Dendrobium mixture regulates hepatic gluconeogenesis in diabetic rats via the phosphoinositide-3-kinase/protein kinase B signaling pathway

Dendrobium mixture ameliorates hepatic injury induced by insulin resistance in vitro and in vivo through the downregulation of AGE/RAGE/Akt signaling pathway

Dendrobium mixture (DM) is a patented Chinese herbal medicine which has been shown to ameliorate type 2 diabetes mellitus (T2DM) with non-alcoholic fatty liver disease (NAFLD) in vivo and in vitro. We aimed to investigate the underlying mechanism of DM as a therapeutic agent in attenuating liver steatosis in relation to type 2 diabetes mellitus (T2DM). DM (16.2 g/kg/d) was administered to db/db mice for 4 weeks. The db/m mice and db/db mice in the control and model groups were given normal saline. Additionally, DM (11.25 g/kg/d) was administered to Sprague-Dawley (SD) rats, and the serum was collected and used in an experiment involving palmitic acid (PA)-induced human liver HepG2 cells with abnormal lipid and glucose metabolism. In db/db mice, the administration of DM significantly alleviated liver steatosis, including histological damage and cell apoptosis. DM was found to prevent the upregulation of the RAGE and AKT1 proteins in liver tissues. The underlying mechanism of DM was further studied in PA-induced HepG2 cells. Post-DM administration serum from SD rats reduced lipid accumulation and regulated glucose metabolism in HepG2 cells. Consequently, it inhibited RAGE/AKT signaling and restored autophagy activity. The upregulated autophagy was associated with the mTOR-AMPK signaling pathway. Furthermore, post-DM administration serum reduced apoptosis of hepatocytes in PA-induced HepG2 cells. Our study supports the potential use of DM as a therapeutic agent for the treatment of NAFLD in T2DM. The mechanism underlying this therapeutic potential is associated with the downregulation of the AGE/RAGE/Akt signaling pathway.

Chinese herbal medicine and its active compounds in attenuating renal injury via regulating autophagy in diabetic kidney disease

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease worldwide, and there is a lack of effective treatment strategies. Autophagy is a highly conserved lysosomal degradation process that maintains homeostasis and energy balance by removing protein aggregates and damaged organelles. Increasing evidence suggests that dysregulated autophagy may contribute to glomerular and tubulointerstitial lesions in the kidney under diabetic conditions. Emerging studies have shown that Chinese herbal medicine and its active compounds may ameliorate diabetic kidney injury by regulating autophagy. In this review, we summarize that dysregulation or insufficiency of autophagy in renal cells, including podocytes, glomerular mesangial cells, and proximal tubular epithelial cells, is a key mechanism for the development of DKD, and focus on the protective effects of Chinese herbal medicine and its active compounds. Moreover, we systematically reviewed the mechanism of autophagy in DKD regulated by Chinese herb compound preparations, single herb and active compounds, so as to provide new drug candidates for clinical treatment of DKD. Finally, we also reviewed the candidate targets of Chinese herbal medicine regulating autophagy for DKD. Therefore, further research on Chinese herbal medicine with autophagy regulation and their targets is of great significance for the realization of new targeted therapies for DKD.

Dendrobium mixture ameliorates type 2 diabetes mellitus with non-alcoholic fatty liver disease through PPAR gamma: An integrated study of bioinformatics analysis and experimental verification

Dendrobium mixture (DM) is a patented Chinese herbal medicine indicated which has anti-inflammatory and improved glycolipid metabolism. However, its active ingredients, targets of action, and potential mechanisms are still uncertain. Here, we investigate the role of DM as a prospective modulator of protection against non-alcoholic fatty liver disease (NAFLD) induced by type 2 diabetes mellitus (T2DM) and illustrate the molecular mechanisms potentially involved. The network pharmacology and TMT-based quantitative protomics analysis were conducted to identify potential gene targets of the active ingredients in DM against NAFLD and T2DM. DM was administered to the mice of DM group for 4 weeks, and db/m mice (control group) and db/db mice (model group) were gavaged by normal saline. DM was also given to Sprague-Dawley (SD) rats, and the serum was subjected to the palmitic acid-induced HepG2 cells with abnormal lipid metabolism. The mechanism of DM protection against T2DM-NAFLD is to improve liver function and pathological morphology by promoting peroxisome proliferator-activated receptor γ (PPARγ) activation, lowering blood glucose, improving insulin resistance (IR), and reducing inflammatory factors. In db/db mice, DM reduced RBG, body weight, and serum lipids levels, and significantly alleviated histological damage of liver steatosis and inflammation. It upregulated the PPARγ corresponding to the prediction from the bioinformatics analysis. DM significantly reduced inflammation by activating PPARγ in both db/db mice and palmitic acid-induced HepG2 cells.

