Insulin-Related Liver Pathways and the Therapeutic Effects of Aerobic Training, Green Coffee, and Chlorogenic Acid Supplementation in Prediabetic Mice

The combined effects of high-intensity interval training and time-restricted feeding on the AKT/FOXO1/PEPCK pathway in diabetic rats

High-intensity interval training (HIIT) and time-restricted feeding (TRF) have shown promise for improving glucose regulation by increasing insulin sensitivity, enhancing glucose uptake, reducing glucose production. Therefore, this study investigates the combined effects of HIIT and TRF on the AKT/FOXO1/PEPCK signaling pathway in the liver tissue of type 2 diabetic rats. 42 male Wistar rats (4-5 weeks of age) were included in the study. The animals were randomly divided into two groups: (1) Standard diet (SD, non-Diabetic (Non-D, n = 7) (2) High-fat diet (HFD, n = 35) for 4 weeks. To induce diabetes, 35 mg/kg of streptozotocin (STZ) was injected intraperitoneally (IP). Animals with blood glucose levels of > 250 mg/dL were considered as diabetic. Diabetic rats were randomly divided into 5 groups (n = 7): (1) Diabetes-exercise (D-EX), (2) Diabetes-TRF (D-TRF), (3) Diabetes-combined TRF and exercise (D-TRF&EX), (4) Diabetes no treatment (D-NT), (5) Diabetes with metformin (D-MET). Interventions (HIIT and TRF) were performed for 10 weeks. Rats in the Non-D group did not exercise and did not receive metformin or TRF. Periodic Acid-Schiff (PAS) staining was used to histologically analyze the liver tissue. Levels of blood glucose, insulin resistance (IR), FOXO1 protein, PEPCK, and area under the curve (AUC) following the IPGTT test, were significantly decreased in treatment groups compared to the D-NT group (p < 0.05). The AKT protein levels (p < 0.01), glycogen content (p < 0.05), and insulin sensitivity (p < 0.001) increased in the treatment groups as compared with the D-NT group. Microscopic examination of the liver tissue in general showed a better tissue arrangement in both treatment groups than in the D-NT group. Combining HIIT and TRF may be effective for improving blood glucose regulation, insulin sensitivity, in type 2 diabetes, as compared to TRF or HIIT interventions alone.

Lyophilized ash gourd (Benincasa hispida (Thunb.) Cogn.) juice alleviates diet-induced prediabetes in a rat model

Prediabetes is characterized by elevated blood sugar levels, indicating an increased risk of developing diabetes. This study evaluated the effects of ash gourd (AG), a tropical fruit from the Cucurbitaceae family, on prediabetes, as well as its phytochemical composition. A prediabetic rat model was developed in Sprague-Dawley (SD) rats by administering a high fat diet (HFD) for 16 weeks. This model exhibited reduced pancreatic function, heightened insulin resistance, and decreased insulin sensitivity compared to a standard diet group, leading to hyperglycemia and dyslipidemia, hallmarks of prediabetic conditions. Histological analysis of hepatic tissue revealed macro- and microvesicular fat accumulation and inflammatory changes, supporting these findings. This study highlights the utility of HFD-induced SD rats as a model for prediabetic conditions. Following this, lyophilized ash gourd juice (LAGJ) powder was administered to the prediabetic rat model to assess its potential for reversing prediabetic conditions. LAGJ administration resulted in a significant reduction in fasting blood sugar (FBS) levels, glucose intolerance, and insulin resistance. Additionally, LAGJ significantly mitigated fatty liver changes compared to the prediabetic untreated control (PUC) group. Histological examination of liver tissue in the LAGJ treated group showed a typical architecture similar to that of the normal control group. These findings indicate that LAGJ could be a promising intervention for individuals with prediabetes who are at risk of developing type 2 diabetes and fatty liver disease. Phytochemical analysis of AG pulp revealed the presence of stigmasterol, stigmasteryl β-glucoside, and 6'-O-palmitoyl stigmasteryl β-glucoside.

