Rat Beta-cells Research Articles

Synergistic Effect of a Flavonoid-Rich Cocoa-Carob Blend and Metformin in Preserving Pancreatic Beta Cells in Zucker Diabetic Fatty Rats.

The loss of functional beta-cell mass in diabetes is directly linked to the development of diabetic complications. Although dietary flavonoids have demonstrated antidiabetic properties, their potential effects on pancreatic beta-cell preservation and their synergistic benefits with antidiabetic drugs remain underexplored. We have developed a potential functional food enriched in flavonoids by combining cocoa powder and carob flour (CCB), which has shown antidiabetic effects. Here, we investigated the ability of the CCB, alone or in combination with metformin, to preserve pancreatic beta cells in an established diabetic context and their potential synergistic effect. Zucker diabetic fatty rats (ZDF) were fed a CCB-rich diet or a control diet, with or without metformin, for 12 weeks. Markers of pancreatic oxidative stress and inflammation, as well as relative beta-cell mass and beta-cell apoptosis, were analyzed. Results demonstrated that CCB feeding counteracted pancreatic oxidative stress by enhancing the antioxidant defense and reducing reactive oxygen species. Moreover, the CCB suppressed islet inflammation by preventing macrophage infiltration into islets and overproduction of pro-inflammatory cytokines, along with the inactivation of nuclear factor kappa B (NFκB). As a result, the CCB supplementation prevented beta-cell apoptosis and the loss of beta cells in ZDF diabetic animals. The observed additive effect when combining the CCB with metformin underscores its potential as an adjuvant therapy to delay the progression of type 2 diabetes.

Histomorphology of the Beta-Cells and Phytochemical Evaluation of Ethanolic Leaf Extract of Africa Star Apple - Chrysophyllum albidum (Sapotaceae)

Objective: Studies have recognized the numerous health benefits of Chrysophyllum albidum. This study examine the phytochemical evaluation of ethanolic leaf extract of C. albidum and its histological effects on the beta-cells of streptozotocin-induced diabetic rats.
 Method: Forty-two Sprague-Dawley rats (170- 200 g) were divided into six (n=7) groups. Groups 1 and 2 were given 10 mL of normal saline; group 3 was given 2 mg/kg of glibenclamide; and groups 4, 5, and 6 were given 125, 250, and 500 mg/kg/ day of C. albidum ethanolic leaf extract, respectively. Except for group 1, animals in groups 2-6 were injected intraperitoneally with 50 mg/kg streptozotocin after 14 days of oral treatment with normal saline, glibenclamide, and extract. For the next 14 days, rats were given normal saline, glibenclamide, and extract. The rats were fasted overnight before sacrifice on day 14; the pancreas was removed under diethyl ether anaesthesia and prepared for histological examination using a modified aldehyde fuchsin staining technique. Standard procedures were used for phytochemical evaluation and proximate analysis.
 Results: It was observed histological that the pancreatic tissues revealed cellular regeneration of the damage beta cells at a doses of 250 and 500 mg/kg/day. Phytochemical screening revealed the following; anthocyanin, cardiac glycosides, alkaloids, flavonoids, phenols, terpenoids, reducing sugar, and tannins while proximate analysis confirmed that the leaf contained 4.83% moisture, 39.59% crude fibre, 3.35% ash, 2.35% crude fats, 3.21% crude proteins and 46.71% carbohydrate.
 Conclusion: The results shows that C. albidum may possess a strong pharmacological activity owing to its rich phyto- constituents. This may have mediated its antidiabetic action by pancreatic beta cells regeneration. Hence, C. albidum could be a potential drug precursor for management of diabetes.
 Bangladesh Journal of Medical Science Vol. 23 No. 01 January’24 Page : 63-73

NGF effects promote the maturation of rat pancreatic beta cells by regulating GLUT2 levels and distribution, and glucokinase activity.

