Citations
We aimed to quantify stress-induced hyperglycemia and differentiate the glucose response between normal animals and those with diabetes. We also examined the pattern in glucose fluctuation induced by stress according to type of diabetes.
To load psychological stress on animal models, we used a predator stress model by exposing rats to a cat for 60 minutes and measured glucose level from the beginning to the end of the test to monitor glucose fluctuation. We induced type 1 diabetes model (T1D) for ten Sprague-Dawley rats using streptozotocin and used five Otsuka Long-Evans Tokushima Fatty rats as obese type 2 diabetes model (OT2D) and 10 Goto-Kakizaki rats as nonobese type 2 diabetes model (NOT2D). We performed the stress loading test in both the normal and diabetic states and compared patterns of glucose fluctuation among the three models. We classified the pattern of glucose fluctuation into A, B, and C types according to speed of change in glucose level.
Increase in glucose, total amount of hyperglycemic exposure, time of stress-induced hyperglycemia, and speed of glucose increase were significantly increased in all models compared to the normal state. While the early increase in glucose after exposure to stress was higher in T1D and NOT2D, it was slower in OT2D. The rate of speed of the decrease in glucose level was highest in NOT2D and lowest in OT2D.
The diabetic state was more vulnerable to stress compared to the normal state in all models, and the pattern of glucose fluctuation differed among the three types of diabetes. The study provides basic evidence for stress-induced hyperglycemia patterns and characteristics used for the management of diabetes patients.
Citations
A limitation in the number of insulin-producing pancreatic beta-cells is a special feature of diabetes. The identification of alternative sources for the induction of insulin-producing surrogate beta-cells is a matter of profound importance. PDX-1/VP16, BETA2/NeuroD, and MafA overexpression have been shown to influence the differentiation and proliferation of pancreatic stem cells. However, few studies have been conducted using adult animal pancreatic stem cells.
Adult pig pancreatic cells were prepared from the non-endocrine fraction of adult pig pancreata. Porcine neonatal pancreas cell clusters (NPCCs) were prepared from neonatal pigs aged 1-2 days. The dispersed pancreatic cells were infected with PDX-1/VP16, BETA2/NeuroD, and MafA adenoviruses. After infection, these cells were transplanted under the kidney capsules of normoglycemic nude mice.
The adenovirus-mediated overexpression of PDX-1, BETA2/NeuroD and MafA induced insulin gene expression in NPCCs, but not in adult pig pancreatic cells. Immunocytochemistry revealed that the number of insulin-positive cells in NPCCs and adult pig pancreatic cells was approximately 2.6- and 1.1-fold greater than those in the green fluorescent protein control group, respectively. At four weeks after transplantation, the relative volume of insulin-positive cells in the grafts increased in the NPCCs, but not in the adult porcine pancreatic cells.
These data indicate that PDX-1, BETA2/NeuroD, and MafA facilitate the beta-cell differentiation of NPCCs, but not adult pig pancreatic cells. Therefore PDX-1, BETA2/NeuroD, and MafA-induced NPCCs can be considered good sources for the induction of pancreatic beta-cells, and may also have some utility in the treatment of diabetes.
Citations