Characterization and comparison of insulinoma tumor model and pancreatic damage caused by the tumor, and identification of possible markers

Insulinoma is a neuroendocrine tumor. It arises from the uncontrolled proliferation of pancreatic β cells. In this study, we created an insulinoma tumor model in nude mice. INS-1 cells were injected in two different ways, subcutaneously (S.C.) or intraperitoneally (I.P.). Body weight, tumor weight, and size were measured. ELISA kits were used analyze to Glucose, insulin, and CA19-9 levels in serum, pancreas, and tumor tissues. KCNN4, KCNK1, GLUT2, IR, HSP70, HSF1, and HSP90 levels were analyzed by western blotting of membrane and/or cytosolic fractions of tumor and pancreas tissue. Tumor formation occurred in nude mice, but it did not occur in Wistar albino rats. The tumor has neuroendocrine cell morphology. Insulin and CA19-9 levels increased in pancreas tissue. In tumor tissue, KCNN4 levels were higher in both membrane and cytosolic fractions, while KCNK1 levels were lower in the membrane fraction of the S.C. group. HSP70 levels were also lower in the S.C. group. In pancreas tissue, KCNK1 levels were lower in the membrane fraction of the S.C. and I.P. groups. GLUT2 levels increased in both groups according to the control group, while IR levels decreased in the S.C. group compared to the control group. However, HSF1 levels increased in the I.P. group, while HSP90 decreased in the S.C. group in pancreatic tissues. The S.C. group is a more suitable insulinoma tumor model. KCNN4, KCNK1, and HSP70 proteins may be important biomarkers in the diagnosis and treatment of insulinoma.

Exendin-4 inhibits small intestinal glucose sensing and absorption through repression of T1R2/T1R3 sweet taste receptor signalling in streptozotocin diabetic mice

The small intestine, which is the area where sugars are absorbed, should be considered in the approaches developed for the treatment of diabetes. However, studies on small intestine damage in diabetic individuals, and the effects of current treatments on the small intestine are very limited. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on small intestine injury in diabetic mice. BALB/c male mice were divided into 4 groups for this study. The first group was given citrate buffer, the second group was given exendin-4, the third group was given streptozotocin (STZ), and the fourth group was given both exendin-4, and STZ. As the results, we determined a decrease in the edema and deterioration in the integrity of the villi, disruption in continuity of the brush border, fibrosis and enterocyte apoptosis, while the TNFα level and crypt cell proliferation were increased in the small intestinal tissue of exendin-4 treated STZ diabetic mice. Furthermore, the levels of duodenal tissue glucose, SGLT1, and GLUT2 were decreased, whereas there was an increase in GIP level in diabetic mice administered with exendin-4. Moreover, we determined that the sweet taste receptors T1R2/T1R3, downstream molecules PLCβ2, α-gustducin and associated secondary messengers IP3, cAMP, which were increased in the duodenal tissue of STZ-diabetic mice, decreased with exendin-4 administration. These findings were evaluated as that exendin-4 reduces glucose absorption by suppressing the T1R2/T1R3 sweet taste signal perception pathway in duodenum of STZ diabetic mice.

Metformin induces mitochondrial remodeling and differentiation of pancreatic progenitor cells into beta-cells by a potential mechanism including suppression of the T1R3, PLCβ2, cytoplasmic Ca+2, and AKT

The main goal of this study was to investigate the molecular changes in pancreatic progenitor cells subject to high glucose, aspartame, and metformin in vitro. This scope of work glucose, aspartame, and metformin were exposed to pancreatic islet derived progenitor cells (PID-PCs) for 10 days. GLUT1's role in beta-cell differentiation was examined by using GLUT1 inhibitor WZB117. Insulin⁺ cell ratio was measured by flow cytometry; the expression of beta-cell differentiation related genes was shown by RT-PCR; mitochondrial mass, mitochondrial ROS level, cytoplasmic Ca2⁺, glucose uptake, and metabolite analysis were made fluorometrically and spectrophotometrically; and proteins involved in related molecular pathways were determined by western blotting. Findings showed that glucose or aspartame exposed cells had similar metabolic and gene expression profile to control PID-PCs. Furthermore, relatively few insulin⁺ cells in aspartame treated cells were determined. Aspartame signal is transmitted through PLCβ2, CAMKK2 and LKB1 in PID-PCs. The most obvious finding of this study is that metformin significantly increased beta-cell differentiation. The mechanism involves suppression of the sweet taste signal's molecules T1R3, PLCβ2, cytoplasmic Ca⁺², and AKT in addition to the direct effect of metformin on mitochondria and AMPK, and the energy metabolism of PID-PCs is remodelled in the direction of oxidative phosphorylation. These findings are very important in terms of determining that metformin stimulates the mitochondrial remodeling and the differentiation of PID-PCs to beta-cells and thus it may contribute to the compensation step, which is the first stage of diabetes development.