The nerve growth factor (NGF) participates in cell survival and glucose-stimulated insulin secretion (GSIS) processes in rat adult beta cells. GSIS is a complex process in which metabolic events and ionic channel activity are finely coupled. GLUT2 and glucokinase (GK) play central roles in GSIS by regulating the rate of the glycolytic pathway. The biphasic release of insulin upon glucose stimulation characterizes mature adult beta cells. On the other hand, beta cells obtained from neonatal, suckling, and weaning rats are considered immature because they secrete low levels of insulin and do not increase insulin secretion in response to high glucose. The weaning of rats (at postnatal day 20 in laboratory conditions) involves a dietary transition from maternal milk to standard chow. It is characterized by increased basal plasma glucose levels and insulin levels, which we consider physiological insulin resistance. On the other hand, we have observed that incubating rat beta cells with NGF increases GSIS by increasing calcium currents in neonatal cells. In this work, we studied the effects of NGF on the regulation of cellular distribution and activity of GLUT2 and GK to explore its potential role in the maturation of GSIS in beta cells from P20 rats. Pancreatic islet cells from both adult and P20 rats were isolated and incubated with 5.6 mM or 15.6 mM glucose with and without NGF for 4 hours. Specific immunofluorescence assays were conducted following the incubation period to detect insulin and GLUT2. Additionally, we measured glucose uptake, glucokinase activity, and insulin secretion assays at 5.6 mM or 15.6 mM glucose concentrations. We observed an age-dependent variation in the distribution of GLUT2 in pancreatic beta cells and found that glucose plays a regulatory role in GLUT2 distribution independently of age. Moreover, NGF increases GLUT2 abundance, glucose uptake, and GSIS in P20 beta cells and GK activity in adult beta cells. Our results suggest that besides increasing calcium currents, NGF regulates metabolic components of the GSIS, thereby contributing to the maturation process of pancreatic beta cells.

The potentials of Robusta (Coffea Robusta L.) and Arabica (Coffea Arabica L.) coffee leaf by-product as anti-diabetic drinks

1) Background: It has been known that coffee leaf contain various bioactives and antioxidants. While diabetes can be indicated by the damage of pancreatic beta cells, numerous studies have reported that many kinds of antioxidants can recover the beta cells. As a result, coffee leaf tea has the potential to be developed as an anti-diabetic beverage. The current study used in vivo experiments to investigate the functionality of coffee leaf tea for diabetic therapy; 2) Methods: Robusta and Arabica coffee leaf were processed as oolong tea. All samples were soft-infused. Healthy and diabetic rats (induced with STZ intraperitonially at 80 mg/kg BW) were treated by injecting the softly infused coffee leaf tea 12 ml/kg BW/day for 28 days; 3) Results: Compared to the glibenclamide treatment, diabetic rats injected with Robusta coffee leaf tea were better at lowering blood sugar (p-value <0.05), as well as maintaning body weight. This is supported by the fact that the number of pancreatic beta cells in diabetic rats injected with Robusta coffee leaf tea was significantly higher than in glibenclamide treated rats (pvalue <0.05). Coffee leaf tea tend to have a lighter sensory profile than oolong tea; 4) Conclusions: It can be concluded that Robusta coffee leaf tea tends to be potentially developed as anti-diabetic drink since it can recover damaged pancreatic beta cells better than glibenclamide, thus helping to decrease blood sugar.

Sublingual Administration of Teucrium Polium-Loaded Nanofibers with Ultra-Fast Release in the Treatment of Diabetes Mellitus: In Vitro and In Vivo Evaluation

In this study, Teucrium polium (TP) methanolic extract, which has antidiabetic activity and protects the β-cells of the pancreas, was loaded in polyethylene oxide/sodium alginate nanofibers by electrospinning and administered sublingually to evaluate their effectiveness in type-2 diabetes mellitus (T2DM) by cell culture and in vivo studies. The gene expressions of insulin, glucokinase, GLUT-1, and GLUT-2 improved in TP-loaded nanofibers (TPF) on human beta cells 1.1B4 and rat beta cells BRIN-BD11. Fast-dissolving (<120 s) sublingual TPF exhibited better sustainable anti-diabetic activity than the suspension form, even in the twenty times lower dosage in streptozotocin/nicotinamide-induced T2DM rats. The levels of GLP-1, GLUT-2, SGLT-2, PPAR-γ, insulin, and tumor necrosis factor-alpha were improved. TP and TPF treatments ameliorated morphological changes in the liver, pancreas, and kidney. The fiber diameter increased, tensile strength decreased, and the working temperature range enlarged by loading TP in fibers. Thus, TPF has proven to be a novel supportive treatment approach for T2DM with the features of being non-toxic, easy to use, and effective.

