Capsaicin is beneficial to hyperlipidemia, oxidative stress, endothelial dysfunction, and atherosclerosis in Guinea pigs fed on a high-fat diet

Thymus atlanticus (Ball) Roussine Aqueous Extract Exerts Lipid-lowering and Anti-atherosclerotic Effects in Hyperlipidemic Guinea Pigs

BACKGROUND

Thymus atlanticus (Ball) Roussine (T. atlanticus) is traditionally used in the Moroccan high Atlas Mountains to treat several disorders, including cardiovascular disease. In the present study, the lipid-lowering and anti-atherosclerotic activities of the traditionally used aqueous extract of T. atlanticus were evaluated on guinea pigs subjected to chronic hyperlipidemia.

METHODS

Animals were given a diet containing 2% cholesterol and 20% lard for 12 weeks. Moreover, thyme extract was given daily at 400 mg/kg. At the end of the experiment, lipid levels and paraoxonase arylesterase activity were measured, and aorta histology was studied.

RESULTS

Our findings revealed that there was an important elevation of blood lipids in the HFD group along with a significant decrease in paraoxonase arylesterase activity (-40.06%). Moreover, the consumption of fat altered the histology of aorta by thickening the intima media and forming atherosclerotic lesions and foam cells in these tissues. However, the administration of thyme extract attenuated HFD-caused alterations by decreasing blood lipids, elevating paraoxonase activity (+24.04%), and limiting the progression of atherosclerotic lesions.

CONCLUSION

We conclude that the supplementation with the aqueous extract of T. atlanticus could potentially protect against hyperlipidemia and consequently, the development of atherosclerosis.

Antimicrobial Properties of Capsaicin: Available Data and Future Research Perspectives

Capsaicin is a phytochemical derived from plants of the genus Capsicum and subject of intensive phytochemical research due to its numerous physiological and therapeutical effects, including its important antimicrobial properties. Depending on the concentration and the strain of the bacterium, capsaicin can exert either bacteriostatic or even bactericidal effects against a wide range of both Gram-positive and Gram-negative bacteria, while in certain cases it can reduce their pathogenicity by a variety of mechanisms such as mitigating the release of toxins or inhibiting biofilm formation. Likewise, capsaicin has been shown to be effective against fungal pathogens, particularly Candida spp., where it once again interferes with biofilm formation. The parasites Toxoplasma gondi and Trypanosoma cruzi have been found to be susceptible to the action of this compound too while there are also viruses whose invasiveness is significantly dampened by it. Among the most encouraging findings are the prospects for future development, especially using new formulations and drug delivery mechanisms. Finally, the influence of capsaicin in somatostatin and substance P secretion and action, offers an interesting array of possibilities given that these physiologically secreted compounds modulate inflammation and immune response to a significant extent.

Ultrasound-Treated and Thermal-Pasteurized Hawthorn Vinegar: Antioxidant and Lipid Profiles in Rats

The hawthorn fruit, a member of the Rosaceae family, is a medicinal plant with numerous therapeutic properties. It has a wide range of variants, with Crataegus tanacetifolia being the most widely recognized species in the world. The hawthorn fruit has various biological activities, including anti-inflammatory, antibacterial, antioxidant, immune-modulating, and anti-carcinogenic properties. This study focused on improving the antioxidant activity of hawthorn vinegar via different methods. We also aimed to investigate the influence of its hepatic antioxidant abilities on health and extend the shelf life of the vinegar. In the study, the vinegar was produced from the hawthorn fruit, and thermal pasteurization and ultrasound techniques were applied. A total of 56 female adult Wistar-Albino rats were allocated into seven groups and administered hawthorn fruit vinegar via oral gavage on a daily basis. The experimental groups included rats treated with pasteurized vinegar (HVP), ultrasound-treated rats (HVU), and an untreated group that received regular vinegar (HVN) at two different dosage levels (0.5 and 1 mL/kg). The SOD, MDA, and CAT antioxidant levels were measured using the ELISA method in plasma and liver tissue samples. The total plasma cholesterol, triglyceride, HDL, LDL, AST, and ALT values were quantified using commercially available kits. The levels of SOD and CAT in the plasma and liver were found to be significantly higher in the HVU1 group compared to all other groups. Furthermore, the HVU1 cohort exhibited the highest HDL value in plasma. The plasma LDL levels were comparably low in both the thermal-pasteurized and ultrasound-treated groups. There were significant expressions of both CAT and SOD in the liver tissues of the HVU groups (analyzed immunohistochemically). These results indicated that hawthorn vinegar administration with 1 mL/kg in group HVU1 could significantly enhance antioxidant capacity in the liver and, consequently, overall health. It can be suggested that the possible therapeutic effects of hawthorn vinegar may boost its antioxidant capabilities and contribute to an overall improvement in quality of life.

