Effects Of Taurine-zinc Coordination Compound On Withdrawal Symptoms In Morphine Dependent Mice And The Relative Mechanisms

Objective Morphine dependence and withdrawal can do harm to CNS. The effects of Tau on antioxidation and cytoprotection play a key role in maintenance of brain function. Zn is generally acknowledged as a protective agent of brain function. It is definite that morphine can influence the physiologic equilibrium of zinc level in vivo. We assumed that TZC can protect CNS neurons from toxicity of morphine addiction, and observed withdrawal syndromes, NOS activity, the proteins expression of nNOS and the genes expression of MT1, ZnT1 mRNAs in cortex and hippocampus of morphine dependent mice, as well as mice fed with TZC. Both the mechanisms of damage caused by morphine dependence and withdrawal on CNS and protections against them were explored.Methods 60 mice were divided into 4 groups randomly(n=15): control group, morphine dependent group, simple withdrawal group and TZC withdrawal group. 30 days later, Morphine was subcutaneously injected into the mice with dose-increasing method to establish morphine dependence model. Withdrawal syndromes were precipitated by intraperitoneal injecting naloxone of 4.5 mg/kg in mice of simple withdrawal group and TZC withdrawal group, and mice of morphine dependent group received the same dose of normal saline. The treatment steps of mice in control group were the same as that in the other groups, and the same dose of normal saline was injected. The intensity of withdrawal syndromes was evaluated. NADPH-d histochemistry, ABC immunohistochemistry and RT-PCR were used to measure the activity of NOS, the levels of proteins expression of nNOS and genes expression of MT1, ZnT1 mRNAs in brain tissue.Results1. The observation result of the withdrawal syndromes The withdrawal syndromes precipitated by naloxone were obviously observed in morphine withdrawal mice. Compared with simple withdrawal group, the number of jumping and "wet dog" shakes, and the body weight loss significantly decreased in the TZC withdrawal group(P<0.05). Mice in control group and morphine dependent group had no syndromes or little. 2. The results of NADPH-d histochemistry and immunohistochemistry Thenumbers of positive neurous of NADPH-d and nNOS of morphine dependent group in CA1 and DG were lower than control group(P<0.05). The numbers of NADPH-d and nNOS positive neurons in cortex, CA₁, CA₃ and DG of simple withdrawal group were lower than control group and morphine dependent group(P<0.05). Compared with simple withdrawal group, the numbers in cortex, CA₁ and DG of TZC withdrawal group were higher(P<0.05);3. The results of RT-PCR(1) The relative content of MT1 mRNA in cortex and hippocampus of morphine dependent group significantly increased, compared with the other three groups(P<0.05). The expression of MT1 mRNA of simple withdrawal group were higher than that of control group(P<0.05), but lower than TZC withdrawal group(P<0.05).(2) In cortex, the relative content of ZnT1 mRNA of morphine dependent group significantly increased than that of the other three groups(P<0.05). Compared with control group, there were significant increases of ZnT1 mRNA in simple withdrawal group and TZC withdrawal group(P<0.05); In hippocampus, the expression of ZnT1 mRNA of simple withdrawal group and TZC withdrawal group significantly increased than that of control group and morphine dependent group(P<0.05). There was no difference between simple withdrawal group and TZC withdrawal group, or control group and morphine dependent group(P>0.05).Conclusions TZC can reduce the withdrawal syndromes precipitated by naloxone in morphine dependent mice, and protect cortical and hippocampal neurons from toxicity of morphine dependence and withdrawal. It suggests that the most important mechanisms are related to increase of the NOS activity, protein expressions of nNOS, as well as increase of genes expression of MT1 mRNA. The relationship between the protection effect of TZC and the change of gene expression of ZnT1 mRNA need further investigation.