Are Hyperglycemia-Induced Changes in the Retina Associated with Diabetes-Correlated Changes in the Brain? A Review from Zebrafish and Rodent Type 2 Diabetes Models.

Diabetes is prevalent worldwide, with >90% of the cases identified as Type 2 diabetes. High blood sugar (hyperglycemia) is the hallmark symptom of diabetes, with prolonged and uncontrolled levels contributing to subsequent complications. Animal models have been used to study these complications, which include retinopathy, nephropathy, and peripheral neuropathy. More recent studies have focused on cognitive behaviors due to the increased risk of dementia/cognitive deficits that are reported to occur in older Type 2 diabetic patients. In this review, we collate the data reported from specific animal models (i.e., mouse, rat, zebrafish) that have been examined for changes in both retina/vision (retinopathy) and brain/cognition, including db/db mice, Goto-Kakizaki rats, Zucker Diabetic Fatty rats, high-fat diet-fed rodents and zebrafish, and hyperglycemic zebrafish induced by glucose immersion. These models were selected because rodents are widely recognized as established models for studying diabetic complications, while zebrafish represent a newer model in this field. Our goal is to (1) summarize the published findings relevant to these models, (2) identify similarities in cellular mechanisms underlying the disease progression that occur in both tissues, and (3) address the hypothesis that hyperglycemic-induced changes in retina precede or predict later complications in brain.

(-)-Epicatechin ameliorates type 2 diabetes mellitus by reshaping the gut microbiota and Gut-Liver axis in GK rats.

As one of the most abundant plant polyphenols in the human diet, (-)-epicatechin (EC) can improve insulin sensitivity and regulate glucose homeostasis. However, the primary mechanisms involved in EC anti-T2DM benefits remain unclear. The present study explored the effects of EC on the gut microbiota and liver transcriptome in type 2 diabetes mellitus (T2DM) Goto-Kakizaki rats for the first time. The findings showed that EC protected glucose homeostasis, alleviated systemic oxidative stress, relieved liver damage, and increased serum insulin. Further investigation showed that EC reshaped gut microbiota structure, including inhibiting the proliferation of lipopolysaccharide (LPS)-producing bacteria and reducing serum LPS. In addition, transcriptome analysis revealed that the insulin signaling pathway may be the core pathway of the EC anti-T2DM effect. Therefore, EC may modulate the gut microbiota and liver insulin signaling pathways by the gut-liver axis to alleviate T2DM. As a diet supplement, EC has promising potential in T2DM prevention and treatment.

Nebivolol Alleviates Vascular Endothelial Insulin Resistance by Inhibiting Endoplasmic Reticulum Stress.

Vascular endothelial insulin resistance (IR) is an important risk factor in the development of vascular complications in diabetes. Prolonged endoplasmic reticulum stress (ERS) contributes to the development and progression of endothelial IR. The current study assessed the effects and mechanism of nebivolol on vascular IR in Goto-Kakizaki (GK) rats and endothelial IR induced by high glucose (33.3 mmol/L) associated with high insulin (10-7 mol/L) in human aortic endothelial cells (HAECs). Rats were divided into Wistar, Wistar + Neb (Wistar rats treated with nebivolol, 10 mg/kg, ig), GK, and GK + Neb (GK rats treated with nebivolol, 10 mg/kg, ig). GK rats showed hyperglycemia, dyslipidemia, impaired glucose homeostasis, metabolic IR, reduced relaxation to insulin, and lower serum nitric oxide (NO) level. Treatment with nebivolol for 4 months ameliorated insulin's vasorelaxation and NO production, and relieved dyslipidemia in GK rats. Additionally, nebivolol increased glucose uptake and NO level in the endothelial IR group in vitro. Nebivolol increased aortic expressions of IRS-1/PI3K/Akt/eNOS relative proteins and GLUT4 and reduced expressions of ERS markers (ATF6, GRP78, and CHOP, p-JNK/JNK). Furthermore, both nebivolol and TUDCA (ERS inhibitor) alleviated the attenuated IRS-1PI3K/Akt/eNOS pathway and enhanced ERS in HAECs IR. Tunicamycin (ERS inducer) not only induced endothelial IR but also blocked nebivolol's alleviation on the IRS-1PI3K/Akt/eNOS pathway and ERS. Nebivolol ameliorated endothelial IR partially by inhibiting ERS and then regulating the IRS-1/PI3K/Akt/eNOS signal.

