Rat Pancreas Tissue Research Articles

DNA protective and antioxidative effects of melatonin in streptozotocin-induced diabetic rats

Diabetes mellitus is a chronic disease characterized by elevated blood sugar levels. In diabetic patients, oxidative stress induced by the presence of excessive free radicals is closely associated with chronic in?ammation, leading to potential tissue damage. Melatonin (MEL) is a compound synthesized by the pineal gland and a scavenger of free radicals. The aim of this study was to research the effects of MEL on oxidative stress and its DNA protective effects in streptozotocin-induced diabetic rats. In total, 32 rats were equally divided into four experimental groups: control, melatonin, diabetic, and diabetic + melatonin. A single dose of streptozotocin (60 mg/kg) was given by intraperitoneal route to induce experimental diabetes. MEL (10 mg/kg daily) was administrated to rats by intraperitoneal route for 6 weeks. Oxidative stress parameters were evaluated in rat liver, kidney, brain, and pancreas tissues. Body weight, plasma glucose, and HbA1c levels were studied. DNA damage was analyzed by comet assay in lymphocytes, while % tail DNA and mean tail moment parameters were evaluated. The study results indicate that the intraperitoneal administration of 10 mg/kg MEL over 6 weeks may cause amelioration in oxidative stress parameters against diabetes, leading to beneficial effects based on % tail DNA and mean tail moment parameters in rat lymphocytes.

Role of high mobility group box-1 and protection of growth hormone and somatostatin in severe acute pancreatitis.

In this study, we investigated the potential role of high-mobility group box 1 (HMGB1) in severe acute pancreatitis (SAP) and the effects of growth hormone (G) and somatostatin (S) in SAP rats. The rats were randomly divided into 6 groups of 20 each: sham-operated, SAP, SAP+saline, SAP+G, SAP+S and SAP+G+S. Ileum and pancreas tissues of rats in each group were evaluated histologically. HMGB1 mRNA expression was measured by reverse transcription-PCR. Levels of circulating TNF-α, IL-1, IL-6, and endotoxin were also measured. In the SAP group, interstitial congestion and edema, inflammatory cell infiltration, and interstitial hemorrhage occurred in ileum and pancreas tissues. The levels of HMGB1, TNF-α, IL-1, IL-6 and endotoxin were significantly up-regulated in the SAP group compared with those in the sham-operated group, and the 7-day survival rate was 0%. In the SAP+G and SAP+S groups, the inflammatory response of the morphological structures was alleviated, the levels of HMGB1, TNF-α, IL-1, IL-6, and endotoxin were significantly decreased compared with those in the SAP group, and the survival rate was increased. Moreover, in the SAP+G+S group, all histological scores were significantly improved and the survival rate was significantly higher compared with the SAP group. In conclusion, HMGB1 might participate in pancreas and ileum injury in SAP. Growth hormone and somatostatin might play a therapeutic role in the inflammatory response of SAP.

Synergistic effect of quercetin and quinic acid by alleviating structural degeneration in the liver, kidney and pancreas tissues of STZ-induced diabetic rats: A mechanistic study

The aim of this study was to investigate the synergistic effects of quercetin (QE) and quinic acid (QA) on a STZ-induced diabetic rat model to determine their potential role in alleviating diabetes and its associated complications. In our study design, diabetic rats were treated with single and combined doses of QE and QA for 45days to analyse their effects on liver, kidney and pancreas tissues. The study result showed that QE and QA treated groups down-regulated hyperglycaemia and oxidative stress by up-regulating insulin and C-peptide levels. Moreover, histological observations of the liver, kidney and pancreas of diabetic rats treated with single and combined doses of QE and QA showed a significant improvement in the structural degeneration. Interestingly, the combination dose of QE and QA (50mg/kg) exhibited maximum inhibition of the pro-apoptotic protein Bax expression and demonstrate enhancement of the anti-apoptotic protein Bcl-2 expression in the kidney tissues, suggesting a protective role in the kidneys of diabetic rats. Taken together, these results indicates the synergistic effects of QE and QA in ameliorating hyperglycaemia, hyperlipidemia and insulin resistance in diabetic rats and therefore, open a new window of research on the combinatorial therapy of flavonoids.

