Insights into modeling streptozotocin-induced diabetes in ICR mice

Animal Models in Diabetic Research-History, Presence, and Future Perspectives

Diabetes mellitus (DM) is a very serious disease, the incidence of which has been increasing worldwide. The beginning of diabetic research can be traced back to the 17th century. Since then, animals have been experimented on for diabetic research. However, the greatest development of diabetes research occurred in the second half of the last century, along with the development of laboratory techniques. Information obtained by monitoring patients and animal models led to the finding that there are several types of DM that differ significantly from each other in the causes of the onset and course of the disease. Through different types of animal models, researchers have studied the pathophysiology of all types of diabetic conditions and discovered suitable methods for therapy. Interestingly, despite the unquestionable success in understanding DM through animal models, we did not fully succeed in transferring the data obtained from animal models to human clinical research. On the contrary, we have observed that the chances of drug failure in human clinical trials are very high. In this review, we will summarize the history and presence of animal models in the research of DM over the last hundred years. Furthermore, we have summarized the new methodological approaches, such as "organ-on-chip," that have the potential to screen the newly discovered drugs for human clinical trials and advance the level of knowledge about diabetes, as well as its therapy, towards a personalized approach.

Vitisin B, a resveratrol tetramer from Vitis thunbergii var. taiwaniana, ameliorates impaired glucose regulations in nicotinamide/streptozotocin-induced type 2 diabetic mice

Background and aim

In Taiwan, Vitis thunbergii var. taiwaniana (VTT) is used in traditional medicine and as a local tea. VTT rich in resveratrol and resveratrol oligomers have been reported to exhibit anti-obesity and anti-hypertensive activities in animal models; however, no studies have investigated type 2 diabetes mellitus (T2DM) treatments. This study aimed to investigate the anti-T2DM effects of resveratrol tetramers isolated from the VTT in nicotinamide/streptozotocin (STZ)-induced Institute of Cancer Research (ICR) mice.

Experimental procedure

The oral glucose tolerance test (OGTT) was used to imitate postprandial blood glucose (BG) regulations in mice by pre-treatment with VTT extracts, resveratrol tetramers of vitisin A, vitisin B, and hopeaphenol 30 min before glucose loads. Vitisin B (50 mg/kg) was administered to treat T2DM-ICR mice once daily for 28 days to investigate its hypoglycemic activity.

Results and conclusion

Mice pre-treated with VTT-S-95EE, or vitisin B (100 mg/kg) 30-min before glucose loading showed significant reductions (P < 0.001) in the area under the curve at 120-min (BG-AUC0-120) than those without pre-treatment with VTT-S-95 E E or vitisin B. Vitisin B-treated T2DM mice showed hypoglycemic activities via a reduction in plasma dipeptidyl peptidase (DPP)-IV activities to maintain insulin actions and differed significantly than those of untreated T2DM mice (P < 0.05), and also reduced BG-AUC0-120 and insulin-AUC0-120 in the OGTT.These in vivo results showed that VTT containing vitisin B would be beneficial for developing nutraceuticals and/or functional foods for glycemic control in patients with T2DM, which should be investigated further.

Hyperglycemia exacerbates dengue virus infection by facilitating poly(A)-binding protein-mediated viral translation

Diabetes mellitus (DM) is highly comorbid with severe dengue diseases; however, the underlying mechanisms are unclear. Patients with DM have a 1.61-fold increased risk of developing dengue hemorrhagic fever. In search of host factors involved in dengue virus (DENV) infection, we used high-glucose (HG) treatment and showed that HG increased viral protein expression and virion release but had no effects on the early stages of viral infection. After HG stimulation, DENV-firefly luciferase-transfected assay and cellular replicon-based assay indicated increased viral translation, whereas using the glucose uptake inhibitor phloretin blocked this effect. HG treatment increased the translational factor poly(A)-binding protein (PABP) in a glucose transporter-associated, PI3K/AKT-regulated manner. Silencing PABP significantly decreased HG-prompted virion production. HG enhanced the formation of the PABP-eukaryotic translation initiation factor 4G complex, which is regulated by protein-disulfide isomerase. Hyperglycemia increased PABP expression, mortality rate, viral protein expression, and viral loads in streptozotocin-induced DM mice. Overall, hyperglycemic stress facilitates DENV infection by strengthening PABP-mediated viral translation.

