The SIRT-1/Nrf2/HO-1 axis: Guardians of neuronal health in neurological disorders

Tea Polyphenols Mitigate Radiation-Induced Ferroptosis and Intestinal Injury by Targeting the Nrf2/HO-1/GPX4 Signaling Pathway

Radiation-induced intestinal injury (RIII) is a significant concern for cancer patients receiving radiation therapy, as it can lead to complications such as radiation enteropathy. Presently, there are limited options for preventing or treating RIII. Tea polyphenols (TP), found in tea, provide various health benefits, but their antiradiation mechanisms are not fully understood. C57BL/6 mice pre-treated with TP for five days showed a significant improvement in survival rates after being exposed to 10 Gy of 60Co radiation. In the same way, abdominal exposure to 15 Gy of 60Co radiation effectively mitigated radiation-induced colon shortening, damage to intestinal tissues, oxidative stress, the release of inflammatory factors, and disruptions in intestinal microbial balance. In addition, TP treatment lowered the elevation of reactive oxygen species (ROS), iron imbalance, mitochondrial damage, and ferroptosis in IEC-6 cells post-irradiation. Utilizing network pharmacology, molecular docking, and affinity testing, we identified that TP has the capability to target the Nrf2/HO-1/GPX4 signaling pathway, while EGCG, a principal constituent of TP, interacts with HSP90 and mitigates radiation-induced ferroptosis. These findings suggest that TP may serve as a promising therapeutic agent to alleviate radiation-induced intestinal injury (RII).

A Highly Potent Apomorphine Derivative Enhancing Neurite Outgrowth via Nrf2 Activation

Apomorphine (APO), a dopamine agonist, activates nuclear factor erythroid 2-related factor 2 (Nrf2) and exerts antioxidant effects, making it a promising candidate for neuroprotection against oxidative stress. This study evaluated neuroplasticity-enhancing properties of newly synthesized APO derivatives, focusing on their ability to promote neurite outgrowth in PC12 cells under nerve growth factor (NGF) stimulation. D55, an APO derivative, retains the hydroxyl group at APO's 11th position while substituting the 10th with an ethoxy group. D55 exhibited the highest potency (EC50 = 0.5661 nM), significantly enhancing neurite outgrowth. APO demonstrated the highest efficacy (Emax ~10-fold increase), while edaravone (Eda) required higher concentrations (EC50 = 22.5 nM) for moderate effects (Emax ~4-fold increase). D30, in which the 11th hydroxyl was replaced with a methoxy group, had no effect. Neurite outgrowth-promoting effects of APO, D55, and Eda were significantly attenuated by Nrf2 siRNA knockdown, confirming that their neuroplasticity effects are Nrf2-mediated. These findings confirm that D55 is a highly potent Nrf2-activating compound with strong neuroprotective potential, providing new insights into its therapeutic applications for neurodegenerative diseases associated with oxidative stress.

Prenatal Exposure To Valproic Acid Induces Increased Autism-Like Behaviors and Impairment of Learning and Memory Functions in Rat Offspring by Upregulating ADAM10 Expression

Autism spectrum disorder (ASD) involves a complex neurodevelopmental pathogenesis. A disintegrin and metalloproteinase 10 (ADAM10) plays a crucial role in embryonic brain development and neural network stability. This study aimed to investigate the influence of ADAM10 on excitation/inhibition (E/I) balance, autism-like behaviors, and learning and memory dysfunction in rats prenatally exposed to valproic acid (VPA) and determine potential intervention strategies. The VPA-exposed group exhibited increased levels of ADAM10 and secreted amyloid precursor protein-α (sAPPα). Moreover, overexpression of glutamate decarboxylase 1 and N-methyl-D-aspartate receptors was observed. High-performance liquid chromatography-mass spectrometry revealed elevated levels of glutamate, glutamine, and γ-aminobutyric acid, as well as an E/I imbalance in the VPA group. Additionally, narrower synaptic clefts as well as increased postsynaptic density and synaptic vesicles were observed. Remarkably, intraperitoneal administration of ADAM10 inhibitor during the critical period of synaptic development significantly improved ASD-like behavior and learning and memory function in VPA-exposed rats. This intervention effectively reduced abnormally high sAPPα levels in the prefrontal cortex and corrected abnormal E/I balance. Thus, inhibiting ADAM10 overexpression may improve the E/I imbalance, alleviate core symptoms of ASD, and improve learning and memory dysfunction. The use of ADAM10 inhibitor represents a potential therapeutic strategy for treating ASD patients with intellectual disabilities.