Alteration of the microRNA expression profile during the activation of pancreatic stellate cells

Objective. Pancreatic stellate cells (PSCs) play a pivotal role in the pancreatic fibrosis associated with chronic pancreatitis and pancreatic cancer. In response to pancreatic injury or inflammation, PSCs are activated to myofibroblast-like cells. MicroRNA (miRNA) is a small RNA, consisting of 17–25 nucleotides, which targets 3'-untranslated region sequences of mRNA. miRNAs regulate a variety of cell functions such as cell proliferation, differentiation, and carcinogenesis. We examined here whether the miRNA expression profiles are altered during the activation of PSCs. Materials and methods. Rat PSCs were isolated from the pancreas tissue of male Wistar rats. PSCs were activated in vitro by culture in serum-containing medium. miRNAs were prepared from quiescent (day 1) PSCs and culture-activated (day 14) PSCs. Agilent's miRNA microarray containing probes for 680 miRNAs was used to identify differentially expressed miRNAs. Ingenuity Pathway Analysis (IPA) was used for the integrated analysis of altered miRNAs. Results. Upon activation, 42 miRNAs were upregulated (>2.0-fold) and 42 miRNAs were downregulated (<0.5-fold). Upregulated miRNAs included miR-31, miR-143, and miR-221. Downregulated miRNAs included miR-126, miR-146a, and miR-150. IPA revealed the most impacted biological processes including cellular development, cellular growth, and cell movement. Interestingly, IPA identified 22 miRNAs affected both in pancreatic cancer and PSC activation. The top network generated by IPA revealed the interactions of altered miRNAs with signaling pathways such as p38 mitogen-activated protein kinase, extracellular-signal–regulated kinase, and Smad2/3. Conclusions. Our results suggest a novel role of miRNAs in the activation of PSCs.

Antidiabetic and antioxidative effect of jiang tang xiao ke granule in high-fat diet and low-dose streptozotocin induced diabetic rats.

Diabetes mellitus (DM), a kind of metabolic disease, is increasing over the last four decades in the world. The purpose of this study was to investigate the effect of Jiang Tang Xiao Ke (JTXK) granule, a naturally occurring ingredient from Chinese herbal medicines, on serum glucose, lipids, and oxidative stress in DM rats induced by high-fat diet and streptozotocin. JTXK granule 9 g/kg (based on crude herb equivalent) and pioglitazone 1.5 mg/kg (as a positive control for comparison) were orally administrated to DM rats for 4 weeks. Results showed that administration of JTXK granule reduced serum glucose, total cholesterol, triglyceride, and low density lipoprotein levels (by 12%, 33%, 57%, and 44%, resp.) but increased high-density lipoprotein level by 69%, compared with the drug-untreated DM rats. Serum malondialdehyde and nitric oxide levels were lowered (by 34% and 52%, resp.) associated with the elevation in serum superoxide dismutase levels (by 60%) after JTXK granule treatment. In addition, JTXK granule suppressed serum alanine aminotransferase activity (up to 50%) and alleviated pathological changes of pancreas and liver tissues in DM rats. The beneficial changes of pioglitazone on biomarkers were also found in DM rats. These findings suggested that JTXK granule may be an alternative medicine for the management of DM.

Outcome of Capparis Spinosa Fruit Extracts Treatment on Liver, Kidney, Pancreas and Stomach Tissues in Normal and Diabetic Rats

