Parkinson's disease (PD), a chronic and common neurodegenerative disease, is characterized by the progressive loss of dopaminergic neurons in the dense part of the substantia nigra and abnormal aggregation of alpha-synuclein. Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by chronic insulin resistance and deficiency in insulin secretion. Extensive evidence has confirmed shared pathogenic mechanisms underlying PD and T2DM, such as oxidative stress caused by insulin resistance, mitochondrial dysfunction, inflammation, and disorders of energy metabolism. Conventional drugs for treating T2DM, such as metformin and glucagon-like peptide-1 receptor agonists, affect nerve repair. Even drugs for treating PD, such as levodopa, can affect insulin secretion. This review summarizes the relationship between PD and T2DM and related therapeutic drugs from the perspective of insulin signaling pathways in the brain.
Humans ; Parkinson Disease/drug therapy* ; Diabetes Mellitus, Type 2/pathology* ; Signal Transduction/physiology* ; Receptor, Insulin/metabolism* ; Animals ; Insulin Resistance/physiology* ; Insulin/metabolism*

OBJECTIVES: To investigate the effects and molecular mechanisms of asiatic acid on β-cell function in type 2 diabetes mellitus (T2DM). METHODS: The T2DM model was established by high fat diet and streptozotocin injection in ICR mice, and the effects of asiatic acid on glucose regulation were investigated in model mice. The islets were isolated from palmitic acid-treated diabetic mice. ELISA was used to detect the glucose-stimulated insulin secretion, tumor necrosis factor (TNF)-α and interleukin (IL)-6. ATP assay was applied to measure ATP production, and Western blotting was used to detect protein expression of mature β cell marker urocortin (Ucn) 3 and mitofusin (Mfn) 2. The regulatory effects of asiatic acid on glucose-stimulated insulin secretion (GSIS) and Ucn3 expression were also investigated after siRNA interference with Mfn2 or treatment with TNF-α. RESULTS: Asiatic acid with the dose of 25 mg·kg^－1·d^－1 had the best glycemic control in T2DM mice and improved the homeostasis model assessment β index. Asiatic acid increased the expression of Mfn2 and Ucn3 protein and improved the GSIS function of diabetic β cells in vitro and in vivo (both P<0.05). Moreover, it improved the ATP production of islets of T2DM mice in vitro (P<0.05). Interfering Mfn2 with siRNA blocked the up-regulation of Ucn3 and GSIS induced by asiatic acid. Asiatic acid inhibited islet TNF-α content and increased Mfn2 and Ucn3 protein expression inhibited by TNF-α. CONCLUSIONS Asiatic acid improves β cell insulin secretion function in T2DM mice by maintaining the β cell maturity, which may be related to the TNF-α/Mfn2 pathway.
Mice ; Animals ; Insulin Secretion ; Diabetes Mellitus, Type 2/drug therapy* ; Islets of Langerhans/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Insulin/therapeutic use* ; Diabetes Mellitus, Experimental ; Mice, Inbred ICR ; Glucose/therapeutic use* ; Interleukin-6/metabolism* ; RNA, Small Interfering/pharmacology* ; Adenosine Triphosphate ; GTP Phosphohydrolases/therapeutic use*

Acarbose is widely used as α-glucosidase inhibitor in the treatment of type Ⅱ diabetes. Actinoplanes sp. is used for industrial production of acarbose. As a secondary metabolite, the biosynthesis of acarbose is quite complex. In addition to acarbose, a few acarbose structural analogs are also accumulated in the culture broth of Actinoplanes sp., which are hard to remove. Due to lack of systemic understanding of the biosynthesis and regulation mechanisms of acarbose and its structural analogs, it is difficult to eliminate or reduce the biosynthesis of the structural analogs. Recently, the advances in omics technologies and molecular biology have facilitated the investigations of biosynthesis and regulatory mechanisms of acarbose and its structural analogs in Actinoplanes sp.. The genes involved in the biosynthesis of acarbose and its structural analogs and their regulatory mechanism have been extensively explored by using bioinformatics analysis, genetic manipulation and enzymatic characterization, which is summarized in this review.
Acarbose/metabolism* ; Diabetes Mellitus, Type 2/drug therapy* ; Genetic Techniques ; Humans

