OBJECTIVE: Here, we investigated the ability of Palmatine to reduce the up-regulation of chaperone proteins Glucose Regulatory Protein 78 (GRP78), and Calreticulin (CALR) protein in a Streptozotocin (STZ)-induced diabetic rat model.
METHODS: Streptozotocin (STZ) induced diabetes in Sprague Dawley rats treated with 2mg/kg of Palmatine for 12 weeks after the elevation of plasma glucose levels above 11mmol/L post-STZ administration. Proteins were extracted from the pancreas after treatment and Two-Dimensional gel electrophoresis (2-DE), PDQuest 2-D analysis software genomic solutions and mass spectrometer were used to analyze differentially expressed protein. Mass Spectrometry (MS/MS), Multidimensional Protein Identification Technology (MudPIT) was used for protein identification.
RESULTS: There was an up-regulation of the expression of chaperone proteins CALR and GRP78 and down-regulation of the expression of antioxidant and protection proteins peroxidoxin 4 (Prdx4), protein disulfide isomerase (PDIA2/3), Glutathione-S-Transferase (GSTs), and Serum Albumin (ALB) in non-diabetic rats. Palmatine treatment down-regulated the expression of chaperone proteins CALR and GRP78 and up-regulated the expression of Prdx4, PDIA2/3, GST, and ALB.
CONCLUSION: Palmatine may have activated antioxidant proteins, which protected the cells against reactive oxygen species and endoplasmic stress. The result is in consonance with our previous report on Palmatine.
OBJECTIVE: The objective of this study was to determine the effects of T3 derivatives, σ-T3, γ-T3 and α-T3 on insulin secretion of rat pancreatic islets in a dynamic culture.
METHOD: Pancreatic islets isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation that provided a stable cell culture environment. Glucose (2.8 mM and 16.7 mM, as basal and stimulant, respectively) and potassium chloride (KCl) (30 mM) were added to the treatment in calcium free medium. The supernatant was collected for insulin measurements.
RESULTS: Short-term exposure (1 h) of σ-T3 to β cells in the stimulant glucose condition significantly potentiated insulin secretion in a dose-dependent manner. γ-T3 and α-T3 also displayed dosedependent effect but were less effective in the activation of insulin secretion. Essentially, KCl, a pancreatic β cell membrane depolarizing agent, added into the treatment further enhanced the insulin secretion of σ-T3, γ-T3 and α-T3 with ED50 values of 504, 511 and 588 µM, respectively.
CONCLUSION: The findings suggest the potential of σ-T3 in regulating glucose-stimulated insulin secretion (GSIS) in response to the intracellular calcium especially in the presence of KCl.
RESEARCH DESIGN AND METHODS: Outcomes of 736 patients with T2DM who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) at an academic center (2004-2012) and had ≥5 years' glycemic follow-up were assessed. Of 736 patients, 425 (58%) experienced diabetes remission (HbA1c <6.5% [48 mmol/mol] with patients off medications) in the 1st year after surgery. These 425 patients were followed for a median of 8 years (range 5-14) to characterize late relapse of diabetes.
RESULTS: In 136 (32%) patients who experienced late relapse, a statistically significant improvement in glycemic control, number of diabetes medications including insulin use, blood pressure, and lipid profile was still observed at long-term. Independent baseline predictors of late relapse were preoperative number of diabetes medications, duration of T2DM before surgery, and SG versus RYGB. Furthermore, patients who relapsed lost less weight during the 1st year after surgery and regained more weight afterward. Prediction models were constructed and externally validated.
CONCLUSIONS: While late relapse of T2DM is a real phenomenon (one-third of our cohort), it should not be considered a failure, as the trajectory of the disease and its related cardiometabolic risk factors is changed favorably after bariatric surgery. Earlier surgical intervention, RYGB (compared with SG) and more weight loss (less late weight regain) are associated with less diabetes relapse in the long-term.