Aim and objectives: Herbal drugs such as, Capparis Spinosa (CS) has been used to treat several diseases from heart and cardiovascular disorders to diabetes in traditional Iranian medicine. The present study was aimed to determine beneficiary effects of CS fruit extract on a number of tissues in healthy and type 1 diabetic rat. Materials and methods: In this experimental study, sixty male wistar rats were randomly divided into 6 groups (n=10) and subjected to gavage tube therapy for one months by following protocol: group I and IV: diabetic control and non-diabetic control rats which only received distilled water; groups II and III: non diabetic treatment rats which received 200 mg/kg and 800 mg/kg CS extract per day respectively; groups V and VI: diabetic treatment rats which received 200 mg/kg and 800 mg/kg CS extract per day respectively. Diabetes was induced by intra-peritoneal injection of 50 mg/kg of streptozotocin (STZ). After 4 weeks, their blood were collected and the serum levels of creatinine, bilirubin, urea, uric acid, AST, ALT and ALP were measured. The liver, kidney, pancreas and stomach tissues were immediately excised, and after slide preparation processes, the histological changes were studied. Results: Our results illustrated that the gastric tissue in the diabetic group showed a small degree of changes and was not affected significantly by administration of the CS fruit extract. Liver, pancreas and kidney of diabetic rats exhibited considerable changes, like cellular necrosis. These changes in diabetic treatment groups were at lowest amounts. The decrease levels of creatinine, liver enzymes, and other factors were supporting these changes. Conclusions: This study demonstrates that the CS fruit extract could be aid prevention of damage to the tissues due to the decreased levels of harmful oxidants in the body in diabetes. Moreover, according to our previous results altogether we showed beneficial impact of the plant on the treatment of diabetes.

Antihyperglycemic Activity of Houttuynia cordata Thunb. in Streptozotocin-Induced Diabetic Rats.

Present study is an attempt to investigate plausible mechanism involved behind antidiabetic activity of standardized Houttuynia cordata Thunb. extract in streptozotocin-induced diabetic rats. The plant is used as a medicinal salad for lowering blood sugar level in North-Eastern parts of India. Oral administration of extract at 200 and 400 mg/kg dose level daily for 21 days showed a significant (P < 0.05) decrease in fasting plasma glucose and also elevated insulin level in streptozotocin-induced diabetic rats. It also significantly reversed all the alterations in biochemical parameters, that is, total lipid profile, blood urea, creatinine, protein, and antioxidant enzymes in liver, pancreas, and adipose tissue of diabetic rats. Furthermore, we have demonstrated that the extract significantly reversed the expression patterns of various glucose homeostatic enzyme genes like GLUT-2, GLUT-4, and caspase-3 levels but did not show any significant effect on PPAR-γ protein expressions. Additionally, the extract positively regulated mitochondrial membrane potential and succinate dehydrogenase (SDH) activity in diabetic rats. The findings justified the antidiabetic effect of H. cordata which is attributed to an upregulation of GLUT-4 and potential antioxidant activity, which may play beneficial role in resolving complication associated with diabetes.

Effect of SB203580 on pathologic change of pancreatic tissue and expression of TNF-α and Il-1β in rats with severe acute pancreatitis

338 Abstract. - OBJECTIVE : This study aimed to investigate the effect of SB203580 which is the inhibitor of p38 mitogen-activated protein kinase on pathologic change of pancreatic tissue and expression of tumor necrosis factor-alpha (TNF- α) and interleukin-1-beta (IL-1 β) in rats with se - vere acute pancreatitis (SAP), Hematoxylin-eosin (HE) staining and immunohistochemistry were carried out in the present study. METHODS: Forty-five male Wistar rats were divided into three groups: the SAP group (N=15), SB203580-treated group (SB group) (N=15), and the control group (N=15). Severe acute pancre - atitis was induced by injection of sodium tauro - cholate into the pancreatic duct. For SB203580- treated group, SB203580 were administered via intraperitoneal injection (10 mg/kg). Serum amy - lase activity was measured 6, 12 and 24 hours respectively after the operation. The pancreas tissue were stained with HE for histopathologi - cal evaluation and the expression of TNF- α and IL-1 β in the pancreatic tissue were determined through inferior vena cava. RESULTS: The results show that the level of amylase in SAP group was higher than that in the other groups. Further, the pancreas tissues of SB group rats were observed more mildly edematous, hemorrhagic and with monocytes in - filtration. Based on immunohistochemical stain - ing, the expression of TNF- α and IL-1 β in SAP rats were significantly increased than those of the control group. However, those of SB203580- treated group were more significantly reduced than those of SAP group ( p < 0.05). CONCLUSIONS: Those data suggest that SB203580, down regulating the expression of pro-inflammatory mediators such as TNF- α and IL-1 β, then through p38 MAPK signaling pathway inhibition, pl ays an important role in the treatment of SAP.

