Triptolide Improves Cognitive Dysfunction in Rats with Vascular Dementia by Activating the SIRT1/PGC-1α Signaling Pathway

miR-30a-5p mediates ferroptosis of hippocampal neurons in chronic cerebral hypoperfusion-induced cognitive dysfunction by modulating the SIRT1/NRF2 pathway

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) is a common cause of brain dysfunction. As a microRNA (also known as miRNAs or miRs), miR-30a-5p participates in neuronal damage and relates to ferroptosis. We explored the in vivo and in vitro effects and functional mechanism of miR-30a-5p in CCH-triggered cognitive impairment through the silent information regulator 1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway.

METHODS

After 1 month of CCH modeling through bilateral common carotid artery stenosis, mice were injected with 2 μL antagomir (also known as anti-miRNAs) miR-30a-5p, with cognitive function evaluated by Morris water maze and novel object recognition tests. In vitro HT-22 cell oxygen glucose deprivation (OGD) model was established, followed by miR-30a-5p inhibitor and/or si-SIRT1 transfections, with Fe2+ concentration, malonaldehyde (MDA) and glutathione (GSH) contents, reactive oxygen species (ROS), miR-30a-5p and SIRT1 and glutathione peroxidase 4 (GPX4) protein levels, NRF2 nuclear translocation, and miR-30a-5p-SIRT1 targeting relationship assessed.

RESULTS

CCH-induced mice showed obvious cognitive impairment, up-regulated miR-30a-5p, and down-regulated SIRT1. Ferroptosis occurred in hippocampal neurons, manifested by elevated Fe2+ concentration and ROS and MDA levels, mitochondrial atrophy, and diminished GSH content. Antagomir miR-30a-5p or miR-30a-5p inhibitor promoted SIRT1 expression and NRF2 nuclear translocation, increased GPX4, cell viability and GSH content, and reduced Fe2+ concentration and ROS and MDA levels. miR-30a-5p negatively regulated SIRT1. In vitro, miR-30a-5p knockout increased NRF2 nuclear translocation by up-regulating SIRT1, inhibiting OGD-induced ferroptosis in HT-22 cells.

CONCLUSION

miR-30a-5p induces hippocampal neuronal ferroptosis and exacerbates post-CCH cognitive dysfunction by targeting SIRT1 and reducing NRF2 nuclear translocation.

Unveiling the interplay of AMPK/SIRT1/PGC-1α axis in brain health: Promising targets against aging and NDDs

The escalating prevalence of neurodegenerative diseases (NDDs) within an aging global population presents a pressing challenge. The multifaceted pathophysiological mechanisms underlying these disorders, including oxidative stress, mitochondrial dysfunction, and neuroinflammation, remain complex and elusive. Among these, the AMPK/SIRT1/PGC-1α pathway emerges as a pivotal network implicated in neuroprotection against these destructive processes. This review sheds light on the potential therapeutic implications of targeting this axis, specifically emphasizing the promising role of flavonoids in mitigating NDD-related complications. Expanding beyond conventional pharmacological approaches, the exploration of non-pharmacological interventions such as exercise and calorie restriction (CR), coupled with the investigation of natural compounds, offers a beacon of hope. By strategically elucidating the intricate connections within these pathways, this review aims to pave the ways for novel multi-target agents and interventions, fostering a renewed optimism in the quest to combat and manage the debilitating impacts of NDDs on global health and well-being.

Diosmetin Ameliorates HFD-induced Cognitive Impairments via Inhibiting Metabolic Disorders, Mitochondrial Dysfunction and Neuroinflammation in Male SD Rats

