The influence of GAPT extraction on synapse loss of APPswe/PS1dE9 transgenic mice via adjusting Bcl-2/Bax balance

VEGF-A in serum protects against memory impairment in APP/PS1 transgenic mice by blocking neutrophil infiltration

Activation of innate immunity in the brain is a prominent feature of Alzheimer's disease (AD). The present study investigated the regulation of innate immunity by wild-type serum injection in a transgenic AD mouse model. We found that treatment with wild-type mouse serum significantly reduced the number of neutrophils and microglial reactivity in the brains of APP/PS1 mice. Mimicking this effect, neutrophil depletion via Ly6G neutralizing antibodies resulted in improvements in AD brain functions. Serum proteomic analysis identified vascular endothelial growth factor-A (VEGF-A) and chemokine (C-X-C motif) ligand 1 (CXCL1) as factors enriched in serum samples, which are crucial for neutrophil migration and chemotaxis, leukocyte migration, and cell chemotaxis. Exogenous VEGF-A reversed amyloid β (Aβ)-induced decreases in cyclin-dependent kinase 5 (Cdk5) and increases in CXCL1 in vitro and blocked neutrophil infiltration into the AD brain. Endothelial Cdk5 overexpression conferred an inhibitory effect on CXCL1 and neutrophil infiltration, thereby restoring memory abilities in APP/PS1 mice. Our findings uncover a previously unknown link between blood-derived VEGF signaling and neutrophil infiltration and support targeting endothelial Cdk5 signaling as a potential therapeutic strategy for AD.

Two polyphenols isolated from Corallodiscus flabellata B. L. Burtt ameliorate amyloid β-protein induced Alzheimer's disease neuronal injury by improving mitochondrial homeostasis

Corallodiscus flabellata B. L. Burtt (CF) is a Chinese folk herb with reported potential for the treatment of Alzheimer's disease (AD). 3,4-Dihydroxyphenylethanol-8-O-[4-O-trans-caffeoyl-β-D-apiofuranosyl-(1→3)-β-D-glucopyranosyl (1→6)][1]-β-D-glucopyranoside (SDC-1-8) and hydroxytyrosol (HT) are two polyphenolic compounds isolated from CF. The aim of this study was to investigate the protective effects of SDC-1-8 and HT on an Aβ_25-35-induced AD model and to study the underlying mechanism. The AD mouse model was established using a brain injection of amyloid β-protein 25-35 (Aβ_25-35, 200 μM), followed by continuous administration of SDC-1-8 and HT for 4 weeks, and found that they improved cognitive dysfunction; ameliorated neuronal damage and apoptosis; decreased oxidative stress, and mitochondrial fission protein levels; and increased mitochondrial fusion protein levels in AD mice. Moreover, SDC-1-8 and HT inhibited mitochondrial membrane depolarization, reduced intracellular stored Ca²⁺ levels, enhanced mitochondrial respiration, increased mitochondrial fusion, and decreased mitochondrial division in Aβ_25-35-induced PC12 cells even in the presence of mdivi-1. Furthermore, molecular docking simulations showed that SDC-1-8 and HT interacted with dynamin-related protein 1 with higher affinity than mitofusin 1. Thus, it is summarized that SDC-1-8 and HT may have neuroprotective effects by balancing the abnormalities of mitochondrial fission and fusion, and SDC-1-8 and HT are the components providing the therapeutic basis of CF.

GAPT regulates cholinergic dysfunction and oxidative stress in the brains of learning and memory impairment mice induced by scopolamine

BACKGROUND

Cholinergic dysfunction and oxidative stress are the crucial mechanisms of Alzheimer's disease (AD). GAPT, also called GEPT (a combination of several active components extracted from the Chinese herbs ginseng, epimedium, polygala and tuber curcumae) or Jinsiwei, is a patented Chinese herbal compound, has been clinically widely used to improve learning and memory impairment, but whether it can play a neuroprotective role by protecting cholinergic neurons and reducing oxidative stress injury remains unclear.

METHODS

Male ICR mice were intraperitoneally injected with scopolamine (3 mg/kg) to establish a learning and memory disordered model. An LC-MS method was established to study the chemical compounds and in vivo metabolites of GAPT. After scopolamine injection, a step-down passive-avoidance test (SDPA) and a Y maze test were used to estimate learning ability and cognitive function. In addition, ELISA detected the enzymatic activities of acetylcholinesterase (AChE), acetylcholine (ACh), choline acetyltransferase (ChAT), malondialdehyde (MDA), glutathione peroxidase (GPX), and total superoxide dismutase (T-SOD). The protein expressions of AChE, ChAT, SOD1, and GPX1 were observed by western blot, and the distribution of ChAT, SOD1, and GPX1 was observed by immunohistochemical staining.

RESULTS

After one-half or 1 month of intragastric administration, GAPT can ameliorate scopolamine-induced behavioral changes in learning and memory impaired mice. It can also decrease the activity of MDA and protein expression level of AChE, increase the activity of Ach, and increase activity and protein expression level of ChAT, SOD, and GPX in scopolamine-treated mice. After one and a half month of intragastric administration of GAPT, echinacoside, salvianolic acid A, ginsenoside Rb1, ginsenoside Rg2, pachymic acid, and beta asarone could be absorbed into mice blood and pass through BBB.

CONCLUSIONS

GAPT can improve the learning and memory ability of scopolamine-induced mice, and its mechanism may be related to protecting cholinergic neurons and reducing oxidative stress injury.