Immunoisolated Transplantation of Purified Langerhans Islet Cells in Testis Cortex of Male Rats for Treatment of Streptozotocin Induced Diabetes Mellitus

The objective of this study is to induce experimental diabetes mellitus by streptozotocin in normal adult Wistar rats via comparison of changes in body weight, consumption of food, volume of water, urine and levels of glucose, insulin and C-peptide in serum, between normal and diabetic rats. Intra-venous injection of 60mg/kg dose of streptozotocin in 250-300g (75-90days) adult Wistar rats makes pancreas swell and causes degeneration in Langerhans islet β-cells and induces experimental diabetes mellitus in 2-4days. For a microscopic study of degeneration of Langerhans islet β-cells of diabetic rats, biopsy from pancreas tissue of diabetic and normal rats, staining and comparison between them, were done. In this process, after collagenase digestion of pancreas, islets were isolated, dissociated and identified by dithizone method and then with enzymatic procedure by DNase and trypsin, the islet cells changed into single cells and β-cells were identified by immune fluorescence method and then assayed by flow-cytometer. Donor tissue in each step of work was prepared from 38 adult male Wistar rats weighted 250-300g (75-90days). Transplantation was performed in rats after 2-4weeks of diabetes induction. In this study, the levels of insulin, C-peptide and glucose in diabetic rats reached to normal range as compared to un-diabetic rats in 20days after transplantation of islet cells. Transplantation was performed under the cortex of testis as immunoisolated place for islet cells transplantation.

Expression of adropin in rat brain, cerebellum, kidneys, heart, liver, and pancreas in streptozotocin-induced diabetes

We have investigated how diabetes affects the expression of adropin (ADR) in rat brain, cerebellum, kidneys, heart, liver, and pancreas tissues. The rats in the diabetic group were administered an intraperitoneal (i.p.) injection of a single dose of 60 mg/kg streptozotocin (STZ) dissolved in a 0.1 M phosphate-citrate buffer (pH 4.5). The rats were maintained in standard laboratory conditions in a temperature between 21 and 23 °C and a relative humidity of 70 %, under a 12-h light/dark cycle. The animals were fed a standard commercial pellet diet. After 10 weeks, the animals were sacrified. ADR concentrations in the serum and tissue supernatants were measured by ELISA, and immunohistochemical staining was used to follow the expression of the hormones in the brain, cerebellum, kidneys, heart, liver, and pancreas tissues. The quantities were then compared. Increased ADR immunoreaction was seen in the brain, cerebellum, kidneys, heart, liver, and pancreas in the diabetes-induced rats compared to control subjects. ADR was detected in the brain (vascular area, pia mater, neuroglial cell, and neurons), cerebellum (neuroglial cells, Purkinje cells, vascular areas, and granular layer), kidneys (glomerulus, peritubular interstitial cells, and peritubular capillary endothelial cells), heart (endocardium, myocardium, and epicardium), liver (sinusoidal cells), and pancreas (serous acini). Its concentrations (based on mg/wet weight tissues) in these tissues were measured by using ELISA showed that the levels of ADR were higher in the diabetic rats compared to the control rats. Tissue ADR levels based on mg/wet weight tissues were as follows: Pancreas > liver > kidney > heart > brain > cerebellar tissues. Evidence is presented that shows ADR is expressed in various tissues in the rats and its levels increased in STZ-induced diabetes; however, this effect on the pathophysiology of the disorder remains to be understood.