Differential effects of OATP2B1 on statin accumulation and toxicity in a beta cell model

An increased risk of new-onset diabetes mellitus has been recently reported for statin therapy, and experimental studies have shown reduced glucose-stimulated insulin secretion (GSIS) and mitochondrial dysfunction in beta cells with effects differing among agents. Organic anion transporting polypeptide (OATP) 2B1 contributes to hepatic uptake of rosuvastatin, atorvastatin and pravastatin, three known substrates. Since OATP2B1 is present in beta cells of the human pancreas, we investigated if OATP2B1 facilitates the local accumulation of statins in a rat beta cell model INS-1 832/13 (INS-1) thereby amplifying statin-induced toxicity. OATP2B1 overexpression in INS-1 cells via adenoviral transduction showed 2.5-, 1.8- and 1.4-fold higher cellular retention of rosuvastatin, atorvastatin and pravastatin, respectively, relative to LacZ control, while absolute intracellular concentration was about twice as high for the lipophilic atorvastatin compared to the more hydrophilic rosuvastatin and pravastatin. After 24 h statin treatment at high concentrations, OATP2B1 enhanced statin toxicity involving activation of intrinsic apoptosis (caspase 3/7 activation) and mitochondrial dysfunction (NADH dehydrogenase activity) following rosuvastatin and atorvastatin, which was partly reversed by isoprenoids. OATP2B1 had no effect on statin-induced reduction in GSIS, mitochondrial electron transport chain complex expression or caspase 9 activation. We confirmed a dose-dependent reduction in insulin secretion by rosuvastatin and atorvastatin in native INS-1 with a modest change in cellular ATP. Collectively, our results indicate a role of OATP2B1, which is abundant in human beta cells, in statin accumulation and statin-induced toxicity but not insulin secretion of rosuvastatin and atorvastatin in INS-1 cells.

Melatonin and probiotic administration ameliorated hyperglycaemia, oxidative stress, and enhanced cytoprotective effect on beta-cells of diabetic rats.

The study aimed at investigating the effects of administering melatonin and a probiotic to streptozotocin-induced diabetic rats on hyperglycaemia, oxidative stress biomarkers and beta-cells. Type 1 diabetes was induced in 5 months-old male Wistar rats by single intraperitoneal (i.p.) administration of freshly-prepared STZ (60mg/kg body weight). Six groups of 10 rats were used and treated once daily for six weeks; (1) Healthy control: normal saline only; (2) Pre-treated with Melatonin (MEL); (3) Diabetic control; (4) Diabetic + Treated with MEL; (5) Diabetic + Treated with Probiotic (Prob); (6) Diabetic + Treated with MEL + Prob. Blood glucose, body weight, activities of antioxidant enzymes and malondialdehyde concentration in serum and tissues, reduced glutathione and immunohistochemical assay. Data obtained were expressed as mean ± standard error of the mean (Mean ± SEM) and subjected to ANOVA followed by Tukey's post hoc test. Melatonin + Probiotic significantly decreased blood glucose concentrations in diabetic treated rats, compared to the diabetic control rats. MEL + Probiotic increased (p < 0.05) superoxide dismutase activity in serum and liver of diabetic rats. MEL + Probiotic reduced (p < 0.05) malondialdehyde concentration in the serum, liver and kidneys, respectively. MEL + Probiotic treated diabetic rats displayed islets with much greater content of insulin. Melatonin + Probiotic combination was more effective in mitigating hyperglycaemia, oxidative stress, and exerted cytoprotective effect on the beta-cells.

Intercellular contacts affect secretion and biosynthesis of pancreatic islet cells.