The Effects of Exercise Training on Glucose Homeostasis and Muscle Metabolism in Type 1 Diabetic Female Mice

Although exercise training is an important recommendation for the management of type 1 diabetes (T1D), most of the available research studies predominantly focus on male subjects. Given the importance of sex as a biological variable, additional studies are required to improve the knowledge gap regarding sex differences in T1D research. Therefore, the purpose of this study was to examine the role of exercise training in mediating changes in glucose homeostasis and skeletal muscle metabolism in T1D female mice. Female mice were injected with streptozotocin (STZ) to induce T1D. Two weeks after STZ injection, control (CON) and STZ mice were exercise trained on a treadmill for 4 weeks. Aerobic exercise training failed to improve glucose tolerance, prevent the decrease in body weight and adipose tissue mass, or attenuate muscle atrophy in T1D female mice. However, insulin sensitivity was improved in T1D female mice after exercise training. Aerobic exercise training maintained skeletal muscle triglyceride content but did not prevent depletion of skeletal muscle or liver glycogen in T1D mice. Gene expression analysis suggested that T1D resulted in decreased glucose transport, decreased ketone body oxidation, and increased fatty acid metabolism in the skeletal muscle, which was not altered by exercise training. These data demonstrate that 4 weeks of aerobic exercise training of a moderate intensity is insufficient to counteract the negative effects of T1D in female mice, but does lead to an improvement in insulin sensitivity.

Evaluation of Active Warming and Surgical Draping for Perioperative Thermal Support in Laboratory Mice

Surgical procedures are commonly performed using mice but can have major effects on their core body temperature, including development of hypothermia. In this study, we evaluated active perioperative warming with and without surgical draping with adherent plastic wrap to refine practices, improve animal welfare, and optimize research experiments. Mice were randomized into treatment groups (n = 6; 8 CD1 mice per group). Treatments included placement within a small-animal forced-air incubator at 38 ° C for 30 min before surgery (Pre), after surgery (Post), or before and after surgery (Both). To explore the effect of surgical draping, one group received incubator warming before and after surgery in addition to surgical draping (Both/ Drape), whereas another group received surgical draping only without incubator warming (Control/Drape). The final group of mice received neither warming nor draping (Control). Subcutaneous temperature transponders were placed in all mice. Approximately 5 d after transponder placement, mice were anesthetized with ketamine-xylazine and underwent laparotomy. Subcutaneous body temperatures were collected perioperatively from transponders, and rectal temperatures were taken every minute during surgery. For recovery from anesthesia, mice were placed either in a standard cage on a warm water blanket set to 38 °C (100.4 °F) or in the incubator. Subcutaneous body temperatures were significantly higher in mice prewarmed for 30 min (Pre, Both, Both/Drape) as compared with mice that were not prewarmed. Anesthetic recovery times were significantly longer for mice placed in the incubator (Pre, Post, Both, Both/Drape) than for those that did not receive incubator warming (Control, Control/Drape). Mean intraoperative rectal temperatures of Both/Drape mice tended to be greater than those of mice in the Both group, suggesting a warming benefit of surgical draping. Using a forced air incubator and adherent plastic draping mitigated body temperature loss in mice during both surgery and postoperative recovery.

Biological Effects of EGCG@MOF Zn(BTC)4 System Improves Wound Healing in Diabetes

Tea contains high levels of the compound epigallocatechin gallate (EGCG). It is considered an important functional component in tea and has anti-cancer, antioxidant, and anti-inflammatory effects. The eight phenolic hydroxyl groups in EGCG’s chemical structure are the basis for EGCG’s multiple biological effects. At the same time, it also leads to poor chemical stability, rendering EGCG prone to oxidation and isomerization reactions that change its original structure and biological activity. Learning how to maintain the activity of EGCG has become an important goal in understanding the biological activity of EGCG and the research and development of tea-related products. Metal–organic frameworks (MOFs) are porous materials with a three-dimensional network structure that are composed of inorganic metals or metal clusters together with organic complexes. MOFs exploit the porous nature of the material itself. When a drug is an appropriate size, it can be wrapped into the pores by physical or chemical methods; this allows the drug to be released slowly, and MOFs can also reduce drug toxicity. In this study, we used MOF Zn(BTC)₄ materials to load EGCG and investigated the sustained release effect of EGCG@MOF Zn(BTC)₄ and the biological effects on wound healing in a diabetic mouse model.