Zinc Prevents Ethanol-Induced Oxidative Damage in Lingual Tissues of Rats

The current study was designed to investigate the effects of zinc sulfate on cell proliferation, metallothionein (MT) immunoreactivity and antioxidant system against acute ethanol-induced oxidative damage in tongue tissues of rats. Wistar albino male rats, 2.5 to 3.0 months, were divided into four groups: Group I (n = 8), intact control rats; group II (n = 8), control animals given only zinc sulfate (100 mg/kg/day, for 3 consecutive days); group III (n = 14), animals given 1 mL absolute ethanol; group IV (n = 11), animals given zinc sulfate and absolute ethanol at the same dose and time. Animals were sacrificed under anesthesia 2 h after ethanol administration or 4 h after the last zinc sulfate treatment. Ethanol administration caused a marked decrease in the number of MT immunopositive cells and the proliferating cells in the lingual epithelium. A statistically significant decline in reduced glutathione levels, catalase activity and superoxide dismutase activities was also observed, whereas a significant elevation of lipid peroxidation levels and lactate dehydrogenase activities was detected in the ethanol group. In contrast, these changes were reversed by administration of zinc sulfate to ethanol-treated rats. In conclusion, it shows that zinc sulfate has therapeutic effects on acute ethanol-induced oxidative damage in the tongue tissues of rats.

Vitamin U prevents valproic acid-induced liver injury through supporting enzymatic antioxidant system and increasing hepatocyte proliferation triggered by inflammation and apoptosis

The aim of this study was to investigate the cellular mechanisms that cause valproic acid (VPA)-induced liver damage and the therapeutic effect of Vitamin U (Vit U) on these mechanisms. Female Sprague Dawley rats were randomly divided into four groups: intact control animals, animals that received Vit U (50 mg/kg/day), animals given VPA (500 mg/kg/day), and animals given both VPA and Vit U. The rats in the Vit U + VPA group were administered Vit U by gavage an hour before VPA administration every day for 15 days. Liver tissues were evaluated through histopathological, biochemical, immunohistochemical, and Western blotting techniques. Administration of Vit U with VPA resulted in (i) prevention of histopathological changes caused by VPA; (ii) blockage of the decrease in catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities; prevention of the elevation in gamma-glutamyl transferase (GGT) activity and advanced oxidation protein products (AOPP) level; (iii) increased in the levels of interleukin-1 beta (IL-1β), active caspase-3, and cytoplasmic cytochrome c; (iv) increase in cleaved poly (ADP-ribose) polymerase (PARP) level and decrease in LC3B (II/I) ratio; (v) increase in the number of proliferating cells nuclear antigen (PCNA) positive hepatocytes. These findings show that Vit U prevents liver damage caused by VPA through increasing the antioxidant enzyme capacity and hepatocyte proliferation by triggering inflammation and apoptosis. These findings suggest that Vit U provides its protective effects against VPA-induced liver damage by stimulating homeostasis and regeneration.

miR-375 induces adipogenesis through targeting Erk1 in pancreatic duct cells under the influence of sodium palmitate

The goal of this study was to research long-term saturated fatty acid overexposure that can induce differentiation of pancreatic duct cells into adipocytes and also into β-cells. The important findings can be summarized as follows: (i) adipogenesis and early stage β-cell differentiation were stimulated in duct cells under lipotoxicity and glucolipotoxicity conditions, (ii) miR-375 expression was upregulated while its target Erk1 was downregulated and miR-375 inhibitor upregulated Erk1 while expression of adipogenesis markers was downregulated in duct cells under both conditions, (iii) apoptosis was induced in β and duct cells under both conditions, (iv) lipotoxicity induced proliferation of co-cultured β-cells. These findings suggest that long-term saturated fatty acid overexposure may cause intrapancreatic fat accumulation by inducing differentiation of duct cells into adipocytes and it may contributes to β-cell compensation by stimulating the early stage of β-cell differentiation in duct cells. In addition, miR-375 may have the potential to be a new target in the treatment of Type 2 diabetes, and NAFPD due to its role in the adipogenesis of duct cells.