Differential expression of phosphoinositide 3-kinase/protein kinase B and Toll-like receptor/nuclear factor kappa B signaling pathways in experimental obesity Wistar rat model

This study aimed to investigate the differential expression of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway in relation to the Toll-like receptor (TLR)/nuclear factor κB (NF-κB) signaling pathway in an obese rat model. A total of 200 8-week-old male Wistar rats were randomly assigned to a control group (Ctrl, n = 40) and an observation group (Obs, n = 160), with obesity induced through a high-fat diet. Following modeling, the Obs group was further divided into a model group, a PI3K/AKT inhibition group, a TLR/NF-κB inhibition group, and a combined PI3K/AKT + TLR/NF-κB inhibition group, with 40 rats in each. Metabolic changes were assessed by monitoring the glucose infusion rate (GIR), as well as conducting an intraperitoneal glucose tolerance test (IPGTT) and an intraperitoneal insulin tolerance test (IPITT). Hematoxylin and eosin staining was utilized to observe morphological changes in adipose tissue, while Western blotting was employed to detect the expression levels of proteins associated with the PI3K/AKT and TLR/NF-κB signaling pathways in adipose tissue. The results indicated that the Obs group exhibited significantly higher blood glucose and insulin levels during the IPGTT and IPITT experiments compared to the Ctrl group (P < 0.05). Additionally, the GIR, as well as the expression levels of p-PI3K and p-AKT proteins in the Obs group, were significantly lower than those in the Ctrl group (P < 0.05). In both the PI3K/AKT inhibition group and the combined PI3K/AKT + TLR/NF-κB inhibition group, the expression of relevant proteins further declined (P < 0.05). These findings suggest that while a high-fat diet decreases the activity of the PI3K/AKT signaling pathway, it concurrently promotes inflammatory responses by upregulating the TLR-4 and NF-κB signaling pathways, indicating a critical role for these pathways in obesity-related metabolic abnormalities.

Porphyra haitanensis glycoprotein regulates glucose homeostasis: targeting the liver

In this study, we investigated the effects of glycoprotein (PG)-mediated regulation of Porphyra haitanensis on liver glucose metabolism in hyperglycemic mouse models, and sought to establish the underlying mechanism, as determined by the changes in liver gene expression and metabolic profiles. The results showed that 30-300 mg kg-1 PG upregulated the expression of the liver genes Ins1, Ins2, Insr, Gys2, Gpi1, Gck, and downregulated the expression of G6pc, G6pc2, and G6pc3, in a concentration-dependent manner. 300 mg kg-1 PG downregulated the concentrations of glucose-related metabolites in the liver, but upregulated lactic acid, 2-aminoacetic acid, and glucose-1-phosphate concentrations. It was assumed that PG regulated liver glucose metabolism by enriching insulin secretion, glycolysis/gluconeogenesis, and the AMPK signaling pathway, and promoting insulin secretion, glycogen synthesis, and glycolysis. Our findings supported the development of P. haitanensis and its glycoproteins as novel natural antidiabetic compounds that regulated blood glucose homeostasis.

Uncovering the key pharmacodynamic material basis and possible molecular mechanism of Xiaoke formulation improve insulin resistant through a comprehensive investigation

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoke formulation (XKF) has been utilized in clinical practice for decades in China as a treatment option for mild to moderate type 2 diabetes. However, there is still a need for systematic research to uncover the key pharmacodynamic material basis and mechanism of XKF.

AIM OF THE STUDY

Aim of to investigate the distribution and metabolism of XKF in normal and insulin resistant (IR) mice were different, and elucidate its key pharmacodynamic material basis and mechanism of action.

MATERIALS AND METHODS

Ultra performance liquid chromatography/time of flight mass spectrometry technology was employed to investigate the differences in XKF absorption, distribution, and metabolism between normal and IR mice across blood, liver, feces, and urine samples. Further, network pharmacology was used to predict target proteins and their associated signaling pathways. Then, molecular docking was utilized to validate the activity of key pharmacodynamic components and targets. Finally, IR HepG2 cells were used to detect the glucose consumption under the action of key pharmacodynamic material basis. In addition, the expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and phospho-protein kinase B (p-AKT) was determined using western blotting.