Hippocampal microRNA-181a overexpression participates in anxiety and ethanol related behaviors via regulating the expression of SIRT-1

Understanding the molecular mechanisms underlying anxiety and ethanol-related behaviors is crucial for developing effective therapeutic interventions. This study identifies a novel role for microRNA miR-181a and its target, Sirtuin 1 (SIRT-1), in the hippocampus as contributors to anxiety-like behavior and voluntary ethanol intake. Using male and female C57BL/6 mice, we explored the causal relationship between hippocampal miR-181a expression and these behaviors. Lentivirus vectors were delivered into the hippocampus for focal miR-181a overexpression in mice. Then behaviors were observed by elevated plus maze (EPM) and open field (OF) tests. Results showed that the viral approach employed to overexpress miR-181a, in the hippocampus, resulted in increased anxiety-like behavior in the EPM and OF tests. Additionally, miR-181a overexpression exacerbated voluntary ethanol intake and preference in the two-bottle choice paradigm without affecting saccharin or quinine consumption. Mechanistically, miR-181a gain-of-function reduced SIRT-1 expression in the hippocampus. These findings demonstrate that miR-181a upregulation in the hippocampus promotes anxiety and ethanol-related behaviors, likely through SIRT-1 repression. This work highlights miR-181a as a key molecular mediator in the epigenetic regulation of mood disorders and ethanol consumption.

Calycosin alleviates ferroptosis and attenuates doxorubicin-induced myocardial injury via the Nrf2/SLC7A11/GPX4 signaling pathway

Background

Heart failure is primarily characterized by damage to the structure and function of the heart. Ferroptosis represents a form of programmed cell death, and studies indicate that it constitutes one of the primary mechanisms underlying cardiomyocyte death in heart failure. Calycosin, a natural compound derived from astragalus, exhibits various pharmacological properties, including anti-ferroptosis, antioxidant effects, and cardiovascular protection. Nonetheless, the specific role of Calycosin in the treatment of ferroptosis in heart failure remains poorly understood.

Objective

This study aims to elucidate the regulatory effect of Calycosin on ferroptosis and its influence on the treatment mechanisms of heart failure through in vivo and in vitro experiments.

Methods

A rat model of heart failure was induced using doxorubicin, and the cardiac function was evaluated through cardiac ultrasound examination and NT-Pro BNP detection. Myocardial injury was assessed using H&E staining and Masson staining. The extent of mitochondrial damage was evaluated through transmission electron microscopy. Concurrently, the level of ferroptosis was analyzed by measuring ferroptosis markers, including MDA, ferrous ions, the GSH/GSSG ratio, and GPX4 activity. Subsequently, the molecular mechanism by which Calycosin exerts its therapeutic effects in heart failure was investigated through immunofluorescence and Western blotting. Finally, H9c2 cardiomyocytes were treated with doxorubicin to simulate myocardial injury, and the mechanism by which Calycosin mediates its effects in the treatment of heart failure was further verified through Nrf2 gene silencing.

Results

Calycosin significantly improves cardiac function in rats, reduces serum NT-Pro BNP levels, and alleviates myocardial cell damage. Additionally, it significantly decreases the levels of ferroptosis in myocardial tissue, as confirmed through transmission electron microscopy and the assessment of ferroptosis markers, including MDA, ferrous ions, GSH, and GPX4 activity. At the molecular level, Calycosin exerts its effects by activating the Nrf2/SLC7A11/GPX4 signaling pathway, evidenced by the upregulation of Nrf2, SLC7A11, GPX4, GSS, and GCL protein expression. This process substantially enhances the antioxidant capacity of rat myocardial tissue and effectively suppresses ferroptosis in myocardial cells. The results obtained from both in vivo and in vitro experiments are consistent. Notably, when Nrf2 is silenced, the protective effect of Calycosin on the myocardium is markedly diminished.

Conclusion

Calycosin effectively treats doxorubicin-induced cardiac injury, and its therapeutic effect is likely closely associated with the activation of the Nrf2/SLC7A11/GPX4 signaling pathway and the inhibition of ferroptosis in myocardial cells. Consequently, Calycosin, as a promising compound against doxorubicin-induced cardiotoxicity, warrants further investigation.