A short review on the features of the non-obese diabetic Goto-Kakizaki rat intestine

The Goto-Kakizaki (GK) rat is a non-obese experimental model of type 2 diabetes mellitus (T2DM) that allows researchers to monitor diabetes-induced changes without jeopardizing the effects of obesity. This rat strain exhibits notable gastrointestinal features associated with T2DM, such as marked alterations in intestinal morphology, reduced intestinal motility, slow transit, and modified microbiota compared to Wistar rats. The primary treatments for diabetic patients include administration of hypoglycemic agents and insulin, and lifestyle changes. Emerging procedures, including alternative therapies, metabolic surgeries, and modulation of the intestinal microbiota composition, have been shown to improve the diabetic state of GK rats. This review describes the morpho-physiological diabetic-associated features of the gastrointestinal tract (GIT) of GK rats. We also describe promising strategies, e.g., metabolic surgery and modulation of gut microbiota composition, used to target the GIT of this animal model to improve the diabetic state.

A short review on the features of the non-obese diabetic Goto-Kakizaki rat intestine

The Goto-Kakizaki (GK) rat is a non-obese experimental model of type 2 diabetes mellitus (T2DM) that allows researchers to monitor diabetes-induced changes without jeopardizing the effects of obesity. This rat strain exhibits notable gastrointestinal features associated with T2DM, such as marked alterations in intestinal morphology, reduced intestinal motility, slow transit, and modified microbiota compared to Wistar rats. The primary treatments for diabetic patients include administration of hypoglycemic agents and insulin, and lifestyle changes. Emerging procedures, including alternative therapies, metabolic surgeries, and modulation of the intestinal microbiota composition, have been shown to improve the diabetic state of GK rats. This review describes the morpho-physiological diabetic-associated features of the gastrointestinal tract (GIT) of GK rats. We also describe promising strategies, e.g., metabolic surgery and modulation of gut microbiota composition, used to target the GIT of this animal model to improve the diabetic state.

Biliopancreatic Limb Length of Small Intestinal Bypass in Non-obese Goto-Kakizaki (GK) Rats Correlates with Gastrointestinal Hormones, Adipokines, and Improvement in Type 2 Diabetes.

BACKGROUND: The purpose of this study was to explore the effects on type 2 diabetes, gastrointestinal hormones, and adipokines after the small intestinal bypass of different biliopancreatic limb (BPL) lengths in non-obese type 2 diabetic rats. METHOD: Small intestinal bypass with the BPL length at 10cm, 20cm, 30cm, and 40cm, respectively, and sham surgery were performed in non-obese GK rats. Fasting serum was collected at 2 days preoperatively and 1, 3, 6, and 9 weeks postoperatively. Body weight and fasting blood glucose (FBG) were measured during the experiment. Glycated hemoglobin (GHb), fasting insulin (FINS), C-peptide, ghrelin, leptin, adiponectin, and somatostatin were measured postoperatively. RESULT: Rats with a bypassed length of 40cm died within 5-9 weeks. No statistically significant was observed in body weight between the sham group and the bypass groups at the 9th week postoperatively. FBG, GHb, FINS, C-peptide, and HOMA-IR in the bypass groups were lower than those in the sham group postoperatively and were negatively correlated with BPL length. Ghrelin and leptin declined compared with preoperative but were not associated with BPL length. Adiponectin of the bypass groups increased after operation and was positively correlated with BPL length. Somatostatin remained stable among groups during the experiment. CONCLUSION: Ghrelin and leptin of non-obese GK rats decreased postoperatively without a linear relationship with the BPL length, while adiponectin increased with positively correlation with the BPL length. In addition, somatostatin remained steady after small intestinal bypass. Further studies are expected to confirm the effect of the BPL length of small intestinal bypass on gastrointestinal hormones and adipokines.

The characterization of metabolites alterations in white adipose tissue of diabetic GK Rats after ileal transposition surgery by an untargeted metabolomics approach.

Dysfunction of adipose tissue could lead to insulin resistance, obesity and type 2 diabetes. Thus, our present study aimed to investigate metabolites alterations in white adipose tissue (WAT) of diabetic GK rats after IT surgery. Ten-week-old male diabetic GK rats were randomly subjected to IT and Sham-IT surgery. Six weeks later, the untargeted metabolomics in WAT of diabetic GK rats was performed. Differential metabolites were selected according to the coefficient of variation (CV) of quality control (QC) sample <30%, variable importance in the projection (VIP) >1 and P < 0.05. Then, the hierarchical clustering of differential metabolites was conducted and the KEGG database was used for metabolic pathway analysis. A total of 50 (in positive ion mode) and 68 (in negative ion mode) metabolites were identified as differential metabolites in WAT of diabetic GK rats between IT group and Sham-IT group, respectively. These differential metabolites were well clustered, which in descending order of the number of involved differential metabolites is ubiquinone and other terpenoid-quinone biosynthesis, AMPK signalling pathway, pantothenate and CoA biosynthesis, ferroptosis, vitamin digestion and absorption, glycerophospholipid metabolism, phenylalanine metabolism, steroid hormone biosynthesis, neuroactive ligand-receptor interaction, porphyrin and chlorophyll metabolism and bile secretion, and correlated with the parameters of body weight, food intake, WAT mass and glucose metabolism, which were significantly improved after IT surgery. The differential metabolites in WAT of diabetic GK rats were mainly related to the pathway of energy metabolism, and correlated with the improved phenotypes of diabetic GK rats after IT surgery.