Protective Effects of an Oxovanadium(IV) Complex with N2O2 Chelating Thiosemicarbazone on Small Intestine Injury of STZ-Diabetic Rats

Vanadium compounds are being investigated as potential therapeutic agents in the treatment of many health problems, primarily diabetes. We aimed to provide the effect of N(1)-4-hydroxysalicylidene-N(4)-salicylidene-S-methyl-isothiosemicarbazidato-oxovanadium(IV) (VOL) on small intestinal injury in experimental male diabetic rats. Four groups were created of 3.0-3.5-month-old rats. The rats were made diabetic by a single dose of streptozotocin (STZ) at 65 mg/kg and grouped as follows: control animals, VOL-given control animals, STZ-induced diabetic animals and STZ-induced diabetic animals given VOL. A daily dose of 0.2 mM/kg vanadium complex was administered orally for 12 days after the inducement of diabetes. On the 12th day, small intestine tissue samples were taken. According to the data obtained from the biochemical analysis, reduced glutathione (GSH) level, catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), superoxide dismutase (SOD), Na⁺/K⁺-ATPase and paraoxanase (PON) activities were increased, whereas sialic acid (SA), xanthine oxidase (XO) and disaccharidases (maltase and saccharidase) activities were decreased in the small intestine tissue of VOL-treated diabetic rats. Microscopic examinations revealed a remarkable decrease in the mucosal necrotic areas, discontinuity in the brush border, deterioration of the villi integrity and oedema inside the villi, but with a mild decrease in the inflammatory cells, deterioration and loss of integrity of the gland in the small intestine of VOL-treated diabetic rats. Moreover, VOL treatment markedly decreased the proliferation of villus cells and especially inflammatory cells in the small intestine of diabetic rats. According to the obtained data, the administration of VOL is a potentially convenient strategy to reducing small intestine injury in diabetic rats.

Investigation of cell death mechanism and activity of esculetin-loaded PLGA nanoparticles on insulinoma cells in vitro

AIM

The purpose of this study was to prepare targeted cancer therapy formulation against insulinoma INS-1 cells and to study its effect on cell death with related mechanisms in vitro.

METHODS

Polylactide-co-glycolide (PLGA) nano-micelles were used for preparation of esculetin nano-formulation (nano-esculetin). The cells were treated with nano-esculetin and free esculetin. Apoptotic and necrotic cell death percentages, cell proliferation, ATP and GTP reductions and insulin levels were investigated on insulinoma INS-1 cells for both free and nano-esculetin formulations.

RESULTS

About 50 mg of PLGA was able to carry 20 mg esculetin in 20 ml of formulation. The obtained optimized formulation was 150 nm, with 92% encapsulation efficiency and a slow-release behaviour was observed during release studies. Nano-esculetin bearing 25, 50 and 100 μg esculetin and free esculetin in equivalent doses successfully decreased cell viability. The prevailing cell death mechanism was necrosis. Along with cell proliferation, intracellular insulin and the ratio of ATP and GTP were decreased even with 12.5, 25 and 50 μg esculetin bearing nano-formulation and its equivalent free esculetin.

CONCLUSIONS

The results revealed that esculetin is able to show its anti-tumor afficacy after loading to PLGA nano-micelles and nano-encapsulation intensifies its cytotoxic activity in vitro. Current study shows that esculetin and its nano formulations are promising agents in treatment of insulinoma.

Galectin-1 exhibits a protective effect against hepatotoxicity induced by dextran sulfate sodium in mice

Galectin-1 is an important mediator that regulates the T-cell-mediated immune response. It has many other biological functions such as cell growth, immunomodulation, and wound healing. The aim of this study was to reveal the role of galectin-1 on liver morphology, cell proliferation, apoptosis, inflammatory and anti-inflammatory mediators, oxidative stress, and antioxidant system in colitis-mediated hepatotoxicity induced by dextran sulfate sodium (DSS). In the present study, adult mice were divided into four groups: The control group intraperitoneally injected with phosphate buffer saline (I), the group which was orally administered with DSS (II), the control group which was injected with galectin-1 (III), and the group which was given DSS and galectin-1 (IV). DSS administration caused degenerative changes and diffuse necrotic damage, an increase in caspase-3 and cyclooxygenase-2 expression, the levels of lipid peroxidation and tumor necrosis factor-alpha, lactate dehydrogenase, and myeloperoxidase activities, and a decrease in cell proliferation, interleukin-10 levels, and antioxidant system parameters in liver tissues. Treatment of DSS group with galectin-1 reversed these effects and prevented liver damage. This study showed that galectin-1 has proliferative, antiapoptotic, anti-inflammatory, and antioxidant effects against DSS-induced liver injury in mice. It is expected considering all results of this study that galectin-1 may be useful as a protective agent against liver toxicity.

The effects of atorvastatin on the kidney injury in mice with pulmonary fibrosis

OBJECTIVES

The present study investigated the effects of atorvastatin on kidney injury in mice with pulmonary fibrosis (PF).

METHODS

Adult mice were divided into four groups: mice treated with intratracheal bleomycin (I) and their controls (II), and mice treated with atorvastatin for 10 days after 7 days from bleomycin treatment (III) and their controls (IV). Mice were dissected on the 21st day.

