemex group,(7.2±0.7)×10⁶) in positive drug control group;the expressions of POMC mRNA were increased(p＜0.01), (the expressions of POMC mRNA were(5.4±1.2)×10⁵,(7.8±0.9)×10⁶ in high dose of Cedemex group,(5.9±0.7)×10⁶ in middle dose of group,(6.0±0.8)×10⁶ in low dose of Cedemex group,(2.3±0.4)×10⁶)in positive drug control group;the expressions of CREB mRNA were decreased(p＜0.01),(the expressions of CREB mRNA were 0.23±0.046 in N group,0.09±0.069 in high dose of Cedemex group,0.14±0.077 in middle dose of Cedemex group,0.16±0.031 in low dose of Cedemex group,0.19±0.068 in positive drug control group).Conclusions:Cedemex can rapidly suppress the occurrence of the abstinent symptom in morphine dependent rats.The mechanisms of these effects may be related with the receptors such as M-receptor,μ-receptor,inflow of calcium ion in periphery,and decrease the contents of neurotransimitters of monoamines,reduce the ratio of cAMP/cGMP,increase the expressions of D₂ R and POMC mRNA,and reduce the expressions of CREB mRNA in CNS.