Small intestine remodeling in male Goto-Kakizaki rats.

BACKGROUND: Obesity is associated with the development of insulin resistance (IR) and type-2 diabetes mellitus (T2DM); however, not all patients with T2DM are obese. The Goto-Kakizaki (GK) rat is an experimental model of spontaneous and non-obese T2DM. There is evidence that the intestine contributes to IR development in GK animals. This information prompted us to investigate small intestine remodeling in this animal model. METHODS: Four-month-old male Wistar (control) and GK rats were utilized for the present study. After removing the small intestine, the duodenum, proximal jejunum, and distal ileum were separated. We then measured villi and muscular and mucosa layer histomorphometry, goblet cells abundance, total myenteric and submucosal neuron populations, and inflammatory marker expression in the small intestinal segments and intestinal transit of both groups of animals. KEY RESULTS: We found that the GK rats exhibited decreased intestinal area (p < 0.0001), decreased crypt depth in the duodenum (p = 0.01) and ileum (p < 0.0001), increased crypt depth in the jejunum (p < 0.0001), longer villi in the jejunum and ileum (p < 0.0001), thicker villi in the duodenum (p < 0.01) and ileum (p < 0.0001), thicker muscular layers in the duodenum, jejunum, and ileum (p < 0.0001), increased IL-1ß concentrations in the duodenum and jejunum (p < 0.05), and increased concentrations of NF-κB p65 in the duodenum (p < 0.01), jejunum and ileum (p < 0.05). We observed high IL-1ß reactivity in the muscle layer, myenteric neurons, and glial cells of the experimental group. GK rats also exhibited a significant reduction in submucosal neuron density in the jejunum and ileum, ganglionic hypertrophy in all intestinal segments studied (p < 0.0001), and a slower intestinal transit (about 25%) compared to controls. CONCLUSIONS: The development of IR and T2DM in GK rats is associated with small intestine remodeling that includes marked alterations in small intestine morphology, local inflammation, and reduced intestinal transit.

Small intestine remodeling in male Goto-Kakizaki rats

Background: Obesity is associated with the development of insulin resistance (IR) and type‐2 diabetes mellitus (T2DM); however, not all patients with T2DM are obese. The Goto–Kakizaki (GK) rat is an experimental model of spontaneous and non‐obese T2DM. There is evidence that the intestine contributes to IR development in GK animals. This information prompted us to investigate small intestine remodeling in this animal model. Methods: Four‐month‐old male Wistar (control) and GK rats were utilized for the present study. After removing the small intestine, the duodenum, proximal jejunum, and distal ileum were separated. We then measured villi and muscular and mucosa layer histomorphometry, goblet cells abundance, total myenteric and submucosal neuron populations, and inflammatory marker expression in the small intestinal segments and intestinal transit of both groups of animals. Key Results: We found that the GK rats exhibited decreased intestinal area (p < 0.0001), decreased crypt depth in the duodenum (p = 0.01) and ileum (p < 0.0001), increased crypt depth in the jejunum (p < 0.0001), longer villi in the jejunum and ileum (p < 0.0001), thicker villi in the duodenum (p < 0.01) and ileum (p < 0.0001), thicker muscular layers in the duodenum, jejunum, and ileum (p < 0.0001), increased IL‐1β concentrations in the duodenum and jejunum (p < 0.05), and increased concentrations of NF‐κB p65 in the duodenum (p < 0.01), jejunum and ileum (p < 0.05). We observed high IL‐1β reactivity in the muscle layer, myenteric neurons, and glial cells of the experimental group. GK rats also exhibited a significant reduction in submucosal neuron density in the jejunum and ileum, ganglionic hypertrophy in all intestinal segments studied (p < 0.0001), and a slower intestinal transit (about 25%) compared to controls. Conclusions: The development of IR and T2DM in GK rats is associated with small intestine remodeling that includes marked alterations in small intestine morphology, local inflammation, and reduced intestinal transit.

[Mechanism of Danzhi Jiangtang Capsules in treatment of diabetic macrovascular disease in GK rats based on correlation between microRNAs and inflammatory factors].

