目的:本研究旨在探讨黄芩茎叶黄酮(SSFs)对脑室内注射冈田酸(OA)所致大鼠认知功能损害的影响及作用机制。
方法:通过脑室内注射OA,在大鼠中建立阿尔茨海默病(AD)的实验模型,导致记忆障碍。采用Morris水迷宫试验证实了记忆障碍模型的成功建立。将表现出明显记忆障碍的大鼠随机分为不同的组,包括一个模型组,三个SSF剂量组(25、50和100mg/kg),阳性对照组给予200mg/kg剂量的银杏叶片(GLT)。评价大鼠的学习记忆能力,进行了Morris水迷宫试验。苏木精-伊红(HE)染色用于观察神经元的任何形态变化。进行免疫组织化学(IHC)以测量胆碱乙酰转移酶(ChAT)蛋白的表达。Western印迹(WB)用于评估Ser262和Ser396处tau蛋白的磷酸化水平。使用紫外分光光度法定量诱导型一氧化氮合酶(iNOS)和组成型一氧化氮合酶(cNOS)的活性。炎症因子的水平,包括白细胞介素-1β(IL-1β),肿瘤坏死因子-α(TNF-α),和白细胞介素-6(IL-6),使用ELISA测量。
结果:在大鼠中,通过侧脑室注射给予OA导致认知障碍,神经病理学改变,以及蛋白质表达和活性水平的改变。具体来说,ChAT蛋白表达显著降低(P<0.01),而Ser262和Ser396的tau蛋白磷酸化水平显著升高(P<0.01)。此外,海马和大脑皮质的iNOS活性显著升高(P<0.01),而cNOS活性降低(P<0.05)。此外,大脑皮质IL-1β和TNF-α水平升高(P<0.01),IL-6水平降低(P<0.05)。向大鼠施用三种剂量的SSF和GLT在上述由OA诱导的病理改变中表现出不同程度的改善。
结论:SSF在侧脑室注射OA后显示出增强大鼠认知功能和减轻记忆障碍的能力。这种有益的作用可能归因于ChAT蛋白表达的调节,tau过度磷酸化,NOS活性,和SSF的炎性细胞因子水平。
OBJECTIVE: The objective of this study is to explore the impact and underlying mechanism of Scutellaria baicalensis Georgi stem and leaf flavonoids (SSFs) on cognitive impairment caused by intracerebroventricular injection of okadaic acid (OA) in rats.
METHODS: An experimental model of Alzheimer\'s disease (AD) was induced in rats by intracerebroventricular injection of OA, resulting in memory impairment. The Morris water maze test was employed to confirm the successful establishment of the memory impairment model. The rats that exhibited significant memory impairment were randomly divided into different groups, including a model group, three SSFs dose groups (25, 50, and 100 mg/kg), and a positive control group treated with Ginkgo biloba tablets (GLT) at a dose of 200 mg/kg. To evaluate the learning and memory abilities of the rats, the Morris water maze test was conducted. Hematoxylin-eosin (HE) staining was used to observe any morphological changes in neurons. Immunohistochemistry (IHC) was performed to measure the expression of choline acetyltransferase (ChAT) protein. Western blotting (WB) was utilized to assess the phosphorylation levels of tau protein at Ser262 and Ser396. The activities of inducible nitric oxide synthase (iNOS) and constitutive nitric oxide synthase (cNOS) were quantified using ultraviolet spectrophotometry. The levels of inflammatory factors, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6), were measured using ELISA.
RESULTS: In rats, the administration of OA via intracerebroventricular injection resulted in cognitive impairment, neuropathological changes, and alterations in protein expression and activity levels. Specifically, the protein expression of ChAT was significantly reduced (P<0.01), while the phosphorylation levels of tau protein at Ser262 and Ser396 were significantly increased (P<0.01). Moreover, iNOS activity in the hippocampus and cerebral cortex exhibited a significant increase (P<0.01), whereas cNOS activity showed a decrease (P<0.05). Furthermore, the levels of IL-1β and TNF-α in the cerebral cortex were elevated (P<0.01), while the level of IL-6 was decreased (P<0.05). The administration of three doses of SSFs and GLT to rats exhibited varying degrees of improvement in the aforementioned pathological alterations induced by OA.
CONCLUSIONS: SSFs demonstrated the ability to enhance cognitive function and mitigate memory deficits in rats following intracerebroventricular injection of OA. This beneficial effect may be attributed to the modulation of ChAT protein expression, tau hyperphosphorylation,
NOS activity, and inflammatory cytokine levels by SSFs.