KEY FINDINGS

Mononuclear cell infiltrations, injured proximal tubule epithelium and p-c-Jun level increased, while cell proliferation and the levels of p-SMAD2, ELK1, p-ELK1, p-ATF2 and c-Jun decreased in the kidney tissue of mice with PF. The atorvastatin treatments to mice with PF resulted in significant increases at the TGF-β activation, cell proliferation and kidney damage and decreases in the levels of p-SMAD2, p-ELK1, p-ATF2 and p-c-Jun, but not change the p-SMAD3, ELK1 and ATF2 in kidneys.

CONCLUSIONS

The depletion of MAPK signals, rather than SMAD signalling, is effective in kidney damage of mice with PF. Atorvastatin did not regress kidney damage in these mice, whereas it increases the kidney injury. The c-Jun-mediated JNK signals could help kidney repair through cell proliferation. The treatment time and doses of atorvastatin should be optimized for regression of kidney damage.

The effects of vitamins and selenium mixture or ranitidine against small intestinal injury induced by indomethacin in adult rats

This study was aimed at investigating morphological and biochemical efficacies of antioxidants on indomethacin-induced small intestinal damage in rats. Group I: control animals (negative control) given only placebo, Group II: (positive control) are animals orally given combination of antioxidants [vitamin C (Vit C), vitamin E (Vit E), β-carotene and sodium selenite (Se)] daily for 3 days, Group III: Rats were given only indomethacin, Group IV: animals were given of antioxidants combination for 3 days, last dose was given 2 hr before the administration of indomethacin. Group V: Animals receiving ranitidine for 3 days (second positive control). Group VI: Animals received ranitidine for 3 days, last dose was given 2 hr before to indomethacin administration. Indomethacin caused degenerative morphological and biochemical changes, which were reversed on antioxidants administration. As a result, we propose that antioxidants combination would be therapeutically beneficial for treating indomethacin-induced lesions of small intestine. PRACTICAL APPLICATIONS: Indomethacin is a widely preferred nonsteroidal anti-inflammatory drug (NSAID) but its side effects on gastrointestinal system are well known. Indomethacin also causes production of reactive oxygen species. Antioxidants and selenium has protective effects. According to the results of this study, antioxidants and selenium can be used as a food supplement for preventing NSAID-induced side effects and toxicity.

4-Methylcatechol stimulates apoptosis and reduces insulin secretion by decreasing betacellulin and inhibin beta-A in INS-1 beta-cells

Insulinoma INS-1 cell line is a pancreatic beta cell tumor which is characterized with high insulin content and secretion in response to increasing glucose levels. 4-Methylcatechol (4-MC) is a metabolite of quercetin, which is known as a potential drug for inhibition of tumorigenesis. The aim of this study was to determine the applying doses of 4-methylcatechol (4-MC) for triggening cell death and decreasing the cell function of rat insulinoma INS-1 beta cells. The rate of apoptosis and the amount of insulin in the cell and the secretions were determined by the ELISA method. Betacellulin (BTC) and inhibin beta-A amounts in both the cell and the glucose induced secretion were investigated by Western blotting. Furthermore, BTC, Inhibin beta-A, Ins1, Ins2, and GLUT2 gene expression levels were determined by the by the real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) method. We noted a significant decrease in cell viability, while an increase in apoptotic cell death by 4-MC treatment. It caused a decrease in the secretion of BTC, expressions of both BTC and inhibin beta-A. We showed a decrease in the expressions of Ins1 and GLUT2, while there is no alteration in the level of insulin protein. Insulin secretion levels increased in INS-1 cells given 4-MC by basal glucose concentration while they did not response to high concentration of glucose, which indicates that 4-MC disrupts the functionality of INS-1 cells. These results revealed that 4-MC induces apoptosis and decreases insulin secretion by reducing BTC and inhibin beta-A in insulinoma INS-1 cells. Thus, 4-MC may be offered as a potential molecule for treatment of insulinoma.

Exendin-4 partly ameliorates - hyperglycemia-mediated tissue damage in lungs of streptozotocin-induced diabetic mice