Currently, accumulating evidence has indicated that overnutrition-associated obesity may result in not only metabolic dysregulations, but also cognitive impairments. This study aimed to investigate the protective effects of Diosmetin, a bioflavonoid compound with multiple biological functions, on cognitive deficits induced by a high fat diet (HFD) and the potential mechanisms. In the present study, oral administration of Diosmetin (25, 50 and 100 mg/kg) for 12 weeks significantly reduced the body weight, restored glucose tolerance and normalized lipid profiles in the serum and liver in HFD-induced obese rats. Diosmetin also significantly ameliorated depression-like behaviors and impaired spatial memory in multiple behavioral tests, including the open field test, elevated plus-maze and Morris water maze, which was in accordance with the decreased pathological changes and neuronal damage in different regions of hippocampus as suggested by H&E and Nissl staining. Notably, our results also indicated that Diosmetin could significantly improve mitochondrial dysfunction induced by HFD through upregulating genes involved in mitochondrial biogenesis and dynamics, increasing mitochondrial ATP levels and inhibiting oxidative stress. Moreover, the levels of key enzymes involved in the TCA cycle were also significantly increased upon Diosmetin treatment. Meanwhile, Diosmetin inhibited HFD-induced microglial overactivation and down-regulated inflammatory cytokines both in the serum and hippocampus. In conclusion, these results indicated that Diosmetin might be a novel nutritional intervention to prevent the occurrence and development of obesity-associated cognitive dysfunction via metabolic regulation and anti-inflammation.

Triptolide attenuates irritable bowel syndrome via inhibiting ODC1

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic disorder of the gut-brain axis with significant morbidity. Triptolide, an active compound extracted from Tripterygium wilfordii Hook F (TwHF), has been widely used as a major medicinal herb in the treatment of inflammatory disease.

METHODS

The chronic-acute combined stress (CAS) stimulation was used to establish IBS rat model. The model rats were then gavaged with triptolide. Forced swimming, marble-burying, fecal weight and abdominal withdrawal reflex (AWR) score were recorded. Pathologic changes in the ileal and colonic tissues were validated by hematoxylin and eosin staining. The inflammatory cytokines and Ornithine Decarboxylase-1 (ODC1) in the ileal and colonic tissues were performed by ELISA and WB.

RESULTS

Triptolide didn't have antidepressant- and antianxiety- effects in rats caused by CAS, but decreased fecal weight and AWR score. In addition, Triptolide reduced the release of IL-1, IL-6, and TNF-α and the expression of ODC1 in the ileum and colon.

CONCLUSION

The therapeutic efficacy of triptolide for IBS induced by CAS was revealed in this study, which may be related to the reduction of ODC1.

A comprehensive review on celastrol, triptolide and triptonide: Insights on their pharmacological activity, toxicity, combination therapy, new dosage form and novel drug delivery routes

Celastrol, triptolide and triptonide are the most significant active ingredients of Tripterygium wilfordii Hook F (TWHF). In 2007, the 'Cell' journal ranked celastrol, triptolide, artemisinin, capsaicin and curcumin as the five natural drugs that can be developed into modern medicinal compounds. In this review, we collected relevant data from the Web of Science, PubMed and China Knowledge Resource Integrated databases. Some information was also acquired from government reports and conference papers. Celastrol, triptolide and triptonide have potent pharmacological activity and evident anti-cancer, anti-tumor, anti-obesity and anti-diabetes effects. Because these compounds have demonstrated unique therapeutic potential for acute and chronic inflammation, brain injury, vascular diseases, immune diseases, renal system diseases, bone diseases and cardiac diseases, they can be used as effective drugs in clinical practice in the future. However, celastrol, triptolide and triptonide have certain toxic effects on the liver, kidney, cholangiocyte heart, ear and reproductive system. These shortcomings limit their clinical application. Suitable combination therapy, new dosage forms and new routes of administration can effectively reduce toxicity and increase the effect. In recent years, the development of different targeted drug delivery formulations and administration routes of celastrol and triptolide to overcome their toxic effects and maximise their efficacy has become a major focus of research. However, in-depth investigation is required to elucidate the mechanisms of action of celastrol, triptolide and triptonide, and more clinical trials are required to assess the safety and clinical value of these compounds.

Triptolide attenuates LPS-induced activation of RAW 264.7 macrophages by inducing M1-to-M2 repolarization via the mTOR/STAT3 signaling

CONTEXT

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of gastrointestinal tract, which can develop into colorectal cancer. Triptolide (TP) is a predominant bioactive ingredient of Tripterygium wilfordii Hook.F., and has been proven to have the therapeutic potential for various human diseases.

