[Comparative study of purgative pharmacological effects and mechanisms of Moringa oleifera leaves and Rhei Radix et Rhizoma].

Moringa oleifera leaves are known for their "Virechana"(purgative) effect in Ayurvedic medicine in India. This study compared the purgative effects and mechanisms of M. oleifera leaves with the reference Rhei Radix et Rhizoma to establish a foundation for the further application of M. oleifera leaves in traditional Chinese medicine(TCM). Using network pharmacology and molecular docking methods, this study identified the material basis, common targets, and signaling pathways through which Rhei Radix et Rhizoma and M. oleifera leaves exerted their purgative pharmacological effects. A low-fiber diet-induced constipation mouse model was established to measure fecal parameters and small intestinal propulsion rate, and histological changes in the colon were observed using HE staining. Relative expression levels of relevant genes and target proteins were assessed using RT-qPCR and immunohistochemistry, respectively. The results showed that mapping the targets of Rhei Radix et Rhizoma and M. oleifera leaves onto the biological process network of constipation revealed close proximity, indicating that they may exert their therapeutic effects on constipation through similar biological processes. Molecular docking results indicated that compounds such as sennoside C and isoquercitrin could target serine/threonine protein kinases(AKT1) and mitogen-activated protein kinase 3(MAPK3), thereby affecting MAPK and calcium signaling pathways to promote defecation. Animal experiments demonstrated that both M. oleifera leaves and Rhei Radix et Rhizoma increased the number of fecal pellets and water content in constipated mice, improved small intestine motility, colon mucosal thickness, and muscle layer thickness, upregulated the gene expression levels of AKT1 and MAPK3 in the colon, and downregulated the expression of AQP3 protein. These findings suggest that M. oleifera leaves and Rhei Radix et Rhizoma share similarities in their therapeutic efficacy and mechanisms for treating constipation. Using Rhei Radix et Rhizoma as a reference can provide a better understanding of the characteristics of the "Virechana"(purgative) effect of M. oleifera leaves in TCM.

Protective role of Dihydromyricetin in Alzheimer's disease rat model associated with activating AMPK/SIRT1 signaling pathway.

The aim of the present study was to understand the possible role of the Dihydromyricetin (DHM) in Alzheimer's disease (AD) rat model through regulation of the AMPK/SIRT1 signaling pathway. Rats were divided into Sham group, AD group, AD + DHM (100 mg/kg) group and AD + DHM (200 mg/kg) group. The spatial learning and memory abilities of rats were assessed by Morris Water Maze. Then, the inflammatory cytokines expressions were determined by radioimmunoassay while expressions of AMPK/SIRT1 pathway-related proteins by Western blot; and the apoptosis of hippocampal cells was detected by TdT-mediated dUTP nick end labeling assay. AD rats had an extended escape latency with decreases in the number of platform crossings, the target quadrant residence time, as well as swimming speed, and the inflammatory cytokines in serum and hippocampus were significantly elevated but AMPK/SIRT1 pathway-related proteins were reduced. Meanwhile, the apoptosis of hippocampal cells was significantly up-regulated with decreased Bcl-2 and increased Bax, as compared with Sham rats (all P<0.05). After AD rats treated with 100 or 200 mg/kg of DHM, the above effects were significantly reversed, resulting in a completely opposite tendency, and especially with 200 mg/kg DHM treatment, the improvement of AD rats was more obvious. DHM exerts protective role in AD via up-regulation of AMPK/SIRT1 pathway to inhibit inflammatory responses and hippocampal cell apoptosis and ameliorate cognitive function.

Histone deacetylase-2 is involved in stress-induced cognitive impairment via histone deacetylation and PI3K/AKT signaling pathway modification.

Exposure to chronic stress upregulates blood glucocorticoid levels and impairs cognition via diverse epigenetic mechanisms, such as histone deacetylation. Histone deacetylation can lead to transcriptional silencing of many proteins involved in cognition and may also cause learning and memory dysfunction. Histone deacetylase­2 (HDAC2) has been demonstrated to epigenetically block cognition via a reduction in the histone acetylation level; however, it is unknown whether HDAC2 is involved in the cognitive decline induced by chronic stress. To the best of authors' knowledge, this is the first study to demonstrate that the stress hormone corticosteroid upregulate HDAC2 protein levels in neuro­2a cells and cause cell injuries. HDAC2 knockdown resulted in a significant amelioration of the pathological changes in N2a cells via the upregulation of histone acetylation and modifications in the phosphoinositide 3­kinase/protein kinase B signaling pathway. In addition, the HDAC2 protein levels were upregulated in 12­month­old female C57BL/6J mice under chronic stress in vivo. Taken together, these findings suggested that HDAC2 may be an important negative regulator involved in chronic stress­induced cognitive impairment.