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion, - plays anti-inflammatory role in atherosclerosis, and has surfactant-releasing effects in lungs. GLP-1 analogues are used in diabetes therapy. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on lung injury in diabetic mice. BALB/c male mice were divided into four groups. The first group was given only citrate buffer, the second group was given only exendin-4, the third group was given only streptozotocin (STZ), and the fourth group was given both exendin-4 and STZ. Exendin-4 (3μg/kg) was administered daily by subcutaneous injection for 30days after mice were rendered diabetic with a single dose of STZ (200mg/kg). Structural alterations, oxidative stress, apoptosis, insulin signaling and expressions of prosurfactant-C, alpha-smooth muscle actin, collagen-I and fibronectin were evaluated in lung tissue. Diabetic mice lungs were characterized by induced oxidative stress, apoptosis, edema, and cell proliferation. They had honeycomb-like alveoli, thicker alveolar walls, and hypertrophic pneumocytes. Although exendin-4 treatment improved pulmonary edema, apoptosis, oxidative stress, and lung injury, it led to the disrupted insulin signaling and interstitial collagen accumulation in the lungs of diabetic mice. Exendin-4 ameliorates hyperglycemia-mediated lung damage by reducing glucose, -oxidative stress and stimulating cell proliferation. However, exendin-4 led to increased lung injury partly by reducing insulin signaling - and collagen accumulation around pulmonary vasculature in diabetic mice.

Involvement of dying beta cell originated messenger molecules in differentiation of pancreatic mesenchymal stem cells under glucotoxic and glucolipotoxic conditions

Beta cell mass regulation represents a critical issue for understanding and treatment of diabetes. The most important process in the development of diabetes is beta cell death, generally induced by glucotoxicity or glucolipotoxicity, and the regeneration mechanism of new beta cells that will replace dead beta cells is still not fully understood. The aim of this study was to investigate the generation mechanism of new beta cells by considering the compensation phase of type 2 diabetes mellitus. In this study, pancreatic islet derived mesenchymal stem cells (PI-MSCs) were isolated from adult rats and characterized. Then, beta cells isolated from rats were co-cultured with PI-MSCs and they were exposed to glucotoxicity, lipotoxicity and glucolipotoxicity conditions for 72 hr. As the results apoptotic and necrotic cell death were increased in both PI-MSCs and beta cells especially by the exposure of glucotoxic and glucolipotoxic conditions to the co-culture systems. Glucotoxicity induced-differentiated beta cells were functional due to their capability of insulin secretion in response to rising glucose concentrations. Moreover, beta cell proliferation was induced in the glucotoxicity-treated co-culture system whereas suppressed in lipotoxicity or glucolipotoxicity-treated co-culture systems. In addition, 11 novel proteins, that may release from dead beta cells and have the ability to stimulate PI-MSCs in the direction of differentiation, were determined in media of glucotoxicity or glucolipotoxicity-treated co-culture systems. In conclusion, these molecules were considered as important for understanding cellular mechanism of beta cell differentiation and diabetes. Thus, they may be potential targets for diagnosis and cellular or therapeutic treatment of diabetes.

Necrotic cell death occur via JNK pathway with the activity of transcription factor c-Jun by 4-MC in INS-1 cell line

In this study, it was aimed to determine the doses of 4-methylcatechol causing cell death in rat insulinoma β-cells (INS-1), to find out the type of cellular death at these doses, and to investigate the molecular mechanism of cellular death occurring. More necrotic cells were observed than apoptosis with the administration of 350, 400, and 450 μM 4-methylcatechol. Lactate dehydrogenase levels, reactive oxygen species, mitochondrial potential loss, ATP, and GTP losses increased at these doses. The JNK and ERK cellular pathway were screened. We observed an increase in p-RAF1 activity, the active JNK amount, the total c-Jun amount, while a decrease in p-RAF1 expression, the total JNK amount, JNK expression, ATF2 expression, active ERK, and its expression and Elk1 expression. It was concluded that cells perform necrotic death by the following options: i) phosphorylated RAF1 activates the JNK pathway with the activity of transcription factor c-Jun; ii) Hsp 70 and Hsp 90 do not show a change inside the cell, rendering the JNK pathway active.

Runt-Related Transcription Factor 2 (Runx2) Is Responsible for Galectin-3 Overexpression in Human Thyroid Carcinoma

Runx2 promotes metastatic ability of cancer cells by directly activating some of the mediators regarding malignancy. Galectin-3 (Gal-3) extensively expressed in normal and transformed cells and it is responsible for many cellular processes. In this study, we aimed to investigate whether there is any relationship between runx2 transcription factor and regulation of galectin-3 expression in different human thyroid carcinoma cell lines. To show effects of runx2 transcription factor on gal-3 expression, we developed runx2 knockdown model in the thyroid carcinoma cell lines; anaplastic 8505C and 8305C and, papillary TPC-1 and follicular FTC-133 by using siRNA transfection. We analyzed the protein expressions and mRNA levels of gal-3 and MMP2/9 in the runx2-silenced cell lines using Western blotting, qPCR, and fluorescent microscopy. Our results showed that mRNA expression levels of gal-3 and MMP2/9 were downregulated in runx2-silenced cell lines. In this investigation, we revealed that regulation of gal-3 expression was strongly correlated with runx2 transcription factor in human thyroid carcinoma. Considering the contribution of human gal-3 in collaboration with MMP2/9 to the malignant characters of many cancers, regulation of their expressions through runx2 seems like one of the key regulatory mechanism for malignant potential of human thyroid carcinoma. Accordingly, runx2 transcription factor inhibitors can be a potential target in order to prevent gal-3 mediated malignancy of human thyroid carcinoma. J. Cell. Biochem. 118: 3911-3919, 2017. © 2017 Wiley Periodicals, Inc.