OBJECTIVE

In our study, we examined the function of TP in the progression of IBD.

METHODS

3-(4,5)dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide assay was used to evaluate the viability of RAW264.7 cells. Quantitative reverse transcription polymerase chain reaction assay was performed to detect the relative gene expression. Western blot was used to detect the relative protein expression. Enzyme-linked immunosorbent assay was utilized to examine the levels of prostaglandin E2 (PGE2), tumor necrosis factor (TNF)-α, interleukin (IL)-10, and IL-6.

RESULT

Our research demonstrated that TP restrained lipopolysaccharide (LPS)-caused activation of RAW264.7 cells, as evidenced by the reduction of PGE2, TNF-α, and IL-6, and increase of IL-10. TP treatment also restrained M1-type macrophage polarization and facilitated M2-type macrophage polarization of RAW 264.7 cells in the presence of LPS. Moreover, TP mitigated LPS-induced activation of the mammalian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) signaling in RAW264.7 cells. Further, activation of the mTOR/STAT3 signaling by MHY1485 attenuated the effect of TP in regulation of macrophage polarization in RAW264.7 cells in the presence of LPS.

CONCLUSION

Overall, our results indicated that TP attenuated LPS-induced activation of RAW 264.7 macrophages by inducing M1-to-M2 repolarization via repression of the mTOR/STAT3 signaling. Therefore, TP might be an effective agent for IBD treatment.

Ligustilide Improves Cognitive Impairment via Regulating the SIRT1/IRE1α/XBP1s/CHOP Pathway in Vascular Dementia Rats

Vascular dementia (VaD), the second cause of dementia, is caused by chronic cerebral hypoperfusion, producing progressive damage to cerebral cortex, hippocampus, and white matter. Ligustilide (LIG), one of the main active ingredients of Angelica sinensis, exerts the neuroprotective effect on neurodegenerative diseases. However, the mechanism remains unclear. An in vivo model of bilateral common carotid artery occlusion and in vitro model of oxygen glucose deprivation (OGD) were employed in this study. LIG (20 or 40 mg/kg/day) was intragastrically administered to the VaD rats for four weeks. The results of the Morris water maze test demonstrated that LIG effectively ameliorated learning and memory deficiency in VaD rats. LIG obviously relieved neuronal oxidative stress damage by increasing the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) and decreasing the level of malondialdehyde (MDA) in VaD rats. Nissl staining showed that LIG increased the number of the Nissl body in VaD rats. After LIG administration, the apoptotic-related protein, Bax, was decreased and Bcl-2 was increased in the hippocampus of VaD rats. Moreover, the expressions of sirtuin 1 (SIRT1) and protein disulfide isomerase (PDI) were decreased, binding immunoglobulin protein (BIP) and phospho-inositol-requiring enzyme-1α (P-IRE1α), X-box binding protein 1 (XBP1s), and C/EBP-homologous protein (CHOP) were increased in VaD rats. After LIG treatment, these changes were reversed. The immunofluorescence results further showed that LIG upregulated the expression of SIRT1 and downregulated the expression of P-IRE1α in VaD rats. In addition, in vitro experiment showed that EX-527 (SIRT1 inhibitor) partly abolished the inhibitory effect of LIG on the IRE1α/XBP1s/CHOP pathway. In conclusion, these studies indicated that LIG could improve cognitive impairment by regulating the SIRT1/IRE1α/XBP1s/CHOP pathway in VaD rats.

Blood–Brain Barrier Dysfunction and the Potential Mechanisms in Chronic Cerebral Hypoperfusion Induced Cognitive Impairment

Chronic cerebral hypoperfusion (CCH) is a major cause of vascular cognitive impairment and dementia (VCID). Although the underlying mechanisms have not been fully elucidated, the emerging data suggest that blood–brain barrier (BBB) dysfunction is one of the pivotal pathological changes in CCH. BBB dysfunction appears early in CCH, contributing to the deterioration of white matter and the development of cognitive impairment. In this review, we summarize the latest experimental and clinical evidence implicating BBB disruption as a major cause of VCID. We discuss the mechanisms of BBB dysfunction in CCH, focusing on the cell interactions within the BBB, as well as the potential role of APOE genotype. In summary, we provide novel insights into the pathophysiological mechanisms underlying BBB dysfunction and the potential clinical benefits of therapeutic interventions targeting BBB in CCH.

