The aim of the present study was to explore the role of orphan G protein-coupled receptor 55 (GPR55) in diabetic gastroparesis (DG). Streptozotocin (STZ) was used to mimic the DG model, and the body weight and blood glucose concentration were tested 4 weeks after STZ injection (i.p.). Electrogastrogram and phenolsulfonphthalein test were used for detecting gastric emptying. Motilin (MTL), gastrin (GAS), vasoactive intestinal peptide (VIP), and somatostatin (SS) levels in plasma were determined using radioimmunology. Real-time PCR and Western blot were applied to identify the expression of GPR55 in gastric tissue, and immunohistochemistry was used to detect the distribution. The effect of lysophosphatidylinositol (LPI), an agonist of GPR55, was observed. STZ mice showed increased blood glucose concentration, lower body weight, decreased amplitude of slow wave, and delayed gastric emptying. LPI antagonized these effects of STZ. Compared to the control group, STZ caused significant decreases of MTL and GAS levels (P < 0.01), as well as increases of SS and VIP levels (P < 0.01). The changes of these hormones induced by STZ were counteracted when using LPI. GPR55 located in mice stomach, and it was up-regulated in DG. Although LPI showed no effects on the distribution and expression of GPR55 in normal mice, it could inhibit STZ-induced GPR55 up-regulation. These results suggest GPR55 is involved in the regulation of gastric movement of DG, and may serve as a new target of DG treatment. LPI, an agonist of GPR55, can protect against STZ-induced DG, and the mechanism may involve the change of GPR55 expression and modification of gastrointestinal movement regulating hormones.
Animals ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Gastroparesis ; metabolism ; pathology ; Lysophospholipids ; pharmacology ; Mice ; Receptors, Cannabinoid ; metabolism

Animals ; Antioxidants ; metabolism ; Diabetes Mellitus, Experimental ; metabolism ; Melatonin ; metabolism ; Physical Conditioning, Animal ; Rats

Diabetic neuropathic pain (DNP) is the most common disabling complication of diabetes. Emerging evidence has linked the pathogenesis of DNP to the aberrant sprouting of sensory axons into the epidermal area; however, the underlying molecular events remain poorly understood. Here we found that an axon guidance molecule, Netrin-3 (Ntn-3), was expressed in the sensory neurons of mouse dorsal root ganglia (DRGs), and downregulation of Ntn-3 expression was highly correlated with the severity of DNP in a diabetic mouse model. Genetic ablation of Ntn-3 increased the intra-epidermal sprouting of sensory axons and worsened the DNP in diabetic mice. In contrast, the elevation of Ntn-3 levels in DRGs significantly inhibited the intra-epidermal axon sprouting and alleviated DNP in diabetic mice. In conclusion, our studies identified Ntn-3 as an important regulator of DNP pathogenesis by gating the aberrant sprouting of sensory axons, indicating that Ntn-3 is a potential druggable target for DNP treatment.
Mice ; Animals ; Diabetes Mellitus, Experimental/metabolism* ; Axons/physiology* ; Diabetic Neuropathies ; Sensory Receptor Cells/metabolism* ; Neuralgia/metabolism*

Tu-Xian decoction (TXD), a traditional Chinese medicine (TCM) formula, has been frequently administered to manage diabetic cognitive impairment (DCI). Despite its widespread use, the mechanisms underlying TXD's protective effects on DCI have yet to be fully elucidated. As a significant regulator in neurodegenerative conditions, death-associated protein kinase-1 (DAPK-1) serves as a focus for understanding the action of TXD. This study was designed to whether TXD mediates its beneficial outcomes by inhibiting DAPK-1. To this end, a diabetic model was established using Sprague-Dawley (SD) rats through a high-fat, high-sugar (HFHS) diet regimen, followed by streptozotocin (STZ) injection. The experimental cohort was stratified into six groups: Control, Diabetic, TC-DAPK6, high-dose TXD, medium-dose TXD, and low-dose TXD groups. Following a 12-week treatment period, various assessments-including blood glucose levels, body weight measurements, Morris water maze (MWM) testing for cognitive function, brain magnetic resonance imaging (MRI), and histological analyses using hematoxylin-eosin (H&E), and Nissl staining-were conducted. Protein expression in the hippocampus was quantified through Western blotting analysis. The results revealed that TXD significantly improved spatial learning and memory abilities, and preserved hippocampal structure in diabetic rats. Importantly, TXD administration led to a down-regulation of proteins indicative of neurological damage and suppressed DAPK-1 activity within the hippocampal region. These results underscore TXD's potential in mitigating DCIvia DAPK-1 inhibition, positioning it as a viable therapeutic candidate for addressing this condition. Further investigation into TXD's molecular mechanisms may elucidate new pathways for the treatment of DCI.
Animals ; Rats ; Brain/metabolism* ; Cognitive Dysfunction/drug therapy* ; Diabetes Mellitus, Experimental/metabolism* ; Hippocampus ; Rats, Sprague-Dawley

OBJECTIVETo investigate the expression of adiponectin and its receptors (AdipoRs) in the retina of normal mice and mice with type 1 diabetes mellitus (T1DM).

