神经肽VGF参与调控脂多糖诱导小鼠认知障碍，焦虑样及抑郁样行为的分子作用

发布时间：2019-05-07 13:07

【摘要】：研究目的:常见神经系统疾病均易伴发或共病焦虑及抑郁障碍,共病使得疾病迁延不愈、显著地增加了疾病的负担。脂多糖(lipopolysaccharide,LPS)诱导外周炎症及中枢免疫反应,导致中枢神经系统发生病理学变化,从而引起神经精神行为障碍。研究表明一种新型神经肽VGF参与了认知功能及抑郁样行为的调控,但是神经肽VGF是否具有调控神经精神共患病中神经炎症及氧化应激反应仍未见报道。本研究通过LPS构建认知障碍、焦虑及抑郁小鼠模型,观察神经肽VGF在神经炎症及氧化应激反应中的作用,期望阐明神经肽VGF保护LPS诱导的认知障碍、焦虑样及抑郁样行为的分子机制。研究方法:使用成年雄性ICR小鼠构建动物模型进行不同的药物干预后通过旷场实验,新物体识别实验、高架0迷宫实验、强迫游泳实验和糖水偏好实验测定小鼠的自主活动能力,认知功能,焦虑样及抑郁行为变化。行为学结束后取脑组织通过蛋白免疫印迹法,酶联免疫吸附法及免疫组化等实验方法进行生化指标测定。研究结果:研究发现LPS诱导小鼠产生认知障碍、焦虑样及抑郁样行为,且能持续出现。但侧脑室注射神经肽VGF碳-末端衍生肽TLQP-62显著抑制LPS诱导的小鼠认知障碍、焦虑及抑郁的发生,且伴随显著的抗氧化应激与抗炎症反应。为进一步研究脑源性神经营养因子(BDNF)参与TLQP-62的保护作用,我们发现慢病毒侧脑室注射介导的海马及前额叶皮层BDNF敲减后,TLQP-62的改善作用被显著削弱。进一步研究发现慢病毒介导的小鼠海马DG区内VGF的敲减,诱导显著的认知障碍、焦虑及抑郁,未见显著的氧化应激反应和炎症反应,但是在敲减VGF表达后同时给予LPS,进一步加重认知障碍、焦虑样及抑郁样行为,且同时能进一步降低BDNF的表达。最后,在慢病毒诱导干扰海马DG区IL-1β表达后,可以显著阻断LPS诱导的认知障碍、焦虑样及抑郁样行为,同样能抑制LPS诱导VGF表达的下调及氧化应激反应和炎症反应。研究结论:本研究进一步证实了LPS能诱导小鼠脑内氧化应激反应和炎症反应参与了其诱导认知障碍、焦虑样及抑郁样行为。进一步证明了BDNF/Trk B/Nrf2信号通路在TLQP-62保护作用中的关键作用及IL-1β在LPS诱导上述变化中的关键作用。率先证明神经肽VGF参与了神经炎症及氧化应激反应的调节作用,从而发挥保护LPS诱导的认知障碍、焦虑及抑郁行为的作用。本研究为深入研究以VGF为靶标的神经精神保护药物奠定了理论基础。
[Abstract]:Objective: common nervous system diseases are prone to concomitant anxiety and depression. Concomitant diseases cause disease to prolong and increase the burden of disease significantly. Lipopolysaccharide (lipopolysaccharide,LPS) induces peripheral inflammation and central immune response, which leads to pathological changes in the central nervous system and neuropsycho-behavioral disorders. Studies have shown that a new type of neuropeptide VGF is involved in the regulation of cognitive function and depression-like behavior, but it has not been reported whether neuropeptide VGF can regulate neuroinflammation and oxidative stress response in neuropsychiatric comorbidities. The aim of this study was to investigate the role of neuropeptide VGF in neuroinflammatory and oxidative stress responses in mice with cognitive impairment, anxiety and depression induced by LPS, and to elucidate the protective effects of neuropeptide VGF on cognitive impairment induced by LPS. The molecular mechanism of anxiety-like and depression-like behavior. Methods: adult male ICR mice were used to construct animal models. After different drug intervention, open-field experiment, new object recognition test and elevated 0-maze test were carried out. The ability of autonomous activity, cognitive function, anxiety-like behavior and depression behavior were measured by forced swimming test and glucose-water preference test. At the end of behavior, brain tissues were detected by Western blot, enzyme-linked immunosorbent assay (Elisa) and immunohistochemistry. Results: LPS induced cognitive impairment, anxiety-like behavior and depression-like behavior in mice. However, intracerebroventricular injection of neuropeptide VGF C-terminal derived peptide TLQP-62 significantly inhibited the occurrence of LPS-induced cognitive impairment, anxiety and depression in mice, accompanied by significant antioxidant stress and anti-inflammatory response. In order to further study the protective effect of brain-derived neurotrophic factor (BDNF) on TLQP-62, we found that after lentiviral lateral ventricular injection-mediated BDNF knockdown in hippocampus and prefrontal cortex, the improvement of TLQP-62 was significantly weakened. Further studies showed that lentivirus-mediated knockdown of VGF in the hippocampal DG region of mice induced significant cognitive impairment, anxiety and depression, and no significant oxidative stress and inflammatory response were observed. However, LPS, was given simultaneously after knock-down of VGF expression. Further aggravating cognitive impairment, anxiety-like and depression-like behavior, and at the same time can further reduce the expression of BDNF. Finally, lentivirus-induced interference with IL-1 尾 expression in hippocampal DG could significantly block LPS-induced cognitive impairment, anxiety-like and depression-like behavior, and also inhibit LPS-induced down-regulation of VGF expression, oxidative stress response and inflammatory response. Conclusion: this study further confirmed that LPS can induce oxidative stress and inflammatory reaction in the brain of mice, which can induce cognitive impairment, anxiety-like and depression-like behavior. The key role of BDNF/Trk B/Nrf2 signaling pathway in the protection of TLQP-62 and the key role of IL-1 尾 in the above changes induced by LPS were further demonstrated. It is demonstrated that neuropeptide VGF participates in the regulation of neuroinflammation and oxidative stress response, thus protecting the cognitive impairment, anxiety and depression induced by LPS. This study lays a theoretical foundation for the further study of neuropsychoprotective drugs targeting VGF.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R749

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