Triptolide protects against white matter injury induced by chronic cerebral hypoperfusion in mice

White matter injury is the major pathological alteration of subcortical ischemic vascular dementia (SIVD) caused by chronic cerebral hypoperfusion. It is characterized by progressive demyelination, apoptosis of oligodendrocytes and microglial activation, which leads to impairment of cognitive function. Triptolide exhibits a variety of pharmacological activities including anti-inflammation, immunosuppression and antitumor, etc. In this study, we investigated the effects of triptolide on white matter injury and cognitive impairments in mice with chronic cerebral hypoperfusion induced by the right unilateral common carotid artery occlusion (rUCCAO). We showed that triptolide administration alleviated the demyelination, axonal injury, and oligodendrocyte loss in the mice. Triptolide also improved cognitive function in novel object recognition test and Morris water maze test. In primary oligodendrocytes following oxygen-glucose deprivation (OGD), application of triptolide (0.001-0.1 nM) exerted concentration-dependent protection. We revealed that the protective effect of triptolide resulted from its inhibition of oligodendrocyte apoptosis via increasing the phosphorylation of the Src/Akt/GSK3β pathway. Moreover, triptolide suppressed microglial activation and proinflammatory cytokines expression after chronic cerebral hypoperfusion in mice and in BV2 microglial cells following OGD, which also contributing to its alleviation of white matter injury. Importantly, mice received triptolide at the dose of 20 μg·kg^-1·d^-1 did not show hepatotoxicity and nephrotoxicity even after chronic treatment. Thus, our results highlight that triptolide alleviates whiter matter injury induced by chronic cerebral hypoperfusion through direct protection against oligodendrocyte apoptosis and indirect protection by inhibition of microglial inflammation. Triptolide may have novel indication in clinic such as the treatment of chronic cerebral hypoperfusion-induced SIVD.

Multifaced role of protein deacetylase sirtuins in neurodegenerative disease

Sirtuins, a class III histone/protein deacetylase, is a central regulator of metabolic function and cellular stress response. This plays a pivotal role in the pathogenesis and progression of diseases such as cancer, neurodegeneration, metabolic syndromes, and cardiovascular disease. Sirtuins regulate biological and cellular processes, for instance, mitochondrial biogenesis, lipid and fatty acid oxidation, oxidative stress, gene transcriptional activity, apoptosis, inflammatory response, DNA repair mechanism, and autophagic cell degradation, which are known components for the progression of the neurodegenerative diseases (NDDs). Emerging evidence suggests that sirtuins are the useful molecular targets against NDDs like, Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Amyotrophic Lateral Sclerosis (ALS). However, the exact mechanism of neuroprotection mediated through sirtuins remains unsettled. The manipulation of sirtuins activity with its modulators, calorie restriction (CR), and micro RNAs (miR) is a novel therapeutic approach for the treatment of NDDs. Herein, we reviewed the current putative therapeutic role of sirtuins in regulating synaptic plasticity and cognitive functions, which are mediated through the different molecular phenomenon to prevent neurodegeneration. We also explained the implications of sirtuin modulators, and miR based therapies for the treatment of life-threatening NDDs.

Triptolide improves neurobehavioral functions, inflammation, and oxidative stress in rats under deep hypothermic circulatory arrest