This study was aimed to investigate the mechanism of Danzhi Jiangtang Capsules( DJC) in the treatment of diabetic macrovascular disease in Goto-Kakizaki( GK) rats. The diabetic macrovascular disease rat model was induced by feeding high-fat and high-sugar combined with endothelial nitric oxide synthase( NOS) inhibitor N-nitro-L-arginine methyl ester( L-NAME)( 0. 1 g·L-1·d-1). According to the random array table,the model rats were randomly divided into the model group,DJC groups( 1 260,630,320 mg·kg-1),atorvastatin group( 105 mg·kg-1) and metformin group( 10 mg·kg-1),with 12 rats in each group. The rats received gavage administration for 8 weeks. Twelve Wistar rats were selected as the normal control group. The changes of body weight,water intake,blood glucose,plasma total cholesterol( TC),triglyceride( TG),high density lipoprotein( HDL-C),low density lipoprotein( LDL-C),interleukin( IL-1ß),IL-6,tumor necrosis factor( TNF-α),nitric oxide( NO),endothelin( ET-1) were observed in these rats. Aortic tissue was taken and the pathological changes were observed by HE staining. RT-PCR was used to detect the mRNA levels of IL-1ß,IL-6,and TNF-α in rat aorta. RT-PCR of the stem loop was used to detect the levels of miRNA-126,miRNA-155,miRNA-146 a,and miRNA-21 in rat plasma and aortic tissue. The canonical correlation between miRNAs and inflammatory factors was then analyzed. The results showed that DJC increased the rat body weight,lowered water intake,reduced the random blood glucose,reversed the rat aorta tissue damage,reduced serum TC,TG,LDL-C,ET-1,IL-1ß,IL-6,TNF-α,as well as miRNA-155,miRNA-146 a and miRNA-21 levels in serum,elevated plasma HDL-C,NO content,reduced the aorta mRNA of IL-1ß,IL-6,TNF-α,and the miRNA-155,miRNA-146 a and miRNA-21,elevated miRNA-126 expression in aorta. Aortic miRNA-126,miRNA-155,miRNA-146 a and miRNA-21 expression levels were typically correlated with the expression of inflammatory factors,among which miRNA-126 was negatively correlated,miRNA-155,miRNA-146 a and miRNA-21 were positively correlated with the factors. These results suggested that DJC had therapeutic effects on diabetic macrovascular diseases,and the mechanism of action may be related to the regulation of miRNA-126,miRNA-155,miRNA-146 a and miRNA-21 levels,as well as the reduction of inflammatory factors and vascular inflammatory response.

Transcriptome Changes of Skeletal Muscle RNA-Seq Speculates the Mechanism of Postprandial Hyperglycemia in Diabetic Goto-Kakizaki Rats During the Early Stage of T2D.

To address how skeletal muscle contributes to postprandial hyperglycemia, we performed skeletal muscle transcriptome analysis of diabetic Goto-Kakizaki (GK) and control Wistar rats by RNA sequencing (RNA-Seq). We obtained 600 and 1785 differentially expressed genes in GK rats compared to those Wistar rats at three and four weeks of age, respectively. Specifically, Tbc1d4, involved in glucose uptake, was significantly downregulated in the skeletal muscle of GK aged both three and four weeks compared to those of age-matched Wistar rats. Pdk4, related to glucose uptake and oxidation, was significantly upregulated in the skeletal muscle of GK aged both three and four weeks compared to that of age-matched Wistar rats. Genes (Acadl, Acsl1 and Fabp4) implicated in fatty acid oxidation were significantly upregulated in the skeletal muscle of GK aged four weeks compared to those of age-matched Wistar rats. The overexpression or knockout of Tbc1d4, Pdk4, Acadl, Acsl1 and Fabp4 has been reported to change glucose uptake and fatty acid oxidation directly in rodents. By taking the results of previous studies into consideration, we speculated that dysregulation of key dysregulated genes (Tbc1d4, Pdk4, Acadl, Acsl1 and Fabp4) may lead to a decrease in glucose uptake and oxidation, and an increase in fatty acid oxidation in GK skeletal muscle at three and four weeks, which may, in turn, contribute to postprandial hyperglycemia. Our research revealed transcriptome changes in GK skeletal muscle at three and four weeks. Tbc1d4, Acadl, Acsl1 and Fabp4 were found to be associated with early diabetes in GK rats for the first time, which may provide a new scope for pathogenesis of postprandial hyperglycemia.

Stem cells from human exfoliated deciduous teeth ameliorate type II diabetic mellitus in Goto-Kakizaki rats.