The effects of Dendrobium species on the metabolic syndrome: A review

Metabolic syndrome (MetS) is known as a global health challenge with different types of health conditions such as hypertension, hyperglycemia, the increasing prevalence of obesity, and hyperlipidemia. Despite much recent scientific progress, the use of traditional herbal medicines with fewer side effects is increasing worldwide. Dendrobium, the second-largest orchid genus, has been used as a natural source of drugs for the treatment of MetS. The beneficial effects of Dendrobium, including anti-hypertension, anti-hyperglycemia, anti-obesity, and anti-hyperlipidemic against MetS have been shown in the scientific evidence. The anti-oxidant and lipid-lowering effects of Dendrobium modulate hyperlipidemia via reducing lipid accumulation and maintaining lipid metabolism. Restoring pancreatic beta cells and regulating the insulin signaling pathway are involved in its antidiabetic properties. The hypotensive effects contribute to increasing nitric oxide (NO) generation and inhibiting extracellular signal-regulated kinase (ERK) signaling. More research projects, especially clinical trials, are needed to investigate the safety, efficacy, and pharmacokinetics of Dendrobium in patients. This review article provides, for the first time, comprehensive information about the efficacy of different species of Dendrobium. The described species can be a source of medicines for the treatment of MetS, which are reported in various evidence.

Research progress of signaling pathways of the natural substances intervene dyslipidemia (Review)

Dyslipidemia is an umbrella term for a range of lipid metabolic disorders in the body. This condition has been widely reported to greatly increase the risk of cardiovascular diseases, threatening human health. In recent years, advances in molecular biology have deepened understanding of the dyslipidemia-related signaling pathways and specific mechanisms underlying dyslipidemia. Signaling pathways possess the ability to transmit an extracellular signal to the inside of the cell, leading to specific biological effects. Lipid metabolism disorders and lipid levels in the blood are frequently affected by aberrant alterations in the dyslipidemia-related signaling pathways. Therefore, further investigations into these pathways are required for the prevention and treatment of dyslipidemia. The present review summarizes the characteristics of six dyslipidemia-associated signaling pathways: Peroxisome proliferator-activated receptor, adenosine monophosphate-activated protein kinase, farnesoid X receptor, forkhead box O, adipocytokine and cyclic adenosine monophosphate signaling pathways. In particular, specific focus was placed on previous experimental studies and reports on the intervention effects of natural substances (compounds from animals, plants, marine organisms and microorganisms) on dyslipidemia.

Dendrobium Mixture Ameliorates Diabetic Nephropathy in db/db Mice by Regulating the TGF-β1/Smads Signaling Pathway

Dendrobium mixture (DMix) is an effective treatment for diabetic nephropathy (DN), but the molecular mechanism underlying its action remains unclear. In this study, we investigated whether DMix regulates the transforming growth factor-β1 (TGF-β1)/Smads signal transduction pathway. Twenty-four db/db mice were randomly divided into three groups: the model, DMix, and gliquidone groups, while eight db/m mice were selected as the normal control group. The drug was administered by continuous gavage for 8 weeks. Body weight (BW), kidney weight (KW), kidney index, fasting blood glucose (FBG), blood lipid, 24-hour urinary albumin excretion rate, blood urea nitrogen, and serum creatinine levels were measured. Pathological changes in the renal tissue were observed under a light microscope. Real-time quantitative PCR and immunohistochemical staining were used to detect the mRNA and protein expression levels of TGF-β1 and alpha-smooth muscle actin (α-SMA), respectively, in renal tissues. TGF-β1, Smad2, p-Smad2, Smad3, p-Smad3, and α-SMA expression levels were measured using western blotting. The results showed that DMix significantly reduced the FBG level, BW, KW, and blood lipid level and improved renal function in db/db mice. Histopathology showed that DMix alleviated glomerular mesangial cell proliferation and renal interstitial fibrosis in db/db mice. Additionally, DMix reduced the protein and mRNA expression levels of TGF-β1 and α-SMA and inhibited Smad2 and Smad3 phosphorylation. We conclude that DMix may inhibit renal fibrosis and delay the progression of DN by regulating the TGF-β1/Smads signaling pathway.

