Streptozotocin-induced Diabetic Pigs Research Articles

Amylase-Dependent Regulation of Glucose Metabolism and Insulin/Glucagon Secretion in the Streptozotocin-Induced Diabetic Pig Model and in a Rat Pancreatic Beta-Cell Line, BRIN-BD11.

The current study was aimed at highlighting the role of blood pancreatic amylase in the regulation of glucose homeostasis and insulin secretion in a porcine model of streptozotocin- (STZ-) induced diabetes and in a rat pancreatic beta-cell line, BRIN-BD11. Blood glucose, plasma insulin, and glucagon levels were measured following a duodenal glucose tolerance test (IDGTT), in four pigs with STZ-induced type 2 diabetes (T2D pigs) and in four pigs with STZ-induced type 1 diabetes (T1D pigs). Four intact pigs were used as the control group. The effect of amylase supplementation on both acute and chronic insulin secretion was determined in a BRIN-BD11 cell line. The amylase infusion had no effect on the glucose utilization curve or glucagon levels in the healthy pigs. However, a significant lowering of insulin release was observed in healthy pigs treated with amylase. In the T2D pigs, the glucose utilization curve was significantly lowered in the presence of amylase, while the insulin response curve remained unchanged. Amylase also significantly increased glucagon release during the IDGTT in the T2D and T1D pigs, by between 2- and 4-fold. Amylase did not affect the glucose utilization curve in the T1D pigs. Amylase supplementation significantly decreased both acute and chronic insulin secretion in the BRIN-BD11 cells. These data confirm our previous observations and demonstrate the participation of pancreatic amylase in glucose absorption/utilization. Moreover, the present study clearly highlights the direct impact of pancreatic blood amylase on insulin secretion from pancreatic beta-cells and its interactions with insulin and glucagon secretion in a porcine model.

Early changes in retinal structure and BMP2 expression in the retina and crystalline lens of streptozotocin-induced diabetic pigs

PurposeThis study aims to evaluate early changes in retinal structure and BMP2 expression in the retina and crystalline lens by comparing streptozotocin-induced diabetic pigs and normal control group pigs.MethodsFive eye samples from five diabetic Micro-pigs (Medikinetics, Pyeongtaek, Korea) and five eye samples from five control pigs bred in a specific pathogen-free area were used. Diabetes was developed through intravenous injection of nicotinamide and streptozotocin, and the average fasting glucose level was maintained at 250 mg/dL or higher for 16 weeks. To evaluate BMP2 expression in the retina and crystalline lens, Western blotting was performed.ResultsIn Hematoxylin and Eosin staining, most diabetic pigs showed structural abnormalities in the inner plexiform layer. The number of nuclei in the ganglion cell layer within the range of 104 μm2 was 3.78±0.60 for diabetic pigs and 5.57±1.07 for control group pigs, showing a statistically significant difference. In immunohistochemical staining, diabetic retinas showed an overall increase in BMP2 expression. In Western blotting, the average BMP2/actin level of diabetic retinas was 1.19±0.05, showing a significant increase compared to the 1.06±0.03 of the control group retinas (P=0.016). The BMP2/actin level of diabetic crystalline lenses was similar to the control group crystalline lenses (P=0.730).ConclusionsCompared to control group pigs, the number of nuclei in the inner nuclear layer of retinas from streptozotocin-induced diabetic pigs decreased, while an increase in BMP2 expression was observed in the retina of diabetic pigs.

Positron emission tomography imaging of the glucagon-like peptide-1 receptor in healthy and streptozotocin-induced diabetic pigs

The glucagon-like peptide-1 receptor (GLP-1R) has been proposed as a target for molecular imaging of beta cells. The feasibility of non-invasive imaging and quantification of GLP-1R in pancreas using the positron emission tomography (PET) tracer [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in non-diabetic and streptozotocin (STZ)-induced diabetic pigs treated with insulin was investigated. Non-diabetic (n = 4) and STZ-induced diabetic pigs (n = 3) from the same litter were examined. Development of diabetes was confirmed by blood glucose values, clinical examinations and insulin staining of pancreatic sections post mortem. Tissue perfusion in the pancreas and kidneys was evaluated by [(15)O]water PET/computed tomography (CT) scans. The in vivo receptor specificity of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 was assessed by administration of either tracer alone or by competition with 3-6.5 μg/kg of Exendin-4. Volume of distribution and occupancy in the pancreas were quantified with a single tissue compartment model. [(15)O]water PET/CT examinations showed reduced perfusion in the pancreas and kidneys in diabetic pigs. [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 uptake in the pancreas of both non-diabetic and diabetic pigs was almost completely abolished by co-injection of unlabeled Exendin-4 peptide. [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 uptake did not differ between non-diabetic and diabetic pigs. In all animals, administration of the tracer resulted in an immediate increase in the heart rate (HR). Pancreatic uptake of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 was not reduced by destruction of beta cells in STZ-induced diabetic pigs.

