Phlorizin ameliorates cognitive and behavioral impairments via the microbiota-gut-brain axis in high-fat and high-fructose diet-induced obese male mice.

The long-term high-fat, high-sugar diet exacerbates type 2 diabetes mellitus (T2DM)-related cognitive impairments. Phlorizin, a well-studied natural compound found in apples and other plants, is recognized for its bioactive properties, including modulation of glucose and lipid metabolism. Despite its established role in mitigating metabolic disorders, the neuroprotective effects of phlorizin, particularly against diabetes-related cognitive dysfunction, have not been fully elucidated. Therefore, the present study aimed to investigate the effect of dietary supplementation of phlorizin on high-fat and high-fructose diet (HFFD)-induced cognitive dysfunction and evaluate the crucial role of the microbiota-gut-brain axis. We found that dietary supplementation of phlorizin for 14 weeks effectively prevented glucolipid metabolism disorder, spatial learning impairment, and memory impairment in HFFD mice. In addition, phlorizin improved the HFFD-induced decrease in synaptic plasticity, neuroinflammation, and excessive activation of microglia in the hippocampus. Transcriptomics analysis shows that the protective effect of phlorizin on cognitive impairment was associated with increased expression of neurotransmitters and synapse-related genes in the hippocampus. Phlorizin treatment alleviated colon microbiota disturbance, mainly manifested by an increase in gut microbiota diversity and the abundance of short-chain fatty acid (SCFA)-producing bacteria. The level of microbial metabolites, including SCFA, inosine 5'-monophosphate (IMP), and D (-)-beta-hydroxybutyric acid (BHB) were also significantly increased after phlorizin treatment. Integrating multiomics analysis observed tight connections between phlorizin-regulated genes, microbiota, and metabolites. Furthermore, removal of the gut microbiota via antibiotics treatment diminished the protective effect of phlorizin against HFFD-induced cognitive impairment, underscoring the critical role of the gut microbiota in mediating cognitive behavior. Importantly, supplementation with SCFA and BHB alone mimicked the regulatory effects of phlorizin on cognitive function. Therefore, phlorizin shows promise as a potential nutritional therapy for addressing cognitive impairment associated with metabolic disorders. Further research is needed to explore its effectiveness in preventing and alleviating neurodegenerative diseases.

Short-term administration of tibolone reduces inflammation and oxidative stress in the hippocampus of ovariectomized rats fed high-fat and high-fructose.

Inflammation and oxidative stress are critical events involved in neurodegeneration. In animal models, it has been shown that chronic consumption of a hypercaloric diet, which leads to inflammatory processes, affects the hippocampus, a brain region fundamental for learning and memory processes. In addition, advanced age and menopause are risk factors for neurodegeneration. Hormone replacement therapy (HRT) ameliorates menopause symptoms. Tibolone (TB), a synthetic hormone, exerts estrogenic, progestogenic and androgenic effects on different tissues. We aimed to determine the effect of short-term TB administration on oxidative stress and inflammation markers in the hippocampus of ovariectomized rats fed a high-fat-and-fructose diet (HFFD). Adult female rats were ovariectomized (OVX) and fed standard diet or HFFD-consisting of 10% lard supplemented chow and 20% high-fructose syrup in the drinking water-and administered vehicle or TB (1 mg/kg for seven days). Finally, we administered hormone receptor antagonists (MPP, RU486 or FLU) to each of the OVX + HFFD + TB groups. Bodyweight, triglycerides and cholesterol, oxidative stress and inflammation markers, and the activity and expression of antioxidant enzymes were quantified in the hippocampus of each experimental group. We observed that short-term TB administration significantly reduced body weight, AGEs, MDA levels, increased SOD and GPx activity, improved GSH/GSSG ratio, and reduced IL-6 and TNF-α. Our findings suggest that short-term administration of TB decreases oxidative stress and reduces inflammation caused by HFFD and early estrogenic decline. These effects occurred via estrogen receptor alpha.

Repression of TXNIP-NLRP3 axis restores intestinal barrier function via inhibition of myeloperoxidase activity and oxidative stress in nonalcoholic steatohepatitis.

