Fentanyl inhibits glucose-stimulated insulin release from β-cells in rat pancreatic islets

AIM： TO explore the effects of fentanyl on insulin release from freshly isolated rat pancreatic islets in static culture. METHODS： Islets were isolated from the pancreas of mature Sprague Dawley rats by common bile duct intraductal collagenase V digestion and were purified by discontinuous Ficoll density gradient centrifugation. The islets were divided into four groups according to the fentanyl concentration： control group （0 ng/mL）, group I （0.3 ng/mL）, group I （3.0 ng/mL）, and group III （30 ng/mL）. In each group, the islets were co-cultured for 48 h with drugs under static conditions with fentanyl alone, fentanyl ＋ 0.1 μg/mL naloxone or fentanyl ＋ 1.0 μg/mL naloxone. Cell viability was assessed by the MTT assay. Insulin release in response to low and high concentrations （2.8 mmol/L and 16.7 mmol/L, respectively） of glucose was investigated and electron microscopy morphological assessment was performed. RESULTS： Low- and high-glucose-stimulated insulin release in the control group was significantly higher than in groups I and II （62.33 ± 9.67 μIU vs 47.75 ± 8.47 μIU, 39.67 ± 6.18 μIU and 125.5 ± 22.04 μIU vs 96.17 ± 14.17 μIU, 75.17 ± 13.57 μIU, respectively, P 〈 0.01） and was lowest in group III （P 〈 0.01）. After adding 1 μg/mL naloxone, insulin release in groups II and II was not different from the control group. Electron microscopy studies showed that the islets were damaged by 30 ng/ml fentanyl. CONCLUSION： Fentanyl inhibited glucose-stimulated insulin release from rat islets, which could be prevented by naloxone. Higher concentrations of fentanyl significantly damaged β-cells of rat islets.

Glucose-responsive erythrocyte-bound nanoparticles for continuously modulated insulin release

Glucose-responsive closed-loop insulin delivery systems represent a promising treatment strategy for diabetes,but current systems generally cannot achieve long-term effects.In this study,we designed an erythrocyte-biomimetic glucose-responsive system(EGRS)by coupling glucose-responsive nanoparticles(GRNs)to red blood cells;these nanoparticles exhibited the dual functions of glucose-responsiveness and persistent presence in circulation.GRNs are generated by encapsulating with insulin through ion crosslinking,followed by coloading with glucose oxidase(GOx)and catalase(CAT),a process that endows the nanoparticles with glucose-responsiveness.Simultaneously,the GRNs are coupled with red blood cells to camouflage them from the immune system,therefore,these erythrocyte-coupled GRNs can circulate in the blood for a long time.Under conditions of hyperglycemia,GOx acts on blood glucose to produce gluconic acid,which causes the rupture of GRNs and efficient release of insulin.Conversely,insulin is only released at the basic rate during hypoglycemia.Thus,EGRS can efficiently and continuously respond to hyperglycemia to maintain blood glucose levels within the normal range.

RNA interference targeting mu-opioid receptors reverses the inhibition of fentanyl on glucose-evoked insulin release of rat islets

Background Mu opioid receptor plays an important role in many physiological functions. Fentanyl is a widely used opioid receptor agonist for analgesia. This study was conducted to test the role of mu-opioid receptor on insulin release by determining whether fentanyl affected insulin release from freshly isolated rat pancreatic islets and if small interfering RNAs （siRNA） targeting mu-opioid receptor in the islets could knock down mu-opioid receptor expression.Methods Islets were isolated from ripe SD rats＇ pancreas by common bile duct intraductal collagenase V digestion and purified by discontinuous Ficoll density gradient centrifugation. The siRNA knock-down of mu-opioid receptor mRNA and protein in islet cells was analyzed by semi-quantitative real time-PCR and Western blotting. After siRNA-transfection for 48 hours, the islets were co-cultured with fentanyl as follows： 0 ng/ml, 3 ng/ml and 30 ng/ml for 48 hours. Then glucose-evoked insulin release was performed. As a control, the insulin release was also analyzed in islets without siRNA-trasfection after being co-cultured with fentanyl for 48 hours.Results After 48 hours of transfections, specific siRNA targeting of mu-opioid receptors produced significant reduction of mu-opioid receptor mRNA and protein （P ＜0.01）. Fentanyl significantly inhibited glucose-evoked insulin release in islets in a concentration dependent manner （P ＜0.01）. But after siRNA-transfection for 48 hours, the inhibition on glucose-evoked insulin reiease was reversed （P ＜0.01）.Conclusions RNA interference specifically reduces mu-opioid receptor mRNA and protein expression, leading to reversal of the fentanyl-induced inhibition on glucose-evoked insulin release of rat islets. The activation of opioid receptor induced by fentanyl functions to inhibit insulin release. The use of RNAi presents a promising tool for future research in diabetic mechanisms and a novel therapy for diabetes.

Effect of Sanhuang Jiangtang (三黄降糖) Recipe on Insulin Peripheral Resistance in Type Ⅱ Diabetes Mellitus

Objective: To observe the effect of Sanhuang Jiangtang recipe (三黄降糖, SAT) on insulinperipheral resistance in Type Ⅱdiabetes mellitus (DM). Methods:Ninety-five patients with type Ⅱ DM wererandomly divided into two groups. Fifty-three cases of SHJT group were given decoction and tablets of SAT orally for 4 -- 6 months. The efficacy was compared with that of 42 cases treated with Glipizide as the control.Before and after treatment standard steamed bread meal test was performed to measure the insulin peripheralsensitivity, insulin release to glucose and insulin sensitivity index. Results: (1 ) The total effective rates of improving insulin peripheral resistance and reducing blood sugar in SHJT group were 79. 2 % and 80. I %, whichwas equivalent to levels in the control group, but SAT recipe was more effective in relieving symptoms of Qideficiency and signs of blood stasis. (2) In SalT group, the insulin peripheral sensitivity and insulin sensitivityindex were significantly increased (P < 0. 05 and 0. of ), meanwhile the fasting blood sugar and blood sugar areawere reduced (P < 0. 05), but the change of insulin release to glucose was blunted. (3 )The lowering of bloodsugar in SHJT group was significantly negative correlated with the changing of degree of insulin peripheral sensitivity and index of insulin sensitivity (P < 0. 01 and 0. 05), but not with that of insulin area. Conclusion: Itsuggested that the treatment of SHJT recipe might decrease insulin peripheral resistance (partial reversal) bymeans of reducing hyperinsulinemia and improving insulin sensitivity.

Development of islet organoids from human induced pluripotent stem cells in a cross-linked collagen scaffold

Islets organoids would have value in the cell replacement therapy for diabetes apart from usual personalized drug screening routes.Generation of a large number of Islets like clusters,with ability to respond to glucose stimulation appears to be an ideal choice.In this study we have generated islet organoids with the ability to respond to glucose stimulation by insulin release.The source of the cells was an iPSC cell line differentiated into the pancreatic progenitors.These cells were assembled in matrigel or cross-linked collagen scaffold and compared for their efficacy to release insulin upon stimulation with glucose.The assembled organoids were examined by immunohistochemistry and expression of the relevant marker genes.The organoids showed expression of islet like markers in both-matrigel and crosslinked collagen scaffold.The islet organoids in both the cases showed release of insulin upon stimulation with glucose.The crosslinked collagen scaffold is quite stable and supports islet cells growth and function.