Healing of Mid-Dermal Burns in a Diabetic Porcine Model

Wound healing is delayed in diabetic patients. We developed a diabetic-porcine burn model and compared the healing of partial-thickness burns in normal and diabetic pigs. We hypothesized that wound healing would be delayed in the diabetic swine. Diabetes mellitus was chemically induced in three domestic pigs (25-50 kg) by intravenous injection of streptozotocin 130 mg/kg over 30 minutes. Glucose levels were maintained between 250 and 500 mg/dl by injecting short-acting or long-acting insulin 1 unit/kg daily as needed. Three weeks later, 14 partial-thickness burns were created on the backs and flanks of each of the anesthetized pigs with a 2.5 x 2.5-cm aluminum bar preheated to 80 degrees C and applied for 20 seconds. A similar number of burns were created on three control nondiabetic pigs. The burns were treated with a topical antibiotic, and 3-mm full-thickness biopsies were taken from all wounds at 7, 10, 14, and 21 days for histomorphologic evaluation using hematoxylin and eosin staining by a board-certified dermatopathologist masked to the type of pig. The main outcome was the percentage of the wound in cross section that was reepithelialized. Comparison of outcomes between normal and diabetic pigs was performed with Student's t-tests. The diabetic pigs gained less weight, and their skin was considerably thinner than in the control pigs. Although the absolute depth of the burns was similar, the relative depth was greater in the diabetic pigs. The percentage of wound reepithelialization was lower in diabetic than in normal pigs at 7 days (1.8% [95% CI: 0-5.5] vs 65.0% [95% CI: 54.2-75.9]; P < .001) as well as at 10 days (19.2% [95% CI: 6.0-32.4] vs 76.9% [95% CI: 59.8-94.0]; P < .001) and 14 days (43.9% [95% CI: 30.4-57.4] vs 99.9% [95% CI: 92.6-100]; P < .001). All burns were completely reepithelialized at 21 days, and none of the wounds were infected. Reepithelialization of partial-thickness burns is delayed in streptozotocin-induced diabetic pigs when compared with normal pigs. It is unclear whether the delay in healing is due to the thinner skin or the metabolic consequences of diabetes or their combination.

Autologous cultured keratinocytes suspensions accelerate re-epithelialization in the diabetic pig

Abstract Introduction: Diabetes is one of the leading causes of chronic wounds in the U.S.A. Its incidence is increasing dramatically due to obesity and old age. Healing of these impaired wounds often represent a difficult challenge with the currently available treament. We recently established a delayed wound-healing model in the Yorkshire pig rendered diabetic by administration of Streptozotocin. This study evaluated epidermal regeneration in fluid treated skin wounds treated with suspensions of cultured autologous keratinocytes. Methods: Diabetes was induced by injecting Streptozotocin into a three months old female Yorkshire pig. Full thickness wounds were created on the dorsum and dressed with polyvinyl chambers to keep the wounds wet and to allow for wound fluid monitoring. Suspensions of keratinocytes were seeded into half of the wounds and Normal Saline into the remaining wounds. Serum glucose and wound fluid glucose concentrations were monitored daily. Wound contraction was monitored and biopsies taken on day 12. Results: The serum glucose was significantly increased for the duration of the experiment (>350 mg/dl). Wound fluid glucose closely followed serum glucose concentration. Transplantation of keratinocytes suspensions significantly accelerated re-epithelialization in the diabetic pig. There was no statistical difference between the contraction rates of wounds treated with a keratinocyte suspension or with normal saline. Day 12Normal SalineKeratinocytes suspensionRe-epithelialization47.8%82.6%Wound contraction33.2%32.9% Conclusions: This study shows that wound healing is delayed in the streptozotocin-induced diabetic pig model. A single-cell suspension of keratinocytes not only survives in the hyperglycemic wound environment but also contributes to the formation of a neo-epithelium, accelerating the rate of healing over saline-treated controls.