BACKGROUND: By 2030, diabetes mellitus (DM) will be the 7th leading cause of death worldwide. Type 2 DM (T2DM) is the most common type of DM and is characterized by insulin resistance and defective ß-cell secretory function. Stem cells from human exfoliated deciduous teeth (SHED) are favorable seed cells for mesenchymal stem cells (MSCs)-based therapy due to their higher proliferation rates and easier access to retrieval. Currently, no study has revealed the therapeutic efficiency of MSCs for T2DM in Goto-Kakizaki (GK) rats. Hence, we aimed to explore the effect of SHED on T2DM in GK rats. MATERIALS AND METHODS: We investigated the effects of SHED on the progression of T2DM in GK rats. SHED and bone marrow mesenchymal stem cells (BMSCs) were injected via the tail vein. Body weight, fasting blood glucose and non-fasting blood glucose were measured before and after administration. At 8 weeks after injection, intraperitoneal insulin tolerance tests (IPITTs) and insulin release tests (IRTs) were performed. Additionally, hematoxylin-eosin (HE) staining, periodic acid-Schiff (PAS) staining and double-label immunofluorescence staining were used to explore the pathological changes in pancreatic islets and the liver. Immunohistochemistry (IHC) was employed to detect SHED engraftment in the liver. Additionally, real-time PCR and western blotting were used to explore glycogen synthesis, glycolysis and gluconeogenesis in the liver. RESULTS: At 8 weeks after SHED injection, T2DM was dramatically attenuated, including hyperglycemia, IPGTT and IRT. Additionally, histological analysis showed that SHED injection improved pancreatic islet and liver damage. Real-time PCR analysis showed that SHED significantly reversed the diabetic-induced increase of G-6-Pase, Pck1 and PK; and significantly reversed the diabetic-induced decrease of GSK3ß, GLUT2, and PFKL. In addition, western blotting demonstrated that SHED significantly reversed the diabetic-induced increase of G-6-Pase and reversed the diabetic-induced decrease of GLUT2, GSK3ß and PFKM. CONCLUSION: Stem cells from human exfoliated deciduous teeth offers a potentially effective therapeutic modality for ameliorating T2DM, including hyperglycemia, insulin resistance, pancreatic islets and liver damage, and decreased glycogen synthesis, inhibited glycolysis and increased gluconeogenesis in the liver.

Integrated 16S rRNA Sequencing, Metagenomics, and Metabolomics to Characterize Gut Microbial Composition, Function, and Fecal Metabolic Phenotype in Non-obese Type 2 Diabetic Goto-Kakizaki Rats.

Type 2 diabetes mellitus (T2DM) is one of the most prevalent endocrine diseases in the world. Recent studies have shown that dysbiosis of the gut microbiota may be an important contributor to T2DM pathogenesis. However, the mechanisms underlying the roles of the gut microbiome and fecal metabolome in T2DM have not been characterized. Recently, the Goto-Kakizaki (GK) rat model of T2DM was developed to study the clinical symptoms and characteristics of human T2DM. To further characterize T2DM pathogenesis, we combined multi-omics techniques, including 16S rRNA gene sequencing, metagenomic sequencing, and metabolomics, to analyze gut microbial compositions and functions, and further characterize fecal metabolomic profiles in GK rats. Our results showed that gut microbial compositions were significantly altered in GK rats, as evidenced by reduced microbial diversity, altered microbial taxa distribution, and alterations in the interaction network of the gut microbiome. Functional analysis based on the cluster of orthologous groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations suggested that 5 functional COG categories belonged to the metabolism cluster and 33 KEGG pathways related to metabolic pathways were significantly enriched in GK rats. Metabolomics profiling identified 53 significantly differentially abundant metabolites in GK rats, including lipids and lipid-like molecules. These lipids were enriched in the glycerophospholipid metabolic pathway. Moreover, functional correlation analysis showed that some altered gut microbiota families, such as Verrucomicrobiaceae and Bacteroidaceae, significantly correlated with alterations in fecal metabolites. Collectively, the results suggested that an altered gut microbiota is associated with T2DM pathogenesis.

The Changes of Serum Metabolites in Diabetic GK Rats after Ileal Transposition Surgery.

BACKGROUND: Ileal transposition (IT) surgery could improve metabolism. Metabolomics has been applied comprehensively in analyzing the global dynamic alterations of metabolites. In the present study, we aimed to investigate serum metabolite alterations in diabetic Goto-Kakizaki (GK) rats after IT surgery. METHODS: Male GK rats were subjected to IT and Sham-IT surgery. Six weeks later, body weight, food intake, fat mass, and serum biochemical parameters were measured. The serum metabolomic fingerprint was analyzed using ultra-performance liquid chromatography-mass spectrometry (LC-MS)-based, non-targeted metabolomic approach. The differential metabolites were identified using principal component analysis and orthogonal partial least squares discriminant analysis. Metabolic pathway analysis was performed using HMDB and KEGG databases. RESULTS: The body weight, food intake, fat mass, serum levels of glucose and insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) of IT rats were significantly decreased when compared with Sham-IT rats (all P < 0.05). In the metabolomics analysis, ten serum differential metabolites were identified. Compared with Sham-IT rats, serum LysoPC(O-18:0) and PG(20:4/20:0) of IT rats were decreased, while genistein 4'-O-glucuronide, 5,6:8,9-Diepoxyergost-22-ene-3,7beta-diol, PI(16:0/18:2(9Z,12Z)), docosapentaenoic acid, 3-Oxo-4,6-choladienoic acid, 3-Oxocholic acid, and TG were increased. Pathway analysis highlighted the following pathways: ether lipid metabolism, alpha linolenic acid and linolenic acid metabolism, incretin synthesis and secretion, free fatty acid receptors, and biosynthesis of unsaturated fatty acids. CONCLUSIONS: IT surgery could significantly decrease body weight and fat mass and improve glucose metabolism in diabetic GK rats. These beneficial effects might be related to the changes of serum metabolites which involved in lipid metabolism, bile acids, and incretin.

