Tiaogeng decoction improves mild cognitive impairment in menopausal APP/PS1 mice through the ERs/NF-κ b/AQP1 signaling pathway

Abstract

People with mild cognitive impairment (MCI) carry a considerable risk of developing dementia. Studies have shown that female sex hormones have long-lasting neuroprotective and anti-aging properties, and the increased risk of MCI and AD is associated with the lack of estrogen during menopause. Previous studies have shown that Tiao Geng Decoction (TGD) may have antioxidant and anti apoptotic properties, which may prevent neurodegenerative diseases. However, whether TGD is effective in improving mild cognitive impairment due to postmenopausal estrogen deficiency and its potential pharmacological mechanisms remain unclear. The aim of this study was to investigate the possible pharmacological mechanisms of TGD in preventing postmenopausal MCI. We utilized RNA-seq technology to screen for differentially expressed genes (DEGs) and enrichment pathways in the hippocampal tissue of different groups of mice. Additionally, we adopted single-cell sequencing technology to study the cell types of Alzheimer's disease (AD) group and Normal Control (NC) group, the differential marker genes of each cell subgroup, and the GO enrichment analysis of each cell type. Both RNA sequencing and single-cell sequencing results showed a significant correlation between TGD and NF-κb pathway in improving mild cognitive impairment in postmenopausal women. The experimental verification results showed that the spatial learning and memory abilities of APP/PS1 model mice were weakened after ovariectomy, and the reproductive cycle on vaginal smears was in the interphase of diestrus. The levels of serum E2, and P-tau181 in mice were significantly down regulated, while the levels of brain tissue homogenate A β 42, IL-1 β, and IL-18 were significantly up-regulated, indicating successful modeling. Combining Western blotting, RT-qPCR, and transmission electron microscopy analyses, it was found that the low estrogen environment induced by oophorectomy can activate the NF-κb signaling pathway, activate the expression of NLRP3 inflammasome and A β secretase BACE1, and induce neuroinflammatory damage in hippocampal astrocytes. These results conform to the modeling characteristics of MCI. After TGD intervention, the spatial learning and memory abilities of MCI mice were significantly improved. The pharmacological validation results indicated that high concentration doses of TGD had a more significant effect on MCI. Subsequently, we used high concentration TGD (0.32 g/ml) as the traditional Chinese medicine group for further validation, protein blotting and RT-qPCR results indicated that TGD can effectively stimulate the secretion of ER α and ER β, inhibit the NF-κb pathway, downregulate BACE1, and inhibit the expression of NLRP3 inflammasome related proteins. In addition, the immunofluorescence results of hippocampal astrocytes showed that TGD can effectively facilitate the expression of AQP1 and significantly lower the sedimentation of A β compared with the model group. Our research suggests that there is a high correlation between a low estrogen environment and the occurrence and development of MCI. TGD may regulate the ERs/NF - κ b/AQP1 signaling pathway, promote estrogen secretion, activate AQP1, reduce A β deposition, reverse MCI neuroinflammatory injury, improve mild cognitive impairment, and prevent the occurrence of AD. This study revealed for the first time that TGD may be a potential new alternative drug for preventing and improving menopausal MCI.

Keywords: Aβ; ERs/NF-κb/AQP1signal pathway; Menopause; Mild cognitive impairment; Neuroinflammatory damage; Tiaogeng decoction.