جستجوی مقالات مرتبط با کلیدواژه « جزایر لانگرهانس » در نشریات گروه « پزشکی »

Stressful events in early-life induce metabolic disorders in adolescence. The aim of this study was to investigate the effect of early-life stress on number or area of Langerhans islets in exposure to foot-shock and psychological stress in male rats.

The rats were divided into six groups: control (without stress), early-stress (stress at 2 weeks of age), pubertal-foot shock (at 8-10 weeks of age), pubertal-psychological stress (psychological stress at 8-10 weeks of age), early-stress + pubertal-foot shock (stress at 2 weeks and foot-shock at 8-10 weeks of age), early-stress + pubertal-psychological stress (early-stress at 2 weeks and psychological stress at 8-10 weeks of age). Stress was induced for five consecutive days (twice daily). At the end of the experiment, following anesthesia with pentobarbital, the rats were decapitated and dissected to remove pancreas tissue to measure the number and area of islets.

Early-life and pubertal stresses alone did not change the number or area of islets. Compared to other interventions, early-life psychological-stress could considerably change the number or area of pancreatic islets.

Early life stress predisposes the organism to morphological changes in endocrine pancreas as an increase in Langerhans islets number or area in exposure to stress later in life.

Background and Cadmium is a highly toxic industrial and environmental pollutant that is known as an important risk factor for developing diabetes. Oxidative stress is reported to be highly associated with diabetes and its complications. The aim of this study was to evaluate the effects of cadmium on oxidative stress response and secretory function of islets of Langerhans from rat pancreas.
Male Sprague-Dawley rats weighing 260-230 g, were divided into two groups, including a control and an experimental group that received cadmium chloride. After intraperitoneal glucose tolerance test (IPGTT) on day 30, the animals were deeply anesthetized and the pancreas was removed for pancreatic islet isolation. Oxidative stress, islet insulin content and secretion were also evaluated in pancreas.
The findings showed a significant increase in blood glucose concentration and significant decreases in body weight, blood insulin level, insulin content, and secretion of pancreatic islet in response to glucose concentrations in cadmium exposed group compared with those of the control group (P In this study, cadmium led to increase in oxidative stress which can be an important factor in the decreased insulin synthesis and secretion from pancreatic beta cells.

According to traditional medicine as hypoglycemic Cyperus Rotundus rhizome, the aim of this study was to investigate the effect of Cyperus Rotundus rhizome on insulin secretion from the islets of Langerhans isolated male mouse. Subjects and This experimental study was carried out on 90 adult Nmari male mice (20-25gr). Pancreatic islets of Langerhans from intact mice were isolated by collagenase digestion method. Then aqueous and 80% methanol extract of Cyperus Rotundus rhizome at 0.1, 0.5 and 1% concentrations and also glyburide at 1 and 10μM applied on isolated islets in culture medium containing three different glucose concentrations (2.8, 5.6 and 16.7 mM). Insulin secretion from islets was evaluated in incubation system and insulin was measured using an ELISA kit. Data analyzed using spss14 and ANOVA test. Insulin secretion significantly increased at 16.7 mM glucose concentration compared with 2.8 mM concentration (p<0.05). In 2.8 and 5.6 mM glucose, glyburide 10μM could increase insulin secretion significantly (p<0.001). Aqueous extract (0.05 and 0.1 percent) in the presence of glucose 2.8 (p<0.001) and 5.6mM (p<0.05) caused the significant increase in insulin secretion, but in the presence of glucose, 16.7mM a significant reduction in insulin production was seen. The results showed that the methanolic extract couldn’t increase the amount of insulin secretion, significantly. The results of this study showed beneficial effects of lower doses (0.05 and 0.1 percent) aqueous extract of Cyperus Rotundus rhizome are the increased secretion of insulin. Probably this plant through effects on insulin secretion islets and, of course, at low doses, can be effective in the treatment of diabetes. ►Please cite this paper as: Ahangarpour A, Ahmadi I, Fathi Moghaddam H. The Effect of Aqueous and Methanolic Extract of Cyperus Rotundus Rhizome on Insulin Secretion from Pancreatic Islets in Male Mouse. Jundishapur Sci Med J 2016;14(6):623-631.