Mechanism of Danzhi Jiangtang Capsules in treatment of diabetic macrovascular disease in GK rats based on correlation between microRNAs and inflammatory factors / 中国中药杂志

This study was aimed to investigate the mechanism of Danzhi Jiangtang Capsules( DJC) in the treatment of diabetic macrovascular disease in Goto-Kakizaki( GK) rats. The diabetic macrovascular disease rat model was induced by feeding high-fat and high-sugar combined with endothelial nitric oxide synthase( NOS) inhibitor N-nitro-L-arginine methyl ester( L-NAME)( 0. 1 g·L-1·d-1). According to the random array table,the model rats were randomly divided into the model group,DJC groups( 1 260,630,320 mg·kg-1),atorvastatin group( 105 mg·kg-1) and metformin group( 10 mg·kg-1),with 12 rats in each group. The rats received gavage administration for 8 weeks. Twelve Wistar rats were selected as the normal control group. The changes of body weight,water intake,blood glucose,plasma total cholesterol( TC),triglyceride( TG),high density lipoprotein( HDL-C),low density lipoprotein( LDL-C),interleukin( IL-1β),IL-6,tumor necrosis factor( TNF-α),nitric oxide( NO),endothelin( ET-1) were observed in these rats. Aortic tissue was taken and the pathological changes were observed by HE staining. RT-PCR was used to detect the mRNA levels of IL-1β,IL-6,and TNF-α in rat aorta. RT-PCR of the stem loop was used to detect the levels of miRNA-126,miRNA-155,miRNA-146 a,and miRNA-21 in rat plasma and aortic tissue. The canonical correlation between miRNAs and inflammatory factors was then analyzed. The results showed that DJC increased the rat body weight,lowered water intake,reduced the random blood glucose,reversed the rat aorta tissue damage,reduced serum TC,TG,LDL-C,ET-1,IL-1β,IL-6,TNF-α,as well as miRNA-155,miRNA-146 a and miRNA-21 levels in serum,elevated plasma HDL-C,NO content,reduced the aorta mRNA of IL-1β,IL-6,TNF-α,and the miRNA-155,miRNA-146 a and miRNA-21,elevated miRNA-126 expression in aorta. Aortic miRNA-126,miRNA-155,miRNA-146 a and miRNA-21 expression levels were typically correlated with the expression of inflammatory factors,among which miRNA-126 was negatively correlated,miRNA-155,miRNA-146 a and miRNA-21 were positively correlated with the factors. These results suggested that DJC had therapeutic effects on diabetic macrovascular diseases,and the mechanism of action may be related to the regulation of miRNA-126,miRNA-155,miRNA-146 a and miRNA-21 levels,as well as the reduction of inflammatory factors and vascular inflammatory response.

[Protective effect of Yiqi Huoxue decoction on kidney in diabetic GK rats].

To investigate the protective effect of Yiqi Huoxue decoction on the kidney in diabetic goto-Kaizaki (GK) rats. Eight Wistar rats were used as normal control group. According to body weight and blood glucose, 16 GK rats were randomly divided into model control group and Yiqi Huoxue group, with 8 rats in each group. Drugs were administrated for 6 weeks. The rats were weighed and fasting blood glucose (FBG) were measured weekly; the glycosylated hemoglobin (HbALc) and 24 h metabolic rate were measured at the end of third and sixth weeks, at the same time, urine was collected to measure urinary glucose (U-GLU), urinary creatinine (U-CREA) and total proteinuria (U-TP) by biochemical method and calculate 24 h protein excretion rate (UAER). At the end of treatment, rats were sacrificed in anesthesia, and creatinin (CREA), uric acid (UA) and cholesterol (CHOL) were detected by biochemical method and glutathione peroxidase (GSH-Px) was detected by manual method with the blood drawn from heart. Both kidneys were taken and weighed to calculate the renal hypertrophy index. The kidneys were placed into neutral formalin and observed under light microscope for pathological change after Periodic Acid-Schiff (PAS) staining. The results showed that as compared with the normal control group, FBG, HbALc, 24 h Metabolic rate, U-GLU, UAER, serum CREA, UA and CHOL levels, as well as renal hypertrophy index were significantly increased (P<0.05) in the model group, while the body weight growth rate, serum GSH-Px level were significantly reduced(P<0.05); in addition, renal glomerular injury and structural changes were observed in the model group. As compared with the model group, serum GSH-Px level was significantly increased (P<0.05) in the Yiqi Huoxue group, While FBG, HbALc, 24 h Metabolic rate, U-GLU, UAER, serum CREA, UA and CHOL levels, as well as renal hypertrophy index were significantly reduced (P<0.05); meanwhile, renal glomerular injury and structural changes were improved in the Yiqi Huoxue group. The results showed that Yiqi Huoxue decoction can significantly increase serum GSH-Px level, reduce FBG, HbALc, 24 h metabolic rate, U-GLU, UAER, serum CREA, UA and CHOL levels, as well as renal hypertrophy index, and improve renal pathology in diabetic GK rats.

