اثر استرس رواني (محدوديت حرحتي ) مزمن بر ترشح انسولين از جزاير لانگرهانس جدا شده موش صحرايي

Effect of chronic psychological stress on insulin secretion from isolated pancreatic islets in rat

Introduction: Despite documented studies, the exact role of stress in diabetes is still unclear. In the present study the effect of chronic psychological stress on insulin release from rat pancreatic islets has been investigated. Materials and Methods: Male Wlstar rats were divided into two equal groups of control and stressed (n=8/group). The animals of the stressed group were exposed to restraint stressors (1 hour twice daily) for 15 and 30 consecutive days. At the beginning and end of the experimental periods the animals were weighed and blood samples were taken to determine the basal plasma levels of glucose, insulin and corticosterone. Following this, the pancreatic islets of 5/group of the above animals were isolated and the static release of insulin in the presence of different glucose concentrations (2.8, 5.6, 8.3, 16.7 mM) was assessed. Results: The results showed that in the stressed group fasting plasma glucose levels on the 15th day were significantly increased compared to those of the control group. However there was no significant increase on the 30th day. Fasting plasma insulin showed a significant decrease on the 15th and 30th days of the experiment in the stressed group. Stressed rats showed significantly higher basal plasma corticosterone levels, only on the 15th day, as compared to the controls. Insulin secretion from islets of the stressed group, in response to increasing concentrations of glucose, showed significant increase on the 30th day of the experiment compared to the control group. Conclusion: The results suggest that chronic psychological stress could increase response of pancreatic Beta cells to glucose and thus, low insulin levels of the stressed animals, in vivo, could be explained by reason(s) other than the reduction of Insulin release capacity of pancreatic Beta cells.