OBJECTIVE: To investigate the protective effects of modified Linggui Zhugan Decoction (, MLZD), a traditional Chinese medicine formula, on obese type 2 diabetes mellitus (T2DM) rats. METHODS: Fifty Sprague-Dawley rats were randomly divided into 5 groups by a random number table, including normal, obese T2DM (ob-T2DM), MLZD low-dose [MLDZ-L, 4.625 g/(kg·d)], MLZD middle-dose [MLD-M, 9.25 g/(kg·d) ] and MLZD high-dose [MLD-H, 18.5 g/(kg·d)] groups, 10 rats in each group. After 4-week intervention, blood samples and liver, pancreas, muscle tissues were collected to assess the insulin resistance (IR), blood lipid, adipokines and inflammation cytokines. The alteration of phosphatidylinositol 3 kinase (PI3K)-protein kinase B (PKB or Akt)/the mammalian target of rapamycin (mTOR)-ribosome protein subunit 6 kinase 1 (S6K1 )/AMP-activated protein kinase (AMPK)-peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 α) pathways were also studied. RESULTS: MLZD dose-dependently reduced fasting blood glucose, fasting insulin, homeostasis model of assessment for IR index and increased insulin sensitive index compared with ob-T2DM rats (P<0.05). Similarly, total cholesterol, triglyceride, low-density lipoprotein cholesterol and free fatty acids were also decreased compared with ob-T2DM rats after 4-week treatment (P<0.05 or P<0.01). Improvements in adipokines and inflammatory cytokines were observed with a raised level of adiponectin and a reduced level of leptin, resistin, tumor necrosis factor-α and interleukin-6 (P<0.05 or P<0.01). MLZD regulated the PI3K-Akt/mTOR-S6K1/AMPK-PGC-1 α pathways and restored the tissue structure of liver and pancreas (P<0.05 or P<0.01). CONCLUSIONS MLZD ameliorated glycolipid metabolism and inflammation, which may be attributed to the regulation of PI3K-Akt/mTOR-S6K1/AMPK-PGC-1 α pathways.
AMP-Activated Protein Kinases/metabolism* ; Animals ; Diabetes Mellitus, Experimental ; Diabetes Mellitus, Type 2/drug therapy* ; Glycolipids ; Inflammation ; Obesity/drug therapy* ; Phosphatidylinositol 3-Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; TOR Serine-Threonine Kinases/metabolism*

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce cardiovascular mortality in patients with diabetes mellitus but the protective mechanism remains elusive. Here we demonstrated that the SGLT2 inhibitor, Empagliflozin (EMPA), suppresses cardiomyocytes autosis (autophagic cell death) to confer cardioprotective effects. Using myocardial infarction (MI) mouse models with and without diabetes mellitus, EMPA treatment significantly reduced infarct size, and myocardial fibrosis, thereby leading to improved cardiac function and survival. In the context of ischemia and nutritional glucose deprivation where autosis is already highly stimulated, EMPA directly inhibits the activity of the Na⁺/H⁺ exchanger 1 (NHE1) in the cardiomyocytes to regulate excessive autophagy. Knockdown of NHE1 significantly rescued glucose deprivation-induced autosis. In contrast, overexpression of NHE1 aggravated the cardiomyocytes death in response to starvation, which was effectively rescued by EMPA treatment. Furthermore, in vitro and in vivo analysis of NHE1 and Beclin 1 knockout mice validated that EMPA's cardioprotective effects are at least in part through downregulation of autophagic flux. These findings provide new insights for drug development, specifically targeting NHE1 and autosis for ventricular remodeling and heart failure after MI in both diabetic and non-diabetic patients.
Animals ; Diabetes Mellitus ; Diabetes Mellitus, Type 2/drug therapy* ; Glucose ; Humans ; Mice ; Myocardial Infarction/metabolism* ; Sodium-Glucose Transporter 2 Inhibitors/therapeutic use* ; Ventricular Remodeling

