[Levels of proinflammatory cytokines and vascular endothelial growth factor in patients with Alzheimer's disease and mild cognitive impairment]

[Neurobiological potential of astragaloside IV and prospects for its use in the treatment of Alzheimer's disease]

The review presents an analysis of experimental data on the study of the neurobiological effects of astragaloside IV, which can be used in the treatment of Alzheimer's disease. Astragaloside IV is a cycloartan triterpene saponin, which is found in the roots of membranous milk vetch (Astragalus membranaceus (Fisch. ex Link) Bunge) and has a very wide range of pharmacological activity. In recent years, this compound has attracted attention due to its diverse neurobiological effects. Studies have shown the ability of astragaloside IV to modulate microglial activity. The protective effect of this saponin on neurons from the effects of glutamate-induced neurotoxicity has been demonstrated. In PC12 cells, astragaloside IV is shown to be able to resolve various types of mitochondrial dysfunction and inhibit endoplasmic reticulum stress. This compound is also a PPARγ agonist. In vivo experiments have shown that the test substance effectively protects synapses as well as improves cognitive functions, including memory and learning. It is concluded that astragaloside IV, apparently, may be used in the future as a multi-purpose complex therapy for Alzheimer's disease.

[Ginkgolide B: mechanisms of neurobiological effects, prospects for use in the therapy of Alzheimer's disease]

The review presents an analysis of experimental data on the study of neurobiological effects of ginkgolide B, which may find application in the therapy of Alzheimer's disease (AD). Ginkgolide B is a diterpene trilactone isolated from the leaves of the relict woody plant Ginkgo biloba L., which has been used for thousands of years in traditional Chinese medicine as a neuroprotective agent. In recent years, this compound has attracted attention because of its wide range of neurobiological effects. The neuroprotective effect of ginkgolide B on brain neurons when exposed to various neurotoxins has been established. This compound has also been shown to effectively protect neurons from the effects of beta-amyloid. Studies have revealed the ability of ginkgolide B to reduce microglia activity and regulate neurotransmitter release. In vivo experiments have shown that this substance significantly increases the expression of brain-derived neurotrophic factor (BDNF) and improves cognitive functions, including memory and learning. It is concluded that ginkgolide B, apparently, may find application in the future as a multi-targeted agent of complex therapy of AD.

VEGF signalling causes stalls in brain capillaries and reduces cerebral blood flow in Alzheimer's mice

Increased incidence of stalled capillary blood flow caused by adhesion of leucocytes to the brain microvascular endothelium leads to a 17% reduction of cerebral blood flow and exacerbates short-term memory loss in multiple mouse models of Alzheimer’s disease.

Here, we report that vascular endothelial growth factor (VEGF) signalling at the luminal side of the brain microvasculature plays an integral role in the capillary stalling phenomenon of the APP/PS1 mouse model.

Administration of the anti-mouse VEGF-A164 antibody, an isoform that inhibits blood–brain barrier hyperpermeability, reduced the number of stalled capillaries within an hour of injection, leading to an immediate increase in average capillary blood flow but not capillary diameter. VEGF-A inhibition also reduced the overall endothelial nitric oxide synthase protein concentrations, increased occludin levels and decreased the penetration of circulating Evans Blue dye across the blood–brain barrier into the brain parenchyma, suggesting increased blood–brain barrier integrity. Capillaries prone to neutrophil adhesion after anti-VEGF-A treatment also had lower occludin concentrations than flowing capillaries.

Taken together, our findings demonstrate that VEGF-A signalling in APP/PS1 mice contributes to aberrant endothelial nitric oxide synthase /occludin-associated blood–brain barrier permeability, increases the incidence of capillary stalls, and leads to reductions in cerebral blood flow. Reducing leucocyte adhesion by inhibiting luminal VEGF signalling may provide a novel and well-tolerated strategy for improving brain microvascular blood flow in Alzheimer’s disease patients.

Functional Compensation and Mechanism of Choline Acetyltransferase in the Treatment of Cognitive Deficits in Aged Dementia Mice

Choline acetyltransferase (ChAT) synthesizes the neurotransmitter acetylcholine (Ach). Exogenous supplementation with ChAT can functionally compensate for decreased Ach levels and ameliorate memory and cognitive deficits. In this paper, the treatment efficacy of recombinant ChAT (peptide transduction domain (PTD)-ChAT) and donepezil were compared in aged dementia mice, and their mechanisms were explored by performing the gene function annotation and enrichment analysis of differentially expressed genes. The Morris water maze test showed that the swimming times of PTD-ChAT-treated (4 mg/kg) and donepezil-treated (0.5 mg/kg) mice with mild and moderate dementia were significantly shortened (P < 0.01 vs aged dementia mice), and no significant changes were observed between the PTD-ChAT- and donepezil-treated groups. In contrast, the swimming times of PTD-ChAT-treated mice with severe dementia were noticeably shorter than those of donepezil-treated mice with severe dementia (P < 0.01), indicating that the treatment efficacy of PTD-ChAT is superior to that of donepezil. The effect of PTD-ChAT was further confirmed in transgenic dementia mice (C57BL/6J-TgN (APP/PS1) ZLFILAS). Gene function annotation and enrichment analysis showed that PTD-ChAT improved cognitive deficits through Ach and was implicated in neuroprotection, synaptic plasticity, neuronal survival, and cerebrovascular remodeling through ACh and vascular endothelial growth factor (VEGF) pathway activation. Donepezil was significantly correlated with the immune inflammatory response and the insulin and IGF-1 signaling pathways. Therefore, although PTD-ChAT and donepezil were both effective in the treatment of aged dementia mice, their mechanisms were significantly different. Our research indicated that PTD-ChAT has potential promise for research on new drugs for AD treatment.