Hypoglycemic property of soy isoflavones from hypocotyl in Goto-Kakizaki diabetic rats.

The present study was carried out to investigate the hypoglycemic effect of soy isoflavones from hypocotyl in GK diabetic rats. A single administration and long-term administration tests were conducted in GK diabetic rats to test the hypoglycemic effect of soy isoflavones. At the end of long-term administration trial, blood protein, cholesterol, triglyceride, glycosylated serum protein, C-reactive protein, insulin, aminotransferase, lipid peroxide, interleukin-6, tumor necrosis factor-α were estimated. Inhibition of soy isoflavones against α-amylase and α-glucosidase, as well as on glucose uptake into brush border membrane vesicles or Caco-2 cells were determined in vitro. In single administration experiment, soy isoflavones reduced postprandial blood glucose levels in GK rats. In long-term administration, hypoglycemic effect of soy isoflavones was first observed at week 12 and maintained till week 16. A significant reduction in fasting blood glucose, C-reactive protein, and lipid peroxide was noted at week 16. However, there was no significant treatment effect on blood insulin. Furthermore, soy isoflavone administration resulted in significant decreases in glycosylated serum protein, tumor necrosis factor-α, and interleukin-6. Other biochemical parameters, such as protein, cholesterol, triglyceride and aminotransferases were not modified, however. The results in vitro showed that soy isoflavones showed a potent inhibitory effect on intestinal α-glucosidase, but not on pancreatic α-amylase. Soy isoflavones also decreased glucose transport potency into brush border membrane vesicles or Caco-2 cells. It is concluded that soy isoflavones from hypocotyl, performs hypoglycemic function in GK rats with type 2 diabetes, maybe via suppression of carbohydrate digestion and glucose uptake in small intestine.

Ellagic Acid Alleviates Hepatic Oxidative Stress and Insulin Resistance in Diabetic Female Rats.

Non-alcoholic fatty liver disease (NAFLD) affects more than 70% of patients with type 2 diabetes mellitus (T2DM) and has become one of the most common metabolic liver diseases worldwide. To date, treatments specifically targeting NAFLD do not exist. Oxidative stress and insulin resistance have been implicated in the pathogenesis of NAFLD in diabetes. Accordingly, the goal of this present study was to determine whether Ellagic acid (EA), a natural antioxidant polyphenol found in berries and nuts, mitigates hepatic oxidative stress and insulin resistance in T2DM rats, and thus alleviates NAFLD. Using adult female Goto Kakizaki (GK) rats, a non-obese and spontaneous model of T2DM, we found that EA treatment significantly lowered fasting blood glucose and reduced insulin resistance, as shown by a 21.8% reduction in the homeostasis model assessment index of insulin resistance (HOMA-IR), while triglyceride and total cholesterol levels remained unchanged. Increased hepatic lipid accumulation and oxidative stress present in diabetic GK rats was markedly reduced with EA treatment. This effect was associated with a downregulation of the NADPH oxidase subunit, p47-phox, and overexpression of NF-E2-related factor-2 (NRF2). Moreover, EA was able to decrease the hepatic expression of hypoxia-inducible factor (HIF-α), a transcription factor linked to hypoxia and hepatic steatosis. We further showed that EA treatment activated an insulin signaling pathway in the liver, as evidenced by increased levels of phosphorylated Akt (Ser 473). In conclusion, our results demonstrate that EA diminishes blood glucose levels and potently suppress NAFLD in diabetic rats via mechanisms that involve reductions in p47-phox and HIF-α, upregulation of NRF2 and enhancement of the Akt signaling pathway in the liver. Together, these results reveal that EA improves hepatic insulin sensitivity and lipid metabolism as a result of its antioxidant effects. This implies an anti-diabetic effect of EA with beneficial effects for the treatment of hepatic complications in T2DM.

Ileal Transposition Surgery Decreases Fat Mass and Improves Glucose Metabolism in Diabetic GK Rats: Possible Involvement of FGF21.