Cell protein biosynthesis is regulated by different factors, but implication of intercellular contacts on alpha and beta cell protein biosyntheses activity has not been yet investigated. Islet cell biosynthetic activity is essential in regulating not only the hormonal reserve within cells but also in renewing all the proteins involved in the control of secretion. Here we aimed to assess whether intercellular interactions affected similarly secretion and protein biosynthesis of rat alpha and beta cells. Insulin and glucagon secretion were analyzed by ELISA or reverse hemolytic plaque assay, and protein biosynthesis evaluated at single cell level using bioorthogonal noncanonical amino acid tagging. Regarding beta cells, we showed a positive correlation between insulin secretion and protein biosynthesis. We also observed that homologous contacts increased both activities at low or moderate glucose concentrations. By contrast, at high glucose concentration, homologous contacts increased insulin secretion and not protein biosynthesis. In addition, heterogeneous contacts between beta and alpha cells had no impact on insulin secretion and protein biosynthesis. Regarding alpha cells, we showed that when they were in contact with beta cells, they increased their glucagon secretion in response to a drop of glucose concentration, but, on the other hand, they decreased their protein biosynthesis under any glucose concentrations. Altogether, these results emphasize the role of intercellular contacts on the function of islet cells, showing that intercellular contacts increased protein biosynthesis in beta cells, except at high glucose, and decreased protein biosynthesis in alpha cells even when glucagon secretion is stimulated.

The Effect Of Kersen (&lt;i&gt;Muntingia calabura&lt;/i&gt;) Extract On The Number Of Pancreatic Beta Cells: Experiment Study In Rat

Type 2 diabetes mellitus is a common type of diabetes which can be caused by an increase in blood sugar levels resulting in a decrease in the number of pancreatic beta cells, dysfunction or apoptosis. To increase the number of pancreatic beta cells, antioxidants are needed. The antioxidant content of kersen leaves can improve pancreatic beta cell disorders due to high blood sugar levels by reducing ROS and RNF so that oxidative stress decreases and the number of pancreatic beta cells increases. Aim of this research, to determine the effect and the most effective dose of kersen leaves ethanol extract on the number of pancreatic beta cells of white rats wistar strain induced by streptozotocin-nicotinamide (STZ-NA). This study used a true experiment post-test only with control group design with STZ-NA-induced KI-KV group and normal control KVI group. KI-KIII was given kersen leaves extract at a dose of 0.3; 0.5 ;0.7 mg/gBW. KIV positive control. KV negative control. At the end of the study, the pancreas of rats was made preparations with immunohistochemical staining and the average pancreatic beta cells from the 5 islets of Langerhans were calculated. The average number of pancreatic beta cells that were most effective from the kersen leaves treatment group was KI (dose of 0.3 mg/gBW) with an average of 39.9. There is an effect of ethanol extract of kersen leaves on increasing the number of pancreatic beta cells in white rats of wistar strain induced by STZ-NA with an effective dose of 0.3 mg/gBW.

Comparative effects of curcumin versus nano-curcumin on histological, immunohistochemical expression, histomorphometric, and biochemical changes to pancreatic beta cells and lipid profile of streptozocin induced diabetes in male Sprague–Dawley rats

Diabetes mellitus is a worldwide problem characterized by hyperglycemia as well as the damage of the microscopic structure of the beta cells of Langerhans pancreatic islets. In the present study, the histological, immunohistochemical, morphometric, and biochemical alterations to pancreatic beta cells in streptozocin (STZ)-induced diabetes were assessed in rats treated with curcumin (CU) (100 mg/kg/day) or nano-curcumin (nCU) (100 mg/kg/day) for 1 month. Twenty-four adult male Wistar albino rats were distributed into four groups: the nondiabetic control group, the diabetic untreated group, and two diabetic groups treated with CU or nCUR, respectively. Blood glucose, serum insulin levels, and lipid profile were measured. The pancreatic tissues were collected and processed into paraffin sections for histological and immunohistochemical examination, oxidative stress markers, and real-time PCR expression for pancreatic and duodenal homeobox 1 (PDX1). The insulin expression in beta cells was assessed using immunohistochemistry. Morphometrically, the percentage area of anti-insulin antibody reaction and the percentage area of islet cells were determined. STZ-induced deteriorating alteration in beta cells led to declines in the number of functioning beta cells and insulin immunoreactivity. In STZ-treated rats, CU and nCUR significantly reduced blood glucose concentration while increasing blood insulin level. It also caused a significant increase in the number of immunoreactive beta cells to the insulin expression and significant reduction of the immunoreactive beta cells to the caspase-3 expression. In conclusion, CU and nCUR could have a therapeutic role in the biochemical and microscopic changes in pancreatic beta cells in diabetes-induced rats through STZ administration with more bio-efficacy of nCUR.