Toxicological screening and evaluation of anti-allergic and anti-hyperglycemic potential of Sonneratia caseolaris (L.) Engl. fruits

Background

Sonneratia caseolaris (L.) Engl. (S. caseolaris) belonging to the Sonneratiaceae family is commonly known as Ora. It is traditionally used as an astringent, antiseptic, to treat sprains, swellings, cough and in arresting hemorrhage. The ethanolic extract of S. caseolaris (L.) Engl. fruits was investigated in the present study for its toxicity as well as anti-allergic and anti-hyperglycemic potentials.

Methods

Major phenolic compounds were identified and quantified by HPLC. Behavioral change, body weight, mortality and different blood parameters were measured to assess the toxicological effect of the extract. Anti-allergic activity was evaluated using TDI-induced allergic model mice. Oral glucose tolerance test (OGTT) and STZ-induced diabetic mice were used to evaluate the anti-hyperglycemic activity.

Results

Crude extract contained ellagic acid, vanillic acid and myrecitin (27.41, 3.06 and 7.93 mg per 100 g dry extract respectively). No major toxicity was observed in both acute and sub-acute toxicity study. Oral administration of the extract significantly ameliorated TDI-induced allergic symptoms like sneezing, scratching, swelling, redness and watery rhinorrhoea in the experimental mice. The extracts also reduced the total and differential count of leukocytes in the blood. The extract treated mice showed significant reduction in blood glucose, SGOT, SGPT, cholesterol, triglycerides, urea, creatinine and bilirubin level.

Conclusions

S. caseolaris contains bioactive phytoconstituents which may be the possible precursors to isolate and characterize the novel compounds targeting the diseases like allergy and diabetes.

EGCG targeting Notch to attenuate renal fibrosisviainhibition of TGFβ/Smad3 signaling pathway activation in streptozotocin-induced diabetic mice

EGCG may improve renal fibrosis by targeting Notchviainhibition of the TGFβ/Smad3 pathway in diabetic mice.

Effects of Cannabidiol on Diabetes Outcomes and Chronic Cerebral Hypoperfusion Comorbidities in Middle-Aged Rats

Diabetes and aging are risk factors for cognitive impairments after chronic cerebral hypoperfusion (CCH). Cannabidiol (CBD) is a phytocannabinoid present in the Cannabis sativa plant. It has beneficial effects on both cerebral ischemic diseases and diabetes. We have recently reported that diabetes interacted synergistically with aging to increase neuroinflammation and memory deficits in rats subjected to CCH. The present study investigated whether CBD would alleviate cognitive decline and affect markers of inflammation and neuroplasticity in the hippocampus in middle-aged diabetic rats submitted to CCH. Diabetes was induced in middle-aged rats (14 months old) by intravenous streptozotocin (SZT) administration. Thirty days later, the diabetic animals were subjected to sham or CCH surgeries and treated with CBD (10 mg/kg, once a day) during 30 days. Diabetes exacerbated cognitive deficits induced by CCH in middle-aged rats. Repeated CBD treatment decreased body weight in both sham- and CCH-operated animals. Cannabidiol improved memory performance and reduced hippocampal levels of inflammation markers (inducible nitric oxide synthase, ionized calcium-binding adapter molecule 1, glial fibrillary acidic protein, and arginase 1). Cannabidiol attenuated the decrease in hippocampal levels of brain-derived neurotrophic factor induced by CCH in diabetic animals, but it did not affect the levels of neuroplasticity markers (growth-associated protein-43 and synaptophysin) in middle-aged diabetic rats. These results suggest that the neuroprotective effects of CBD in middle-aged diabetic rats subjected to CCH are related to a reduction in neuroinflammation. However, they seemed to occur independently of hippocampal neuroplasticity changes.

Wdr13 and streptozotocin-induced diabetes

Type I diabetes, though contributes to only 5–10% of total diabetes cases, is a rising concern in today’s world. Our previous studies have shown that the absence of WDR13 in mouse results in pancreatic β-cell hyper-proliferation. Also, amelioration of the diabetic phenotype on introgression of Wdr13-null (Wdr13^-/0) mutation in genetically diabetic mice (Lepr^db/db) [type II diabetes] was observed. It was thus, interesting to see the role of WDR13 in streptozotocin-mediated diabetes in mice, a model for type I diabetes. Wdr13^-/0 mice along with its wild type (Wdr13^+/0 mice) littermates were administered streptozotocin intraperitoneally for 5 consecutive days. Blood glucose levels and body weights of these mice were monitored for subsequent 5 weeks and then they were sacrificed for physiological and histological analyses. Results showed that Wdr13^-/0 mice exhibited higher serum insulin levels, better glucose clearance and significantly higher number of proliferating β-cells; reiterating the finding that absence of WDR13 helps in β-cell hyper-proliferation and recovery from diabetes; further underscoring WDR13 as a key target molecule for diabetes treatment/amelioration.