Down-Regulation of Aquaporin 1 in Rats With Experimental Acute Necrotizing Pancreatitis

The objectives of this study were to investigate the expression of aquaporin 1 in capillary endothelial cells of rats with experimental acute necrotizing pancreatitis (ANP) and to explore its pathogenic role in capillary leak. Sixty-four male Sprague-Dawley rats were randomly divided into control (n = 32) and ANP groups (n = 32). Eight rats in each group were killed at 3, 6, 12, and 18 hours after induction of experimental models. Quantity of ascites and levels of serum amylases were measured. Capillary permeability in pancreas, lung, and intestinal tissue was detected by Evans blue extravasation method. Aquaporin 1 expression in pancreas, lung, and intestinal tissue was detected by real-time polymerase chain reaction, immunohistochemical staining, and Western blot. Serum amylase level was significantly higher in ANP group than in controls (P < 0.05). Evans blue concentration in tissues in the ANP group was significantly higher than that in controls (P < 0.05). Aquaporin 1 mRNA and protein expressions in tissues were significantly less in the ANP group than in the controls (P < 0.05). The expression of aquaporin 1 was down-regulated in the pancreas, lung, and intestinal tissue of ANP rats, which could play an important role in the pathogenesis of capillary leak syndrome.

Effects of Shenmai injection on the expression of intercellular adhesion molecule-1 in rats with severe acute panereatitis

Objective To explore the impact of Shenmai injection on the levels of plasma soluble intercellular adhesion molecule-1 ( sICAM-1 ) and ICAM-1 mRNA in the pancreas tissue of rats with severe acute pancreatitis (SAP).Methods One hundred and eight SD male rats were randomly divided into three groups:sham operation group (group A),SAP model group (group B),Shenmai injection group ( group C).The rats in groups B and C were further divided into four subgroups based on the time points of constructing model:4,8,16 and 24 h subgroups (n =12 each).The levels of plasma sICAM-1 and the ICAM-1 mRNA in the pancreas tissue of rats were compared among the three groups.Results The levels of plasma sICAM-1 were significantly higher in group B than in 4,8,16 and 24 h subgroups of group A (128.07±15.86 vs 87.31 ±13.16,142.33±22.61 vs 98.82 ±11.39,187.45±17.39 vs 129.51 ±15.61,and 176.18 ± 19.36 vs 123.57 ± 17.03) ( all P ＜0.05).The levels of plasma sICAM-1 were significantly lower in group C than those in 4,8,16 and 24 h subgroups of group B (92.55 ± 8.09 vs 128.07 ± 15.86,105.28 ± 14.29 vs 142.33 ± 22.61,142.36 ± 18.25 vs 187.45 ± 17.39,131.32 ± 21.83 vs 176.18 ±19.36) ( all P ＜ 0.05 ).The expression of 1CAM-1 mRNA in the pancreatic tissue was significantly higher in group B than that in4,8,16 and 24 h subgroups of group A (0.97 ±0.12 vs 0.52 ±0.11,1.08 ±0.18 vs 0.61±0.13,1.32±0.18 vs0.82±0.14,1.23 ±0.09vs0.74±0.13) (allP＜0.05).The expression of ICAM-1 mRNA in the pancreatic tissue was significantly lower in group C than that in 4,8,16 and 24 h subgroups of group B ( 0.59 ± 0.13 vs 0.97 ± 0.12,0.68 ± 0.09 vs 1.08 ± 0.18,0.96 ±0.20vs1.32±0.18,0.88±0.09vs1.23±0.09) (allP＜0.05).Conclusion Shenmai injection could improve microcirculation and protect rats with SAP through decreasing the levels of plasma sICAM-1and the ICAM-1 mRNA of the pancreas tissue. Key words: Severe acute pancreatitis ; Intercellular adhesion molecule-1 ; Shenmai injection

EUK-8 and EUK-134 reduce serum glucose and lipids and ameliorate streptozotocin-induced oxidative damage in the pancreas, liver, kidneys, and brain tissues of diabetic rats