Potential benefits of spicy food consumption on cardiovascular outcomes in patients with diabetes: A cohort study of the China Kadoorie Biobank

OBJECTIVES

Dietary capsaicin from spicy foods has potential benefits for those with cardiometabolic diseases (CMDs). However, there is no evidence linking spicy food consumption with cardiovascular outcomes in individuals with diabetes. The aim of this study was to explore the association between spicy food consumption and the incidence of major adverse cardiovascular events (MACEs) in individuals with diabetes from the CKB (China Kadoorie Biobank) study and to provide evidence-based dietary recommendations for those with CMDs.

METHODS

This prospective study enrolled 26 163 patients with diabetes without coronary heart disease, stroke, or cancer from the CKB study. Of the 26 163 patients enrolled, 17 326 never or rarely ate spicy food (non-spicy group), and 8837 ate spicy food ≥1 d/wk (spicy group). The primary outcomes were MACEs, including cardiac death, non-fatal myocardial infarction, and stroke. Cox proportional hazards models were used to estimate the hazard ratio (HR) of MACEs and their associated 95% confidence intervals (CIs).

RESULTS

During a median follow-up of 8.5 y, MACEs occurred in 5465 participants (20.9%), with 3820 (22%) and 1645 (18.6%) cases occurring in the non-spicy and spicy groups, respectively. Spicy food consumption was independently associated with a decreased tendency for MACEs, with an adjusted HR of 0.94 (95% CI, 0.89-1.00; P = 0.041). Subgroup analysis showed consistency in the results that the regular spicy eating groups were associated with significantly lower incidence of MACEs than the non-spicy group. There was no statistical difference in the incidence of MACEs among the three different spicy eating frequency groups.

CONCLUSION

This cohort study revealed that the consumption of spicy food was independently associated with a reduced incidence of adverse cardiovascular events in Chinese adults with diabetes, suggesting a beneficial effect on cardiovascular health. Further studies are needed to confirm the association between the consumption of different doses of spicy food and cardiovascular outcomes and the exact mechanism of action.

Salvianolic acid A alleviates atherosclerosis by inhibiting inflammation through Trc8-mediated 3-hydroxy-3-methylglutaryl-coenzyme A reductase degradation

BACKGROUND

Atherosclerosis is the most prevalent cardiovascular disease and remains the major contributor to death and mortality globally. Salvianolic acid A (SalA) is a water-soluble phenolic acid that benefits atherosclerosis. However, the mechanisms of SalA protecting against atherosclerosis remain unclear.

PURPOSE

We aimed to determine whether SalA prevents atherosclerosis by modulating 3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) degradation via the ubiquitin-proteasomal pathway.

METHODS

The animal and cellular models of atherosclerosis were established by subjecting apolipoprotein E (ApoE) knockout mice to a high-fat diet (HFD) and exposing human umbilical vein endothelial cells (HUVECs) to oxidized low-density lipoprotein (ox-LDL), respectively.

RESULTS

Our results showed that similar to atorvastatin, SalA suppressed atherosclerotic plaque formation, improved serum lipid accumulation, and reduced cholesterol levels in HFD-fed ApoE^-/- mice. Moreover, SalA protected HUVECs from ox-LDL-caused cell viability reduction and lipid accumulation. The mechanism study revealed that SalA reduced the production of proinflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, and augmented the generation of the anti-inflammatory cytokine IL-10 in ApoE^-/- mice and HUVECs, accompanied by increased HMGCR ubiquitination and degradation via translocation in renal carcinoma on chromosome 8 (Trc8), insulin-induced gene (Insig)1 and Insig2. Furthermore, the knockdown of Trc8 abolished the SalA-induced HMGCR degradation and anti-atherosclerosis activity.

CONCLUSION

SalA rescues atherosclerosis by inhibiting inflammation through the Trc8-regulated degradation of HMGCR. These findings underscore Trc8 as a potential target of atherosclerosis.