METHODSC57BL/6 mice were randomly divided into control group and streptozotocin-induced T1DM group. Two months after the modeling, the total protein and adiponectin protein expression in the retina and choroid were measured using BCA method and enzyme-linked immunosorbent assay, respectively. Quantitative RT-PCR was performed to detect the mRNA expressions of AdipoRs in the retina and choroid, and Western blotting was employed to examine the protein expressions of AdipoRs in the retina.

RESULTSAdiponectin and AdipoRs proteins were expressed in the retina and choroid in normal mice. The expressions of adiponectin and AdipoR1 were up-regulated in the retina of mice with T1DM while AdipoR2 expression exhibited no significant changes.

CONCLUSIONAdiponectin and AdipoR1 may play an important role in the evolvement of type 1 diabetic retinopathy.

Adiponectin ; metabolism ; Animals ; Diabetes Mellitus, Experimental ; metabolism ; Diabetes Mellitus, Type 1 ; metabolism ; Diabetic Retinopathy ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Receptors, Adiponectin ; metabolism ; Retina ; metabolism

OBJECTIVE: To analyze the effect of conjugated linoleic acid (CLA) on glucose and lipid metabolism in obese diabetic (db/db) mice. METHODS: db/db mice were randomized for treatment with saline or CLA mixture administered intragastrically. The changes in body weight, dietary intake, water intake, oral glucose tolerance, triglyceride and total cholesterol were recorded after the treatments. HE staining and oil red O staining were used to assess liver pathologies and fatty acid content. The expression levels of PPARα, PPARγ, CD36, CHREBP and SREBP-1c were detected using real-time PCR and Western blotting. HepG2 cells were treated with CLA and linoleic acid and the expressions of PPARα, ACC, P-ACC, and CD36 were detected; the level of acetyl-CoA in the cell supernatant was detected using ELISA. RESULTS: CLA treatment obviously reduced the dietary and water intake of db/db mice, effectively reduced the body weight and decreased serum triglyceride and cholesterol levels ( < 0.05). CLA significantly reduced fasting blood glucose, increased glucose tolerance, reduced the accumulation of lipid droplets in the liver and improved lipid metabolism in db/db mice. The mice showed significantly increased expression of PPARα ( < 0.05) and lowered CD36 expression ( < 0.001) in the liver after CLA treatment. Cellular experiments showed that CLA significantly up-regulated PPARα ( < 0.001) and P-ACC and decreased the expression of CD36 ( < 0.01). ELISA showed that acetyl-CoA was significantly up-regulated in the cells after CLA treatment ( < 0.01). CONCLUSIONS The mixture of two conjugated linoleic acid isomers can reduce fasting blood glucose, increase glucose tolerance and improve glycolipid metabolism in db/db mice by enhancing the expression of PPARα, increasing P-ACC and inhibiting CD36 expression.
Animals ; Diabetes Mellitus, Experimental ; Glucose ; Linoleic Acids, Conjugated ; Lipid Metabolism ; Liver ; Mice ; Triglycerides

OBJECTIVETo study effects of insulin treatment on intracellular lipid content in livers and insulin resistance of type 2 diabetic rats.

METHODSType 2 diabetic rats were induced by injecting streptozotocin (25 mg/kg) and fat rich food. Then according to the results of the oral glucose tolerance test (OGTT) and glucose-induced insulin secretion test (IST), the rats were divided into two groups: control group (DC) and insulin treated group (DI). Normal rats (NC) served as controls. The treatment of each group with either NPH insulin (4 approximately 6 U . kg-1. d-1), or saline continued for 4 weeks. Body weight, OGTT, IST, blood lipids, intracellular lipids in liver and liver histology were studied. The insulin sensitivity index (ISI) was applied to assess the status of insulin resistance.

RESULTSBlood lipid and intracellular lipids in livers in the DC were higher than those in NC (t = 2.59 approximately 15.77, P < 0.05) and the ISI was lower (t = 3.16, P < 0.05), with many fatty droplets appearing in the livers. In comparison to DC, DI showed that blood lipids were decreased, but lipids in livers were markedly increased (TG, TC, FFA increased 55.7%, 19.87%, 22.2%, respectively), and fatty droplets in hepatocytes were larger, but the ISI did not change significantly.

CONCLUSIONInsulin treatment can make blood glucose normal, increase the intracellular lipid content in the liver, and not increase the insulin resistance significantly.