In this study, the effects of EUK-8 and EUK-134, as two newly classified antioxidants, on the sera levels of glucose, insulin, lipids, nitric oxide (NO) and also on the extent of lipid peroxidation (measured in term of thiobarbituric acid reactive substances, TBARS), reactive oxygen species (ROS) formation and the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT) as well as reduced glutathione (GSH)] in the liver, pancreas, brain and kidneys of streptozotocin (STZ)-induced diabetic rats were evaluated. Results indicated that oral daily administration of EUK-8, EUK-134 (each at 20 mg/kg), and glibenclamide (2.5 mg/kg), as the control drug, to the diabetic rats for 21 consecutive days improved the sera levels of lipids and glucose along with insulin level to varying extents. In addition, treatment of rats with EUK-8, EUK-134, and/or glibenclamide decreased the TBARS, NO, and ROS levels and increased the activities of SOD and CAT as well as the GSH content in various tissues compared to untreated diabetic rats. In conclusion, this study indicated that EUK-8 and Euk-134 compounds improved the antioxidant status by reducing lipid peroxidation and enhancing the antioxidant enzymes activities in various tissues of diabetic rats.

D-saccharic acid-1,4-lactone ameliorates alloxan-induced diabetes mellitus and oxidative stress in rats through inhibiting pancreatic beta-cells from apoptosis via mitochondrial dependent pathway

Oxidative stress plays a vital role in diabetic complications. To suppress the oxidative stress mediated damage in diabetic pathophysiology, a special focus has been given on naturally occurring antioxidants present in normal diet. d-saccharic acid 1,4-lactone (DSL), a derivative of d-glucaric acid, is present in many dietary plants and is known for its detoxifying and antioxidant properties. The aim of the present study was to evaluate the beneficial role of DSL against alloxan (ALX) induced diabetes in the pancreas tissue of Swiss albino rats. A dose-dependent study for DSL (20–120 mg/kg body weight) was carried out to find the effective dose of the compound in ALX-induced diabetic rats. ALX exposure elevated the blood glucose, glycosylated Hb, decreased the plasma insulin and disturbed the intra-cellular antioxidant machineries whereas oral administration of DSL at a dose of 80 mg/kg body weight restored these alterations close to normal. Investigating the mechanism of the protective activity of DSL we observed that it prevented the pancreatic β-cell apoptosis via mitochondria-dependent pathway. Results showed decreased mitochondrial membrane potential, enhanced cytochrome c release in the cytosol and reciprocal regulation of Bcl-2 family proteins in the diabetic rats. These events were also found to be associated with increased level of Apaf-1, caspase 9, and caspase 3 that ultimately led to pancreatic β-cell apoptosis. DSL treatment, however, counteracted these changes. In conclusion, DSL possesses the capability of ameliorating the oxidative stress in ALX-induced diabetes and thus could be a promising approach in lessening diabetic complications.

Identification of trans-tiliroside as active principle with anti-hyperglycemic, anti-hyperlipidemic and antioxidant effects from Potentilla chinesis

The present study was carried out to isolate and identify trans-tiliroside as principal compound with anti-hyperglycemic, anti-hyperlipidemic and antioxidant effects from Potentilla chinesis. A bioactive compound, trans-tiliroside was isolated from the ethanol extract of Potentilla chinesis and its administration dose was optimized and patented. The normal, alloxan-induced diabetic mice and streptozotocin-induced diabetic rats were used to evaluate the anti-hyperglycemic, anti-hyperlipidemic and antioxidant effects of trans-tiliroside from Potentilla chinesis. Biochemical parameters were assayed in blood samples of different groups of alloxan-induced diabetic mice and streptozotocin-induced diabetic rats. The level of fasting serum glucose levels, triglycerides (TG) and total cholesterol (TC) in alloxan-induced diabetic mice were significantly decrease after daily oral administration of trans-tiliroside in normal and diabetic mice at doses of 0.4, 0.8 and 1.6 mg/kg/day, for 15 days. Blood glucose level was significant decrease in STZ induced diabetic rats by trans-tiliroside (1.2 and 0.3mg/kg body weight for 10 weeks). The content of TC, low density lipoprotein (LDL-C) and TG levels were decreased and high density lipoprotein (HDL-C) content was increased, so lipid metabolism was improved. Moreover, trans-tiliroside revealed antioxidant activity as shown by increased activities of superoxide dismutase (SOD), decreased level of malondialdehyde (MDA) in diabetic rats. Histological morphology examination showed that the trans-tiliroside restored the damage of pancreas tissues in rats with diabetes mellitus. Trans-tiliroside, a constituent from Potentilla chinesis, revealed significant anti-hyperglycemic, anti-hyperlipidemic and antioxidant activities.