Brazilian green propolis extracts modulate cholesterol homeostasis in a preclinical guinea pig model: an in vitro and in vivo study

Green propolis produced by Apis melífera bees, having Baccharis dracunculifolia D.C. (Asteraceae) as the primary botanical source, has been used in traditional medicine to treat numerous disorders. However, studies evaluating propolis' potential in treating cardiovascular diseases via its effects on cholesterol metabolism are lacking. Therefore, this study investigated the effects of green propolis extracts on lipid metabolism in hypercholesterolemic guinea pigs. Chemical characterization of ethanolic extracts of green propolis samples was undertaken using HPLC. The in vitro characterization included an evaluation of the antioxidant capacity of the hydroalcoholic extract of green propolis (DPPH and FRAP assays) and its ability to act as an inhibitor of the HMG-CoA reductase enzyme. In vivo, we investigated the effect of the hydroalcoholic extract of green propolis on lipid metabolism in hypercholesterolemic guinea pigs. Results obtained validated previous reports of significant antioxidant activity. HPLC analysis confirmed that coumaric acid, artepillin C, and baccharin were the most common and abundant compounds in green propolis samples among the studied compounds. Furthermore, the compounds in these extracts acted as effective HMG-CoA reductase inhibitors in vitro. In vivo assays demonstrated that a hypercholesterolemic diet significantly reduced serum levels of the HDL cholesterol fraction. Simvastatin and propolis hydroalcoholic extracts promoted a significant increase in HDL cholesterol, suggesting that these extracts can improve the serum lipid profile of hypercholesterolemic guinea pigs. Results obtained in this study provide a perspective on the possible hypocholesterolemic effect of green propolis, suggesting that it can improve the serum lipid profile in hypercholesterolemic guinea pigs.

Capsicum Waste as a Sustainable Source of Capsaicinoids for Metabolic Diseases

Capsaicinoids are pungent alkaloid compounds enriched with antioxidants, anti-microbial, anti-inflammatory, analgesics, anti-carcinogenic, anti-obesity and anti-diabetic properties. These compounds are primarily synthesised in the placenta of the fruit and then transported to other vegetative parts. Different varieties of capsicum and chillies contain different capsaicinoid concentrations. As capsicums and chillies are grown extensively throughout the world, their agricultural and horticultural production leads to significant amount of waste generation, in the form of fruits and plant biomass. Fruit wastes (placenta, seeds and unused fruits) and plant biowaste (stems and leaves) can serve as sources of capsaicinoids which can provide opportunities to extract these compounds for development of nutraceutical products using conventional or advanced extraction techniques. Capsaicin and dihydrocapsaicin are two most abundantly found pungent compounds. Considering the health benefits of capsaicinoids, these compounds can help in reducing metabolic disease complications. The development of an advanced encapsulation therapy of safe and clinically effective oral capsaicinoid/capsaicin formulation seem to require evaluation of strategies to address challenges related to the dosage, limited half-life and bioavailability, adverse effects and pungency, and the impacts of other ligands antagonising the major capsaicinoid receptor.

Dietary Capsaicin: A Spicy Way to Improve Cardio-Metabolic Health?

Today's sedentary lifestyle with too much food and too little exercise has made metabolic syndrome a pandemic. Metabolic syndrome is a major risk factor for type-2 diabetes and cardiovascular disease. New knowledge of medical and nutraceutical intervention in the early stages of metabolic syndrome is central to prevent these deadly complications. People who eat chili pepper on a regular basis seem to stay healthier and live longer than those who do not. Animal experiments suggest a therapeutic potential for dietary capsaicin, the active principle in hot chili pepper, to reduce the risk of developing metabolic syndrome. This is an attractive theory since capsaicin has been a culinary staple for thousands of years, and is generally deemed safe when consumed in hedonically acceptable doses. The broad expression of the capsaicin receptor TRPV1 in metabolically active tissues lends experimental support to this theory. This review critically evaluates the available experimental and clinical evidence for and against dietary capsaicin being an effective dietary means to improve cardio-metabolic health. It comes to the conclusion that although a chili pepper-rich diet is associated with a reduced risk of dying due to cardiovascular disease, dietary capsaicin has no clear effect on blood glucose or lipid profiles. Therefore, the reduced mortality risk may reflect the beneficial action of digested capsaicin on gut microbiota.

Lycium barbarum polysaccharides and capsaicin modulate inflammatory cytokines and colonic microbiota in colitis rats induced by dextran sulfate sodium

