Multi-strain probiotics ameliorate Alzheimer's-like cognitive impairment and pathological changes through the AKT/GSK-3β pathway in senescence-accelerated mouse prone 8 mice.

Alzheimer's disease (AD), the most prevalent type of dementia, still lacks disease-modifying treatment strategies. Recent evidence indicates that maintaining gut microbiota homeostasis plays a crucial role in AD. Targeted regulation of gut microbiota, including probiotics, is anticipated to emerge as a potential approach for AD treatment. However, the efficacy and mechanism of multi-strain probiotics treatment in AD remain unclear. In this study, 6-month-old senescence-accelerated-mouse-prone 8 (SAMP8) and senescence-accelerated-mouse-resistant 1 (SAMR1) were utilized. The SAMP8 mice were treated with probiotic-2 (P2, a probiotic mixture of Bifidobacterium lactis and Lactobacillus rhamnosus) and probiotic-3 (P3, a probiotic mixture of Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus rhamnosus) (1 × 109 colony-forming units) once daily for 8 weeks. Morris water maze (MWM) and novel object recognition (NOR) tests were employed to assess the memory ability. 16S sequencing was applied to determine the composition of gut microbiota, along with detecting serum short-chain fatty acids (SCFAs) concentrations. Neural injury, Aβ and Tau pathology, and neuroinflammation level were assessed through western blot and immunofluorescence. Finally, potential molecular mechanisms was explored through transcriptomic analysis and western blotting. The MWM and NOR test results indicated a significant improvement in the cognitive level of SAMP8 mice treated with P2 and P3 probiotics compared to the SAMP8 control group. Fecal 16S sequencing revealed an evident difference in the α diversity index between SAMP8 and SAMR1 mice, while the α diversity of SAMP8 mice remained unchanged after P2 and P3 treatment. At the genus level, the relative abundance of ten bacteria differed significantly among the four groups. Multi-strain probiotics treatment could modulate serum SCFAs (valeric acid, isovaleric acid, and hexanoic acid) concentration. Neuropathological results demonstrated a substantial decrease in neural injury, Aβ and Tau pathology and neuroinflammation in the brain of SAMP8 mice treated with P3 and P2. Transcriptomic analysis identified the chemokine signaling pathway as the most significantly enriched signaling pathway between SAMP8 and SAMR1 mice. Western blot test indicated a significant change in the phosphorylation level of downstream AKT/GSK-3β between the SAMP8 and SAMR1 groups, which could be reversed through P2 and P3 treatment. Multi-strain probiotics treatment can ameliorate cognitive impairment and pathological change in SAMP8 mice, including neural damage, Aβ and Tau pathology, and neuroinflammation. This effect is associated with the regulation of the phosphorylation of the AKT/GSK-3β pathway.

Xiao-Hang Q ，Si-Yue C ，Hui-Dong T 《-》

Antisense oligonucleotide against GSK-3β in brain of SAMP8 mice improves learning and memory and decreases oxidative stress: Involvement of transcription factor Nrf2 and implications for Alzheimer disease.

Glycogen synthase kinase (GSK)-3β is a multifunctional protein that has been implicated in the pathological characteristics of Alzheimer's disease (AD), including the heightened levels of neurofibrillary tangles, amyloid-beta (Aβ), and neurodegeneration. In this study we used 12-month-old SAMP8 mice, an AD model, to examine the effects GSK-3β may cause regarding the cognitive impairment and oxidative stress associated with AD. To suppress the level of GSK-3β, SAMP8 mice were treated with an antisense oligonucleotide (GAO) directed at this kinase. We measured a decreased level of GSK-3β in the cortex of the mice, indicating the success of the antisense treatment. Learning and memory assessments of the SAMP8 mice were tested post-antisense treatment using an aversive T-maze and object recognition test, both of which observably improved. In cortex samples of the SAMP8 mice, decreased levels of protein carbonyl and protein-bound HNE were measured, indicating decreased oxidative stress. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a transcription factor known to increase the level of many antioxidants, including glutathione-S transferase (GST), and is negatively regulated by the activity of GSK-3β. Our results indicated the increased nuclear localization of Nrf2 and level of GST, suggesting the increased activity of the transcription factor as a result of GSK-3β suppression, consistent with the decreased oxidative stress observed. Consistent with the improved learning and memory, and consistent with GSK-3b being a tau kinase, we observed decreased tau phosphorylation in brain of GAO-treated SAMP8 mice compared to that of RAO-treated SAMP8 mice. Lastly, we examined the ability of GAO to cross the blood-brain barrier and determined it to be possible. The results presented in this study demonstrate that reducing GSK-3 with a phosphorothionated antisense against GSK-3 improves learning and memory, reduces oxidative stress, possibly coincident with increased levels of the antioxidant transcriptional activity of Nrf2, and decreases tau phosphorylation. Our study supports the notion of GAO as a possible treatment for AD.