RESULTS

The study demonstrates significant distinctions in plasma and liver number and abundance of alkaloids, organic acids, flavonoids, iridoids and saponins between normal and IR mice when XKF was administered. Further analysis has shown that the representative components of XKF, including berberine, chlorogenic acid, calycosin, swertiamarin and astragaloside IV have significantly different metabolic pathways in plasma and liver. Prototypes and metabolites of these components were rarely detected in the urine and feces of mice. According to the network pharmacological analysis, these differential components are predicted to improve IR by targeting key factors such as SRC, JUN, HRAS, NOS3, FGF2, etc. Additionally, the signaling pathways involved in this process include PI3K-AKT pathway, GnRH signaling pathway, and T cell receptor signaling pathway. In addition, in vitro experiments indicate that berberine and its metabolites (berberine and demethyleneberine), chlorogenic acid and its metabolites (3-O-ferulic quinic acid and 5-O-ferulic quinic acid), calycosin and swertiamarin could improve IR in IR-HepG2 cells by elevating the expression of PI3K and AKT, leading to an increase in glucose consumption.

CONCLUSION

The key pharmacodynamic material basis of XKF, such as berberine and its metabolites (berberrubine and demethyleneberberine), chlorogenic acid and its metabolites (3-O-feruloylquinic acid and 5-O-feruloylquinic acid), calycosin and swertiamarin influence the glucose metabolism disorder of IR-HepG2 cells by regulating the PI3K/AKT signalling pathway, leading to an improvement in IR.

Mitochondria-associated membranes contribution to exercise-mediated alleviation of hepatic insulin resistance: Contrasting high-intensity interval training with moderate-intensity continuous training in a high-fat diet mouse model

OBJECTIVE

Mitochondria-associated membranes (MAMs) serve pivotal functions in hepatic insulin resistance (IR). Our aim was to explore the potential role of MAMs in mitigating hepatic IR through exercise and to compare the effects of different intensities of exercise on hepatic MAMs formation in high-fat diet (HFD) mice.

METHODS

Male C57BL/6J mice were fed an HFD and randomly assigned to undergo supervised high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). IR was evaluated using the serum triglyceride/high-density lipoprotein cholesterol ratio (TG/HDL-C), glucose tolerance test (GTT), and insulin tolerance test (ITT). Hepatic steatosis was observed using hematoxylin-eosin (H&E) and oil red O staining. The phosphatidylinositol 3-kinase/protein kinase B/glycogen synthase kinase 3 beta (PI3K-AKT-GSK3β) signaling pathway was assessed to determine hepatic IR. MAMs were evaluated through immunofluorescence (colocalization of voltage-dependent anion-selective channel 1 [VDAC1] and inositol 1,4,5-triphosphate receptor [IP3R]).

RESULTS

After 8 weeks on an HFD, there was notable inhibition of the hepatic PI3K/Akt/GSK3β signaling pathway, accompanied by a marked reduction in hepatic IP3R-VDAC1 colocalization levels. Both 8-week HIIT and MICT significantly enhanced the hepatic PI3K/Akt/GSK3β signaling and colocalization levels of IP3R-VDAC1 in HFD mice, with MICT exhibiting a stronger effect on hepatic MAMs formation. Furthermore, the colocalization of hepatic IP3R-VDAC1 positively correlated with the expression levels of phosphorylation of protein kinase B (p-AKT) and phosphorylation of glycogen synthase kinase 3 beta (p-GSK3β), while displaying a negative correlation with serum triglyceride/high-density lipoprotein cholesterol levels.

CONCLUSION

The reduction in hepatic MAMs formation induced by HFD correlates with the development of hepatic IR. Both HIIT and MICT effectively bolster hepatic MAMs formation in HFD mice, with MICT demonstrating superior efficacy. Thus, MAMs might wield a pivotal role in exercise-induced alleviation of hepatic IR.

Protein succinylation, hepatic metabolism, and liver diseases

Succinylation is a highly conserved post-translational modification that is processed via enzymatic and non-enzymatic mechanisms. Succinylation exhibits strong effects on protein stability, enzyme activity, and transcriptional regulation. Protein succinylation is extensively present in the liver, and increasing evidence has demonstrated that succinylation is closely related to hepatic metabolism. For instance, histone acetyltransferase 1 promotes liver glycolysis, and the sirtuin 5-induced desuccinylation is involved in the regulation of the hepatic urea cycle and lipid metabolism. Therefore, the effects of succinylation on hepatic glucose, amino acid, and lipid metabolism under the action of various enzymes will be discussed in this work. In addition, how succinylases regulate the progression of different liver diseases will be reviewed, including the desuccinylation activity of sirtuin 7, which is closely associated with fatty liver disease and hepatitis, and the actions of lysine acetyltransferase 2A and histone acetyltransferase 1 that act as succinyltransferases to regulate the succinylation of target genes that influence the development of hepatocellular carcinoma. In view of the diversity and significance of protein succinylation, targeting the succinylation pathway may serve as an attractive direction for the treatment of liver diseases.