Since aloe vera plant has many medical benefits, the present study aimed to investigate the protective effects of Aloe vera gel on the pancreatic islets and beta cells. This experimental study consisted of 50 mature male rats aged 2-3 months and weighed 200-250 g, who were randomly divided into five groups (n=10). Group I (control) did not receive any treatments, and group II were diabetized via Streptozotocin (IP) in 65 mg/kg, whose blood sample was taken after one week. Rats with blood glucose more than 250 mg/dL were considered as diabetic. Group III diabetic rats received the Aloe vera gel daily with dosage of 400 mg/kg, and group IV diabetic rats received insulin in 10 units/rat. Group V involved healthy rats which received only Aloe vera gel. After the last Aloe vera gel administration, blood glucose and body weight of all groups were measured on 15th and 30th days. Animals were euthanized with ether. Then tissues samples were collected from pancreas gland and fixed in 10% neutral buffered formalin solution. The 5-6 µ sections were made by paraffin embedding method and stained using haematoxylin-eosin (H&E) and Aldehyde fuchsin stains. Ultimately, the histomorphometrical parameters were evaluated. The mean number and size of pancreatic islets and beta cells of Langerhans islets decreased significantly in the diabetic group compared to the control group. The number of beta cells and diameter of langerhans islets increased significantly in the rats treated by Aloe vera gel in comparison to diabetic group at the end of 15th and 30th days. Applying Aloe vera gel seems to improve the renewal and restoration of langerhans islets and beta cells of pancreas gland in the diabetic rat.

Nowadays according to our life style high percent of people are exposed to different acute stressors which may result in various metabolic disorders. In order to more clarify the effect of acute psychological stress، which is very common in the societies، on insulin secretion from isolated islets the present study was designed. Animals were divided into control and experimental groups (n= 6/group). Stress was induced acutely by a communication box. Then insulin secretion from isolated islets of Langerhans was studied statically. Plasma glucose، insulin and corticosterone levels were measured. In addition the adrenal glands’ weight was also evaluated. Acute psychological stress did not change basal plasma corticosterone levels significantly. Whereas، immediately after acute exposure to stress، plasma corticosterone level significantly increased compared to the control group. Acute stress increased plasma insulin concentration markedly. The weight of adrenal glands and HOMA-IR index showed no significant change in the experimental group. Stress exposure resulted in no significant change of insulin secretion from islets. From the results of the present study، it could be concluded that application of acute psychological stress، despite the significant increase of plasma corticosterone concentration did not change insulin secretion from isolated islets of Langerhans.

It has been shown that Capparis spinosa fruit has hypoglycemic، antioxidant، antiinflammatory، and analgesic properties. The aim of the present study was to determine the effects of Capparis spinosa fruit on histomorphological changes in pancreas after triggering diabetes mellitus in male rats. Forty Wistar rats (150- 200 g، 6 weeks of age) were randomly divided into five equal groups of 8 animals. Groups III، IV and V received intraperitoneal injection of streptozotocin. Blood glucose of the groups was measured، using a glucometer، after 72 hours. After 10 days، Group II، IV and V daily received 30، 20 and 30 mg/kg extract of Capparis spinosa respectively، for three weeks. Blood glucose was measured in the beginning of the study and at the end of every week. Besides، insulin of the blood was measured at the end of the study. The number of β cells and diameter of islets of Langerhans were determined using hematoxylin- phloxine staining. The collected data was analyzed by means of one-way ANOVA، using SPSS software (V: 13). Mean number of β cells and diameter of the islets significantly decreased in the diabetic control group compared to the nondiabetic controls. Histological assessments showed a significant increase in the number of β cells، diameter of islets، and amount of insulin in groups treated with hydroalcoholic extract of Caparis Spinosa compared to the diabetic control group. Administration of Capparis spinosa extract could increase the number of β cells and improve the function of damaged pancreas in diabetic rats.

It has been shown that the Juglans regia leaves have hypoglycemic، diuretic and blood pressure reduction properties. The objective of the present study was to examine the histopathology effects of Juglans regia leaves on diabetes mellitus in rats.

Forty-eight Wistar rats (150- 200 g) were randomized into six groups of 8 animals. Groups III، IV، V and VI received intraperitoneal injection of streptozotocin to make diabetic model. Blood glucose was measured by glucometer after 72 hours. After 10 days، Group II، IV and V received 400، 200 and 400 mg/kg Juglans regia extract، respectively and group VI treated with 4 mg/kg glybenclamid for four weeks. Group I were fed with normal diet and group III received distilled water (diabetic control). The body weight and blood glucose were measured in every week. The number of β cells and diameter of islets of Langerhans were determined using hematoxylin-floxin staining. The collected data was analyzed by the SPSS software using one-way ANOVA.

The number of β cells and diameter of islets decreased significantly in diabetic control compare to the normal group. Treatment with 400 mg/kg of Juglans regia extract showed a significant decrease in blood glucose، a significant increase in diameter of islets and number of β cells compared to diabetic control group. The pancreas / body weight ratio increased in diabetic rats compare to the treatment group.