This study investigated the neuroprotective effects of triptolide (TPL) in a rat model of cardiopulmonary bypass with deep hypothermia circulatory arrest (DHCA). Rats were randomly divided into six groups: control, sham, DHCA, and DHCA + TPL (100, 200, 300 μg/kg). Neurobehavioral functions were measured using the elevated plus-maze, Y-maze, and Morris water maze tests. Levels of inflammatory cytokines, oxidative stress indices, and brain neurotrophins were measured by ELISA. Microglial activation and cell death was measured by immunofluorescence staining and TUNEL assay, respectively. Finally, activation of the Nrf2 pathway and NF-κB were detected by western blot. The elevated plus-maze, Y-maze, and Morris water maze tests all showed that TPL mitigated anxiety-like behavior, working memory, spatial learning, and memory in DHCA rats. TPL inhibited inflammatory responses and oxidative stress, as well as increased brain neurotrophin levels in DHCA rats. Moreover, TPL attenuated microglia activation and cell death in DHCA rats. Finally, TPL activated the Nrf2 pathway and inhibited NF-κB activity in DHCA rats. These results demonstrated that TPL improved neurobehavioral functions, neuroinflammation, and oxidative stress in DHCA rats, which may be associated with the Nrf2 and NF-κB pathways.

Combinational Pretreatment of Colony-Stimulating Factor 1 Receptor Inhibitor and Triptolide Upregulates BDNF-Akt and Autophagic Pathways to Improve Cerebral Ischemia

Ki20227, a selective inhibitor of colony-stimulating factor 1 receptor (CSF1R), has been suggested to regulate microglia inflammatory function and neuronal synaptic plasticity. Triptolide (TP) pretreatment has neuroprotective effects through its anti-inflammatory and antiapoptotic features in ischemic stroke mice. However, the underlying mechanism and pathway are presently unclear. We thus investigated the association between neuroprotective effects of combined TP and Ki20227 and BDNF-Akt and autophagy pathways. Ki20227 was administrated for 7 days, and TP was administered once 24 hours prior to building the ischemic stroke model in C57BL/6 mice. Behavioral tests, Golgi staining, immunofluorescence, and western blot analyses were employed to examine neuroprotective effects of TP and Ki20227. TP and Ki20227 pretreatments improved the neurobehavioral function in stroke mice. Synaptic protein expressions and density of dendritic spine density were upregulated in Ki20227 and TP pretreated stroke mice. Further, optimized integration of TP and Ki20227 pretreatments upregulated the NeuN expression and downregulated Iba1 expression after stroke. In addition, both TP and Ki20227 pretreatments significantly upregulated BDNF, p-Akt/Akt, and Erk1/2 protein expressions and autophagy related proteins (LC3II/I, Atg5, and p62), indicating the activation of BDNF and autophagic pathways. Optimized integration of TP and Ki20227 can improve cerebral ischemia by inhibiting CSF1R signal and trigger autophagy and BDNF-Akt signaling pathways to increase dendritic spine density and synaptic protein expressions, which in turn enhances neurobehavioral function.

Reduced serum SIRT1 levels in patients with Parkinson's disease: a cross-sectional study in China

BACKGROUND

Parkinson's disease (PD) is a movement disorder lacking of validated biomarkers. Experimental studies support the potential value of silent information regulator 1 (SIRT1) in neurodegeneration including PD. We aim to detect the serum levels of SIRT1 in PD patients in order to assess its value as a potential biomarker of PD.

METHODS

Fifty-eight PD patients and 91 healthy controls were included. Serum SIRT1 was determined by enzyme-linked immunosorbent assay (ELISA) and compared between controls and PD patients. Spearman correlation coefficient was analyzed to study the relationship between serum SIRT1 and clinical parameters in PD patients. Receiver operating characteristic (ROC) analysis was conducted to assess the diagnostic value of serum SIRT1 in PD identification.

RESULTS

Serum SIRT1 was significantly reduced in PD patients compared with controls. According to the ROC curve, the optimal cut-off point was 0.47 ng/ml with the sensitivity of 71% and specificity of 71%. Serum SIRT1 level was related to age of onset, disease duration, Hoehn-Yahr staging scale (H-Y stage), Unified Parkinson's Disease Rating Scale III (UPDRS III), and Mini-Mental State Examination (MMSE). PD patients with cognitive impairment had lower serum SIRT1 than those with normal cognitive ability.

CONCLUSIONS

Serum SIRT1 was reduced in PD patients and associated with disease severity and cognitive function. Our results indicate that SIRT1 may be a potential biomarker for PD.