Vitamin U has a protective effect on valproic acid-induced renal damage due to its anti-oxidant, anti-inflammatory, and anti-fibrotic properties

The aim of present study was to investigate the effect of vitamin U (vit U, S-methylmethionine) on oxidative stress, inflammation, and fibrosis within the context of valproic acid (VPA)-induced renal damage. In this study, female Sprague Dawley rats were randomly divided into four groups: Group I consisted of intact animals, group II was given vit U (50 mg/kg/day, by gavage), group III was given VPA (500 mg/kg/day, intraperitonally), and group IV was given VPA + vit U. The animals were treated by vit U 1 h prior to treatment with VPA every day for 15 days. The following results were obtained in vit U + VPA-treated rats: (i) the protective effect of vit U on renal damage was shown by a significant decrease in histopathological changes and an increase in Na(+)/K(+)-ATPase activity; (ii) anti-oxidant property of vit U was demonstrated by a decrease in malondialdehyde levels and xanthine oxidase activity and an increase in glutathione levels, catalase and superoxide dismutase activities; (iii) anti-inflammatory property of vit U was demonstrated by a decrease in tumor necrosis factor-α, interleukin-1β, monocyte chemoattractant protein-1 levels, and adenosine deaminase activity; (iv) anti-fibrotic effect of vit U was shown by a decrease in transforming growth factor-β, collagen-1 levels, and arginase activity. Collectively, these data show that VPA is a promoter of inflammation, oxidative stress, and fibrosis which resulted in renal damage. Vit U can be proposed as a potential candidate for preventing renal damage which arose during the therapeutic usage of VPA.

The role of ghrelin on apoptosis, cell proliferation and oxidant-antioxidant system in the liver of neonatal diabetic rats

Ghrelin is a multifunctional peptide hormone which stimulates appetite and regulates glucose metabolism and adipogenesis. The purpose of this study was to investigate whether ghrelin has protective effects in the liver of streptozocin (STZ) diabetic rats or not. Wistar-type neonatal rats were divided into four groups: I. Controls, II. Ghrelin administrated controls, III. STZ-diabetic rats, and IV. Ghrelin administrated diabetic rats. On the second day after birth, 100 mg/kg STZ was administered intraperitoneally in a single dose to induce diabetes in rats. 100 µg/kg/day ghrelin was administrated to rats subcutaneously for 4 weeks. Ghrelin administration improved histopathologic changes in STZ-diabetic liver. Obestatin immunoreactivity has been shown in livers of neonatal rats. The immunoreactivity of obestatin increased in diabetic rats and a decline was observed in ghrelin administrated diabetic rats. Caspase 8 and 3 immunoreactivities increased in diabetic rats; however, ghrelin administration differently affected caspases 8 and 3 immunoreactivities. Proliferating cell nuclear antigen immunoreactivities decreased in diabetic rats and in ghrelin administrated diabetic rats. Serum alanine (P < 0.05) and aspartate transaminase (P < 0.0001) and serum alkaline phosphatase (P < 0.0001) activities were decreased in ghrelin administrated diabetic rats compared to the diabetic rats. Gamma glutamyl transferase activity (P < 0.001) decreased in ghrelin administrated diabetic rats compared to the diabetic rats. The response of antioxidants including glutathione levels, catalase and superoxide dismutase activities were altered in ghrelin administrated diabetic rats. Our findings indicate that ghrelin administration affects hepatic functions in neonatal diabetic rats and might be considered as a therapeutic agent.

The protective effects of prostaglandin E1 on lung injury following renal ischemia-reperfusion in rats

For the purposes of the present study, the protective effect of prostaglandin E1 (PGE1) on lung injury following renal ischemia-reperfusion (RIR) was investigated. Adult male rats were divided into four groups, namely, (I) control rats given physiological saline; (II) rats given PGE1 (20 μg/kg, intravenously); (III) rats subjected to RIR; and (IV) rats subjected to RIR given PGE1 30 min prior to ischemia and just before reperfusion. The right nephrectomy was performed in the RIR model. The left renal pedicle was occluded for 60 min to induce ischemia and then the left kidney was subjected to reperfusion for 60 min. The lungs of rats were used for microscopic and biochemical analyses. Although rats subjected to RIR did not exhibit heavy degenerative alterations in the lung structure, they possessed pulmonary interstitial edema. Lung glutathione levels and catalase, superoxide dismutase, glutathione peroxidase, and tissue factor (TF) activities were decreased in rats subjected to RIR, while lung lipid peroxidation, myeloperoxidase (MPO), xanthine oxidase and serum lactate dehydrogenase (LDH) activities, and blood urea and serum creatinine levels were increased in these rats when compared with the control group. PGE1 treatments resulted in the regression of oxidative stress via induction of antioxidant system, the decreased MPO and LDH activities, the reduced urea and creatinine levels, and the induced TF activity in rats subjected to RIR, while edema still remained permanent. We conclude that PGE1 may be useful in preventing lung injury with the exception of edema that occurred as a result of RIR in rats.