The administration of Juglans regia extract can cause recovery of β cells number and improve the size of islets of Langerhans in diabetic model rats.

Vaccinium arctostaphylos is one of the medicinal plants used in the treatment of diabetes. But the mechanisms responsible for its antidiabetic action have not been well defined. This study was undertaken to investigate the possible effect of V. arctostaphylos on insulin release from rat-isolated Langerhans islets. The islets were incubated in the presence of 3 or 10 mM glucose with or without milrinone (0.1 and 0.01%) and hydro-alcoholic extract of V. arctostaphylos (0.1 and 0.1%) for 60 min. The concentration of insulin was measured in samples of incubation medium. The increase of glucose concentration in incubation medium from 3 to 10 mM resulted in a significant increase of insulin secretion. Milrinone at 0.1 mM significantly increased insulin release evoked by 10 mM glucose. However, none of the extract concentrations affected the insulin release. Our data demonstrated that V. arctostaphylos had no insulinotropic property and its effects on diabetes mediated by other mechanisms which should be clarified in future studies.

Metformin is a widely used medicine for treatment of type 2 diabetes. In this study, the effect of various doses of metformin on the mouse islets of langerhans volume was investigated. Twenty four C57BL/6 adult male mice weighting 30±5 gr were randomly divided into 4 groups. Normal saline was given to the control group (group 4) and the experimental groups (groups 1-3) received 75, 150 and 300 mg/kg metformin daily by intraperitoneal injection for seven days. One day after the last injection the mice were sacrificed by cervical dislocation and their pancreases were fixed in 10% formalin for histological studies. The volume of the islets of langerhans was estimated by using Cavalieri method. Volume of the islets of langerhans in doses of 75 and 150 mg/kg Metformin showed a non-significant difference in comparison to control group (P>0.05). 300 mg/kg metformin treated mice showed a significant increase in islets of langerhans volume compared to the control group (P<0.05). Metformin increases in the islets of langerhans volume in a dose-dependent manner. Increasing effects of Metformin on the islets of langerhans volume may be due to proliferation or hypertrophy of beta cells.

Recent data shows that retinoic acid (RA) signaling is required for early pancreatic development in animals, whereas the effects of exogenous All-trans Retinoic Acid (ATRA) on gestation day (GD) 10 in later development have not been well documented.

In this experimental interventional study, female rats, were randomly divided into two groups (experimental and control, n=5 each). Animals in the experimental group received single dose (100 mg /kg) of ATRA orally on GD 10 and fetuses were observed on GD 18.The fetus pancreas (from both the experimental and control groups each n=24) were processed for staining and followed by measuring the accumulation of pancreatic acinus and pancreatic ductile associated with the islets of langerhans. In addition, the mean diameter of pancreatic acinus, acinar cells and related nucleus were measured. Statistical analysis was done by student t-test, P value<0.05 being considered significant.

In the experimental embryos on GD 18, the mean accumulation of pancreatic acinus (23.5%), and pancreatic ductile, associated with the islets of langerhans (76%) per field were increased. There was a significant difference in accumulation of pancreatic acinus (P< 0.0001) and pancreatic ductile, associated with the islets of langerhans (P< 0.0001), between the groups in this regard. The mean diameter of pancreatic acinus and the related nucleus were compared in the two groups, and results showed significant (P< 0.0001) decrease of this parameter in the experimental group.

Results suggest that ATRA may have positive effects on proliferation, differentiation and maturation of pancreatic acinus and pancreatic ductile associated with the islets of langerhans.

Teucrium Polium (Labiatae) grows widespread in Iran and reduces blood sugar in-vivo. To examine the mechanism of this effect, in this study we explored the effects of aqueous-alcoholic extract of this plant on insulin secretion of isolated rat pancreatic islets. In this experimental study, the upper parts of the plant (stem, flowers and leaves) have been ground and extracted by incubating in 500ml of 50% alcohol at 40 oC for 72 hours. Then the solvent was evaporated in vacuum and reconstituted in DMSO which diluted with Kreb's solution, rats were anesthetized with thiopental, for isolation of Islets, in each experiment. The pancreases were isolated and digested with collagenase and isolated islets were collected manually under a stereomicroscope. Isolated islets were pre-incubated in Kreb’s buffer with 3mM for 30min and then incubated with glucose 3mM or 10mM) with or without Isobutyl-Methylxanthine (IBMX) or the extract (0.1% and 1%) for one hour. Our results showed that 10mM glucose stimulated insulin secretion. IBMX augmented glucose-induced insulin release (GIIR) in a dose-dependent manner. However, the extract, in concentration of 0.1%, did not change GIIR and in a concentration of 1% significantly decreased GIIR. Teucrium Polium extract has not insulinotropic property. The mechanism of inhibitory effect of the extract in the concentration of 1% is not clear and is may be due to the toxicity which the extract produces in high concentrations. We may conclude that the in vivo hypoglycemic effect of is probably the result of changing the rate of glucose metabolism or increasing the sensitivity of peripheral tissue to insulin.