Active ingredients in the natural products have been considered to be used for alleviating the symptoms of ulcerative colitis, hence the effects of Lycium barbarum polysaccharides (LP) and capsaicin on dextran sulfate sodium (DSS)-induced colitis in rats were investigated. Rats were grouped into normal, DSS induced colitis, and colitis treated with 100 mg LP/kg body weight, 12 mg capsaicin/kg body weight, or combined 50 mg LP/kg body weight and 6 mg capsaicin/kg body weight. Treatment with LP or capsaicin was orally fed by gavage for 4 weeks, and 5% DSS was fed via drinking water for 6 days during week 3. Colon tissue and cecum content were collected for analysis. Treatments with LP and/or capsaicin ameliorated disease activity index scores, severity of colon distortion, and shrinkage of colon length. LP and capsaicin decreased colonic pro-inflammatory cytokine (IFN-γ, IL-17A, and IL-22) levels. Cecal microbiota in colitis rats were enriched with the genus Turicibacter and Lachnospira. The relative abundance of genus Ruminiclostridium_9 and Ruminoclostridium_1 was increased by LP and capsaicin treatment, respectively. Pretreatment with LP or capsaicin inhibits the severity of colonic damage in rats with DSS-induced colitis via anti-inflammation and modulation of colonic microbiota.

Capsaicin Ameliorates High-Fat Diet-Induced Atherosclerosis in ApoE−/− Mice via Remodeling Gut Microbiota

Capsaicin is a pungent alkaloid abundantly present in peppers with outstanding biological activities, including the anti-atherosclerosis effect. Previous studies revealed that gut microbiota played an important role in the beneficial effects of capsaicin, but whether it is essential for the anti-atherosclerosis effect of capsaicin is unclear. This study evaluated the anti-atherosclerosis effect of capsaicin in ApoE^−/− mice and further explored the role of depleting gut microbiota in the improvement of atherosclerosis. The results showed that capsaicin administration could prevent the development of atherosclerosis and improve serum lipids and inflammation, while antibiotic intervention abolished the alleviation of atherosclerosis by capsaicin. In addition, capsaicin administration could significantly increase the abundance of Turicibacter, Odoribacter, and Ileibacterium in feces, and decrease the abundance of deoxycholic acid, cholic acid, hypoxanthine, and stercobilin in cecal content. Our study provides evidence that gut microbiota plays a critical role in the anti-atherosclerosis effect of capsaicin.

Contribution of Oxidative Stress (OS) in Calcific Aortic Valve Disease (CAVD): From Pathophysiology to Therapeutic Targets

Calcific aortic valve disease (CAVD) is a major cause of cardiovascular mortality and morbidity, with increased prevalence and incidence. The underlying mechanisms behind CAVD are complex, and are mainly illustrated by inflammation, mechanical stress (which induces prolonged aortic valve endothelial dysfunction), increased oxidative stress (OS) (which trigger fibrosis), and calcification of valve leaflets. To date, besides aortic valve replacement, there are no specific pharmacological treatments for CAVD. In this review, we describe the mechanisms behind aortic valvular disease, the involvement of OS as a fundamental element in disease progression with predilection in AS, and its two most frequent etiologies (calcific aortic valve disease and bicuspid aortic valve); moreover, we highlight the potential of OS as a future therapeutic target.

Hawthorn fruit acid consumption attenuates hyperlipidemia-associated oxidative damage in rats

Context

Hyperlipidemia is a highly prevalent risk factor for atherosclerosis and stroke. The currently available medications used to treat Hyperlipidemia cannot improve its oxidative stress damage. Consumption of hawthorn can regulate blood sugar and blood lipids, and its rich fruit acid is a natural antioxidant that can improve oxidative stress damage.

Objective

The present research aimed to investigate the protective effect of hawthorn fruit acid (HFA) on hyperlipidemia and to determine its potential molecular mechanism.

Materials and methods

Sprague-Dawley rats were fed a high-fat diet (HFD) to induce hyperlipidemia and treated orally with hawthorn fruit acids (HFA). Serum and liver levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), superoxide dismutase (SOD), hydrogen peroxide (CAT), and malondialdehyde (MDA) were measured. Human hepatocellular carcinoma cell lines (HepG2) cells were treated with 0.1 mM oleic acid and HFA (0.125, 0.25 mg/mL), and intracellular TC, TG, HDL-C, SOD, CAT and MDA were measured. Changes in LDLR, HMGCR, Nrf2, HO-1, NQO1 protein and gene expression were analyzed by Western blot and qPCR.

Results

This study found that HFA treatment effectively reduced the level of triglyceride, cholesterol, and glucose, and attenuated hepatic steatosis in rats. Additionally, oxidative stress damage of rats was effectively reduced by treatment with HFA. Western blot and qPCR analysis indicated that HFA treatment inhibited fat accumulation in HepG2 cells by upregulating LDLR and downregulating HMGCR gene expression. HFA inhibits oleic acid (OA)-induced oxidative damage to HepG2 by activating the Nrf2/HO-1 signaling pathway.

