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Purpose in many cases, especially opioids morphine can play a good analgesic effect, however, because the effect is less than ideal, or drug side effects, drug tolerance, dependence and impact of the use of opioids. How to improve the efficacy and reduce the side effects of opioids, become the focus of attention of the clinical applications and basic research. Morphine dependence in mice model study of melatonin (melatonin, MT) the role of anti-morphine dependence, to explore MT endorphins dependence nuclei or brain melatonin receptor, morphine receptors and neurotrophic factor , nerve growth factor interaction between clarifying MT anti-of morphine dependence role and possible mechanisms, might as drug treatment for MT and its homologues new drugs or for withdrawal of adjuvant therapy used in clinical zoology experimental basis, and deepen our understanding of drug understanding of the mechanism of molecular neurobiology of addiction. Methods and Materials experimental mice were divided into normal saline (control, NS) group, morphine (pathology, MP) group, melatonin (treatment, MT) Ⅰ - Ⅲ group. Mice by intraperitoneal administration of morphine group injected morphine 70mg/kg body weight (0.5 mL), twice daily, for seven consecutive days. Saline group mice intraperitoneal administration by injection 0.5ml saline every morning and evening, seven days in a row. MT mice treated with intraperitoneal administered injections of morphine 70mg/kg body weight, twice daily, for seven consecutive days; same time, every night in the intraperitoneal injection of morphine while MT 10mg/kg, 20mg/kg, 40 mg / kg body weight. Using position preference experiment to observe the establishment of the mice in each group to evaluate and determine the residence time of the black box and white box model of morphine dependence in mice. Record weight loss before and after administration of each group of experimental mice, the number of hops, irritation, etc., from behavior to determine MT dependent inhibition of morphine. Behavior after the completion of the study, the experimental mice were sacrificed, and the brain, using immunohistochemistry, western-blotting method melatonin receptor-a (MTR-a) Determination of the relevant brain regions of mice in each group, melatonin receptor-b (MTR-b), the the morphine receptor-μ (MP-μ), neurotrophic factor 3 (NT-3), nerve growth factor (NGF) differentially expressed. Results 1. Conditioned place preference experiment (conditioned place preference, CPP) evaluate the formation of morphine dependence in mice. Observed after administration of morphine-dependent mice in the non-favored side (white box) to stay significantly longer time than before administration, the mice showed significant CPP effect. Further observed the behavior of mice in the number of hops, irritability situation, weight loss. The results showed, the given MT mice were significantly better than the morphine group, no significant changes in the mice before and after administration of saline group. Histopathological observation, optical microscopy can be seen the morphine (pathology, MP) mice, the hippocampus, the nucleus accumbens, prefrontal cortex visible to varying degrees of neuronal cell bodies nucleoplasm loose, cell edema, balloon-like change, nuclear condensation and fragmentation, and even degeneration and necrosis. The melatonin (treatment, MT) group and normal saline (control, NS) mice brain tissue no pathological changes. Immunohistochemical detection of hippocampus (hippocampus) and in the ventral tegmental area (ventral tegmental area of ??the midbrain, VTA) the MTR-a, the MTR-b, MP-μ positive cells were scattered single or small group of cells distributed, positive The site is mainly in the cytoplasm. MP-μ protein expression in the morphine group was the highest, followed by melatonin group, the lowest saline group; the MTR-a, MTR-b protein was highly expressed in the melatonin group, followed by saline group, morphine group was the lowest; Accordingly, NGF, NT-3-positive cells in the melatonin group was the highest, followed by saline group, the lowest morphine group. 3 immunoblot detection hippocampus, forebrain and midbrain ventral MTR-a, MTR-b, MP-μ protein expression, and the results show that: the treatment group the MTR-a, MTR-b protein was highly expressed in the morphine group MP- μ protein is highly expressed. Discussion and conclusion to the establishment of a stable and reliable model of morphine dependence in mice, by behavior, immunohistochemistry, electrophoresis immunoblotting method to detect different brain regions active substance melatonin receptors, opioid receptor and nerve growth factor, morphine dependence in mice, the proof of MT formation has a certain inhibitory nerve growth factor secretion by activation of nerve cells, may on the one hand, on the other hand may be a combination of morphine and its receptor expression melatonin receptor antagonist nerve cells to inhibit morphine dependence formation and protect the role of nerve tissue.
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