Chronic folate deficiency induces glucose and lipid metabolism disorders and subsequent cognitive dysfunction in mice

Previous studies have shown that folate levels were decreased in patients with type 2 diabetes (T2D) and further lowered in T2D patients with cognitive impairment. However, whether folate deficiency could cause T2D and subsequent cognitive dysfunction is still unknown. The present study aimed to explore the effects of chronic folate deficiency (CFD) on glucose and lipid metabolism and cognitive function in mice. Seven-week-old mice were fed with either a CFD or control diet for 25 weeks. Serum folate was significantly reduced, whereas serum total homocysteine was significantly increased in the CFD group. Moreover, CFD induced obesity after a 6-week diet treatment, glucose intolerance and insulin resistance after a 16-week-diet treatment. In addition, CFD reduced the hepatic p-Akt/Akt ratio in response to acute insulin administration. Moreover, CFD increased serum triglyceride levels, upregulated hepatic Acc1 and Fasn mRNA expression, and downregulated hepatic Cd36 and ApoB mRNA expression. After a 24-week diet treatment, CFD induced anxiety-related activities and impairment of spatial learning and memory performance. This study demonstrates that folate deficiency could induce obesity, glucose and lipid metabolism disorders and subsequent cognitive dysfunction.

Wound healing can be improved by (-)-epigallocatechin gallate through targeting Notch in streptozotocin-induced diabetic mice

Delayed wound healing is one of the most prominent clinical manifestations of diabetes and lacks satisfactory treatment options. Persistent inflammation occurs in the late phase of wound healing and impairs the healing process in mice with diabetes mellitus (DM). In this study, we observed that the late wound healing in streptozotocin (STZ)-induced DM mice could be improved by (-)-epigallocatechin gallate (EGCG). The macrophage accumulation, inflammation response, and Notch signaling can be inhibited by EGCG in the skin wounds of DM mice. Furthermore, we found that the LPS-induced inflammation response including overactivated Notch signaling, was inhibited by EGCG in mouse macrophages. Moreover, we confirmed that EGCG could directly bind with mouse Notch-1. In addition, our studies indicated that diabetic wound healing was improved by EGCG treatment before or after the inflammation phase by targeting the Notch signaling pathway, which suggests that the pre-existing diabetic wound healing can be improved by EGCG. To summarize, wound healing can be improved by EGCG through targeting Notch in STZ-induced DM mice. Our findings provide insight into the therapeutic strategy for diabetic wounds and offer EGCG as a novel potential medicine to treat chronic wounds.-Huang, Y.-W., Zhu, Q.-Q., Yang, X.-Y., Xu, H.-H., Sun, B., Wang, X.-J., Sheng, J. Wound healing can be improved by (-)-epigallocatechin gallate through targeting Notch in streptozotocin-induced diabetic mice.

Softened food reduces weight loss in the streptozotocin-induced male mouse model of diabetic nephropathy

The streptozotocin (STZ)-induced diabetic mouse is a widely used model of diabetes and diabetic nephropathy (DN). However, it is a well-known issue that this model is challenged by high weight loss, which despite supportive measures often results in high euthanization rates. To overcome these issues, we hypothesized that supplementing STZ-induced diabetic mice with water-softened chow in addition to normal chow would reduce weight loss, lower the need for supportive treatment, and reduce the number of mice reaching the humane endpoint of 20% weight loss. In a 15 week STZ-induced DN study we demonstrated that diabetic male mice receiving softened chow had reduced acute weight loss following STZ treatment ( p = 0.045) and additionally fewer mice were euthanized due to weight loss. By supplementing the diabetic mice with softened chow, no mice reached 20% weight loss whereas 37.5% of the mice without this supplement reached this humane endpoint ( p = 0.0027). Excretion of corticosterone metabolites in faeces was reduced in diabetic mice on softened chow ( p = 0.0007), suggesting lower levels of general stress. Finally, it was demonstrated that the water-softened chow supplement did not significantly affect the induction of key disease parameters, i.e. %HbA1C and albuminuria nor result in abnormal teeth wear. In conclusion, supplementation of softened food is refining the STZ-induced diabetic mouse model significantly by reducing stress, weight loss and the number of animals sacrificed due to humane endpoints, while maintaining the key phenotypes of diabetes and nephropathy.