Dendrobium mixture attenuates renal damage in rats with diabetic nephropathy by inhibiting the PI3K/Akt/mTOR pathway

Dendrobium mixture (DMix) is a Traditional Chinese Medicine widely used for preventing and treating diabetic nephropathy (DN). Autophagy contributes to DN development and progression. The present study aimed to investigate the mechanism underlying the protective effects of DMix on the kidneys of rats with DN and to determine whether this involves autophagy. Herein, a high‑sugar and high‑fat diet, combined with the intra‑abdominal injection of low‑dose streptozocin, was used to induce DN in 40 Sprague‑Dawley male rats. In total, 10 additional rats were used as controls. The rats with DN were then randomly divided into three groups and treated with DMix, gliquidone or saline via gastric administration for 8 weeks. Body weight, kidney weight, kidney index, fasting blood glucose (FBG), blood lipid, hemoglobin A1c (HbA1c), insulin, blood urea nitrogen and serum creatinine levels, as well as the 24‑h urinary albumin excretion rate (UAER) were measured. H&E, Periodic Acid‑Schiff and Masson staining were used to examine the renal pathology. The mRNA and protein expression levels of LC3 and Beclin‑1 in renal tissues were measured using reverse transcription‑quantitative PCR and immunohistochemistry, respectively. Western blotting was conducted to measure the protein expression levels of PI3K, phosphorylated (p)‑PI3K, Akt, p‑Akt, mTOR, p‑mTOR, LC3 and Beclin‑1 in renal tissues. It was found that DMix significantly reduced the FBG, blood lipids, HbA1c and insulin levels, kidney weight, kidney index and UAER in rats with DN, as well as improved renal function. Rats with DN showed notable glomerular hypertrophy, an increase in mesangial matrix content and renal interstitial fibrosis. Moreover, DMix notably reduced kidney damage. The results demonstrated that DMix inhibited the phosphorylation of PI3K, Akt and mTOR in the kidney tissues of rats with DN, and increased the protein and mRNA expression levels of LC3 and Beclin‑1. Therefore, it was suggested that DMix has protective effects on the kidney of rats with DN, which may be associated with the inhibition of the PI3K/Akt/mTOR signaling pathway and activation of renal autophagy by this traditional medicine.

Identification, Biological Activities and Biosynthetic Pathway of Dendrobium Alkaloids

Dendrobium is a genus of flowering plants belonging to the Orchidaceae family with more than 1,400 species. Many Dendrobium species have been used as medicinal plants in several Asian countries for thousands of years. Alkaloids were reported as the major biological markers due to their complex chemical compositions and various types. In this review, we summarized the structural types of alkaloids, their pharmacological activities, as well as the mechanisms of biological activities. More than sixty alkaloids were isolated and identified from the Dendrobium genus. Moreover, the pharmacological effects of Dendrobium alkaloids as hepatic lipid and gluconeogenesis regulation, as neuroprotection, and as anti-tumor, anti-inflammatory, anti-diabetes, and anti-virus factors were described. Besides, the total chemical synthesis of dendrobine is provided, while the biosynthetic pathway of dendrobine has been proposed based on the functions of associated genes. For applications of these invaluable herbs, more researches on the extraction of biological markers from compounds are needed. Further confirmation of the proposed biosynthetic pathways is anticipated as well.

