辣椒素对慢性脑低灌注大鼠认知行为受损及海马线粒体-内质网结构偶联表达的影响

目的:观察在辣椒素(capsaicin)作用下,慢性脑低灌注(CCH)状态大鼠认知行为的改变及海马CA1区线粒体-内质网结构偶联(MAMs)的表达变化,探讨2者在缺血致认知功能障碍中可能的作用。方法:将48只健康雄性SD大鼠随机分为假手术(sham)组、CCH组、辣椒素组和溶媒(solvent)组。通过永久性结扎双侧颈总动脉(BCCAO)建立大鼠CCH模型。术后第7天,capsaicin组腹腔内注射辣椒素2.5 mg/kg,每周2次,连用4周,溶媒组相同条件下给予等量溶媒。各组于术后4周应用Morris水迷宫实验、物体辨别实验和旷场实验检测认知相关行为学指标。应用透射电镜和免疫荧光双重标记检测大鼠海马CA1区线粒体-内质网结构偶联的变化,Western blot实验检测海马组织中线粒体融合蛋白2(Mfn2)的表达。结果:术后4周行为学实验结果显示,与假手术组相比,CCH大鼠的学习记忆功能受损;与溶媒组比较,capsaicin组大鼠的空间学习记忆功能明显改善。透射电镜及免疫荧光双重标记观察结果表明,与假手术组相比,CCH大鼠海马CA1区的MAMs疏松;与溶媒组比较,capsaicin组大鼠中线粒体-内质网之间关联增加(P<0.05)。Western blot结果表明,与假手术组相比,CCH组大鼠海马组织的Mfn2蛋白水平降低;与溶媒组相比,capsaicin组大鼠海马组织的Mfn2蛋白水平增高(P<0.05)。结论:慢性脑低灌注可致大鼠空间学习记忆能力明显受损,MAMs疏松。辣椒素可通过上调海马线粒体-内质网结构偶联的表达,从而改善CCH大鼠受损的认知功能。

Effects of capsaicin on cognitive impairment and mitochondria-associated endoplasmic reticulum membranes in rats with chronic cerebral hypoperfusion

AIM: To observe the effects of capsaicin on cognitive impairment and mitochondria-associated endoplasmic reticulum membranes(MAMs) of hippocampal CA1 area in the rats with chronic cerebral hypoperfusion(CCH), and to investigate the underlying molecule mechanism of cognitive defects induced by ischemia. METHODS: Healthy male Sprague-Dawley(SD) rats(n=48) were randomly divided into sham operation(sham) group,CCH model(CCH) group, capsaicin group,and solvent group, 12 rats in each group. Capsaicin at 2.5 mg/kg was intraperitoneally injected twice a week for 4 weeks, starting on the 7 th day after surgery. The rats in solvent group were given the same amount of solvent at the same time and under the same conditions. Morris water maze, object recognition test and open field test were conducted to analyze the cognitive related behavior performance on the 4 th week after surgery. The changes of MAMs in the hippocampal CA1 region were observed under transmission electron microscope, the co-localization of the MAMs was observed by immunofluorescence double-labeling, and the expression of mitofusin 2(Mfn2) in the hippocampal tissue was determined by Western blot.RESULTS: Four weeks after the operation, the behavior tests showed that the cognitive function of CCH rats was impaired compared with sham operation group. Compared with solvent group, spatial learning and memory in capsaicin group was improved significantly. The results of transmission electron microscope and confocal microscope showed that the distance of MAMs in the hippocampal CA1 area of CCH rats was increased compared with sham operation group, and the co-localization of the contacts was decreased(P<0.05). Compared with solvent group, the correlation between the mitochondria and ER in capsaicin group was increased(P<0.05). The protein level of Mfn2 in CCH group was significantly lower than that in sham group(P<0.05). Compared with solvent group, the protein level of Mfn2 in capsaicin group was higher(P<0.05). CONCLUSION: CCH rats showed decreased cognitive function and loosen MAMs. Capsaicin improves the cognitive behavior of CCH rats by up-regulation of MAMs.