Conclusion

HFA administration can provide health benefits by counteracting the effects of hyperlipidemia caused by an HFD in the body, and the underlying mechanism of this event is closely related to the activation of the Nrf2/HO-1 signaling pathway.

Capsaicin for Weight Control: “Exercise in a Pill” (or Just Another Fad)?

Medical management of obesity represents a large unmet clinical need. Animal experiments suggest a therapeutic potential for dietary capsaicin, the pungent ingredient in hot chili peppers, to lose weight. This is an attractive theory since capsaicin has been a culinary staple for thousands of years and is generally deemed safe when consumed in hedonically acceptable, restaurant-like doses. This review critically evaluates the available experimental and clinical evidence for and against capsaicin as a weight control agent and comes to the conclusion that capsaicin is not a magic “exercise in a pill”, although there is emerging evidence that it may help restore a healthy gut microbiota.

Endothelial shear stress signal transduction and atherogenesis: From mechanisms to therapeutics

Atherosclerotic vascular disease and its complications are among the top causes of mortality worldwide. In the vascular lumen, atherosclerotic plaques are not randomly distributed. Instead, they are preferentially localized at the curvature and bifurcations along the arterial tree, where shear stress is low or disturbed. Numerous studies demonstrate that endothelial cell phenotypic change (e.g., inflammation, oxidative stress, endoplasmic reticulum stress, apoptosis, autophagy, endothelial-mesenchymal transition, endothelial permeability, epigenetic regulation, and endothelial metabolic adaptation) induced by oscillatory shear force play a fundamental role in the initiation and progression of atherosclerosis. Mechano-sensors, adaptor proteins, kinases, and transcriptional factors work closely at different layers to transduce the shear stress force from the plasma membrane to the nucleus in endothelial cells, thereby controlling the expression of genes that determine cell fate and phenotype. An in-depth understanding of these mechano-sensitive signaling cascades shall provide new translational strategies for therapeutic intervention of atherosclerotic vascular disease. This review updates the recent advances in endothelial mechano-transduction and its role in the pathogenesis of atherosclerosis, and highlights the perspective of new anti-atherosclerosis therapies through targeting these mechano-regulated signaling molecules.

Capsaicinoid-Glucosides of Fresh Hot Pepper Promotes Stress Resistance and Longevity in Caenorhabditis elegans

In this study, capsaicin-glucoside and dihydro-capsaicin-glucoside derived from fresh hot-red pepper were isolated and identified using UPLC-ESI-Q-TOF-MS/PDA. Synchronized worms were treated with capsaicinoid-glucosides (CG), and then lifespan and stress resistance were examined. The 50 µg/ml concentration of CG-intake could effectively protect the Caenorhabditis elegans (C. elegans) against stresses factors including oxidation and heat as well as reactive oxygen species (ROS), thereby enhancing the survival of CG-treated worms under stress. Enhancing stress resistance in CG-treated worms could be due to the increased expressions of stress-related genes in C. elegans such as daf-16, skn-1 and their downstream target genes (sod-3, hsp-16.2, gst-4 and gcs-1). Lifespan study of different C. elegans strains and RT-PCR showed that the CG-mediated lifespan extension was dependent on DAF-16/FOXO and SKN-1/Nrf2 transcription factors. The study is a step forward in exploring the stress resistance and anti-aging properties of this beneficial extract. Thus, this study will be useful in formulating remedies for stresses factors and age associated disorders.

The protective effects of capsaicin on oxidative damage-induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin in rats

The present study aimed to investigate the protective role of capsaicin in a rat model of 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD)-induced toxicity. Exposure to TCDD which is an environmental toxicant causes severe toxic effects in the animal and human tissues. Therefore, the potential protective effect of capsaicin in TCDD-induced organ damage was investigated in rats by measuring thiobarbituric acid reactive substances (TBARS) level, superoxide dismutase (SOD) activity, and glutathione (GSH) level in the heart, liver, and kidney tissues for oxidant/antioxidant balance. Thirty-two healthy adults (250-300 g weight and 3-4 months old) male Wistar albino rats were randomly distributed into four equal groups (n = 8): Control, CAP, TCDD, TCDD + CAP. A dose of 2 μg/kg TCDD or a dose of 25 mg/kg capsaicin were dissolved in corn oil and orally administered to the rats for 30 days. The results indicated that TCDD-induced oxidative stress by increasing the level of TBARS and by decreasing the levels of GSH, and SOD activity in the tissues of rats. However, capsaicin treatment was significantly decreased TBARS levels and was significantly increased GSH level and SOD activity (p < 0.05). In addition, capsaicin (25 mg/kg) significantly attenuated TCDD-induced histopathological alteration associated with oxidative stress in the heart, liver, and kidney tissues (p < 0.05). As capsaicin regulates oxidative imbalance and attenuates histopathological alterations in the rat tissues, it may be preventing agents in TCDD toxicity.