Diabetic nephropathy (DN) is one of the most common complications of diabetes mellitus, which is characterized in renal tubulointerstitial fibrosis (TIF). The current study was designed to investigate the protective effect of Jujuboside A (Ju A) on TIF in type 2 diabetes (T2DM) mice, and explore its underlying anti-fibrosis mechanism. A mouse T2DM model was established using high fat diet (HFD) feeding combined with intraperitoneal injection of streptozotocin (STZ). Then, diabetic mice were treated with Ju A (10, 20 and 40 mg·kg^-1·d^-1, i.g.) for 12 weeks. Results showed that administration of Ju A not only down-regulated fasting blood glucose (FBG) levels, but also improved hyperlipidemia and renal function in diabetic mice. Moreover, the reduced ECM accumulation was observed in the renal cortex of Ju A treated diabetic mice, while the TIF progression was also attenuated by Ju A through blocking the epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells (RTECs). Further mechanism studies showed that Ju A treatment effectively down-regulated the protein expression and subsequent nuclear translocation of Yin Yang 1 (YY1) in the renal cortex of diabetic mice, and reduced the levels of transforming growth factor-β1 (TGF-β1) in the serum and renal cortex of Ju A treated mice. According to invitro studies, the up-regulated YY1/TGF-β1 signaling pathway was restored by Ju A in high glucose (HG) cultured HK-2 cells. Taken together, these findings demonstrated that Ju A can ameliorate the TIF of DN through down-regulating the YY1/TGF-β1 signaling pathway.
Animals ; Blood Glucose ; Diabetes Mellitus, Experimental/metabolism* ; Diabetes Mellitus, Type 2/drug therapy* ; Diabetic Nephropathies/metabolism* ; Fibrosis ; Mice ; Saponins ; Signal Transduction ; Streptozocin ; Transforming Growth Factor beta1/metabolism*

Peptide dual agonists toward both glucagon-like peptide 1 receptor (GLP-1R) and glucagon receptor (GCGR) are emerging as novel therapeutics for the treatment of type 2 diabetes mellitus (T2DM) patients with obesity. Our previous work identified a Xenopus GLP-1-based dual GLP-1R/GCGR agonist termed xGLP/GCG-13, which showed decent hypoglycemic and body weight lowering activity. However, the clinical utility of xGLP/GCG-13 is limited due to its short in vivo half-life. Inspired by the fact that O-GlcNAcylation of intracellular proteins leads to increased stability of secreted proteins, we rationally designed a panel of O-GlcNAcylated xGLP/GCG-13 analogs as potential long-acting GLP-1R/ GCGR dual agonists. One of the synthesized glycopeptides 1f was found to be equipotent to xGLP/GCG-13 in cell-based receptor activation assays. As expected, O-GlcNAcylation effectively improved the stability of xGLP/GCG-13 in vivo. Importantly, chronic administration of 1f potently induced body weight loss and hypoglycemic effects, improved glucose tolerance, and normalized lipid metabolism and adiposity in both db/db and diet induced obesity (DIO) mice models. These results supported the hypothesis that glycosylation is a useful strategy for improving the in vivo stability of GLP-1-based peptides and promoted the development of dual GLP-1R/GCGR agonists as antidiabetic/antiobesity drugs.
Mice ; Animals ; Glucagon-Like Peptide 1/metabolism* ; Receptors, Glucagon/therapeutic use* ; Xenopus laevis/metabolism* ; Diabetes Mellitus, Type 2/drug therapy* ; Glycopeptides/therapeutic use* ; Obesity/drug therapy* ; Hypoglycemic Agents/pharmacology* ; Peptides/pharmacology*