Hair corticosterone measurement in mouse models of type 1 and type 2 diabetes mellitus

In diabetes, glucocorticoid secretion increases secondary to hyperglycemia and is associated with an extensive list of disease complications. Levels of cortisol in humans, or corticosterone in rodents, are usually measured as transitory biomarkers of stress in blood or saliva. Glucocorticoid concentrations accumulate in human or animal hair over weeks and could more accurately measure the cumulative stress burden of diseases like chronic diabetes. In this study, corticosterone levels were measured in hair in verified rodent models of diabetes mellitus. To induce type 1 diabetes, C57BL/6J mice were injected with streptozotocin and blood and hair samples were collected 28days following induction. Leptin receptor deficient (db/db) mice were used as a spontaneous model of type 2 diabetes and blood and hair samples were collected at 8weeks of age, after the development of hyperglycemia and obesity. Corticosterone levels from serum, new growth hair and total growth hair were analyzed using an enzyme immunoassay. Corticosterone levels in new growth hair and serum were significantly elevated in both models of diabetes compared to controls. In contrast, corticosterone levels in old hair growth did not differ significantly between diabetic and non-diabetic animals. Thus, hair removal and sampling of new hair growth was a more sensitive procedure for detecting changes in hair corticosterone levels induced by periods of hyperglycemia lasting for 4weeks in mice. These results validate the use of hair to measure long-term changes in corticosterone induced by diabetes in rodent models. Further studies are now needed to validate the utility of hair cortisol as a tool for measuring the stress burden of individuals with diabetes and for following the effects of long-term medical treatments.

Extracted Triterpenes from Antrodia cinnamomea Reduce the Inflammation to Promote the Wound Healing via the STZ Inducing Hyperglycemia-Diabetes Mice Model

This research evaluated the effects of triterpenes on the regulation of STZ-induced hyperglycaemic diabetes through an anti-inflammatory response. Diabetic mice were orally administered various concentrations of triterpenes on a daily basis. Weight gain, volume of drinking water, and liver and spleen weight were recorded and evaluated. These evaluations presented a positive regulation to the abnormal metabolism appearance compared to the diabetic mice. In the diabetic mice, the detection of adiponectin production or elevated levels of inflammatory factors such as CCL1 and TPO expression were found to reduce hyperglycaemia and thereby induce an inflammatory response. Moreover, to the best of our knowledge, hyperglycaemia impairs the tissue healing associated with an increased and prolonged inflammatory response. An investigation of the anti-inflammatory response in wound healing as affected by the triterpenes verified the promotion of wound recovery.

Animal models for diabetes: Understanding the pathogenesis and finding new treatments

Diabetes mellitus is a lifelong, metabolic disease that is characterised by an inability to maintain normal glucose homeostasis. There are several different forms of diabetes, however the two most common are Type 1 and Type 2 diabetes. Type 1 diabetes is caused by the autoimmune destruction of pancreatic beta cells and a subsequent lack of insulin production, whilst Type 2 diabetes is due to a combination of both insulin resistance and an inability of the beta cells to compensate adequately with increased insulin release. Animal models are increasingly being used to elucidate the mechanisms underlying both Type 1 and Type 2 diabetes as well as to identify and refine novel treatments. However, a wide range of different animal models are currently in use. The majority of these models are suited to addressing certain specific aspects of diabetes research, but may be of little use in other studies. All have pros and cons, and selecting an appropriate model for addressing a specific question is not always a trivial task and will influence the study results and their interpretation. Thus, as the number of available animal models increases it is important to consider the potential roles of these models in the many different aspects of diabetes research. This review gathers information on the currently used experimental animal models of both Type 1 and Type 2 diabetes and evaluates their advantages and disadvantages for research purposes and details the factors that should be taken into account in their use.