Effects of Danhong injection on dyslipidemia and cholesterol metabolism in high-fat diets fed rats

ETHNOPHARMACOLOGICAL RELEVANCE

Danhong injection (DHI) is a Chinese medical injection applied to the clinical treatment of cardiovascular diseases that has anti-inflammatory, antiplatelet aggregation and antithrombotic effects. This study aimed to explore the effects of DHI on dyslipidemia and cholesterol metabolism in high-fat diet-fed rats.

METHODS

Sprague Dawley (SD) rats were randomly divided into six groups: normal group (Normal); hyperlipidemia model group (Model); DHI-treated groups at doses of 1.0 mL/kg, 2.0 mL/kg, 4.0 mL/kg; and simvastatin positive control group (2.0 mg/kg). The hypolipidemic effects of DHI were evaluated by measuring serum lipid levels, hepatic function and oxidative stress, respectively. And pathological changes in liver tissues were determined using hematoxylin-eosin (H&E) and oil red O staining. Moreover, the mRNA and protein expression levels of cholesterol metabolism related genes were detected by real-time PCR (RT-PCR) and Western blot.

RESULTS

Compared with the Model group, DHI treatment markedly decreased the liver index and improved the pathological morphology of liver tissues. DHI treatment dose-dependently decreased the levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), and free fatty acids (FFA) in serum or liver tissues (P < 0.01 or P < 0.05), and increased the high-density lipoprotein cholesterol (HDL-C) and tripeptide glutathione (GSH) (P < 0.01 or P < 0.05). The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were increased in the DHI-treated groups (P < 0.01 or P < 0.05), while the alanine transaminase (ALT) and aspartate transaminase (AST) were decreased (P < 0.01 or P < 0.05). Furthermore, the expression levels of LDL receptor (LDLR), cholesterol 7-α-hydroxylase (CYP7A1), liver X receptor α (LXRα), and peroxisome proliferator-activated receptor α (PPARα) were dose-dependently upregulated in the DHI-treated groups, whereas the expression of sterol regulatory element-binding protein-2 (SREBP-2) was downregulated.

CONCLUSIONS

Our study demonstrated that DHI markedly ameliorated hyperlipidemia rats by regulating serum lipid levels, inhibiting hepatic lipid accumulation and steatosis, improving hepatic dysfunction, and reducing oxidative stress. The potential mechanism was also tentatively investigated and may be related to the promotion of bile acid synthesis via activation of the PPARα-LXRα-CYP7A1 pathway. Therefore, DHI could be regarded as a potential hypolipidemic drug for the treatment of hyperlipidemia.

TRPV1 activation inhibits phenotypic switching and oxidative stress in vascular smooth muscle cells by upregulating PPARα

The proliferation and migration of vascular smooth muscle cells (VSMCs) is one of main reasons of vascular remodeling and is the pathogenesis of atherosclerosis and other vascular diseases. Transient receptor potential vanilloid 1 (TRPV1) is the specific receptor of capsaicin. TRPV1 has been previously reported to inhibit proliferation, migration and phenotypic switching, but the regulatory mechanisms and relevant signalling pathways are not clear. The aim of this study was to investigate the effects of capsaicin-activated TRPV1 on VSMC phenotypic switching. In this study, oxidized low density lipoprotein (ox-LDL) was used to induce the proliferation and migration of VSMCs. Our data showed that the VSMC proliferation induced by ox-LDL was dependent on the concentration of ox-LDL. Nevertheless, the data showed that capsaicin activated TRPV1 significantly decreased ox-LDL-induced superoxide anion generation. Phenotypic switching of VSMCs was inhibited by the activation of TRPV1. Furthermore, capsaicin decreased ox-LDL-induced superoxide anion generation by activating peroxisome proliferator activated receptor α (PPARα). TRPV1 inhibited VSMC phenotypic switching via upregulated expression of PPARα. It may be considered a useful target for the treatment of vascular remodeling.