Objective: Ileal transposition (IT) surgery has been reported to improve glucose and lipid metabolism, and fibroblast growth factor 21 (FGF21) is a powerful metabolic regulator. In the present study, we aimed to investigate the effects of IT surgery on metabolism and its possible relationship with the FGF21 signaling pathway in diabetic Goto-Kakizaki (GK) rats. Methods: Ten-week-old male GK rats were subjected to IT surgery with translocation of a 10 cm ileal segment to the proximal jejunum (IT group) or sham surgery without the ileum transposition (Sham-IT group). Rats in the no surgery group did not receive any surgical intervention. Six weeks later, body weight, fat mass, fasting blood glucose (FBG), and serum levels of FGF21 and leptin were measured. The expression of the FGF21 signaling pathway and white adipose tissue (WAT) browning-related genes in the WAT and liver were evaluated by real-time reverse transcription polymerase chain reaction (RT-qPCR) and western blot. Results: IT surgery significantly decreased the body weights and FBG levels and increased the insulin sensitivity of GK rats. The total WAT mass of the IT rats showed a 41.5% reduction compared with the Sham-IT rats, and serum levels of FGF21 and leptin of the IT rats decreased by 26.3 and 61.7%, respectively (all P < 0.05). The mRNA levels of fibroblast growth factor receptor 1 (FGFR1) and its co-receptor ß klotho (KLB) in the perirenal WAT (pWAT) of the IT rats were 1.4- and 2.4-fold that of the Sham-IT rats, respectively, and the FGFR1 protein levels were 1.7-fold of the Sham-IT rats (all P < 0.05). In accordance with the pWAT, the protein levels of FGFR1 and KLB in the epididymal WAT (eWAT) of the IT rats notably increased to 3.0- and 3.9-fold of the Sham-IT rats (P < 0.05). Furthermore, uncoupling protein 1 (UCP1) protein levels in the eWAT and pWAT of the IT rats also increased to 2.2- and 2.3-fold of the Sham-IT rats (P < 0.05). However, the protein levels of FGFR1 and KLB in the subcutaneous WAT (sWAT) of the IT rats decreased by 34.4 and 72.1%, respectively, compared with the Sham-IT rats (P < 0.05). In addition, the protein levels of FGF21 and KLB in the livers of IT rats were 3.9- and 2.3-fold of the Sham-IT rats (all P < 0.05). Conclusions: IT surgery significantly decreased fat mass and improved glucose metabolism in diabetic GK rats. These beneficial roles of IT surgery were probably associated with its stimulatory action on the expression of FGFR1 and KLB in both the eWAT and the pWAT, thereby promoting UCP1 expression in these tissues.

Protective effect of Yiqi Huoxue decoction on kidney in diabetic GK rats / 中国中药杂志

To investigate the protective effect of Yiqi Huoxue decoction on the kidney in diabetic goto-Kaizaki (GK) rats. Eight Wistar rats were used as normal control group. According to body weight and blood glucose, 16 GK rats were randomly divided into model control group and Yiqi Huoxue group, with 8 rats in each group. Drugs were administrated for 6 weeks. The rats were weighed and fasting blood glucose (FBG) were measured weekly; the glycosylated hemoglobin (HbALc) and 24 h metabolic rate were measured at the end of third and sixth weeks, at the same time, urine was collected to measure urinary glucose (U-GLU), urinary creatinine (U-CREA) and total proteinuria (U-TP) by biochemical method and calculate 24 h protein excretion rate (UAER). At the end of treatment, rats were sacrificed in anesthesia, and creatinin (CREA), uric acid (UA) and cholesterol (CHOL) were detected by biochemical method and glutathione peroxidase (GSH-Px) was detected by manual method with the blood drawn from heart. Both kidneys were taken and weighed to calculate the renal hypertrophy index. The kidneys were placed into neutral formalin and observed under light microscope for pathological change after Periodic Acid-Schiff (PAS) staining. The results showed that as compared with the normal control group, FBG, HbALc, 24 h Metabolic rate, U-GLU, UAER, serum CREA, UA and CHOL levels, as well as renal hypertrophy index were significantly increased (<0.05) in the model group, while the body weight growth rate, serum GSH-Px level were significantly reduced(<0.05); in addition, renal glomerular injury and structural changes were observed in the model group. As compared with the model group, serum GSH-Px level was significantly increased (<0.05) in the Yiqi Huoxue group, While FBG, HbALc, 24 h Metabolic rate, U-GLU, UAER, serum CREA, UA and CHOL levels, as well as renal hypertrophy index were significantly reduced (<0.05); meanwhile, renal glomerular injury and structural changes were improved in the Yiqi Huoxue group. The results showed that Yiqi Huoxue decoction can significantly increase serum GSH-Px level, reduce FBG, HbALc, 24 h metabolic rate, U-GLU, UAER, serum CREA, UA and CHOL levels, as well as renal hypertrophy index, and improve renal pathology in diabetic GK rats.