Pancreatic microexons regulate islet function and glucose homeostasis.

Pancreatic islets control glucose homeostasis by the balanced secretion of insulin and other hormones, and their abnormal function causes diabetes or hypoglycaemia. Here we uncover a conserved programme of alternative microexons included in mRNAs of islet cells, particularly in genes involved in vesicle transport and exocytosis. Islet microexons (IsletMICs) are regulated by the RNA binding protein SRRM3 and represent a subset of the larger neural programme that are particularly sensitive to SRRM3 levels. Both SRRM3 and IsletMICs are induced by elevated glucose levels, and depletion of SRRM3 in human and rat beta cell lines and mouse islets, or repression of particular IsletMICs using antisense oligonucleotides, leads to inappropriate insulin secretion. Consistently, mice harbouring mutations in Srrm3 display defects in islet cell identity and function, leading to hyperinsulinaemic hypoglycaemia. Importantly, human genetic variants that influence SRRM3 expression and IsletMIC inclusion in islets are associated with fasting glucose variation and type 2 diabetes risk. Taken together, our data identify a conserved microexon programme that regulates glucose homeostasis.

Apollo-IRE1: A genetically encoded sensor for live cell and multiplexed imaging of ER stress.

Several metabolic diseases, such as Alzheimer's, diabetes, and arthritis, are caused in part by the cellular accumulation of improperly folded proteins in the Endoplasmic Reticulum (ER). In response to protein misfolding, a transmembrane stress-sensor called IRE1α activates the Unfolded Protein Response (UPR) to maintain protein folding homeostasis. To measure ER stress response in living beta-cells with spatial and temporal resolution, we developed a genetically encoded sensor based on fluorescent protein-tagged IRE1α. This sensor homo-oligomerizes to dimeric and tetrameric conformations under early and chronic ER stress, respectively, resulting in homoFRET and an associated decrease in steady-state fluorescence anisotropy (i.e., decreased IRE1 anisotropy/polarisation of fluorescence due oligomerization (Apollo-IRE1)). Apollo-IRE1 responds to chemical and physiological (high glucose) stress in a rat beta-cell line (INS-1E) and mouse islets. Preliminary data suggest that UPR-associated XBP1 mRNA splicing is highly correlated with sensor response. Furthermore, individual cells with the highest sensor response (correlating to late-stage UPR) show elevated levels of pro-apoptotic protein TXNIP. The single colour design of Apollo sensors also makes them ideal for multiplexing, offering an exciting opportunity to explore multiparametric analysis of cellular metabolic characteristics. To demonstrate the multiplexing capability of Apollo-IRE1, we will explore simultaneously imaging of a sensor for NADPH (Apollo-NADP+) and by immunofluorescence with other ER stress markers. These data validate and demonstrate the utility of Apollo-IRE1 in sensing early and chronic ER stress through live cell imaging and multiplexed analysis.

