A Study Of The Role Of Melatonin On Inhibition Of Mouse Morphine Addiction

ObjectiveIn many cases,the opiods,especially morphine have an analgesia effect.However,there are some exceptions,for example,some patients had no satisfactory effect after having the opiods,or the application of the opiods have not resulted into satisfactory effect because of side effects of medicine,drug resistance or drug dependence.As a result,how to improve the efficacy of the opioids and reduce its side effects has become the focus of clinical and basic research.In our study,Mouse model of morphine dependence were applied to investigate the role of melatonin(MT) on anti-morphine.The interactions between the MT and the brain nuclei morphine or brain regions of melatonin receptors,the opioid receptor and neurotrophic factor and nerve growth factor were explored.The role of MT against the possible mechanism of morphine was clarified for the MT and its homologues possibly used as drugs or to provide some experimental and theoretical basis of Zoology in the clinical application of adjuvant therapy for withdrawal,so that the understanding of the molecular neurobiology of drug addiction knowledge of the mechanisms was deepened. Methods and MaterialsThe experimental mice were divided into control(saline NS), pathology(morphine) group,Melatonin(treatment,MT)Ⅰ-Ⅲgroup.The mice in MT were injected with morphine 70mg/kg by the means of intraperitoneal drug delivery,each in the morning and evening within 7 days.The mice in saline NS were injected with 0.5 ml saline in the mornings and evenings within 7 days.The mice in MT treatment group were injected with morphine 70mg/kg by the means of intraperitoneal drug delivery,each in the morning and evening within 7 days.Each evening while in morphining the MT 10 mg/kg,20mg/kg and 40mg/kg were injected.The resident time in the black and white box observed through Place Preference experiment was to determine the model of morphine dependence in mice.Such conditions about mice in each groups as weights losses,the numbers of jumping and their moods changes were recorded.The inhibitions of the morphine dependence in mice was determined from the behavioral viewpoint.After behavioral research,the mice were killed to extract the brains,the differences among the brain regions of mice MTR-1,MTR-2,morphine u receptors, neurotrophic factor 3(NT-3) and nerve growth factor(NGF) were detected by the using of immunohistochemistry and western-blotting method. Results1.The morphine dependence of mice was evaluated by Conditioned Place Preference.It was observed after administration of morphine in non-preferred side(white box)that stay time is obviously longer than before it.Mice showed significant CPP effect.If the numbers of jumping of mice,moods' changes,weight losses were further observed, it was showed in the results that the MT mice was superior to those in the morphine group and those mice in the saline group have no significant changes before and after administration.2.After Observing for Histopathologics and light microscopy,the mice hippocampus,nucleus accumbens,prefrontal cortex and other cells in morphine(pathology,MP) showed the osteoporotic of different degrees of nuclear neurons,cell edema,ballooning degeneration,nuclear condensation and fragmentation and even necrosis.The pathological changes of mice brain tissue in Melatonin and normal saline groups were not found.Immunohistochemistry,hippocampus(hippocampus) and (VTA) MTR-a,MTR-b,MP-μstaining positive cells in the ventral tegmental area,VTA were scattered single or small group of cells.The positive parts of were mainly in the cytoplasm.The MP-μprotein is the highest in the morphine group,followed by melatonin group and the saline group the lowest.The MTR-a,MTR-b protein was highly expressed in the melatonin group and saline group the second,the lowest expression of morphine group;Accordingly,NGF,NT-3 positive cells were highest in the melatonin group,followed by the saline group and the morphine group the lowest.3.The MTR-a,MTR-b,MP-μprotein in the ventral forebrain and midbrain areas were western blotted.It was showed in the result that the MTR-a,MTR-b protein in treatment group was highly expressed.The MP-μprotein in morphine group was expressed.Discussion and ConclusionThe stable and reliable mouse model of morphine dependence in mice was established to detect the faded black receptor,opioid receptor and nerve growth factor and other active substances in different brain regions.All that have done can show that MT has some inhibition effects on the morphine dependence of the mice.On one hand,the nerve growth factors may secrete by activating nerve cells.On the other hand,the morphine receptors antagonist from the black neural cells may bind its receptors to inhibit the formation of morphine dependence and protection of nerve tissue.