Dysfunction of the intestinal barrier function occurs in hepatic injury, but the specific mechanisms responsible are largely unknown. Recently, NOD-like receptor 3 (NLRP3) inflammasome functions in impairing endothelial barrier function. In this study, we test the hypothesis that TXNIP-NLRP3 axis repression prevents against intestinal barrier function disruption in nonalcoholic steatohepatitis (NASH). First, lipopolysaccharide (LPS)-induced alterations in expression of ZO-1 and occludin, myeloperoxidase (MPO) activity, reactive oxygen species (ROS) level, and transepithelial electric resistance (TEER) in intestinal epithelial cells (IECs) isolated from C57BL/6 wild-type (WT) and TXNIP-/- mice were evaluated. The underlying regulatory mechanisms of TXNIP knockout in vivo were investigated with the detection of expressions of TXNIP, NLRP3 and ZO-1, and occludin, the interaction of TXNIP-NLRP3, MPO activity, ROS level, permeability of intestinal mucosa, levels of inflammatory factors in serum, and LPS concentration. We identified that TXNIP knockout promoted ZO-1 and occludin expression, yet reduced MPO activity, ROS level, and cell permeability in IECs, indicating restored the intestinal barrier function. However, LPS upregulated TXNIP and NLRP3 expression, as well as contributed to the interaction between TXNIP and NLRP3 in vitro. Furthermore, TXNIP was significantly upregulated in the intestinal mucosa of NASH mice and its knockout repaired the intestinal barrier disrupt, inhibited expression of inflammatory factors, and reduced LPS concentration as well as hepatic injury in vivo. Taken together, our findings demonstrated that inhibited the activation of the TXNIP-NLRP3 axis reduced MPO activity and oxidative stress and thus restoring the intestinal barrier function in NASH. TXNIP-NLRP3 axis may be a promising therapeutic strategy for the NASH treatment.

High-calorie diet inflates steatogenic effects of valproic acid in mice.

Valproic acid (VPA) is an anti-epileptic drug used in patients with convulsive seizures and psychic disorders. Despite its therapeutic use, VPA administration is associated with several side effects of which hepatosteatosis (lipid deposition in liver >10% of organ weight) is of concern. Recently, the consumption of western-type diet rich in fat and simple sugar has increased, the pathological consequences of which has been linked to the escalating incidence of metabolic disorders. The hypothesis of the study is that the metabolic stress induced by high-calorie diet may potentiate VPA-induced hepatosteatosis. Two groups of Swiss Mus musculus male mice weighing 25-35 g were fed either normal chow or high fat and high fructose diet (HFFD) and maintained for 30 days. On the 16th day of the experiment, VPA (100 mg/kg bw) administration was initiated in one set of animals from each group and the other set was left without VPA treatment. Assays were done in the hemolysate, plasma and liver tissue of mice after the experimental period. Deregulated lipid metabolism, loss of insulin sensitivity, enhanced CYP2E1 activity and oxidative damage, and diminution of cellular antioxidants were observed in animals that received HFFD and VPA. HFFD-fed mice are sensitized to VPA toxicity than the normal chow-fed counterparts. The results of this study show that preformed metabolic derangements due to high-energy diet may infuriate VPA-induced hepatosteatosis and insulin resistance.

Genistein and sex hormone treatment alleviated hepatic fat accumulation and inflammation in orchidectomized rats with nonalcoholic steatohepatitis.