Chard (Beta vulgaris var. cicla) extract improved hyperglycemia-induced oxidative stress and surfactant-associated protein alterations in rat lungs

CONTEXT

Chard is used as an antidiabetic agent by the diabetic patients in Turkey.

OBJECTIVE

The effect of chard extract [Beta vulgaris L. var. cicla (Chenopodiaceae)] on the antioxidant system and the expression of surfactant-associated proteins (SP) in the lungs of hyperglycemic rats were examined.

MATERIALS AND METHODS

Hyperglycemia was induced by a single dose of streptozotocin (60 mg/kg) provided intraperitoneally. Fourteen days after the rats were rendered hyperglycemic, the chard (2 g/kg/d), insulin (6 U/kg/d), and chard plus insulin (as mentioned above) were administered to rats for 45 d. On day 60, rats' lungs were removed. Oxidative stress parameters and SP expression were assayed.

RESULTS

The lungs of hyperglycemic rats were characterized by the induced lipid and protein oxidation, elevated myeloperoxidase and xanthine oxidase activities, decreased glutathione levels, and reduced tissue factor and antioxidant enzymes activities (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase). Chard treatment alone and chard treatment combined with insulin were capable of achieving a regression of pulmonary oxidative stress, by inhibiting lipid and protein oxidation, and restoring the antioxidant system of hyperglycemic rats. SP-A expressions were significantly unchanged in all groups, whereas pro-SP-C and SP-D expressions were reduced in hyperglycemic rats. Pro-SP-C and SP-D levels were increased by chard and insulin administrations alone and combined in hyperglycemic rats.

DISCUSSION AND CONCLUSION

All treatments have a positive effect on the surfactant and antioxidant systems of the lungs of hyperglycemic rats. The best therapeutic effect was provided by treatment with chard extract alone in the compensation of hyperglycemic symptoms.

Δ9-tetrahydrocannabinol treatment improved endothelium-dependent relaxation on streptozotocin/nicotinamide-induced diabetic rat aorta

OBJECTIVE

In this study, we investigated the possible effect of Δ(9)-tetrahydrocannabinol (THC), a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, on metabolic control and vascular complications of diabetes in streptozotocin/nicotinamide (STZ/NIC) induced type 2 diabetes mellitus.

MATERIAL AND METHODS

Type 2 diabetes was induced with 65 mg/kg STZ, 15 minute later 85 mg/kg NIC was given intraperitoneally (i.p.) to rats. Three days after diabetes induction, THC (3 mg/kg/day, i.p.) was given for 7 days to diabetic rats. Body weight and plasma glucose levels of rats were measured in all groups before and at the end of 3 weeks after diabetes induction. Acetylcholine (Ach) and sodium nitroprusside (SNP) potency and maximum relaxant effects were calculated on aortic rings pre-contracted with noradrenaline (NA).

RESULTS

At the end of 3 weeks, blood glucose levels of diabetic group significantly increased in comparison with the control group. Increased plasma glucose levels were significantly decreased by the treatment of THC. Ach induced relaxation was impaired whereas endothelium-independent relaxation to SNP was unaffected on isolated diabetic rat aorta. THC treatment enhanced Ach induced relaxation on diabetic rat aortas.

DISCUSSION

These results suggested that THC improved endothelium-dependent relaxation in STZ/NIC induced diabetic rat aorta and that these effects were mediated at least in part, by control of hyperglycemia and enhanced endothelial nitric oxide bioavailability.

