Astaxanthin alleviates pathological brain aging through the upregulation of hippocampal synaptic proteins

Astaxanthin reduces TBPH-induced neurobehavioral deficits in mice by the ROS-ERK1/2-FOS pathway

The persistence of the novel brominated flame retardant, bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH), in the environment and its potential for bioaccumulation in living organisms, including humans, further exacerbate its health risks. Therefore, ongoing research is crucial for fully understanding the extent of TBPH's neurotoxicity and for developing effective mitigation strategies. This study aims to investigate the potential neurotoxicity of TBPH on mouse neurobehavior and to evaluate the protective effects of the natural antioxidant astaxanthin (AST) against TBPH-induced neurotoxicity. The results indicate that exposure to TBPH can lead to a decline in learning and memory abilities and abnormal behaviors in mice, which may be associated with oxidative stress responses and apoptosis in the hippocampus. TBPH may disrupt the normal function of hippocampal neurons by activating the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. Mice exposed to TBPH treated with AST showed improved learning and memory abilities in the Morris water maze (MWM) and Step-down test (SDT). AST, through its antioxidant action, was able to significantly reduce the increase in reactive oxygen species (ROS) levels induced by TBPH, the increased expression of apoptosis markers, and the activation of the ERK1/2-FOS signaling pathway, alleviating TBPH-induced apoptosis in hippocampal neurons and improving neurobehavioral outcomes. These findings suggest that AST may alleviate the neurotoxicity of TBPH by modulating molecular events related to apoptosis and the ERK1/2-FOS signaling pathway. Thus, this study provides evidence for AST as a potential interventional strategy for the prevention or treatment of cognitive decline associated with environmental neurotoxicant exposure.

Codonopsis pilosula water extract delays D-galactose-induced aging of the brain in mice by activating autophagy and regulating metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Codonopsis pilosula (C. pilosula), also called "Dangshen" in Chinese, is derived from the roots of Codonopsis pilosula (Franch.) Nannf. (C. pilosula), Codonopsis pilosula var. Modesta (Nannf.) L.D.Shen (C. pilosula var. modesta) or Codonopsis pilosula subsp. Tangshen (Oliv.) D.Y.Hong (C. pilosula subsp. tangshen), is a well-known traditional Chinese medicine. It has been regularly used for anti-aging, strengthening the spleen and tonifying the lungs, regulating blood sugar, lowering blood pressure, strengthening the body's immune system, etc. However, the mechanism, by which, C. pilosula exerts its therapeutic effects on brain aging remains unclear.

AIM OF THE STUDY

This study aimed to investigate the underlying mechanisms of the protective effects of C. pilosula water extract (CPWE) on the hippocampal tissue of D-galactose-induced aging mice.

MATERIALS AND METHODS

In this research, plant taxonomy has been confirmed in the "The Plant List" database (www.theplantlist.org). First, an aging mouse model was established through the intraperitoneal injections of D-galactose solution, and low-, medium-, and high-dose CPWE were administered to mice by gavage for 42 days. Then, the learning and memory abilities of the mice were examined using the Morris water maze tests and step-down test. Hematoxylin and eosin staining was performed to visualize histopathological damage in the hippocampus. A transmission electron microscope was used to observe the ultrastructure of hippocampal neurons. Immunohistochemical staining was performed to examine the expression of glial fibrillary acidic protein (GFAP), the marker protein of astrocyte activation, and autophagy-related proteins, including microtubule-associated protein light chain 3 (LC3) and sequestosome 1 (SQSTM1)/p62, in the hippocampal tissues of mice. Moreover, targeted metabolomic analysis was performed to assess the changes in polar metabolites and short-chain fatty acids in the hippocampus.

