ABSTRACT
Astrocytes are important nerve cells in the central nervous system （CNS）， which mainly play a key role in nutrition and support. Astrocytes and neurons undergo close energy coupling and substance coupling， which are closely related and interact with each other. In recent years， many studies have shown that the astrocyte-neuron coupling imbalance plays a central role in the occurrence and progression of Alzheimer's disease （AD） and serves as an important therapeutic target receiving increasing attention. According to traditional Chinese medicine （TCM） theory， the main pathogenesis of AD is kidney deficiency and marrow inadequacy， and in clinical medication， kidney-tonifying and marrow-filling TCM prescriptions are often employed with satisfactory results achieved. As reported， many kidney-tonifying and marrow-filling prescriptions exhibit regulatory and protective effects on the imbalance of astrocyte-neuron coupling， suggesting that the effect of kidney-tonifying and marrow-filling prescriptions in treating AD may have some internal relationship with its regulation of the imbalance of astrocyte-neuron coupling. This article reviewed the underlying internal relationship between the imbalance of astrocyte-neuron coupling and the pathogenesis of kidney deficiency and marrow inadequacy in AD and the research progress in the intervention mechanism of TCM for tonifying the kidney and filling the marrow.
ABSTRACT
ObjectiveTo explore the mechanism of Dihuang Yinzi in improving astrocyte injury and glycolysis in Alzheimer's disease （AD） mice via regulating the phosphatidylinositol 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway， thereby improving the cognitive function of AD mice. MethodForty male APP/PS1 transgenic mice aged four months were randomly divided into a model group and a model + Dihuang Yinzi （0.25 g·kg-1） group， with 20 mice in each group. Forty C57BL/6J mice with the same background and same age were randomly divided into a control group and a control + Dihuang Yinzi （0.25 g·kg-1） group， with 20 mice in each group. The mice in the control + Dihuang Yinzi group and the model + Dihuang Yinzi group were administered with Dihuang Yinzi by gavage， and those in the control group and the model group received an equal volume of sterilized normal saline， once a day for 150 days. Morris water maze test was performed to test the ability of navigation and space exploration of mice. The protein expression of p-PI3K， PI3K， p-Akt， Akt， phosphofructokinase-1 （PFK-1）， and aldehyde dehydrogenase 3 family member B2 （ALDH3B2） in mouse brain tissues was measured by Western blot. An immunofluorescence assay was performed to detect astrocyte morphology and the expression level of ALDH3B2. ResultAs compared with the control group， the model group showed prolonged escape latency during the 2nd to 5th days of the location-based navigation （P<0.05， P<0.01）， reduced number of times crossing the target area of the platform， shortened residence time in the target quadrant （P<0.05， P<0.01）， prolonged residence time in the opposite quadrant （P<0.05）， increased surface area of the cell body and total length of cell protrusions of astrocytes （P<0.05， P<0.01）， and down-regulated protein expression of p-PI3K， p-Akt， ALDH3B2， and PFK-1 （P<0.01）， while the above experimental indexes were not significantly different in the control + Dihuang Yinzi group. Compared with the model group， the model + Dihuang Yinzi group showed shortened escape latency of APP/PS1 mice during the 2nd to 5th days of the location-based navigation （P<0.05， P<0.01）， increased number of times crossing the platform， prolonged target quadrant residence time （P<0.05， P<0.01）， shortened residence time in the opposite quadrant （P<0.05）， reduced surface area of the cell body and total length of cell protrusions of astrocytes （P<0.05）， and up-regulated protein expression of p-PI3K， p-Akt， ALDH3B2， and PFK-1 （P<0.01）. ConclusionDihuang Yinzi can improve the learning and memory ability of AD mice by activating the PI3K/Akt signaling pathway and up-regulating the protein expression of PFK-1 and ALDH3B2 to protect against astrocyte injury in brain tissues and improve glycolysis.