Effect of Caesalpinia bonduc Polyphenol Extract on Alloxan-Induced Diabetic Rats in Attenuating Hyperglycemia by Upregulating Insulin Secretion and Inhibiting JNK Signaling Pathway

Caesalpinia bonduc has been used in herbal medicines for the treatment of a wide range of diseases from decades. The present study has explored the remedial potential and underlying mechanism of polyphenol extract of Caesalpinia bonduc in alloxanized diabetic rats. HPLC/MS analysis confirmed the presence of phenolics in considerable concentrations in Caesalpinia bonduc extract. Administration of different doses (250 and 500 mg/kg) of CPP extract to hyperglycemic rats for 8 weeks restored blood and serum glucose, insulin, glycosylated hemoglobin, leptin, amylin, and carbohydrate metabolizing enzymes level towards normal compared to alloxanized diabetic group. The effect of CPP extract on various genes such as Pdx-1, Ins-1, ngn-3, GLUT-4, and IRS-1 in insulin signaling pathway and Traf-4, Traf-6, and Mapk-8 in MAPK downstream JNK cascade was examined through qRT-PCR to access the core molecular mechanism involved in CPP-induced recovery of diabetes. Results have revealed that CPP extract reduced oxidative stress in pancreatic β cells by restoring free radical scavenging potential, reducing the mRNA expression of Mapk-8, Traf-4, and Traf-6, and increasing the Pdx-1, Ins-1, ngn-3, GLUT-4, and IRS-1 expression ensuing regeneration of β cells and subsequent insulin release from pancreas. The results obtained in this study recommend that CPP extract may be a promising therapeutic restorative agent in the treatment of diabetes mellitus.

Resveratrol improves high-fat diet-induced insulin resistance in mice by downregulating the lncRNA NONMMUT008655.2

As essential players in the field of diabetes treatment, resveratrol (RSV) has received much attention in recent years. However, it is unclear whether it can improve insulin resistance by regulating the long-chain non-coding RNA (lncRNA). The objective of this study was to investigate whether RSV improves high-fat diet-induced insulin resistance in mice by regulating thelncRNANONMMUT008655.2 in vivo and in vitro. To this end, animal and cell insulin resistance models were developed. Specifically, C57BL/6J mice were fed a high-fat diet (HFD) and administered RSV for eight weeks. Additionally, mouse Hepa cells were treated with palmitic acid, transfected with siRNA NONMMUT008655.2, and treated with RSV. Treated mice and cells were then compared to normal controls that were not exposed to RSV. In the animal model, RSV was found to decrease the levels of fasting blood glucose, triglycerides, and low-density lipoprotein cholesterol, as well as the insulin index and area under the curve; while increasing the insulin sensitivity index. Besides, RSV decreased the expression levels of SOCS3, G6PC, and FOXO1 yet increased that of p-Akt and p-FOXO1 in mice. The same results were observed following knockdown of NONMMUT008655.2 in cells. Overall, our results suggest that RSV may improve hepatic insulin resistance and control blood glucose levels by downregulating lncRNA NONMMUT008655.2.

Resveratrol Upregulates mmu-miR-363-3p via the PI3K-Akt Pathway to Improve Insulin Resistance Induced by a High-Fat Diet in Mice

PURPOSE

This study aimed to investigate how resveratrol (RSV) improves high-fat diet (HFD)-induced hepatic insulin resistance in mice via microRNA (miRNA) mmu-miR-363-3p in vitro and in vivo.

MATERIALS AND METHODS

C57BL/6J mice were fed a HFD for 8 weeks to establish an insulin resistance model. The model mice were treated or not with RSV for 6 weeks. Differential miRNA expression in mouse liver tissues was analyzed by high-throughput sequencing. Mouse HepG2 cells were treated with palmitic acid (PA) to establish a cell model of insulin resistance. HepG2 cells were transfected with mmu-miR-363-3p inhibitor or mimic, and the expression of PI3K-Akt signaling pathway-related proteins was analyzed.

RESULTS

Based on the high-throughput sequencing analysis, mmu-miR-363-3p was identified as a major miRNA involved in the action of RSV on insulin resistance. Based on KEGG pathway enrichment analysis, PI3K-Akt signaling was found to be significantly enriched among differentially expressed miRNAs, and this pathway is closely related to insulin resistance. RSV treatment reduced the expression of FOXO1 and G6PC, which are downstream of the PI3K-Akt pathway. In the cell model, mmu-miR-363-3p inhibitor significantly suppressed p-Akt and p-PI3K levels, but enhanced those of FOXO1 and G6PC. In contrast, mmu-miR-363-3p mimic significantly enhanced the p-Akt and p-PI3K levels, but suppressed FOXO1 and G6PC expression, which was similar to the effect of RSV.

CONCLUSION

RSV improves insulin resistance by upregulating miRNA mmu-miR-363-3p via the PI3K-Akt pathway.