Effects of capsaicin on laying performance, follicle development, and ovarian antioxidant capacity in aged laying ducks

The present study was conducted to evaluate the effects of dietary addition of capsaicin (CAP) on egg production performance, follicular development, and ovarian antioxidant capacity in laying ducks. Three hundred seventy eight 58-wk-old laying ducks were randomly divided into 3 treatments, each treatment consisted 6 replicates, with 12 individually caged laying ducks per replicate. Ducks fed a basal diet served as control, the other 2 groups of ducks were fed the same diet containing 150 mg/kg CAP but in the manner of feed restriction (pair-fed) or ad libitum fed. The experiment lasted for 8 wk. The results showed that the dietary supplementation with CAP under conditions of ad libitum feeding increased feed intake (P < 0.001) and tended (P < 0.1) to increase egg production and egg weight in laying ducks but had no effects on daily egg mass and feed conversion ratio. The relative weight of large yellow follicles from the 2 CAP-supplemented groups at 64 wk of age were significantly higher than that of the controls (P = 0.01). The relative weight of the small yellow follicles in the CAP free-fed group was significantly higher than that of the other 2 groups (P < 0.01). Capsaicin supplementation under ad libitum feding conditions tended to increase the number of dominant follicles in laying ducks (P = 0.06). The ovarian mRNA expression of genes related to calcium signaling (TRPV4, ATP2A2, ITPR1, and CaM) in the CAP ad libitum fed groups were significantly higher than those of the other 2 groups (P < 0.05). The ovarian mRNA expression of CDK1 in CAP free-fed ducks was significantly higher than that of the other 2 groups (P = 0.01). Capsaicin supplementation significantly increased the plasma glutathione peroxidase activity (P < 0.01) in comparison with the control group but reduced the malondialdehyde content in the ovaries of laying ducks (P < 0.01). The results of this study indicates that dietary supplementation of CAP increased feed intake and improved egg production performance probably by activating calcium signaling pathway and improving redox status.

Small rodent models of atherosclerosis

The ease of breeding, low cost of maintenance, and relatively short period for developing atherosclerosis make rodents ideal for atherosclerosis research. However, none of the current models accurately model human lipoprotein profile or atherosclerosis progression since each has its advantages and disadvantages. The advent of transgenic technologies much supports animal models' establishment. Notably, two classic transgenic mouse models, apoE-/- and Ldlr-/-, constitute the primary platforms for studying underlying mechanisms and development of pharmaceutical approaches. However, there exist crucial differences between mice and humans, such as the unhumanized lipoprotein profile, and the different plaque progression and characteristics. Among rodents, hamsters and guinea pigs might be the more realistic models in atherosclerosis research based on the similarities in lipoprotein metabolism to humans. Studies involving rat models, a rodent with natural resistance to atherosclerosis, have revealed evidence of atherosclerotic plaques under dietary induction and genetic manipulation by novel technologies, notably CRISPR-Cas9. Ldlr-/- hamster models were established in recent years with severe hyperlipidemia and atherosclerotic lesion formation, which could offer an alternative to classic transgenic mouse models. In this review, we provide an overview of classic and innovative small rodent models in atherosclerosis researches, including mice, rats, hamsters, and guinea pigs, focusing on their lipoprotein metabolism and histopathological changes.

The impact of capsaicinoids on APP processing in Alzheimer's disease in SH-SY5Y cells

The vanilloid capsaicin is a widely consumed spice, known for its burning and "hot" sensation through activation of TRPV1 ion-channels, but also known to decrease oxidative stress, inflammation and influence tau-pathology. Beside these positive effects, little is known about its effects on amyloid-precursor-protein (APP) processing leading to amyloid-β (Aβ), the major component of senile plaques. Treatment of neuroblastoma cells with capsaicinoids (24 hours, 10 µM) resulted in enhanced Aβ-production and reduced Aβ-degradation, leading to increased Aβ-levels. In detailed analysis of the amyloidogenic-pathway, both BACE1 gene-expression as well as protein-levels were found to be elevated, leading to increased β-secretase-activity. Additionally, γ-secretase gene-expression as well as activity was enhanced, accompanied by a shift of presenilin from non-raft to raft membrane-domains where amyloidogenic processing takes place. Furthermore, impaired Aβ-degradation in presence of capsaicinoids is dependent on the insulin-degrading-enzyme, one of the major Aβ-degrading-enzymes. Regarding Aβ-homeostasis, no differences were found between the major capsaicinoids, capsaicin and dihydrocapsaicin, and a mixture of naturally derived capsaicinoids; effects on Ca²⁺-homeostasis were ruled out. Our results show that in respect to Alzheimer's disease, besides the known positive effects of capsaicinoids, pro-amyloidogenic properties also exist, enhancing Aβ-levels, likely restricting the potential use of capsaicinoids as therapeutic substances in Alzheimer's disease.