Animals ; Diabetes Mellitus, Experimental ; drug therapy ; metabolism ; Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; Insulin ; therapeutic use ; Insulin Resistance ; Lipid Metabolism ; Liver ; metabolism ; Male ; Rats ; Rats, Wistar

OBJECTIVE: To investigate the nucleolus expression in the diabetic cardiomyopathy. METHODS: The rats were divided into a control group and a type II diabetic cardiomyopathy group (model group). In the model group, rats were fed with high-fat and high-sugar food (rats were intravenously injected with 60 mg/kg chain urea with cephalosporins in the 5th and 6th weeks in mice). The level of blood glucose was determined at the end of 8th week and the level of fasting blood glucose was examined at the end of 20th week. The ratio of the heart mass and body mass was calculated, and the pathological changes in myocardial morphology were observed. The immunohistochemical method and Western blot were used to detect the expression level of myocardial nucleolin. RESULTS: The level of fasting blood glucose was significantly increased in the diabetic model group than that in the control group (P<0.05). Rats in the model group were found hypertrophic cardic cells, with fracture, dissolusion, and disordered arrangement. Immunohistochemical staining and Western blot showed the protein levels of myocardial nucleolin in the model group were obviously higher than those in the control group (P<0.05). CONCLUSION Nucleolin may play a role in the pathogenesis and development of the diabetic cardiomyopathy.
Animals ; Blood Glucose ; Diabetes Mellitus, Experimental ; metabolism ; Diabetic Cardiomyopathies ; metabolism ; Myocardium ; pathology ; Phosphoproteins ; metabolism ; RNA-Binding Proteins ; metabolism ; Rats

OBJECTIVETo get a better understanding of the mechanisms underlying type 1 diabetes mellitus, the differentially expressed pancreatic proteins from multiple low-dose streptozotocin (MLD-SIZ) mouse and normal mouse were analyzed and compared.

METHODS20 male rats were separated into 2 groups (n=10): model mice treated with MLD-STZ and normal mice,differences of pancreatic proteome among in the two groups of mice, were analyzed by two dimensional polyacryamide gel electrophoresis (2DE). Protein quantification was analyzed and the differentially expressed spots were identified using mass spectrometry and MASCOT database searching.

RESULTSCompared with control group, 23 proteins had changed significantly in the model group, 8 proteins expression were up-regulated, 15 proteins expressions down-regulated significantly. Using MALDI-TOF-MS, 15 proteins with significant change were identified by peptide fingerprinting map and the results were searched in MASCOT database. The function analyzed showed that proteins with change were associated with metabolic, anti-oxidant, structural, catalytic enzymes and chaperone, et al.

CONCLUSIONType 1 diabetes is probably exerted via multi-target and multi-path mechanism. The proteins with significant change are newly target for type 1 diabetes early diagnosis and treatment.

Animals ; Diabetes Mellitus, Experimental ; physiopathology ; Diabetes Mellitus, Type 1 ; chemically induced ; metabolism ; physiopathology ; Male ; Mice ; Pancreas ; metabolism ; Proteins ; metabolism ; Proteomics ; methods ; Streptozocin

OBJECTIVE: To investigate the effect of dihydromyricetin (DHM) on cardiac insufficiency in diabetic rats and explore the underlying mechanism. METHOD: Twenty-four male SD rats were randomized equally into normal control group, type 2 diabetes (T2DM) group fed on a high-glucose and high-fat diet for 6 weeks with low-dose streptozotocin (STZ) injection, metformin (MET) group with daily intragastric administration of MET (150 mg/kg) for 8 weeks after T2DM modeling, and dihydromyricetin (DHM) group with daily intragastric administration of DHM (250 mg/kg) for 8 weeks after modeling. The levels of fasting blood glucose, low density lipoprotein (LDL-C), triglyceride (TG), total cholesterol (TC), high density lipoprotein (HDL-C) and glycosylated hemoglobin (HbA1c) of the rats were measured, and plasma levels of insulin and high mobility group protein-1 (HMGB1) were detected with ELISA. The cardiac function of the rats was assessed using color echocardiography, ECG was measured using a biological signal acquisition system, and myocardial pathology was observed with HE staining. The protein expressions of HMGB1, nuclear factor-κB (NF-κB) p65 and phospho-NF-κB p65 (p-NF-κB p65) in the myocardial tissue were detected using Western blotting. RESULTS: Compared with the control group, the rats in T2DM group showed significant anomalies in cardiac function after modeling with significantly increased plasma HMGB1 level and expressions of HMGB1, NF-κB p65 and p-NF-κB p65 proteins in the myocardial tissue (P < 0.05 or 0.01). Treatment with DHM significantly improved the indexes of cardiac function of the diabetic rats (P < 0.05 or 0.01), decreased plasma HMGB1 level and down-regulated the protein expressions of HMGB1 and p-NF-κB p65 in the myocardial tissue (P < 0.05 or 0.01). CONCLUSION DHM treatment can improve cardiac function in diabetic rats possibly by down-regulation of HMGB1 and phospho-NF-κB p65 expressions in the myocardium.
Animals ; Diabetes Mellitus, Experimental/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Flavonols ; HMGB1 Protein ; Heart Failure ; Male ; Metformin/therapeutic use* ; NF-kappa B/metabolism* ; Rats ; Rats, Sprague-Dawley