Influence of morphine on synaptophysin expression and synapse structure in hippocampus of mice / 第二军医大学学报

ABSTRACT

Objective: To study the influence of morphine on the expression of synaptophysin (SYN) and synapse structure in mice hippocampus, so as to provide pathological evidence for studying the development and treatment of chronic morphine intoxication, addiction and abstinence symptoms of morphine. Methods: Twenty mice were evenly randomized into control group and experiment group. Mice in control group were injected with normal saline (0.1 ml daily) and those in experimental group were injected with morphine (0.1 ml, 1 mg daily). Thirty days later the mice in 2 groups were killed and their brain tissues were harvested and made into slices, stained with immunohistochemical techniques (SP) and photographed under the light microscope. The images were analyzed with the image analytical system and the data were statistically analyzed. Results: In the control group, positive staining of SYN was found in the entorhinal area, subiculum, stratum plextiforme, polymorphic layer of gyrus dentatus, stratum oriens, and stratum radiatum of hippocampus; weak positive staining of SYN was noticed in the stratum lacunosum-moleculare of hippocampus; positive staining of SYN was also found the membrane of pyramidal cells and granule cells, with the mean gray scale value of the hippocampal structure being 132.84 ± 8.67. Positively stained neurons was also found in the entorhinal area and the subiculum, with a intensity of (7.80 ± 1.03)/mm2. In the experiment group, the subiculum and polymorphic layers of gyrus dentatus were positively stained for SYN; the entorhinal area, stratum oriens, stratum radiatum and stratum lacunosum-moleculare of hippocampus were strongly positive of SYN; the membrane of pyramidal cells and granule cells were also strongly positive of SYN, with the mean gray scale value of the hippocampal structure being 116.27 ± 5.70. Strongly stained neurons were also found in the entorhinal area and the subiculum, with the intensity being (11.90 ± 1.45)/mm2. The number of SYN positive neurons and the intensity of SYN in the experimental group were higher than those in the control group (P<0.01). The hippocampal strucure looked like ground glass, with slight staining and many pyknotic nuclei and bubbles. Conclusion: Morphine can promote the SYN expression and apoptosis of neurons in the hippocampus, and therefore affect the structure and the function of the synapses in it.