Controlled-release neurotensin-loaded silk fibroin dressings improve wound healing in diabetic rat model

Diabetic foot ulcers(DFU),which may lead to lower extremity amputation,is one of the severe and chronic complications of diabetic mellitus.This study aims to develop,and use dressings based on Silk fibroin(SF)as the scaffold material,gelatin microspheres(GMs)as the carrier for the neurotensin(NT),a neuropeptide that acts as an inflammatory modulator in wound healing and NT as accelerate wound healing drug to treat DFU.We evaluated the wound healing processes and neo-tissue formation in rat diabetic model by macroscopic observation,histological observation(H&E staining and Masson's trichrome staining)and immunofluorescence analysis at 3,7,14,21 and 28 post-operation days.Our results show that the NT/GMs/SF group performance the best not only in macroscopic healing and less scars in 28 post-operation days,but also in fibroblast accumulation in tissue granulation,collagen expression and deposition at the wound site.From release profiles,we can know the GMs are a good carrier for control release drugs.The SEM results shows that the NT/GMs/SF dressings have an average pore size are 40–80μm and a porosity of∼85%,this pore size is suit for wound healing regeneration.These results suggest that the NT/GMs/SF dressings may work as an effective support for control release NT to promote DFU wound healing.

Effects of Shuang Dan Ming Mu Capsule on Expression of VEGF-a, VEGF-b, VEGF-c and the VEGF receptor, Flk-1, in Diabetic Retinopathy Rats

Objective The effects of Shuang Dan Ming Mu capsule on expression of VEGF-a,VEGF-b,VEGF-c and the VEGF receptor,Flk-1,were examined in a diabetic retinopathy rats model.Methods Forty Sprague-Dawley(SD)rats were randomized into Groups A(blank),B(model),C(Shuang Dan Ming Mu)and D(positive control)group,with each group containing10rats and20eyes.Rats from groups B,C and D were administered one dose of50mg/kg streptozotocin(STZ)by tail vein injection to establish a diabetic rat model.One week after model preparation,medication was continuously administered by gavage.After gavage for8weeks,the animals were sacrificed and retinal expression of VEGF-a,VEGF-b,VEGF-c and Flk-1was quantified by immunohistochemical analysis.Results At week8of drug administration after model preparation,the average protein expression grayscale values for VEGF-a,VEGF-b,VEGF-c and Flk-1in the rats model,Shuang Dan Ming Mu and positive control groups were all lower than those in the normal group,while the mean optical density values were higher than those in the normal group.When the model group was compared to the normal group,the difference was extremely significant(P<0.01).The mean grayscale values of VEGF-a,VEGF-b,VEGF-c and Flk-1in the Shuang Dan Ming Mu and positive control groups were all higher than those in the model group,while the mean optical density values were lower than those in the model group(P<0.05or0.01).Conclusion Shuang Dan Ming Mu capsule can significantly decrease the expression of VEGF-a,VEGF-b,VEGF-c and Flk-1in the retinas of diabetic model rats and exhibit some protective effects in their retinas.

Hypoglycemic and Hypolipidemic Effects of Lycium barbarum Polysaccharide in Diabetic Rats

Objective To study the antidiabetic effects and the underlying molecular mechanisms of Lycium barbarum polysaccharide（LBP） and its DEAE cellulose elution fraction LBP-IV in diabetic rats induced by high fat diet（HFD） and streptozotocin（STZ）. Methods After ig administration of LBP-IV [50, 100, and 200 mg/（kg·d）] and LBP [100 mg/（kg·d）] once daily for consecutive 4 weeks to diabetic rats, the glucose and lipids in blood, m RNA expression of phosphoenolpyruvate carboxykinase（PEPCK）, sterol regulatory element binding-protein-1c（SREBP-1c）, and fatty acid synthase（FAS） in liver were determined. Results Ig administration of LBP and LBP-IV significantly decreased the levels of blood glucose, Hb A1 c, TC, TG, and LDL-C, as well as the hepatic m RNA expression of PEPCK, SREBP-1c, and FAS, whereas significantly increased the oral glucose tolerance of diabetic rats. Conclusion The findings suggest that the antidiabetic effects of LBP and LBP-IV are associated with the decreased hepatic m RNA expression of PEPCK, SREBP-1c, and FAS in HFD-STZ induced diabetic rats.

Effects of timely insulin treatment on protection of β cells in a rat model of type 2 diabetes mellitus

Background Insulin treatment plays a key role in management of diabetes mellitus. Clinical researches showed that extra improvements in restoration of insulin secretion of pancreatic β cells were found in patients with newly diagnosed type 2 diabetes. The purpose of this study was to investigate the effects of early insulin treatment on insulin mRNA expression and morphological alterations of β cells in a Sprague Dawley (SD) rat model of type 2 diabetes. Methods A rat model of type 2 diabetes mellitus (T2DM) was induced by a high fat diet (high energy, HE) and low doses of streptozotoxin (STZ, 40 mg/kg). A group of diabetic rats was then injected with protamine zinc insulin (PZI, 1-2 U·kg -1·d -1) for one week. Insulin mRNA expression, morphological features of pancreatic islets, and metabolic parameters were examined in rats using reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and other techniques. Results In insulin-treated diabetic rats, insulin mRNA levels prominently increased by 81.3% (P<0.05), as compared with untreated diabetic rats. Moreover, timely insulin treatment noticeably improved the insulin content of β cells, with an increase of 10.2% (P<0.05), despite a slight reduction in fasting blood glucose (FBG), triglyceride (TG), and free fatty acid (FFA) levels, as compared to an untreated diabetic group. Conclusion Insulin treatment at the onset of T2DM effectively improves insulin synthesis, as confirmed by morphological changes to β cells in a rat model of type 2 diabetes.