Testosterone deficiency has been reported to accelerate nonalcoholic fatty liver disease (NAFLD). However, there are minimal data on the risk of NAFLD in transgender women and the treatment of NAFLD in this population. This study aimed to investigate the treatment effects and the mechanisms of action of genistein and sex hormones in orchiectomized (ORX) rats with nonalcoholic steatohepatitis (NASH) induced by a high fat high fructose diet (HFHF). Seven-week old male Sprague-Dawley rats were randomly divided into 7 groups (n = 6 each group); 1) control group, 2) ORX + standard diet group, 3) HFHF group, 4) ORX + HFHF group, 5) ORX + HFHF diet + testosterone group (50 mg/kg body weight (BW) once weekly), 6) ORX + HFHF diet + estradiol group (1.6 mg/kg BW daily), and 7) ORX + HFHF diet + genistein group (16 mg/kg BW daily). The duration of treatment was 6 weeks. Liver tissue was used for histological examination by hematoxylin and eosin staining and hepatic fat measurement by Oil Red O staining. Protein expression levels of histone deacetylase3 (HDAC3) and peroxisome proliferator-activated receptor delta (PPARδ) were analyzed by immunoblotting. Hepatic nuclear factor (NF)-ĸB expression was evaluated by immunohistochemistry. Rats in the ORX + HFHF group had the highest degree of hepatic steatosis, lobular inflammation, hepatocyte ballooning and the highest percentage of positive Oil Red O staining area among all groups. The expression of HDAC3 and PPARδ was downregulated, while NF-ĸB expression was upregulated in the ORX + HFHF group when compared with control and ORX + standard diet groups. Testosterone, estradiol and genistein treatment improved histological features of NASH together with the reversal of HDAC3, PPARδ and NF-ĸB protein expression comparing with the ORX + HFHF group. In summary, genistein and sex hormone treatment could alleviate NASH through the up-regulation of HDAC3 and PPARδ, and the suppression of NF-ĸB expression.

Colonic L-cell impairment in aged subjects with type 2 diabetes leads to diminished GLP-1 production.

AIMS: Glucagon-like peptide 1 (GLP-1) is produced by the L subtype of enteroendocrine cells (EECs). Patients with type 2 diabetes (T2D) exhibit reduced incretin effect, but the pathophysiology and functional change of the L-cells remain unclear. Deciphering the mechanisms of the biological changes in L-cells under T2D conditions may assist in the research of gut-based strategies for T2D therapy. METHODS: We investigated the fasting serum GLP-1 levels and the distribution of colonic L-cells in young and aged participants with and without T2D. Additionally, we established an aged male T2D Wistar rat model subjected to a long-term high-fat and high-fructose (HFHF) diet. Histological investigations and single-cell RNA sequencing (scRNA-seq) analyses were performed to explore the mechanisms underlying functional changes in the colonic EECs. RESULTS: We observed a decline in circulating GLP-1 levels and a reduced number of colonic L-cells in elderly patients with T2D. The mechanisms underlying impaired L-cell formation and disturbed GLP-1 production were revealed using aged T2D rats induced by a long-term HFHF diet. The scRNA-seq results showed that the transcription factors that regulate L-cell commitment, such as Foxa1, were downregulated, and the expression of genes that participate in encoding GLP-1, GLP-1 posttranslational processing, hormone secretion, and nutrient sensing was disturbed. CONCLUSIONS: Taken together, the reduced L-cell lineage commitment and disturbed L-cell functions might be the major cause of the reduced GLP-1 production in aged populations with T2D. Our study provides new insights for identifying novel targets in colonic L-cells for improving endogenous GLP-1 production.

The Role of a High-Fat, High-Fructose Diet on Letrozole-Induced Polycystic Ovarian Syndrome in Prepubertal Mice.

This study aims to investigate the effects of a high-fat, high-fructose (HF/HFr) diet on metabolic/endocrine dysregulations associated with letrozole (LET)-induced Polycystic Ovarian Syndrome (PCOS) in prepubertal female mice. Thirty-two prepubertal C57BL/6 mice were randomly divided into four groups of eight and implanted with LET or a placebo, with simultaneous administration of an HF/HFr/standard diet for five weeks. After sacrifice, the liver and blood were collected for selected biochemical analyses. The ovaries were taken for histopathological examination. The LET+HF/HFr group gained significantly more weight than the LET-treated mice. Both the LET+HF/HFr and the placebo-treated mice on the HF/HFr diet developed polycystic ovaries. Moreover the LET+HF/HFr group had significantly elevated testosterone levels, worsened lipid profile and indices of insulin sensitivity. In turn, the HF/HFr diet alone led to similar changes in the LET-treated group, except for the indices of insulin sensitivity. Hepatic steatosis also occurred in both HF/HFr groups. The LET-treated group did not develop endocrine or metabolic abnormalities, but polycystic ovaries were seen. Since the HF/HFr diet can cause substantial metabolic and reproductive dysregulation in both LET-treated and placebo mice, food items rich in simple sugar-particularly fructose-and saturated fat, which have the potential to lead to PCOS progression, should be eliminated from the diet of young females.