ABSTRACT
ObjectiveTo explore the mechanism of Dihuang Yinzi （DHYZ）in improving astrocyte injury in the brain and regulating energy metabolism and autophagy disorder in Alzheimer's disease （AD） model mice. MethodForty male APP/PS1 transgenic mice aged four months were randomly divided into a model group and a model + DHYZ group （2.5 g·kg-1）， with 20 mice in each group. Forty C57BL/6J mice with the same background and same age were randomly divided into a control group and a control + DHYZ group （2.5 g·kg-1）， with 20 mice in each group. The mice in the control group and the model group were administered with an equal volume of sterilized normal saline by gavage， once a day for 150 days. Novel object recognition test and step-down test were performed to evaluate the learning and memory ability of mice. The expression of glial fibrillary acidic protein （GFAP） in astrocytes was detected by immunofluorescence and Western blot. High-performance liquid chromatography （HPLC） was used to detect adenosine triphosphate （ATP）， adenosine diphosphate （ADP）， and adenosine monophosphate （AMP） in brain tissues of mice， and the data obtained were used to calculate energy charge （EC） levels. The phosphorylation levels of liver kinase B1 （LKB1）， adenosine 5′-monophosphate （AMP）-activated protein kinase （AMPK）， UNC-51-like kinase 1 （ULK1）， and mammalian target of rapamycin （mTOR） and the expression levels of autophagy-related proteins Beclin-1， microtuble-associated protein 1 light chain 3 （LC3）-Ⅱ/LC3-Ⅰ， and p62 in mouse brain were measured by Western blot. ResultCompared with the control group， the model group showed decreased novel object recognition index， shortened retention latency， increased error times in the step-down test， up-regulated protein expression of GFAP， decreased content of ATP， ADP， and EC in brain tissues， elevated AMP ， increased levels of p-AMPK， p-LKB1， and p-mTOR， and protein expression of p62 ， and down-regulated p-ULK1 level and protein expression of Beclin-1 and LC3-Ⅱ/LC3-Ⅰ（P<0.01）， while the above experimental indexes were not significantly different in the control + DHYZ group. Compared with the model group， the model + DHYZ group showed increased novel object recognition index（P<0.05）， prolonged retention latency（P<0.01）， decreased error times（P<0.01） in the step-down test， reduced protein expression of GFAP（P<0.05）， increased content of ATP， ADP， and EC in brain tissues （P<0.05， P<0.01）， decreased AMP content（P<0.05）， reduced p-AMPK， p-LKB1， and p-mTOR levels and protein expression of p62， and up-regulated p-ULK1 level and protein expression of Beclin-1 and LC3-Ⅱ/LC3-Ⅰ（P<0.01）. ConclusionBy protecting astrocytes， DHYZ can improve energy metabolism and autophagy disorder in AD mice to improve the learning and memory ability of model mice.
ABSTRACT
ObjectiveTo investigate the mechanism of Dihuang Yinzi in improving astrocyte injury and protecting synaptic structure and function in the brain of Alzheimer's disease （AD） mice. MethodForty male APP/PS1 transgenic mice aged four months were randomly divided into a model group and a model + Dihuang Yinzi （0.25 g·kg-1） group， with 20 mice in each group. Forty C57BL/6J mice with the same background and same age were randomly divided into a control group and a control + Dihuang Yinzi （0.25 g·kg-1） group， with 20 mice in each group. The mice in the control + Dihuang Yinzi group and the model + Dihuang Yinzi group were administered with Dihuang Yinzi by gavage， and those in the control group and the model group received an equal volume of sterilized normal saline， once a day for 150 days. The learning and memory ability of mice was tested by the light-dark box test and Y-maze spontaneous alternation test. The content of glutamate （Glu） and glutamine （Gln） was measured by liquid chromatography-tandem mass spectrometry （LC-MS）. Long-term potentiation （LTP） assay was used to detect synaptic plasticity in brain tissues. The protein expression levels of excitatory amino acid transporter 2 （EAAT2）， postsynaptic density protein95 （PSD95）， and synaptophysin （SYN） in brain tissues were measured by Western blot. Immunofluorescence was used to assess the localization and expression of EAAT2. Colorimetry was performed to detect Na+-K+ ATPase activity in mouse brain tissues. ResultAs compared with the control group， the model group showed shortened residence latency （P<0.01）， increased number of errors （P<0.01） in the light-dark box test， reduced spontaneous alternation behaviors （P<0.01）， no significant difference in the total number of arm entries in the Y-maze spontaneous alternation test， down-regulated expression of EAAT2， PSD95， and SYN （P<0.01）， blunted activity of Na+-K+ ATPase （P<0.01）， up-regulated Glu level （P<0.01）， down-regulated Gln level （P<0.01）， and reduced relative population spike （PS） amplitude and the slope of excitatory postsynaptic potential （EPSP） （P<0.05， P<0.01）， while the above experimental indexes were not significantly different in the control + Dihuang Yinzi group. Compared with the model group， the model + Dihuang Yinzi group displayed prolonged residence latency （P<0.05）， decreased number of errors （P<0.01） in the light-dark box test， increased spontaneous alternation behaviors （P<0.01）， no significant difference in the total number of arm entries in the Y-maze spontaneous alternation test， up-regulated expression of EAAT2， PSD95， and SYN （P<0.01）， potentiated activity of Na+-K+ ATPase （P<0.01）， reduced Glu level （P<0.01）， up-regulated Gln level （P<0.01）， and increased PS amplitude and EPSP slope （P<0.01）. ConclusionDihuang Yinzi can improve cognitive dysfunction in AD mice by protecting astrocytes， increasing Glu uptake to reduce its abnormal accumulation， and protecting synaptic structure and function.