The Effect of Insulin Loaded Nanoparticles on Immuno-reactivity of Beta Cells in Rats with Diabetes Type 1

The Effect of Insulin Loaded Nanoparticles on Immuno-reactivity of Beta Cells in Rats with Diabetes Type 1

Co-treatment with grape seed extract and mesenchymal stem cells in vivo regenerated beta cells of islets of Langerhans in pancreas of type I-induced diabetic rats

BackgroundNowadays, diabetes mellitus is known as a silent killer because individual is not aware that he has the disease till the development of its complications. Many researchers have studied the use of stem cells in treatment of both types of diabetes. Mesenchymal stem cells (MSCs) hold a lot of potential for regenerative therapy. MSCs migrate and home at the damaged site, where they can aid in the repair of damaged tissues and restoring their function. Oxidative stress and inflammation represent a huge obstacle during MSCs transplantation. Therefore, the present study aimed to evaluate the role of grape seed extract (GSE) administration during MSCs transplantation in streptozotocin (STZ)-induced type I diabetes. Furthermore, testing some of GSE components [procyanidins(P)-B1 and P-C1] in conjunction with MSCs, in vivo, was performed to determine if one of them was more effective in relieving the measured attributes of diabetes more than the whole GSE.MethodsFirstly, GSE was prepared from the seeds of Muscat of Alexandria grapes and characterized to identify its phytochemical components. Experimental design was composed of control group I, untreated diabetic group II, GSE (300 mg/kg)-treated diabetic group III, MSCs (2 × 106 cells/rat)-treated diabetic group IV and GSE (300 mg/kg)/MSCs (2 × 106 cells/rat)-treated diabetic group V. Type I diabetes was induced in rats by intravenous injection with 65 mg/kg of STZ. Treatment started when fasting blood glucose (FBG) level was more than 200 mg/dl; GSE oral administration started in the same day after MSCs intravenous injection and continued daily for 30 consecutive days.ResultsThe results showed that GSE/MSCs therapy in type I-induced diabetic rats has dramatically managed homeostasis of glucose and insulin secretion; together with, improvement in levels of inflammatory markers and oxidative stress.ConclusionCo-treatment with GSE and MSCs in vivo regenerates beta cells in type I-induced diabetic rats.

Young adult male LEW.1WR1 rats have reduced beta cell area and develop glucose intolerance

Prediabetes affects 1 in 3 American adults and is characterized by insulin resistance, insulin hypersecretion, and impaired glucose tolerance. Weanling LEW.1WR1 (1WR1) rats have increased blood insulin concentrations, so we hypothesized that young adult 1WR1 rats would develop impaired glucose tolerance due to the poor regulation of insulin. We monitored glucose tolerance, insulin tolerance, and weight gain for 10 weeks to assess if there was a decline in glucose processing over time. 1WR1 rats were significantly more glucose intolerant after 8 weeks. 1WR1 rats had increased body mass, yet abdominal fat mass was not significantly increased. Although the 1WR1 rats had increased circulating insulin and glucagon protein levels, 1WR1 rat beta cell area was significantly reduced. There may be underlying insulin resistance as evidenced by dysfunctional insulin regulation during fasting. Understanding the metabolic phenotype of this rat model can provide insight into the human pathophysiological changes that increase susceptibility to glucose intolerance and prediabetes.

1458-P: Lipophagy Is Constitutively Active in Pancreatic Beta Cells and Maintains Insulin Secretion

