Quercetin-3-O-β-d-glucuronide in the Nuciferine Leaf Polyphenol Extract Promotes Neurogenesis Involving the Upregulation of the Tropomyosin Receptor Kinase (Trk) Receptor and AKT/Phosphoinositide 3-Kinase Signaling Pathway

Quercetin protects against neuronal toxicity by activating the PI3K/Akt/GSK-3β pathway in vivo models of MPTP-induced Parkinson's disease

BACKGROUND

Quercetin is a flavonoid commonly found in various fruits, vegetables, and grains. Studies have demonstrated that quercetin may help protect neuronal cells from damage caused by neurotoxins associated with Parkinson's disease, however, the underlying mechanism remains unclear.

AIM

The current study aimed to investigate the neuroprotective effects of quercetin in MPTP-induced Parkinson's disease mouse models and elucidate its mechanistic role in modulating the PI3K/Akt/GSK-3β signaling pathway.

MATERIALS AND METHODS

Male C57BL/6 mice were divided into control, MPTP, quercetin, and MPTP + quercetin groups. The protective effects of quercetin on Parkinson's disease in mice were evaluated using animal behaviour analysis, histopathological examination, and immunofluorescence staining. Subsequently, network pharmacology was utilized to determine the primary target sites of quercetin in Parkinson's disease. Finally, western blotting and molecular docking techniques were applied to validate the identified targets.

RESULTS

Quercetin significantly improved motor deficits in MPTP mice, reduced neuronal atrophy, and preserved TH+ dopaminergic neurons. Western blotting analysis revealed quercetin upregulated anti-inflammatory IL-10 (p < 0.01) and TGF-β (p < 0.01) while suppressing pro-inflammatory IL-1β (p < 0.01) and iNOS (p < 0.01). It activated the PI3K/Akt/GSK-3β pathway by increasing phosphorylation of PI3K (p < 0.01), Akt (p < 0.01), and GSK-3β (p < 0.01). Quercetin also elevated anti-apoptotic Bcl-2 (p < 0.01) and reduced pro-apoptotic Bax (p < 0.01) and Caspase-9 (p < 0.01). Molecular docking confirmed strong binding between quercetin and PI3K/Akt/GSK-3β (binding energies: -6.44 to -5.24 kcal/mol).

CONCLUSION

Quercetin alleviates Parkinson's disease pathology by inhibiting neuroinflammation, reducing apoptosis, and activating the PI3K/Akt/GSK-3β pathway. These findings underscore its potential as a multi-target therapeutic agent for Parkinson's disease.

Corticosterone-induced postpartum depression induces depression-like behavior and impairs hippocampal neurogenesis in adolescent offspring via HPA axis and BDNF-mTOR pathway

Postpartum depression (PPD) adversely affects the growth and development of the offspring, increasing the risk of various internalizing behaviorsduring adolescence. Studies have shown that corticosterone (CORT)-induced PPD affects neurogenesis in the offspring, which is closely related to the onset of depression. However, the underlying mechanisms of these changes in the offspring of PPD mothers remain unexplored. In this study, we demonstrated postpartum mice treated with high CORT experienced activation of the hypothalamic-pituitary-adrenal (HPA) axis, which induced depressive-like behavior and impaired maternal caring behavior. Furthermore, adolescent offspring of PPD mice exhibited depression-like behavior, and learning and memory deficits. These offspring also showed diminished levels of DCX+, decreased levels of synaptic proteins, and reduced dendritic spine density and length in hippocampus. Additionally, we detected increased serum stressed hormones and decreased hippocampal glucocorticoid receptor (GR) protein level in the offspring. We also found the offspring exhibited reduced expression of brain-derived neurotrophic factor (BDNF) and the phosphorylation tyrosine kinase receptor B (TrkB), protein kinase B (AKT), and mammalian target of rapamycin (mTOR) proteins in hippocampus. These results indicated that the behavioral deficits and neuronal damage observed in the offspring of PPD mice may be related to HPA axis dysfunction and inhibition of the BDNF-mTOR pathway. In conclusion, our findings confirm that CORT induces depression-like behavior and impairs maternal caring behavior in maternal mice, which in turn affects their offspring's emotion and cognitive behavior. This impact is characterized by the activation of the HPA axis and inhibition of the BDNF-mTOR pathway.

Nelumbo nucifera leaves extract ameliorated scopolamine-induced cognition impairment via enhanced adult hippocampus neurogenesis

In this presentation, we explored the molecular mechanisms of N. nucifera leaf water extracts (NLWEs) and polyphenol extract (NLPE) on scopolamine-induced cell apoptosis and cognition defects. The administration of NLWE and NLPE did not alter the body weight and serum biomarker rs and significantly ameliorated scopolamine-induced cognition impairment according to Y-maze test analysis. In mice, treatment with scopolamine disrupted normal histoarchitecture in the hippocampus, whereas the administration of NLWE and NLPE reversed the phenomenon. Western blot analysis revealed that scopolamine mitigated the expression of doublecortin (DCX), nestin, and NeuN, and cotreatment with NLWE or NLPE significantly recovered the expression of these proteins. NLWE and NLPE upregulated DCX and NeuN expression in the hippocampus region, as evidenced by immunohistochemical staining analysis of scopolamine-treated mice. NLWE and NLPE obviously elevated brain-derived neurotrophic factor (BDNF) and enhanced its downstream proteins activity. NLWE and NLPE attenuated scopolamine-induced apoptosis by reducing Bax and increased Bcl-2 expression. In addition, scopolamine also triggered apoptosis in human neuroblastoma SH-SY5Y cells whereas co-treatment with NLWE or quercetin-3-glucuronide (Q3G) reversed the phenomenon. NLWE or Q3G enhanced Bcl-2 and reduced Bax expression in the presence of scopolamine in SH-SY5Y cells. NLWE or Q3G recovered the inhibitory effects of scopolamine on neurogenesis and BDNF signals in SH-SY5Y cells. Overall, our results revealed that N. nucifera leaf extracts and Q3G promoted adult hippocampus neurogenesis and prevented apoptosis to mitigate scopolamine-induced cognition dysfunction through the regulation of BDNF signaling pathway.

Unlocking the Potential: Quercetin and Its Natural Derivatives as Promising Therapeutics for Sepsis

Sepsis is a syndrome of organ dysfunction caused by an uncontrolled inflammatory response, which can seriously endanger life. Currently, there is still a shortage of specific therapeutic drugs. Quercetin and its natural derivatives have received a lot of attention recently for their potential in treating sepsis. Here, we provide a comprehensive summary of the recent research progress on quercetin and its derivatives, with a focus on their specific mechanisms of antioxidation and anti-inflammation. To obtain the necessary information, we conducted a search in the PubMed, Web of Science, EBSCO, and Cochrane library databases using the keywords sepsis, anti-inflammatory, antioxidant, anti-infection, quercetin, and its natural derivatives to identify relevant research from 6315 articles published in the last five years. At present, quercetin and its 11 derivatives have been intensively studied. They primarily exert their antioxidation and anti-inflammation effects through the PI3K/AKT/NF-κB, Nrf2/ARE, and MAPK pathways. The feasibility of these compounds in experimental models and clinical application were also discussed. In conclusion, quercetin and its natural derivatives have good application potential in the treatment of sepsis.