RESULTS

First, CPWE alleviated cognitive impairment and ameliorated hippocampal tissue damage in aging mice. Furthermore, CPWE markedly alleviated mitochondrial damage, restored the number of autophagosomes, and activated autophagy in the hippocampal tissue of aging mice by increasing the expression of LC3 protein and reducing the expression of p62 protein. Meanwhile, the expression levels of the brain injury marker protein GFAP decreased. Moreover, quantitative targeted metabolomic analysis revealed that CPWE intervention reversed the abnormal levels of L-asparagine, L-glutamic acid, L-glutamine, serotonin hydrochloride, succinic acid, and acetic acid in the hippocampal tissue of aging mice. CPWE also significantly regulated pathways associated with D-glutamine and D-glutamate metabolism, nitrogen metabolism, arginine biosynthesis, alanine, aspartate, and glutamate metabolisms, and aminoacyl-tRNA biosynthesis.

CONCLUSIONS

CPWE could improve cognitive and pathological conditions induced by D-galactose in aging mice by activating autophagy and regulating metabolism, thereby slowing down brain aging.

Pretreatment with Liposome-Encapsulated Shrimp Shell Extract Attenuated Neuronal Damage and Death in Aβ1-42-Induced Memory Deficits in Rats

The accumulation of amyloid-beta (Aβ) peptides is a crucial factor in the neuronal degeneration of Alzheimer's disease (AD). The current study investigated the underlying neuroprotective mechanisms of shrimp shell extract (SSE) and liposome-encapsulated SSE (SSE/L) against Aβ1-42-induced neuronal damage and death in rats. Intracerebroventricular infusion of Aβ1-42 effectively induced memory decline, as observed in a reduction of the rat's discriminating ability in the novel object recognition and novel object location tasks. Oral pretreatment with 100 mg/kg of SSE demonstrated no preventive effect on the memory decline induced by Aβ1-42 infusion. However, treatment with SSE/L 100 mg/kg BW effectively attenuated memory deficits in both behavioral assessments following two and four weeks after Aβ1-42 infusion. Moreover, SSE/L exerted neuroprotective effects by reducing lipid peroxidation and increasing Nrf2/HO-1 expression. There was a significant decrease in Iba1 and GFAP (biomarkers of microglia and astrocyte activity, respectively), as well as a decrease in the levels of NF-κB expression and the inflammatory cytokines TNF-α and IL-6 in the cortical and hippocampal tissues. Treatment with SSE/L also reduced the pro-apoptotic proteins Bax and cleaved caspase-3 while raising the anti-apoptotic protein Bcl2. In addition, the beneficial effects of SSE/L were along with the effects of a positive control commercial astaxanthin (AST). The findings of this study indicated that SSE/L provided neuroprotective effects on Aβ1-42-induced AD rats by ameliorating oxidative stress, neuroinflammation and apoptotic cell death. Therefore, SSE/L might be employed to prevent and mitigate Aβ accumulation-induced neurotoxicity in AD.

Astaxanthin attenuates cognitive deficits in Alzheimer's disease models by reducing oxidative stress via the SIRT1/PGC-1α signaling pathway

OBJECTIVE

Oxidative stress plays a pivotal role in neurodegenerative diseases. Astaxanthin (AST) can play a neuroprotective role owing to its long-chain conjugated unsaturated double bond, which imparts potent antioxidant, anti-neuroinflammatory, and anti-apoptotic properties. However, the biological mechanisms underlying these effects remain unknown. Therefore, this study aimed to investigate and validate the protective effect of AST on neuronal senescence and apoptosis caused by oxidative stress induced by Aβ25-35 peptide, with the goal of preventing the onset of cognitive dysfunction.

METHODS

Alzheimer's disease models comprising ICR mice and PC12 cells were established using Aβ25-35. The Morris water maze test was used to assess mouse behavior. Nissl staining revealed morphological changes in the mouse hippocampal neurons. To elucidate the mechanism of action of AST, ICR mice and PC12 cells were treated with the silent information regulator 1 (SIRT1) inhibitor nicotinamide (NAM). Additionally, immunofluorescence, western blotting, and reverse transcription polymerase chain reaction were used to evaluate changes in the expression of Bcl-2 and Bax in the mouse hippocampus, and SIRT1/PGC-1α signaling pathway proteins were detected. Moreover, the oxidative stress markers in ICR mice and PC12 cells were evaluated. Further, CCK-8 assays, Annexin V/PI double staining, and β-galactosidase activity assays were performed in PC12 cells to evaluate the anti-senescence and apoptotic effects of AST.