070 Epidermal Wound Healing is Delayed in Streptozotocin Induced Diabetic PIGS

Streptozotocin‐induced diabetes is a well established model of diabetes in rodents. However, these small mammals differ from humans in a number of anatomical and physiological ways, in contrast to pigs, who are more similar to humans. No diabetic pig model has been used for the study of wound healing. Our hypothesis is that re‐epithelialization would be delayed in the streptozotocin induced diabetic pig. Method: Diabetes was induced by injecting Streptozotocin into two three month old female Yorkshire pigs. 52 full thickness wounds were created on the dorsum and dressed with polyvinyl chambers to keep the wounds wet and to allow for wound fluid monitoring. Serum glucose and wound fluid glucose concentrations were monitored daily. Wound contraction was monitored and biopsies taken on multiple days for re‐epithelialization measurements. Results: The serum glucose was significantly increased for the duration of the experiment (&gt;350 mg/dl). Wound fluid glucose closely followed serum glucose concentration. There was no statistical difference between the contraction rates of wounds in diabetic pigs and healthy pigs. Re‐epithelialization was significantly delayed in diabetic wounds. Reepithelialization Day 12 Day 14 Day 16 Diabetic pig 38% 59% 82% Healthy pig 96% 100% 100% Conclusion: Epidermal regeneration of full thickness wounds is significantly delayed in the Streptozotocin induced diabetic pig. This is a very useful model of impaired wound healing because of the close similarity to human skin. The wound chambers add the advantage of monitoring and manipulating the wound environment.

Upregulation of PKC genes and isozymes in cardiovascular tissues during early stages of experimental diabetes.

The protein kinase C (PKC) pathway has recently been recognized as an important mechanism in the development of diabetic complications including cardiomyopathy and angiopathy. Although an increase in PKC kinase activity has been detected in the cardiovascular system of diabetic patients and animals, it is unclear whether the same pathological condition alters PKC at the transcriptional and translational levels. In this study we assessed quantitatively the mRNA and protein expression profiles of PKC isozymes in the heart and vascular tissues from streptozotocin-induced diabetic pigs. Partial regions of the porcine PKCalpha, beta1, and beta2 mRNAs were sequenced, and real-time RT-PCR assays were developed for PKC mRNA quantification. The results showed a significant increase in the mRNA levels of PKCalpha, beta1, and beta2 in the heart at 4-8 wk of diabetes. In concomitance, the PKCbeta1 and beta2 genes, but not the PKCalpha gene, were upregulated in the diabetic aorta. Correspondingly, there was a significant increase in the protein expression of PKCalpha and beta2 in the heart and PKCbeta2 in the aorta with a time course correlated to that of mRNA expression. In summary, PKCbeta2 was significantly upregulated in the heart and aorta at both the transcriptional and translational levels during early stages of experimental diabetes, suggesting that PKCbeta2 may be a prominent target of diabetic injury in the cardiovascular system.

Hypoglycaemic effect of Opuntia lindheimeri Englem in a diabetic pig model.

The hypoglycaemic activity of Opuntia lindheimeri Englem. was investigated in non-diabetic (control pigs) and streptozotocin-induced diabetic pigs using an enteral (oral) route of administration. Following the administration of O. lindheimeri extract (0, 250 or 500 mg/kg body weight), blood glucose concentrations in control pigs fluctuated around initial baseline concentrations, but were not consistently affected by either the dose of O. lindheimeri or by the time following administration. In contrast, administration of O. lindheimeri extract to STZ-treated pigs resulted in both a dose- (p < 0.001) and time-dependent (p < 0.001) decrease in blood glucose concentrations. The hypoglycaemic effect of the extract was apparent within 1 h of administration, with maximal effects occurring at 4 h after administration. These results confirm the hypoglycaemic effect of O. lindheimeri extract in a diabetic pig model. In addition, given the physiological similarities of the pig to humans, this model will be of tremendous use in assessing the long-term effects of Opuntia administration on the secondary problems associated with diabetes.