Farr SA ，Ripley JL ，Sultana R ，Zhang Z ，Niehoff ML ，Platt TL ，Murphy MP ，Morley JE ，Kumar V ，Butterfield DA ... -  《-》

Tanshinone IIA regulates glycogen synthase kinase-3β-related signaling pathway and ameliorates memory impairment in APP/PS1 transgenic mice.

Our previous findings indicated that tanshinone IIA (tan IIA), a natural component extracted from the root and rhizome of danshen, significantly attenuated β-amyloid accumulation, neuroinflammation, and endoplasmic reticulum stress, as well as improved learning and memory deficits in APP/PS1 transgenic mouse model of Alzheimer's disease (AD). However, whether tan IIA can ameliorate tau pathology and the underlying mechanism in APP/PS1 mice remains unclear. In the current study, tan IIA (15 mg/kg and 30 mg/kg) or saline was intraperitoneally administered to the 5-month-old APP/PS1 mice once daily for 4 weeks. The open-field test, novel object recognition test, Y-maze test, and Morris water maze test were performed to assess the cognitive function. Nissl staining, immunohistochemistry, TUNEL, and western blotting were conducted to explore tau hyperphosphorylation, neuronal injury, and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt)/glycogen synthase kinase-3β (GSK-3β) signaling pathway. The activity of GSK-3β, acetylcholinesterase (AChE), choline acetyltransferase (ChAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px), and the level of malondialdehyde (MDA) were measured using commercial kits. Our results revealed that tan IIA treatment significantly ameliorated behavioral deficits and improved spatial learning and memory ability of APP/PS1 mice. Additionally, tan IIA markedly attenuated tau hyperphosphorylation and prevented neuronal loss and apoptosis in the parietal cortex and hippocampus. Simultaneously, tan IIA reversed cholinergic dysfunction and reduced oxidative stress. Furthermore, tan IIA activated the PI3K/Akt signaling pathway and suppressed GSK-3β. Taken together, the above findings suggested that tan IIA improves cognitive decline and tau pathology may through modulation of PI3K/Akt/GSK-3β signaling pathway.

Peng X ，Chen L ，Wang Z ，He Y ，Ruganzu JB ，Guo H ，Zhang X ，Ji S ，Zheng L ，Yang W ... -  《-》

Lactobacillus plantarum DP189 prevents cognitive dysfunction in D-galactose/AlCl(3) induced mouse model of Alzheimer's disease via modulating gut microbiota and PI3K/Akt/GSK-3β signaling pathway.

Song X ，Zhao Z ，Zhao Y ，Wang Z ，Wang C ，Yang G ，Li S ... -  《-》

Sulforaphene Ameliorates Neuroinflammation and Hyperphosphorylated Tau Protein via Regulating the PI3K/Akt/GSK-3β Pathway in Experimental Models of Alzheimer's Disease.

Alzheimer's disease (AD) is the most common form of dementia characterized by progressive loss of cognitive functions due to neuronal death mainly in the hippocampal and cortical brain. Sulforaphene (SF) is one of the main isothiocyanates isolated from a Chinese herb Raphani Semen. In this study, we aimed to investigate the neuroprotective effects of SF using in vitro and in vivo models of AD. Streptozotocin (STZ) was intracranially injected into the rats; then, SF (25 and 50 mg/kg) was given orally once a day for 6 consecutive weeks. After drug treatment, the cognitive functions were assessed using the Morris Water Maze Test (MWMT). After the MWMT, the rats were euthanized and brain tissues were collected. In the in vitro test, BV-2 microglia were pretreated with SF (1 and 2 μM) for 1 h and then stimulated with lipopolysaccharide (LPS) for another 23 h. Both molecular and histological methods were used to unravel the action mechanisms and elucidate the signaling pathway. The MWMT results showed that SF treatment significantly improved the STZ-induced cognitive deficits in rats. SF treatment markedly suppressed the production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) but increased the release of IL-10 in the STZ-treated rats. In addition, SF significantly inhibited the phosphorylation of tau protein at Thr205, Ser396, and Ser404 sites, while enhancing the ratios of p-Akt (Ser473)/Akt and p-GSK-3β (Ser9)/GSK-3β in the hippocampus of the STZ-treated rats. On the other hand, SF (1 and 2 μM) treatment also markedly attenuated the cytotoxicity induced by LPS in BV-2 cells. In addition, SF treatment obviously suppressed the releases of nitric oxide (NO), TNF-α, and IL-6 in the LPS-stimulated BV-2 cells. Moreover, SF treatment significantly mitigated the nuclear translocation of p-NF-κB p65 and the ratio of p-GSK-3β (Ser9)/GSK-3β in LPS-stimulated BV-2 cells. Taken together, SF possessed neuroprotective effects against the STZ-induced cognitive deficits in rats and LPS-induced neuroinflammation in BV-2 cells via modulation of the PI3K/Akt/GSK-3β pathway and inhibition of the NF-κB activation, suggesting that SF is a promising neuroprotective agent worthy of further development into AD treatment.

Yang W ，Liu Y ，Xu QQ ，Xian YF ，Lin ZX ... -  《-》