RESULTS

In vivo experiments showed that Aβ25-35 impaired cognitive function, promoted morphological changes in hippocampal neurons, decreased Bcl-2 expression, increased Bax expression, decreased superoxide dismutase and GSH-px levels, and increased reactive oxygen species and malondialdehyde levels. Conversely, AST alleviated the impact of Aβ25-35 in mice, with reversed outcomes. NAM administration reduced SIRT1 and PGC-1α expression in the hippocampus. This decrease was accompanied by cognitive dysfunction and hippocampal neuron atrophy, which were also evident in the mice. Additionally, in vitro experiments showed that Aβ25-35 could promote oxidative stress and induce the senescence and apoptosis of PC12 cells. Nonetheless, AST treatment counteracted this effect by inhibiting oxidative stress and altering the state of PC12 cells. Notably, the Aβ + NAM group exhibited the most significant rates of senescence and apoptosis in PC12 cells following NAM treatment.

CONCLUSION

AST can improve cellular senescence and apoptosis mediated by oxidative stress via the SIRT1/PGC-1α signaling pathway and plays a vital role in inhibiting neuronal senescence and apoptosis and enhancing cognitive ability.

Targeting impaired nutrient sensing via the sirtuin pathway with novel compounds to prevent or treat dementia: A systematic review

BACKGROUND

Dementia is prevalent in aged populations and is associated with disability and distress for those affected. Therapeutic benefits of drugs targeting dementia are small. Impaired nutrient sensing pathways have been implicated in the pathogenesis of dementia and may offer a novel treatment target.

AIMS

This systematic review collated evidence for novel therapeutic compounds that modify nutrient sensing pathways, particularly the sirtuin pathway, in preventing cognitive decline or improving cognition in normal ageing, mild cognitive impairment (MCI), and dementia.

METHODS

PubMed, Embase and Web of Science databases were searched using key search terms. Articles were screened using Covidence systematic review software. The risk of bias was assessed using the Systematic Review Center for Laboratory animal Experimentation (SYRCLE)'s risk of bias tool for animal studies and Cochrane Risk of Bias tool v 2.0 for human studies.

RESULTS

Out of 3841 articles, 68 were included describing 38 different novel therapeutic compounds that modulate the nutrient sensing pathway via the sirtuin pathway. In animal models (58 studies), all investigated novel therapeutic compounds showed cognitive benefits. Ten studies were human intervention trials targeting normal ageing (1 study) and dementia populations (9 studies). Direct sirtuin (silent mating type information regulation 2 homolog) 1 (SIRT1) activators Resveratrol and Nicotinamide derivatives improved cognitive outcomes among human subjects with normal cognition and MCI.

CONCLUSION

Animal studies support that modulation of the sirtuin pathway has the potential to improve cognitive outcomes. Overall, there is a clear lack of translation from animal models to human populations.

Astaxanthin delays brain aging in senescence-accelerated mouse prone 10: inducing autophagy as a potential mechanism

Brain aging is a complex biological process often associated with a decline in cognitive functions and motility. Astaxanthin (AST) is a strong antioxidant capable of crossing the blood-brain barrier. The effect of AST on brain aging and its physiological and molecular mechanism are still unclear. The study aimed to investigate whether AST from AstaReal A1010 improved brain aging by inducing autophagy in SAMP10 mice. Different concentrations of AstaReal A1010 were intragastrically administered to 6-month-old SAMP10 mice for 3 months. The results demonstrated that AST delayed age-related cognitive decline, motor ability and neurodegeneration, upregulated the expression levels of autophagy-related genes beclin-1 and LC3 in the brain. It may induce autophagy by regulating IGF-1/Akt/mTOR and IGF-1/Akt/FoxO3a signaling. Treatment with autophagy inhibitor 3-methyladenine (3MA) partly reversed the anti-aging effect of AST. In conclusion, our findings suggest that AST may induce autophagy by regulating IGF-1/Akt/mTOR and IGF-1/Akt/FoxO3a signaling, thereby delaying age-related neurodegeneration and cognitive decline in SAMP10 mice.