Lipid droplets (LDs) , organelles important for intracellular lipid metabolism, are actively formed in rat and human adult beta cells and affect islet function and health. Acute mobilization of LDs by adipose triglyceride lipase in beta cells is known to support insulin secretion. As LD degradation by lysosomal acid lipase (LIPA) through lipophagy is an alternative pathway for LD catabolism, we addressed whether LIPA regulates beta cell function. LDs in human beta cells are associated with autophagy (LC3) and lysosomal (LAMP1) markers. LIPA suppression via siRNA and LIPA inhibitor (lalistat2) in INS1 cells increased LD size (DMSO 0.5 vs. Lali2 1.5 µm2/cell, p&amp;lt;0.05, p value by Student’s t test unless specified otherwise) and number (Scr 2/cell vs. siLIPA 14/cell, p&amp;lt;0.05; DMSO 4.5/cell vs. Lali2 16/cell, p&amp;lt;0.05) . Rat and human beta cells treated with Lali2 also showed increased in LD area and/or number of LDs per cell (p&amp;lt;0.05) . In all three models, LIPA suppression increased TG contents confirming constitutively active lipophagy. While acute inhibition of LIPA by Lali2 had little effect on glucose-stimulated insulin secretion (GSIS) , chronic (over 48 h) LIPA suppression by Lali2 or siRNA reduced GSIS from INS1 cells, rat islets, and human islets. Lentiviral shRNA transduction in human pseudoislets decreased insulin secretion in response to glucose (41 ± 10.5% of Scr, p&amp;lt;0.05) and to KCl (61.3 ±16.1% of Scr, p&amp;lt;0.05) in vitro. When Scr and shLIPA human pseudoislets were transplanted under kidney capsules of NSG mice on Western diet, human insulin secretion in response to intraperitoneal glucose load was blunted in mice carrying shLIPA islets compared with shScr control (2-Way ANOVA, p&amp;lt;0.05) . In summary, lipophagy is constitutively active in human and rat beta cells and serves as a pathway for LD catabolism that is acutely insensitive to glucose. However, LIPA mediated LD catabolism is needed for beta cell function in a long-term. Disclosure S.Liu: None. B.R.Brennecke: None. U.Yang: None. J.A.Ankrum: None. Y.Imai: None. Funding National Institute of Diabetes andDigestive and Kidney Diseases (R01=DK090490) U.S. Department of Veterans Affairs (IBX005107)

The hypoglycemic and regenerative effect of the pancreas using instant porridge mix of pumpkin and brown rice flour on diabetic rats

Diabetes is a congenital disease resulting from inefficiencies in insulin production and activities. Instant porridge mixed with pumpkin and brown rice (instant porridge mix) can be a functional food to lower blood sugar. This study aimed to determine the hypoglycemic activity and the ability of instant porridge mix to regenerate pancreatic beta cells in diabetic rats. Diabetes was induced by Streptozotocin (STZ). Instant porridge mix was used to substitute the standard feed AIN-93 at 0, 10, 20, and 30% levels. The hypoglycemic activity test used 30 Sprague Dawley rats assigned to five groups with six each. The groups were (1) normal rats fed with standard feed AIN-93, (2) DM/diabetes mellitus rats fed with AIN 93 feed, (3) DM rats fed with 10% instant porridge mix, (4) DM rats fed with 20% instant porridge mix, and (5) DM rats fed with 30% instant porridge mix. The treatment was carried out for twenty-eight days, and blood sampling was carried out at seven-day intervals for blood analysis to determine glucose levels. At the end of the study, the levels of MDA (malondialdehyde) and blood glucose in the liver of the rats were also analyzed. A histopathology test was also done on the pancreas. The results showed that feed substitution (20%) with instant porridge mix significantly (p &lt;0.05) reduced the level of blood glucose from 271.81 to 99.66 mg.dL-1 in DM rats. In conclusion, DM rats fed with 20% instant porridge mix were the best treatment for hypoglycemic and regenerative effects of the pancreas.

Autoantibodies directed against glutamate decarboxylase interfere with glucose-stimulated insulin secretion in dispersed rat islets.

Islet autoantibodies, including autoantibodies directed against the 65kDa isoform of glutamate decarboxylase (GAD65Ab), are present in the majority of patients with newly diagnosed type 1 diabetes (T1D). Whereas these autoantibodies are historically viewed as an epiphenomenon of the autoimmune response with no significant pathogenic function, we consider in this study the possibility that they impact the major islet function, namely glucose-stimulated insulin secretion. Two human monoclonal GAD65Ab (GAD65 mAb) (b78 and b96.11) were investigated for uptake by live rat beta cells, subcellular localization and their effect on glucose-stimulated insulin secretion. The GAD65 mAbs were internalized by live pancreatic beta cells, where they localized to subcellular structures in an epitope-specific manner. Importantly, GAD65 mAb b78 inhibited, while GAD65 mAb b96.11 enhanced, glucose-stimulated insulin secretion (GSIS). These opposite effects on GSIS rule out non-specific effects of the antibodies and suggest that internalization of the antibody leads to epitope-specific interaction with intracellular machinery regulating insulin granule release. The most likely explanation for the alteration of GSIS by GAD65 Abs is via changes in GABA release due to inhibition or change in GAD65 enzyme activity. This is the first report indicating an active role of GAD65Ab in the pathogenesis of T1D.