A novel mice model of metabolic syndrome: the high-fat-high-fructose diet-fed ICR mice

Currently, the metabolic syndrome (MS) is occurring at growing rates worldwide, raising extensive concerns on the mechanisms and therapeutic interventions for this disorder. Herein, we described a novel method of establishing MS model in rodents. Male Institute of Cancer Research (ICR) mice were fed with high-fat-high-fructose (HFHF) diet or normal chow (NC) respectively for 12 weeks. Metabolic phenotypes were assessed by glucose tolerance test, insulin tolerance test and hyperinsulinemic-euglycemic clamp. Blood pressure was measured by a tail-cuff system. At the end of the experiment, mice were sacrificed, and blood and tissues were harvested for subsequent analysis. Serum insulin levels were measured by ELISA, and lipid profiles were determined biochemically. The HFHF diet-fed ICR mice exhibited obvious characteristics of the components of MS, including obvious obesity, severe insulin resistance, hyperinsulinemia, dislipidemia, significant hypertension and hyperuricemia. Our data suggest that HFHF diet-fed ICR mice may be a robust and efficient animal model that could well mimic the basic pathogenesis of human MS.

Differential anti-diabetic effects and mechanism of action of charantin-rich extract of Taiwanese Momordica charantia between type 1 and type 2 diabetic mice

Momordica charantia Linn. (Cucurbitaceae), also called bitter melon, has traditionally been used as a natural anti-diabetic agent for anti-hyperglycemic activity in several animal models and clinical trials. We investigated the differences in the anti-diabetic properties and mechanism of action of Taiwanese M. charantia (MC) between type 1 diabetic (T1D) and type 2 diabetic (T2D) mice. To clarify the beneficial effects of MC, we measured non-fasting glucose, oral glucose tolerance, and plasma insulin levels in KK/HIJ mice with high-fat diet-induced diabetes (200 mg/kg/day of charantin-rich extract of MC [CEMC]) and in ICR mice with STZ-induced diabetes. After 8 weeks, all the mice were exsanguinated, and the expression of the insulin-signaling-associated proteins in their tissue was evaluated, in coordination with the protective effects of CEMC against pancreatic β-cell toxicity (in vitro). Eight weeks of data indicated that CEMC caused a significant decline in non-fasting blood glucose, plasma glucose intolerance, and insulin resistance in the KK/HIJ mice, but not in the ICR mice. Furthermore, CEMC decreased plasma insulin and promoted the sensitivity of insulin by increasing the expression of GLUT4 in the skeletal muscle and of IRS-1 in the liver of KK/HIJ mice; however, CEMC extract had no effect on the insulin sensitivity of ICR mice. In vitro study showed that CEMC prevented pancreatic β cells from high-glucose-induced cytotoxicity after 24 h of incubation, but the protective effect was not detectable after 72 h. Collectively, the hypoglycemic effects of CEMC suggest that it has potential for increasing insulin sensitivity in patients with T2D rather than for protecting patients with T1D against β-cell dysfunction.

The use of animal models in diabetes research

Diabetes is a disease characterized by a relative or absolute lack of insulin, leading to hyperglycaemia. There are two main types of diabetes: type 1 diabetes and type 2 diabetes. Type 1 diabetes is due to an autoimmune destruction of the insulin-producing pancreatic beta cells, and type 2 diabetes is caused by insulin resistance coupled by a failure of the beta cell to compensate. Animal models for type 1 diabetes range from animals with spontaneously developing autoimmune diabetes to chemical ablation of the pancreatic beta cells. Type 2 diabetes is modelled in both obese and non-obese animal models with varying degrees of insulin resistance and beta cell failure. This review outlines some of the models currently used in diabetes research. In addition, the use of transgenic and knock-out mouse models is discussed. Ideally, more than one animal model should be used to represent the diversity seen in human diabetic patients.

Single dose streptozotocin-induced diabetes: considerations for study design in islet transplantation models

Streptozotocin (STZ)-induced diabetes mellitus (DM) offers a very cost-effective and expeditious technique that can be used in most strains of rodents, opening the field of DM research to an array of genotypic and phenotypic options that would otherwise be inaccessible. Despite widespread use of STZ in small animal models, the data available concerning drug preparation, dosing and administration, time to onset and severity of DM, and any resulting moribundity and mortality are often limited and inconsistent. Because of this, investigators inexperienced with STZ-induced diabetes may find it difficult to precisely design new studies with this potentially toxic chemical and account for the severity of DM it is capable of inducing. Until a better option becomes available, attempts need to be made to address shortcomings with current STZ-induced DM models. In this paper we review the literature and provide data from our pancreatic islet transplantation experiments using single high-dose STZ-induced DM in NCr athymic nude mice with hopes of providing clarification for study design, suggesting refinements to the process, and developing a more humane process of chemical diabetes induction.