Technological readiness of commercial microalgae species for foods

Microalgae have great potential as a future source to meet the increasing global demand for foods. Several microalgae are permitted as safety sources in different countries and regions, and processed as commercial products. However, edible safety, economic feasibility, and acceptable taste are the main challenges for microalgal application in the food industry. Overcome such challenges by developing technology accelerates transition of microalgae into sustainable and nutritious diets. In this review, edible safety of Spirulina, Chlamydomonas reinhardtii, Chlorella, Haematococcus pluvialis, Dunaliella salina, Schizochytrium and Nannochloropsis is introduced, and health benefits of microalgae-derived carotenoids, amino acids, and fatty acids are discussed. Technologies of adaptive laboratory evolution, kinetic model, bioreactor design and genetic engineering are proposed to improve the organoleptic traits and economic feasibility of microalgae. Then, current technologies of decoloration and de-fishy are summarized to provide options for processing. Novel technologies of extrusion cooking, delivery systems, and 3D bioprinting are suggested to improve food quality. The production costs, biomass values, and markets of microalgal products are analyzed to reveal the economic feasibility of microalgal production. Finally, challenges and future perspectives are proposed. Social acceptance is the major limitation of microalgae-derived foods, and further efforts are required toward the improvement of processing technology.

Astaxanthin: A promising therapeutic agent for organ fibrosis

Fibrosis is the end-stage pathological manifestation of many chronic diseases. Infiltration of inflammatory cells and activation of myofibroblasts are the most prominent features of fibrosis, with excessive deposition of extracellular matrix (ECM) in tissues leading to organ tissue damage, which eventually progresses to organ failure and leads to high mortality rates. At present, a large number of studies have been conducted on tissue fibrosis, and the pathological mechanism of fibrosis development has generally been recognized. However, the prevention and treatment of fibrosis is still an unsolved problem, and a shortage of drugs that can be used in the clinic persists. Astaxanthin (ASTX), a carotenoid, is widely known for its strong antioxidant capacity. ASTX also has other biological properties, such as anti-inflammatory, antiaging and anticancer properties. Recently, many papers have reported that ASTX inhibits the occurrence and development of fibrosis by regulating signaling molecular pathways, such as transforming growth factor-β/small mother against decapentaplegic protein (TGF-β1/Smad), sirtuin 1 (SIRT1), nuclear factor kappa-B (NF-κB), microRNA, nuclear factor-E2-related factor 2/antioxidant response element (Nrf 2/ARE) and reactive oxygen species (ROS) pathways. By targeting these molecular signaling pathways, ASTX may become a potential drug for the treatment of fibrotic diseases. In this review, we summarize the therapeutic effects of ASTX on organ fibrosis and its underlying mechanisms of action. By reviewing the results from in vitro and in vivo studies, we analyzed the therapeutic prospects of ASTX for various fibrotic diseases and provided insights into and strategies for exploring new drugs for the treatment of fibrosis.