Nuclear expression of interleukin-33 in pancreatic stellate cells

Activated pancreatic stellate cells (PSCs) play a pivotal role in pancreatic fibrosis in chronic pancreatitis and pancreatic cancer. Recent studies have suggested a role of IL-33, a newly identified IL-1 family member, in fibrosis. We here examined the expression of IL-33 and the IL-33-mediated regulation of cell functions in PSCs. PSCs were isolated from human and rat pancreas tissues. The expression of IL-33 was examined by Western blotting, PCR, ELISA, and immunostaining. The roles of IL-33 in the regulation of PSC functions were examined by using recombinant IL-33 and small interfering RNA. Activated PSCs expressed IL-33 in the nucleus, and the expression was increased by IL-1β, TNF-α, PDGF-BB, and IFN-γ, but not TGF-β1. Nuclear IL-33 expression was also observed in the pancreatic acinar and ductal cells. IL-1β induced IL-33 expression mainly through the activation of NF-κB and ERK pathways and partially through that of p38 MAP kinase, whereas PDGF-BB induced IL-33 expression mainly through the activation of ERK pathway. PSCs expressed soluble ST2, ST2L, and IL-1RAcP, but the expression level of ST2L was relatively low. Recombinant IL-33 did not stimulate key cell functions of PSCs. Decreased IL-33 expression by small interfering RNA resulted in decreased proliferation in response to PDGF-BB. In conclusion, activated PSCs expressed IL-33 in the nucleus. IL-33 might regulate the PDGF-induced proliferation in PSCs.

VMH lesions downregulate the expression of Per2 gene in the pancreas in the rat

The mammalian circadian system contains both central and peripheral oscillators. It was reported that the rhythmic expressions of period homolog 2 (per2) mRNA in peripheral tissues were abolished by the suprachiasmatic nucleus (SCN) lesions. However, there are no reports that ventromedial hypothalamic (VMH) lesions can directly affect the expression of clock genes in pancreas and liver. In the present study, we examined whether VMH lesions can affect the expression of the clock gene, per2 in these organs. Total RNA was extracted from rat pancreas and liver tissues, and differences in the gene expression profiles between rats at day 3 after VMH lesioning and sham-VMH-lesioned rats were investigated using DNA microarray and real-time quantitative analysis. These results showed that VMH lesions downregulated the expression of the clock gene, per2 in the pancreas, but not the liver in the morning. There is a possibility that VMH lesions may affect the expression of the clock gene, per2 in the pancreas.

Molecular determinants of the profibrogenic effects of endothelin-1 in pancreatic stellate cells

To gain molecular insights into the expression and functions of endothelin-1 (ET-1) in pancreatic stellate cells (PSC). PSCs were isolated from rat pancreas tissue, cultured, and stimulated with ET-1 or other extracellular mediators. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2'-deoxyuridine into DNA and cell migration was studied in a transwell chamber assay. Gene expression at the level of mRNA was quantified by real-time polymerase chain reaction. Expression and phosphorylation of proteins were monitored by immunoblotting, applying an infrared imaging technology. ET-1 levels in cell culture supernatants were determined by an enzyme immunometric assay. To study DNA binding of individual transcription factors, electrophoretic mobility shift assays were performed. Among several mediators tested, transforming growth factor-beta1 and tumour necrosis factor-alpha displayed the strongest stimulatory effects on ET-1 secretion. The cytokines induced binding of Smad3 and NF-kappaB, respectively, to oligonucleotides derived from the ET-1 promoter, implicating both transcription factors in the induction of ET-1 gene expression. In accordance with previous studies, ET-1 was found to stimulate migration but not proliferation of PSC. Stimulation of ET-1 receptors led to the activation of two distinct mitogen-activated protein kinases, p38 and extracellular signal-regulated kinases (ERK)1/2, as well as the transcription factor activator protein-1. At the mRNA level, enhanced expression of the PSC activation marker, alpha-smooth muscle actin and two proinflammatory cytokines, interleukin (IL)-1beta and IL-6, was observed. This study provides novel lines of evidence for profibrogenic and proinflammatory actions of ET-1 in the pancreas, encouraging further studies with ET-1 inhibitors in chronic pancreatitis.