Syzygium aqueum (Burm.f.) Alston Prevents Streptozotocin-Induced Pancreatic Beta Cells Damage via the TLR-4 Signaling Pathway.

Although several treatments are available for the treatment of type 2 diabetes mellitus, adverse effects and cost burden impose the search for safe, efficient, and cost-effective alternative herbal remedies. Syzygium aqueum (Burm.f.) Alston, a natural anti-inflammatory, antioxidant herb, may suppress diabetes-associated inflammation and pancreatic beta-cell death. Here, we tested the ability of the bioactive leaf extract (SA) to prevent streptozotocin (STZ)-induced oxidative stress and inflammation in pancreatic beta cells in rats and the involvement of the TLR-4 signaling pathway. Non-fasted rats pretreated with 100 or 200 mg kg−1 SA 2 days prior to the STZ challenge and for 14 days later had up to 52 and 39% reduction in the glucose levels, respectively, while glibenclamide, the reference standard drug (0.5 mg kg−1), results in 70% reduction. Treatment with SA extract was accompanied by increased insulin secretion, restoration of Langerhans islets morphology, and decreased collagen deposition as demonstrated from ELISA measurement, H and E, and Mallory staining. Both glibenclamide and SA extract significantly decreased levels of TLR-4, MYD88, pro-inflammatory cytokines TNF-α, and TRAF-6 in pancreatic tissue homogenates, which correlated well with minimal pancreatic inflammatory cell infiltration. Pre-treatment with SA or glibenclamide decreased malondialdehyde, a sensitive biomarker of ROS-induced lipid peroxidation, and restored depleted reduced glutathione in the pancreas. Altogether, these data indicate that S. aqueum is effective in improving STZ-induced pancreatic damage, which could be beneficial in treating type 2 diabetes mellitus.

Decreased proliferation of aged rat beta cells corresponds with enhanced expression of the cell cycle inhibitor p27KIP1.

Over 400 million people are diabetic. Type 1 and type 2 diabetes are characterized by decreased functional β-cell mass and, consequently, decreased glucose-stimulated insulin secretion. A potential intervention is transplantation of β-cell containing islets from cadaveric donors. A major impediment to greater application of this treatment is the scarcity of transplant-ready β-cells. Therefore, inducing β-cell proliferation ex vivo could be used to expand functional β-cell mass prior to transplantation. Various molecular pathways are sufficient to induce proliferation of young β-cells; however, aged β-cells are refractory to these proliferative signals. Given that the majority of cadaveric donors fit an aged demographic, defining the mechanisms that impede aged β-cell proliferation is imperative. We demonstrate that aged rat (5-month-old) β-cells are refractory to mitogenic stimuli that otherwise induce young rat (5-week-old) β-cell proliferation. We hypothesized that this change in proliferative capacity could be due to differences in cyclin-dependent kinase inhibitor expression. We measured levels of p16INK4a , p15INK4b , p18INK4c , p19INK4d , p21CIP1 , p27KIP1 and p57KIP2 by immunofluorescence analysis. Our data demonstrates an age-dependent increase of p27KIP1 in rat β-cells by immunofluorescence and was validated by increased p27KIP1 protein levels by western blot analysis. Interestingly, HDAC1, which modulates the p27KIP1 promoter acetylation state, is downregulated in aged rat islets. These data demonstrate increased p27KIP1 protein levels at 5 months of age, which may be due to decreased HDAC1 mediated repression of p27KIP1 expression. As the majority of transplant-ready β-cells come from aged donors, it is imperative that we understand why aged β-cells are refractory to mitogenic stimuli. Our findings demonstrate that increased p27KIP1 expression occurs early in β-cell aging, which corresponds with impaired β-cell proliferation. Furthermore, the correlation between HDAC1 and p27 levels suggests that pathways that activate HDAC1 in aged β-cells could be leveraged to decrease p27KIP1 levels and enhance β-cell proliferation.