Gamma-amino butyric acid (GABA), an amino acid, present in some inhibitory neurons of the central nervous system, is also found in relatively high levels in the islets of Langerhans. Results of different studies concerning the effect of GABA on insulin secretion are controversial. The aim of this study was to determine the role of GABA and GABAB receptors on glucose-stimulated insulin secretion in isolated islets of rats. The collagenase digestion technique was used to isolate the islets from pancreata of 45 male Wistar rats (200-250g). Insulin secretion was assessed in eight islets in each cup exposed to different concentrations of glucose (8.3 and 16.7 mM) in the presence or absence of GABA(25, 50, 100 µM), baclofen (10, 20, 50 µM) (GABAB agonist) and saclofen (50,100 µM) (GABAB antagonist). Insulin concentration was measured by the ELISA method. Insulin release was reported as mean±SEM U/islet/50min and p values of <0.05 were considered significant. GABA inhibited glucose (8.3 and 16.7 mM)-induced insulin secretion in isolated islets (P<0.05). Different concentrations of baclofen had no significant effect on glucose-induced insulin secretion however glucose (16.7mM) stimulated insulin secretion in the presence of 100 µM saclofen (91±8.8 µU/islet/60min) was significantly (p<0.05) higher compared to insulin secretion stimulated by 16.7mM glucose alone (67.7±2.58 µU/islet/60min). These findings indicate that GABA has an inhibitory effect on glucose-induced insulin secretion and therefore it may play a regulatory role in insulin secretion. This effect needs to be taken in to account in the pathophysiology of diabetes.

Regarding the adverse effect of stress on glycemic control in type 2 diabetic patients, the present study investigates the function of Glibenclamide on insulin release from β cells of rat pancreatic islets, subsequent to chronic psychological stress exposure. In this study 30 male Wistar rats were divided into equal groups of control and experiment (5 groups). Four different restraint stressors with random sequence were used 1h twice daily for 15 and 30 days. 24 hours after the last stress session, static insulin secretion from isolated pancreatic islets of each animal were evaluated in the presence of 5.6, 8.3 and 16.7 mM glucose. Also insulin release in response to 5.6 mM glucose in the presence of 10 μM Glibenclamide was evaluated. The insulin release from isolated islets of the stress experienced animals was significantly increased only on the 30th day as compared to the control animals. In the experiment group, insulin release from the islets in the presence of 5.6 mM glucose alone was significantly increased on the 15th and 30th days as compared to the first day. However, in the control group there was no significant increase in insulin release at the similar conditions. In contrast to the control group, insulin release in response to 5.6 mM glucose in the presence of 10 μM Glibenclamide revealed no significant difference in the experiment group on the 1st 15th and 30th days as compared to the insulin release in the presence of 5.6 mM glucose alone. Insulin release from the isolated islets exposed to 5.6 mM glucose in the presence of 10 μM Glibenclamide, on different experimental days was not significantly different between the control and experiment groups. According to the results of this study, it appears that chronic psychological stress decreases the responsiveness of pancreatic β cells to Glibenclamide, subsequently could prevent the augmentation of insulin release induced by the drug. This finding is worthy to consider in metabolic control of diabetic patients whom consume the agent.

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. Male Wistar 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. 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. The results suggest that chronic psychological stress could increase response of pancreatic β 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 β cells.

Urtica dioica, or the stinging nettle, is recommended by ancient medical texts for the treatment of high blood sugar. We set up a perifusion system, in which an exact number of islets of Langerhans were exposed to an active component of the leaf extract of Urtica dioica, obtained by TLC. The active component was then injected into the peritoneum of both normal and diabetic rats to evaluate response in vivo. There was a marked increase in insulin secretion in vitro, as determined by ELISA. In vivo, there was an increase in blood insulin content following intraperitoneal injection. The increase in serum insulin observed at 60 minutes was associated with a decrease in blood glucose, checked several times during the observation period. Maximum insulin release over 120 minutes was equal to five times the baseline value. The decrease in blood sugar correlated with both the timing and magnitude of insulin release. Notwithstanding the magnitude of the changes observed, the results obtained in normal and diabetic rats were similar.