Anti-Diabetic Effect of a Shihunine-Rich Extract of Dendrobium loddigesii on 3T3-L1 Cells and db/db Mice by Up-Regulating AMPK-GLUT4-PPARα

The stems of Dendrobium loddigesii, a Chinese herb, are often used to treat diabetes and its polar extract is rich in shihunine, a water-soluble Orchidaceae alkaloid, but little is known about the anti-diabetes effects and mechanism of shihunine. This study investigated the anti-diabetic effect of a shihunine-rich extract of D. loddigesii (DLS) based on 3T3-L1 cells and db/db mice. The underlying mechanisms were primarily explored using Western blot analysis and immunohistochemical staining. The 3T3-L1 cell experiments showed that DLS can reduce the intracellular accumulation of oil droplets as well as triglycerides (p < 0.001) and promote the 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2deoxyglucose (2-NBDG) uptake of 3T3-L1 cells (p < 0.001). The animal experiments confirmed that after 8 weeks of DLS treatment, the body weight, fasting blood sugar, and serum lipid levels of mice were significantly lowered, and the oral glucose tolerance test and serum insulin level were significantly improved compared to the no-treatment diabetes mellitus group. Further histomorphology observation led to the conclusion that the quantities of islet cells were significantly increased and the increase in adipose cell size was significantly suppressed. The immunohistochemical test of pancreatic tissue revealed that DLS inhibited the expression of cleaved cysteine aspartic acid-specific protease 3 (cleaved caspase-3). Western blot experiments showed that DLS had agonistic effects on adenosine monophosphate (AMP)-activated protein kinase phosphorylation (p-AMPK) and increased the expression levels of peroxisome proliferator-activated receptor α (PPARα) and glucose transporter 4 (GLUT4) in liver or adipose tissues. These data suggest that the shihunine-rich extract of D. loddigesii is an anti-diabetic fraction of D. loddigesii. Under our experimental condition, DLS at a dose of 50 mg/kg has good anti-diabetic efficacy.

PTEN inhibitor VO-OHpic attenuates inflammatory M1 macrophages and cardiac remodeling in doxorubicin-induced cardiomyopathy

Doxorubicin (Doxo) is an effective agent commonly used in cancer therapeutics. Unfortunately, Doxo treatment can stimulate cardiomyopathy and subsequent heart failure, limiting the use of this drug. The role of phosphatase and tensin homolog (PTEN) in apoptosis has been documented in Doxo-induced cardiomyopathy (DIC) and heart failure models. However, whether direct inhibition of PTEN attenuates apoptosis, cardiac remodeling, and inflammatory M1 macrophages in the DIC model remains elusive. Therefore, the present study was designed to understand the effects of VO-OHpic (VO), a potent inhibitor of PTEN, in reducing apoptosis and cardiac remodeling. At day 56, echocardiography was performed, which showed that VO treatment significantly ( P < 0.05) improved heart function. Immunohistochemistry, TUNEL, and histological staining were used to determine apoptosis, proinflammatory M1 macrophages, anti-inflammatory M2 macrophages, and cardiac remodeling. Our data show a significant increase in apoptosis, hypertrophy, fibrosis, and proinflammatory M1 macrophages with Doxo treatment, whereas VO treatment significantly reduced apoptosis, adverse cardiac remodeling, and proinflammatory M1 macrophages significantly ( P < 0.05) compared with the Doxo-treated group. Western blot analysis confirmed the reduction of phosphorylated PTEN and increase in phosphorylated AKT protein expression in the Doxo + VO-treated group. Moreover, VO administration increased anti-inflammatory M2 macrophages. Collectively, our data suggest that VO treatment attenuates apoptosis and adverse cardiac remodeling, a process that is mediated through the PTEN/AKT pathway, resulting in improved heart function in DIC. NEW & NOTEWORTHY Doxorubicin-induced cardiomyopathy (DIC) is still a major issue in patients with cancer. These novel findings on the phosphatase and tensin homolog inhibitor VO-OHpic in DIC is the first report, as per the best of our knowledge, that VO-OHpic significantly decreases apoptosis, fibrosis, hypertrophy, adverse cardiac remodeling, and proinflammatory M1 macrophages and increases anti-inflammatory M2 macrophages along with significantly improved cardiac function. VO-OHpic could be a future therapeutic agent for patients with DIC.