Cognitive Protective Mechanism of Crocin Pretreatment in Rat Submitted to Acute High-Altitude Hypoxia Exposure

Inadequate oxygen availability at high altitude leads to oxidative stress, resulting in hippocampal neurodegeneration and memory impairment. In our previous study, we found that the cognitive dysfunction occurred when male SD rat was rapidly exposed to 4200 m of high altitude for 3 days. And we also found that crocin showed a cognitive protective effect under hypoxia by regulating SIRT1/PGC-1α pathways in rat's hippocampus. In this article, focused on factors related to SIRT1/PGC-1α pathways, we proposed to further elucidate crocin's pharmacological mechanism. Adult male Sprague-Dawley rats were randomly divided into five groups: control group, hypoxia group (rats were rapidly transported to high altitude of 4200 m for 72 h), and crocins+hypoxia groups (pretreatment with crocin of 25, 50, and 100 mg/kg/d for 3 days). The learning and memory ability was tested by Morris water maze analysis. Hippocampal histopathological changes were observed by HE staining and Nissl staining. The expression of NRF1, TFAM, Bcl-2, Bax, and caspase-3 was detected by immunohistochemistry, RT-PCR, and western blotting test. The contents of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSHPx) were detected by the TBA, WST, and colorimetry method. Neuronal apoptosis was observed by TUNEL staining. After crocin pretreatment, the traveled distance was significantly reduced and the percentage of time in the target quadrant was significantly increased tested by Morris water maze. And neuronal damage in the hippocampus was also significantly ameliorated based on HE staining and Nissl staining. Furthermore, in hippocampus tissue, mitochondrial biosynthesis-related factors of NRF1, TFAM expression was increased; oxidative stress factors of SOD, GSH, and GSHPx expression level were increased, and MDA and glutathione disulfide (GSSG) level were decreased; antiapoptotic protein Bcl-2 expression was increased, and proapoptotic proteins Bax and caspase-3 expression were decreased, with a manner of crocin dose dependent. Therefore, the cognitive protective mechanism of crocin in rat under acute hypoxia was related to promoting mitochondrial biosynthesis, ameliorating oxidative stress injury, and decreasing neuronal apoptosis.

AMPK-SIRT1-PGC1α Signal Pathway Influences the Cognitive Function of Aged Rats in Sevoflurane-Induced Anesthesia

To understand the effect of AMP-activated protein kinase (AMPK)-SIRT1 (silent information regulator 1)-PPARγ coactivator-1α (PGC1α) signaling pathway on the cognitive function of sevoflurane-anesthetized aged rats. Aged rats were divided into Normal group, Sevo group (Sevoflurane anesthesia), Sevo + AICAR (the AMPK activator) group, Sevo + EX527 group (the AMPK inhibitor), and Sevo + AICAR + EX527 group. The cognitive function of rats was determined by the Morris water maze. Hippocampal neuronal apoptosis was evaluated by TUNEL and Fluoro-Jade C (FJC) staining, and the expression of cleaved caspase-3 was detected by immunohistochemistry. ROS, SOD, and MDA levels and the fluorescence intensity of GFAP in the hippocampus were assayed. The mitochondrial membrane potential (MMP), mitochondrial mass, ATP level, and the expression of AMPK-SIRT1-PGC1α were determined by the corresponding methods. Rats in the Sevo group manifested significant extension in the escape latency, with fewer platform crossings; and meanwhile, the apoptotic rate, the number of FJC-positive cells, and the fluorescence intensity of GFAP of neurons were elevated, with up-regulation of cleaved caspase-3. Moreover, the level of MDA and ROS was increased evidently, with significant down-regulation of SOD activity, ATP, mitochondrial mass and MMP levels, and AMPK, SIRT1 and PGC-1α protein expressions. However, sevoflurane-induced changes above were improved after the administration of AICAR, and EX527 could reverse AICAR-induced improvements in Sevo-anesthetized aged rats. Activating AMPK-SIRT1-PGC1α pathway can improve the cognitive function and mitigate the neuronal injury in Sevo-anesthetized aged rats by antagonizing the oxidative stress and maintaining the mitochondrial function.