Protective role of arjunolic acid in response to streptozotocin-induced type-I diabetes via the mitochondrial dependent and independent pathways

Increasing evidences in both experimental and clinical studies suggest that oxidative stress is involved in the pathogenesis of diabetic tissue damage. Pancreatic β-cell death is the cause of decreased insulin production in diabetes. Streptozotocin (STZ) is widely used to induce experimental diabetes due to its ability to selectively target and destroy insulin producing pancreatic β-cells via the formation of both reactive oxygen species (ROS) and RNS (reactive nitrogen species). This study investigated the prophylactic role of arjunolic acid (AA) against STZ-induced diabetes in the pancreas tissue of the Swiss albino rats (as a working model). We observed that STZ administration (at a dose of 65 mg/kg body weight, injected in the tail vain) caused increased production of both ROS and RNS in the pancreas tissue of experimental animals. Formation of these reactive intermediates decreased the intracellular antioxidant defense, increased the levels of lipid peroxidation, protein carbonylation, serum glucose and TNF-α. Investigating the signaling pathways, we found that STZ administration caused the activation of phospho-ERK1/2, phospho-p38, NF-κB and destruction of mitochondrial transmembrane potential, release of cytochrome c as well as activation of caspase 3 in the pancreas tissue keeping the levels of total ERK1/2 and p38 significantly unchanged. Treatment of animals with AA (at a dose of 20 mg/kg body weight, orally) both prior and post to the STZ administration effectively reduced these adverse effects by inhibiting the excessive ROS and RNS formation as well as by down-regulating the activation of phospho-ERK1/2, phospho-p38, NF-κB and mitochondrial dependent signal transduction pathways leading to apoptotic cell death. Combining all, these results suggest that AA plays some beneficial roles against STZ-induced diabetes.

Pancreatic stellate cells express Toll-like receptors

Toll-like receptors (TLRs) are proteins involved in recognition of foreign pathogen-associated molecular patterns (PAMPs) and activation of innate immunity. This study aimed to clarify whether pancreatic stellate cells (PSCs), a major profibrogenic cell type in the pancreas, expressed TLRs and responded to PAMPs. PSCs were isolated from rat pancreas tissue, and expression of TLRs was examined. PSCs were treated with lipoteichoic acid (a ligand for TLR2), polyinosinic-polycytidylic acid (a ligand for TLR3), lipopolysaccharide (a ligand for TLR4), or flagellin (a ligand for TLR5). The effects of the TLR ligands on key cell functions and activation of signaling pathways were examined. The ability of PSCs to perform endocytosis and phagocytosis was also examined. PSCs expressed TLR2, 3, 4, and 5, as well as the associated molecules CD14 and MD2. All of the TLR ligands activated nuclear factor-kappaB, and three classes of mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase). TLR ligands induced expression of monocyte chemoattractant protein 1, cytokine-induced neutrophil chemoattractant 1 (a rat homolog of interleukin-8), and inducible nitric oxide synthase, but not proliferation or type I collagen production. PSCs could perform fluid-phase and receptor-mediated endocytosis, as well as phagocytosis of Escherichia coli. PSCs expressed a variety of TLRs and responded to TLR ligands, leading to the activation of signaling pathways and proinflammatory responses. PSCs could process exogenous antigens by endocytosis and phagocytosis. PSCs might play a role in the immune functions of the pancreas through the recognition of PAMPs.