This study focused on the ameliorative effects of gypenosides(GPS) on insulin sensitivity and inflammatory factors in rats with type 2 diabetes mellitus(T2 DM) and explored their possible molecular mechanisms. After the successful establishment of T2 DM model, diabetic rats were randomly divided into four groups, including model group, GPS groups(200, 100 mg·kg~(-1)) and metformin group(100 mg·kg~(-1)), with healthy rats serving as the control. After 6-week intragastric administration, fasting blood glucose(FBG) and oral glucose tolerance were examined. The levels of insulin, C-peptide, tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), interleukin-6(IL-6) and C-reactive protein(CRP) in serum were examined. Then the homeostasis model assessment of insulin resistance(HOMA-IR) and insulin sensitivity index(ISI) were calculated. The protein expression levels of phosphorylated insulin receptor substrate-1(p-IRS-1) and phosphorylated protein kinase B(p-Akt) in skeletal muscle were measured by Western blot, as well as those of phosphorylated inhibitor of nuclear factor-κB(NF-κB) kinase β(p-IKKβ), phosphorylated alpha inhibitor of NF-κB(p-IκBα) and phosphorylated p65 subunit of NF-κB(p-p65) in adipose tissue. The relative expression levels of glucose transporter 4(GLUT4) mRNA in skeletal muscle and NF-κB mRNA in adipose tissue were measured by qRT-PCR, and the morphological changes of pancreatic tissue were observed. Compared with the model group, the GPS groups witnessed significant decrease in FBG, marked amelioration of impaired oral glucose tolerance and significant increase in ISI. Further, the high-dose GPS group saw significantly reduced HOMA-IR, TNF-α, IL-1β and CRP, significantly increased expression levels of p-IRS-1(Tyr), p-Akt and GLUT4, and markedly inhibited p-IRS-1(Ser), p-IKKβ, p-IκBα, p-p65 and NF-κB. The concentration of CRP and the expression levels of p-IRS-1(Ser), p-IKKβ, p-IκBα and NF-κB were remarkably reduced in the low-dose GPS group. However, GPS was found less effective in the regulation of serum insulin, C-peptide and IL-6 levels and the alleviation of pancreatic islet injury. The results indicated that GPS can reduce FBG and improve insulin sensitivity in diabetic rats possibly by regulating the NF-κB signaling pathway, inhibiting inflammation, and thereby regulating the expression of key proteins in the insulin signaling pathway.
Animals ; Diabetes Mellitus, Experimental/drug therapy* ; Diabetes Mellitus, Type 2/genetics* ; Gynostemma ; Insulin ; Insulin Resistance ; NF-kappa B/metabolism* ; Plant Extracts ; Rats ; Signal Transduction

Exercise is vital for diabetics to improve their blood glucose level. However, the quantitative relationship between exercise modes (including types, intensity, time, etc.) and the blood glucose is still not clear. In order to answer these questions, this paper established a blood glucose metabolic model based on ordinary differential equation method. Furthermore, a silico method was adopted to study the effects of different aerobic exercise intensities (light, moderate and vigorous) on blood glucose and optimal strategies of insulin infusion for type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). Additionally, the universality of proposed model and insulin infusion strategies was verified based on 1 000 virtual diabetes patients' simulation. The experimental results showed that: (1) Vigorous-intensity aerobic exercise may result in hypoglycemia (< 3.89 mmol/L), which was so harmful to health that diabetics should avoid. Compared with moderate-intensity exercise, the light-intensity aerobic exercise intuitively lowered blood glucose slowly and caused a relative long high-blood-glucose (> 6.11 mmol/L) period, however, its overall blood glucose risk index (BGRI) was lower. (2) Insulin dosage of the optimized strategies decreased by 50% and 84% for T1DM and T2DM when they did moderate intensity exercise. As for light intensity exercise, the dosage of insulin was almost the same as they didn't do exercise, but BGRI decreased significantly. (3) The simulations of 1 000 virtual diabetic patients manifested that the proposed model and the insulin infusion strategies had good universality. The results of this study can not only help to improve the quantitative understanding about the effects of aerobic exercise on blood glucose of diabetic patients, but also contribute to the regulation and management of blood glucose in exercise mode.
Blood Glucose ; metabolism ; Computer Simulation ; Diabetes Mellitus, Type 1 ; drug therapy ; metabolism ; Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; Exercise ; Humans ; Insulin ; administration & dosage ; Models, Theoretical

Alkaline Phosphatase ; metabolism ; Asian Continental Ancestry Group ; Bone Density Conservation Agents ; therapeutic use ; China ; Denosumab ; therapeutic use ; Diabetes Mellitus, Type 2 ; complications ; Female ; Humans ; Hyperlipidemias ; complications ; Hypertension ; complications ; Middle Aged ; Osteitis Deformans ; complications ; diagnostic imaging ; drug therapy ; metabolism ; Pelvic Bones ; diagnostic imaging ; Renal Insufficiency, Chronic ; complications ; Singapore ; Tibia ; diagnostic imaging ; Treatment Outcome