Effects Of Exercise Training And Chlorogenic Acid Supplementation On Hepatic Lipid Metabolism In Prediabetes Mice

BACKGRUOUND

Since prediabetes is a risk factor for metabolic syndromes, it is important to promote a healthy lifestyle to prevent prediabetes. This study aimed to determine the effects of green coffee (GC), chlorogenic acid (CGA) intake, and exercise training (EX) on hepatic lipid metabolism in prediabetes male C57BL/6 mice.

METHODS

Forty-nine mice were randomly divided into two groups feeding with a normal diet (n=7) or a high-fat diet (HFD, n=42) for 12 weeks. Then, HFD mice were further divided into six groups (n=7/group): control (pre-D), GC, CGA, EX, GC+EX, and CGA+EX. After additional 10 weeks under the same diet, plasma, and liver samples were obtained.

RESULTS

HFD-induced prediabetes conditions with increases in body weight, glucose, insulin, insulin resistance, and lipid profiles were alleviated in all treatment groups. Acsl3, a candidate gene identified through an in silico approach, was lowered in the pre-D group, while treatments partly restored it. HFD induced adverse alterations of de novo lipogenesis- and β oxidation-associated molecules in the liver. However, GC and CGA supplementation and EX reversed or ameliorated these changes. In most cases, GC or CGA supplementation combined with EX has no synergistic effect and the GC group had similar results to the CGA group.

CONCLUSION

These findings suggest that regular exercise is an effective non-therapeutic approach for prediabetes, and CGA supplementation could be an alternative to partially mimic the beneficial effects of exercise on prediabetes.

Green Coffee Bean Extract Potentially Ameliorates Liver Injury due to HFD/STZ-Induced Diabetes in Rats

The goal of the current study was to examine the therapeutic potential of green coffee bean extract (GCBE) in the treatment of diabetic hepatic damage induced by high-fat diet (HFD) and streptozotocin (STZ) administration. The novelty of this study lies in constructing a newly stabilized in vivo obese diabetic animal model in rats using HFD/STZ for investigating the dose-dependent effect of two commonly used doses of GCBE in hepatoprotection against oxidative stress-induced hepatic damage by measuring many parameters that have not been carried out previously in other studies. GCBE that was used in this study was a hot water extract of green coffee beans with a concentration of 0.1 g ml−1. Male albino rats were given a single dose of STZ (35 mg kg−1), and HFD to induce diabetes mellitus (DM). For 28 days, two separate doses of GCBE 50 mg kg−1 and 100 mg kg−1 were administered orally to diabetic animals. Leptin, liver enzymes, oxidative stress parameters, inflammatory parameters, fasting plasma glucose (FPG), fasting plasma insulin (FPI), and lipid profile levels were examined. Real-time PCR and ELISA were used to quantitatively detect the mRNAs of the genes involved in the insulin signaling pathway, the genes involved in glucose metabolism, and the amounts of proteins. The levels of FPG, lipid profile, liver enzymes, inflammatory markers, and leptin in the HFD/STZ diabetic group revealed a considerable spike, while they considerably decreased after GCBE treatment in a dose-dependent manner. After GCBE treatment, the diabetic group showed a significant rise in the antioxidant markers glutathione, superoxide dismutase, and catalase, as well as a decrease in malondialdehyde and nitric oxide levels. The liver changes caused by HFD/STZ were entirely reversed by GCBE, and most intriguingly, in a dose-dependent manner. We concluded that GCBE can repair the hepatic oxidative damage caused by HFD and STZ by reversing all the previously measured parameters and improving the insulin signaling pathways. GCBE demonstrated strong antifree radical activity and significantly protected cells from oxidative damage caused by HFD/STZ.