DNA hypomethylation promotes learning and memory recovery in a rat model of cerebral ischemia/reperfusion injury

Cerebral ischemia/reperfusion injury impairs learning and memory in patients. Studies have shown that synaptic function is involved in the formation and development of memory, and that DNA methylation plays a key role in the regulation of learning and memory. To investigate the role of DNA hypomethylation in cerebral ischemia/reperfusion injury, in this study, we established a rat model of cerebral ischemia/reperfusion injury by occlusion of the middle cerebral artery and then treated the rats with intraperitoneal 5-aza-2′-deoxycytidine, an inhibitor of DNA methylation. Our results showed that 5-aza-2′-deoxycytidine markedly improved the neurological function, and cognitive, social and spatial memory abilities, and dose-dependently increased the synaptic density and the expression of SYP and SHANK2 proteins in the hippocampus in a dose-dependent manner in rats with cerebral ischemia/reperfusion injury. The effects of 5-aza-2′-deoxycytidine were closely related to its reduction of genomic DNA methylation and DNA methylation at specific sites of the Syp and Shank2 genes in rats with cerebral ischemia/reperfusion injury. These findings suggest that inhibition of DNA methylation by 5-aza-2′-deoxycytidine promotes the recovery of learning and memory impairment in a rat model of cerebral ischemia/reperfusion injury. These results provide theoretical evidence for stroke treatment using epigenetic methods.

Effectively Improve the Astaxanthin Production by Combined Additives Regulating Different Metabolic Nodes in Phaffia rhodozyma

Astaxanthin is an important natural resource that is widely found in marine environments. Metabolic regulation is an effective method for improving astaxanthin production in Phaffia rhodozyma. Most studies have focused on single regulators, which have limited effects. In this study, 16 metabolic regulators were screened to improve astaxanthin production in high-yield and wild-type strains. Fluconazol and glutamic acid increased astaxanthin volumetric yield in MVP14 by 25.8 and 30.9%, respectively, while ethanol increased astaxanthin volumetric yield in DSM626, 29.3%. Furthermore, six additives that inhibit the competing pathways and promote the main pathway for astaxanthin synthesis were selected for combination treatment. We found that the optimal combination was penicillin, ethanol, triclosan, and fluconazol, which increased astaxanthin cell yield by 51%. Therefore, we suggest that simultaneously promoting the master pathways (mevalonate) and inhibiting competing pathways (fatty acid synthesis and ergosterol) is the best strategy to improve astaxanthin cell yield. Moreover, regulators of the biomass pathway should be avoided to improve cell yield. This study provides a technical basis for the utilisation of astaxanthin in P. rhodozyma.

Astaxanthin Prevents Diet-Induced NASH Progression by Shaping Intrahepatic Immunity

Dietary change leads to a precipitous increase in non-alcoholic fatty liver disease (NAFLD) from simple steatosis to the advanced form of non-alcoholic steatohepatitis (NASH), affecting approximately 25% of the global population. Although significant efforts greatly advance progress in clarifying the pathogenesis of NAFLD and identifying therapeutic targets, no therapeutic agent has been approved. Astaxanthin (ASTN), a natural antioxidant product, exerts an anti-inflammation and anti-fibrotic effect in mice induced with carbon tetrachloride (CCl₄) and bile duct ligation (BDL); thus, we proposed to further investigate the potential effect of ASTN on a diet-induced mouse NASH and liver fibrosis, as well as the underlying cellular and molecular mechanisms. By treating pre-development of NASH in mice induced with a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD), we have demonstrated that oral administration ASTN preventively ameliorated NASH development and liver fibrosis by modulating the hepatic immune response, liver inflammation, and oxidative stress. Specifically, ASTN treatment led to the reduction in liver infiltration of monocyte-derived macrophages, hepatic stellate cell (HSC) activation, oxidative stress response, and hepatocyte death, accompanied by the decreased hepatic gene expression of proinflammatory cytokines such as TNF-α, TGF-β1, and IL-1β. In vitro studies also demonstrated that ASTN significantly inhibited the expression of proinflammatory cytokines and chemokine CCL2 in macrophages in response to lipopolysaccharide (LPS) stimulation. Overall, in vivo and in vitro studies suggest that ASTN functions as a promising therapeutic agent to suppress NASH and liver fibrosis via modulating intrahepatic immunity.