Effect of Eucommia ulmoides leaves on hyperuricemia and kidney injury induced by a high-fat/high-fructose diet in rats.

Objectives: To investigate the protective and preventive treatment effects of Eucommia ulmoides leaves on a rat model of high-fat and high-fructose diet (HFFD) induced hyperuricemia and renal injury. Materials and Methods: Network pharmacology and molecular-docking methods were used to predict the effects and action mechanisms of the major components of E. ulmoides leaves on hyperuricemia. Combining literature collection, we used SciFinder and the Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and Analysis Platform to collect E. ulmoides leaf flavonoid and iridoid components. Swiss Target Prediction, Similarity ensemble approach (SEA), GeneCards, and the Online Mendelian Inheritance in Man (OMIM) database were used to obtain core targets, and the Search Tool for Recurring Instances of Neighbouring Genes (STRING) protein database was used as core target for gene ontology enrichment Set and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Molecular docking was applied to predict the pathways regulating the metabolism of uric acid. The selected targets and targeting efficacy were validated using a rat model of hyperuricemia and renal injury induced by a high-fat and high-fructose diet. Results: A total of 32 chemical components with effective targets, which regulated the PI3K-AKT pathway and endocrine resistance, were collected. Molecular docking results showed that iridoids and flavonoids are bound to proteins related to inflammation and uric acid metabolism. In addition, it was verified via animal experiments that an E. ulmoides leaf extract ameliorated hyperuricemia, renal injury, and inflammation, which are closely related to the targets Interleukin- 6 (IL-6), Tumor necrosis factor-α (TNF-α), Toll-Like Receptor 4 (TLR4), and Glucose transporter 9 (GLUT9). Conclusion: E. ulmoides leaf flavonoids and iridoids ameliorate hyperuricemia and uric-acid-induced inflammation through a multi-component, multi-target, and multi-pathway mechanism, which provides a theoretical basis for the development of therapeutics from E. ulmoides leaf components.

Chlorogenic Acid Ameliorates High-Fat and High-Fructose Diet-Induced Cognitive Impairment via Mediating the Microbiota-Gut-Brain Axis.

Chlorogenic acid (CGA) displays cognition-improving properties, but the underlying mechanisms remain unclear. Herein, CGA supplementation (150 mg/kg body weight) for 14 weeks significantly prevented obesity and insulin resistance, cognitive-behavioral disturbances, and synaptic dysfunction induced by a high-fat and high-fructose diet (HFFD). Moreover, CGA supplementation enhanced the expression of genes enriched in the neuroactive ligand-receptor interaction pathway and reduced inflammatory factor expressions. Furthermore, CGA treatment increased gut microbiota diversity and the level of bacterial genera producing SCFAs. CGA also decreased the concentration of energy metabolism substrates, while it increased phosphorylcholine. Finally, we observed a significant correlation among synaptic transmission genes, gut microbiota, and neurotransmission in the CGA supplementation group by targeted multiomics analysis. Together, our results supported that the alteration of gut microbiota and metabolite composition is the underlying mechanism of CGA improving cognitive function. CGA is also a promising intervention strategy to prevent HFFD-induced cognitive impairment.

Sea-Buckthorn Flavonoids Alleviate High-Fat and High-Fructose Diet-Induced Cognitive Impairment by Inhibiting Insulin Resistance and Neuroinflammation.

