目的:研究脑源性神经营养因子(proBDNF)前体及其高亲和力受体p75NTR在情绪相关脑区神经元中的表达(前额叶皮质,海马体,和杏仁核)在中风后抑郁(PSD)的大鼠中,并通过向PSD大鼠侧脑室注射组织型纤溶酶原激活剂(t-PA),探讨情感相关脑区神经元中proBDNF和p75NTR的表达水平,这显著改善了应激诱导的抑郁样行为,从而进一步验证了上述结果。
方法:大鼠随机分为4组:正常对照组(n=8),抑郁症组(n=8),中风组(n=8),和PSD组(n=8)。采用线栓法建立大鼠中风模型,PSD动物模型是通过慢性不可预测的轻度应激(CUMS)和单独喂养诱导的。进行了行为测试,包括体重测量,露天试验,和蔗糖偏好测试。免疫荧光双标记法检测PSD大鼠模型情绪相关脑区神经元中proBDNF和p75NTR的表达。CUMS治疗四周后,选择PSD组。大鼠输注t-PA(3μg溶解在6μL盐水中,勃林格键英格尔海姆),proBDNF(3μg溶于6μL盐水,Abcam),使用连接到注射针头的注射泵,连续7天每天一次或等量NS。连续给药7天后,通过评分评估动物行为,采用免疫荧光双标记法检测PSD大鼠模型情绪相关脑区proBDNF和p75NTR的表达。
结果:与正常对照组和中风组相比,体重,蔗糖水消耗,PSD组的垂直运动距离明显较低(P<0.05)。相比之下,与proBDNF注射组和生理盐水注射组相比,重量,蔗糖水消耗,场水平运动,PSD侧脑室插管后,t-PA注射组的垂直运动距离明显增加。双重免疫荧光显示,PSD大鼠前额叶皮质和海马中proBDNF和p75NTR的神经元表达高于对照组(P<0.05)。在杏仁核里,PSD组proBDNF和P75NTR的表达水平较对照组明显降低(P<0.05)。对注射t-PA后PSD大鼠情绪相关脑区proBDNF和P75NTR的表达水平检测结果显示,proBDNF和P75NTR在前额叶皮质中显著降低,海马体,PSD大鼠杏仁核与NS组和proBDNF组比较(P<0.05)。
结论:情绪相关脑区神经元脑源性神经营养因子前体proBDNF及其受体p75NTR的表达增加可能在PSD的发病中起重要作用。t-PA降低了情感相关脑区神经元中proBDNF及其受体p75NTR的表达,并显着改善了应激诱导的抑郁样行为。因此,有理由认为外源性注射t-PA可减轻PSD患者的抑郁症状。通过注射t-PA减少proBDNF的表达可能为治疗压力相关的情绪障碍提供新的治疗方法。
OBJECTIVE: To investigate the expression of the precursor of brain-derived neurotrophic factor (proBDNF) and its high-affinity receptor
p75NTR in neurons of emotion-related brain areas (prefrontal cortex, hippocampus, and amygdala) in rats with post-stroke depression (PSD), and to explore the expression levels of proBDNF and
p75NTR in neurons of emotion-related brain areas by injecting tissue plasminogen activator (t-PA) into the lateral ventricle of PSD rats, this significantly improved the stress-induced depression-like behavior,thus further validating the above results.
METHODS: Rats were randomly divided into four groups: a normal control group (n = 8), a depression group (n = 8), a stroke group (n = 8), and a PSD group (n = 8). The rat model of stroke was established by thread embolism, and the PSD animal model was induced by chronic unpredictable mild stress (CUMS) and solitary feeding. Behavioral tests were conducted, including weight measurement, open field tests, and sucrose preference tests. Immunofluorescence double labeling was used to detect the expression of proBDNF and
p75NTR in neurons of emotion-related brain regions in the PSD rat model. Four weeks after CUMS treatment, the PSD group was selected. Rats were infused with t-PA (3 μg dissolved in 6 μL saline, Boehringer Ingelheim), proBDNF (3 μg dissolved in 6 μL saline, Abcam), or equal-volume NS once per day for 7 consecutive days using the syringe pump connecting to injection needles. After 7 days of continuous administration, animal behavior was assessed through scoring, and the expression of proBDNF and p75NTR in the emotion-related brain regions of the PSD rat model was detected using immunofluorescence double labeling.
RESULTS: Compared with the normal control group and the stroke group, the body weight, sucrose water consumption, and vertical movement distance in the PSD group were significantly lower (P < 0.05). In contrast, when compared with the proBDNF injection group and saline injection group, the weight, sucrose water consumption, field horizontal movement, and vertical movement distance of the t-PA injection group significantly increased after PSD lateral ventricle intubation.Double immunofluorescence revealed a higher neuronal expression of proBDNF as well as p75NTR in the prefrontal cortex and hippocampus of PSD rats compared to control animals (P < 0.05). In the amygdala, the expression levels of proBDNF and
P75NTR were significantly reduced in the PSD group compared to the control group (P < 0.05). The results of the expression levels of proBDNF and
P75NTR in the emotion-related brain regions of PSD rats injected with t-PA showed that proBDNF and P75NTR was significantly reduced in the prefrontal cortex, hippocampus, and amygdala of PSD rats compared to those of the NS and proBDNF groups (P < 0.05).
CONCLUSIONS: The increased expression of the brain-derived neurotrophic factor precursor proBDNF and its receptor p75NTR in neurons of emotion-related brain regions may play an important role in the pathogenesis of PSD.t-PA reduced the expression of proBDNF and its receptor p75NTR in neurons emotion-related brain regions and significantly improved the stress-induced depression-like behavior. Therefore, it is reasonable to assume that exogenous injection of t-PA may alleviate the depressive symptoms of PSD patients.Reducing the expression of proBDNF by injecting t-PA may provide a novel therapeutic approach for the treatment of stress-related mood disorders.