Naringin Reverses High-Cholesterol Diet-Induced Vascular Dysfunction and Oxidative Stress in Rats via Regulating LOX-1 and NADPH Oxidase Subunit Expression

Hypercholesterolaemia is associated with oxidative stress and endothelial dysfunction and leads to the development of atherosclerosis. Naringin exhibits cardiovascular protective and antioxidant properties. Therefore, the aim of this study was to assess the effect of naringin administration on vascular oxidative stress and endothelial dysfunction in hypercholesterolaemic rats and to elucidate its underlying mechanism. Sprague Dawley rats were fed a diet with 1.5% cholesterol (HCD) for 8 weeks to induce hypercholesterolaemia. Naringin (100 mg/kg body weight) was orally administrated to rats during the last 4 weeks of the diet treatment. After 8 weeks, the thoracic aorta was isolated to determine vascular function and nitric oxide (NO) levels. The aortic superoxide anion (O₂⁻) level was detected using dihydroethidium (DHE) fluorescence staining. Protein expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, and inducible nitric oxide synthase (iNOS), as well as oxidative damage markers, was also evaluated in aortae. Naringin treatment of hypercholesterolaemic rats enhanced aortic NO levels, restored endothelium-dependent responses to acetylcholine (ACh), and reduced aortic O₂⁻ levels. Furthermore, naringin treatment decreased LOX-1, NADPH oxidase subunits (p47^phox, Nox2, and Nox4), and iNOS as well as oxidative damage markers (3-nitrotyrosine (3-NT) and 4-hydroxynonenal (4-HNE)) expression in aortic tissues from hypercholesterolaemic rats. These results demonstrate that naringin treatment improves endothelium dysfunction in hypercholesterolaemic rats, at least partially by decreasing oxidative stress via downregulation of LOX-1 and NADPH oxidase.

Antiobesity, Regulation of Lipid Metabolism, and Attenuation of Liver Oxidative Stress Effects of Hydroxy-α-sanshool Isolated from Zanthoxylum bungeanum on High-Fat Diet-Induced Hyperlipidemic Rats

Zanthoxylum bungeanum is a traditional Chinese medicine (TCM) used to relieve pain, dispel dampness, stop diarrhea, and prevent itching. The aim of this study was to investigate the antiobesity and hypolipidemic effects of hydroxy-α-sanshool (HAS) isolated from Z. bungeanum on hyperlipidemic rats. Wistar rats (n = 48) were randomly divided into six groups: (1) normal diet rats (ND), (2) high-fat diet- (HFD-) treated rats, (3) HFD+fenofibrate-treated rats (HFD+FNB), (4) HFD+low dose of HAS-treated rats (HFD+LD, 9 mg/kg), (5) HFD+middle dose of HAS-treated rats (HFD+MD, 18 mg/kg), and (6) HFD+high dose of HAS-treated rats (HFD+HD, 36 mg/kg). The body weight and food intake of the rats were recorded during the treatment period. After 4 weeks of HAS treatment, abdominal adipose tissues were observed and total cholesterol (T-CHO), triglycerides (TG), high-density lipoprotein (HDL) cholesterol (HDL-C), and low-density lipoprotein (LDL) cholesterol (LDL-C) of serum and liver tissues were determined. Furthermore, histochemical examinations using oil red O and hematoxylin-eosin staining (H&E) were carried out and levels of malondialdehyde (MDA) and glutathione (GSH) and activities of superoxide dismutase (SOD) in the liver were determined. After HFD feeding, the body weight gain and food efficiency ratio of HFD rats were significantly enhanced (p < 0.05vs. ND rats) and HAS treatment (18 and 36 mg/kg) significantly decreased the body weight gain and food efficiency ratio (p < 0.05vs. HFD rats). In addition, HAS treatment could decrease the abdominal adipose tissues and liver adipocytes. Furthermore, HAS treatment significantly decreased the T-CHO, TG, and LDL-C, whereas it increased HDL-C (p < 0.05vs. HFD rats) in serum and the liver. HAS treatment increased the GSH level and SOD activity in the liver (p < 0.05vs. HFD rats), whereas it decreased the levels of MDA (p < 0.05vs. HFD rats). mRNA analyses suggested that HAS treatment increases the expression of Pparg (proliferator-activated receptor γ) and Apoe (peroxisome apolipoprotein E). Immunohistochemistry and Western blotting indicated that HAS stimulation increased the levels of PPARγ and APOE in the liver, as a stress response of the body defense system. These results revealed that HAS exerts antiobesity and hypolipidemic activities in HFD rats by reducing liver oxidative stress and thus could be considered as a potential candidate drug to cure or prevent obesity and hyperlipidemia.