Sea-buckthorn flavonoids (SFs) have been used as functional food components for their bioactive potential in preventing metabolic complications caused by diet, such as obesity and inflammation. However, the protective effect of SFs on cognitive functions is not fully clear. In this study, a high-fat and high-fructose diet (HFFD)-induced obese mice model was treated with SFs for 14 weeks. It was found that the oral SF administration (0.06% and 0.31% w/w, mixed in diet) significantly reduced bodyweight gain and insulin resistance in the HFFD-fed mice. SFs significantly prevented HFFD-induced neuronal loss and memory impairment in behavioral tests. Additionally, SFs also suppressed the HFFD-induced synaptic dysfunction and neuronal damages by increasing the protein expressions of PSD-95. Furthermore, SF treatment activated the ERK/CREB/BDNF and IRS-1/AKT pathways and inactivated the NF-κB signaling and its downstream inflammatory mediator expressions. In conclusion, SFs are a potential nutraceutical to prevent high-energy density diet-induced cognitive impairments, which could be possibly explained by their mediating effects on insulin signaling and inflammatory responses in the brain.

Probucol prevents blood-brain barrier dysfunction and cognitive decline in mice maintained on pro-diabetic diet.

An emerging body of evidence consistently suggests that compromised blood-brain barrier integrity may be causally associated with cognitive decline induced by type-2 diabetes. Our previous studies demonstrated that selected anti-inflammatory/anti-oxidative agents can preserve the integrity of blood-brain barrier and prevent neuroinflammation in mouse models of dysfunctional blood-brain barrier. Therefore, we have tested whether the previously proven blood-brain barrier protective agent, probucol, can prevent blood-brain barrier breakdown and cognitive decline in a dietary-induced murine model of diabetic insulin resistance. After 6-month chronic ingestion of a diet high in fat and fructose, the mice became insulin resistant. The high-fat and high-fructose-fed mice showed significant cognitive decline assessed by Morris water maze, concomitant with significant elevations in cortical and hippocampal glial acidic fibrillary protein and Fluoro Jade-C staining, indicating heightened neuroinflammation and neurodegeneration, respectively. The integrity of blood-brain barrier in high-fat and high-fructose-fed mice was substantially compromised, and this showed a significant association with heightened neurodegeneration. Co-provision of probucol with high-fat and high-fructose diet completely prevented the cognitive decline and blood-brain barrier dysfunction. Similarly, metformin was able to restore the cognitive function in high-fat and high-fructose-fed mice, while its blood-brain barrier protective effects were modest. These data suggest that probucol may prevent cognitive decline induced by insulin resistance by preserving the integrity of blood-brain barrier, whereas metformin's neuroprotective effects may be mediated through a separate pathway.

Effect of tetrahydrocurcumin on the profiles of drug-metabolizing enzymes induced by a high fat and high fructose diet in mice.

Cytochrome P450 (CYP), a superfamily of hepatic monooxygenase enzymes, catalyzes biotransformation of endogenous compounds and xenobiotics. Modification of CYPs associated with metabolic diseases and continuous consumption of diet with excessive energy levels. Tetrahydrocurcumin (THC) exhibited beneficial effects in metabolic syndromes such as diabetic mellitus and dyslipidemia. The present study aimed to investigate the effects of THC and vitamin E (vitE) on the expression profiles of CYPs in the livers of mice fed with the high fat and high fructose diet. In addition to ad libitum access to commercial regular diet, the high fat and high fructose diet (HFD) group of adult male ICR mice was administered a HFD, which consisted of intragastric administration of hydrogenated soybean oil (1mL/day) and the addition of 20% fructose to the drinking water for 8weeks. During the induction period, subgroups of mice (n=5) were daily intragastrically administered with THC (100 or 200mg/kg/day) or vitE (100mg/kg/day). The expressions of CYP mRNA and protein were quantified using real-time PCR and the levels of these proteins were quantified using immunoblotting. Continuous consuming of high fat and high fructose for 8weeks significantly increased the expressions of Cyp1a1, Cyp1a2, Cyp1b1, Cyp2c29, and Cyp3a11 while THC ultimately normalized these CYPs profiles. In the control mice, most of the investigated CYPs was unchanged by THC, with the exception that the Cyp1a1, Cyp2b9, and Cyp3a11 proteins were elevated. These findings provided additional important information on the effects of THC on diet induced-metabolic dysfunctions. However, drug interactions due to the use of THC as an alternative supplement are of concern, particularly in the combinations that include a drug that is a substrate of Cyp1a1, Cyp2b9, and Cyp3a11.