Exendin-4 attenuates renal tubular injury by decreasing oxidative stress and inflammation in streptozotocin-induced diabetic mice

In this study, we aimed to research the restorative effects of exendin-4, a GLP-1 analog, on renal tubular injury in streptozotocin-induced diabetes model. BALB/c male mice were divided into four groups: non-diabetic, non-diabetic + exendin-4 (3 μg/kg), diabetic and diabetic + exendin-4. In our diabetic model, we observed renal injury mainly in tubular area rather than glomeruli and exendin-4 decreased tubular injury with its glucose lowering effect. Besides, PCNA positive tubular cells, activities of LDH and Na(+)-K(+)-ATPase were also significantly declined by the administration of exendin-4. Furthermore, exendin-4 attenuated the levels of ROS, MDA, 8-OHdG, proinflammatory cytokines (TNF-α, IL-1β), chemokine MCP-1, ICAM-1, and fibrosis-related molecules (transforming growth factor β1 and fibronectin). In consistent with reducing tubular injury, macrophage infiltration and both MCP-1 and ICAM-1 production in tubular cells were decreased. These results indicate that exendin-4 may decrease renal tubular injury seen in the beginning of diabetic nephropathy by decreasing ROS production and inflammation.

Carbon tetrachloride-induced kidney damage and protective effect of Amaranthus lividus L. in rats

This study was designed to evaluate the protective effect of water extract of Amaranthus lividus L. ( A. lividus) (Amaranthaceae) on carbon tetrachloride (CCl4)-induced toxicity in kidneys of rats. For this purpose, male albino Wistar rats were pretreated with A. lividus (250 and 500 mg/kg body weight (b.w.)) daily for 9 days and a single dose of CCl4 was applied intraperitoneally (50% in olive oil; 1.5 mL/kg b.w.) on the 10th day. All rats were killed 24 h after CCl4 administration, and kidneys were excised and used for determination of histopathological and biochemical parameters. CCl4 administration caused a remarkable increase in lipid peroxidation (LPO) and glutathione levels and glutathione- S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase, myeloperoxidase (MPO) activities and a decrease in catalase (CAT) activity when compared to the control group. Pretreatment with A. lividus (250 and 500 mg/kg b.w.) significantly prevented the elevation in LPO level and MPO activity as well as protected the decrease in CAT activity but did not alter other biochemical parameters. The protective effect of A. lividus was further evident through the decreased histological alterations in kidneys. In conclusion, this study has indicated that A. lividus possesses protective and antioxidant effects against CCl4-induced oxidative kidney damage.

Activation of polyamine catabolic enzymes involved in diverse responses against epibrassinolide-induced apoptosis in LNCaP and DU145 prostate cancer cell lines

Epibrassinolide (EBR) is a biologically active compound of the brassinosteroids, steroid-derived plant growth regulator family. Generally, brassinosteroids are known for their cell expansion and cell division-promoting roles. Recently, EBR was shown as a potential apoptotic inducer in various cancer cells without affecting the non-tumor cell growth. Androgen signaling controls cell proliferation through the interaction with the androgen receptor (AR) in the prostate gland. Initially, the development of prostate cancer is driven by androgens. However, in later stages, a progress to the androgen-independent stage is observed, resulting in metastatic prostate cancer. The androgen-responsive or -irresponsive cells are responsible for tumor heterogeneity, which is an obstacle to effective anti-cancer therapy. Polyamines are amine-derived organic compounds, known for their role in abnormal cell proliferation as well as during malignant transformation. Polyamine catabolism-targeting agents are being investigated against human cancers. Many chemotherapeutic agents including polyamine analogs have been demonstrated to induce polyamine catabolism that depletes polyamine levels and causes apoptosis in tumor models. In our study, we aimed to investigate the mechanism of apoptotic cell death induced by EBR, related with polyamine biosynthetic and catabolic pathways in LNCaP (AR+), DU145 (AR-) prostate cancer cell lines and PNT1a normal prostate epithelial cell line. Induction of apoptotic cell death was observed in prostate cancer cell lines after EBR treatment. In addition, EBR induced the decrease of intracellular polyamine levels, accompanied by a significant ornithine decarboxylase (ODC) down-regulation in each prostate cancer cell and also modulated ODC antizyme and antizyme inhibitor expression levels only in LNCaP cells. Catabolic enzymes SSAT and PAO expression levels were up-regulated in both cell lines; however, the specific SSAT and PAO siRNA treatments prevented the EBR-induced apoptosis only in LNCaP (AR+) cells. In a similar way, MDL 72,527, the specific PAO and SMO inhibitor, co-treatment with EBR during 24 h, reduced the formation of cleaved fragments of PARP in LNCaP (AR+) cells.

The role of epidermal growth factor in prevention of oxidative injury and apoptosis induced by intestinal ischemia/reperfusion in rats

Intestinal ischemia/reperfusion is a major problem which may lead to multiorgan failure and death. The aim of the study was to evaluate the effects of epidermal growth factor (EGF) on apoptosis, cell proliferation, oxidative stress and the antioxidant system in intestinal injury induced by ischemia/reperfusion in rats and to determine if EGF can ameliorate these toxic effects. Intestinal ischemia/reperfusion injury was produced by causing complete occlusion of the superior mesenteric artery for 60 min followed by a 60-min reperfusion period. Animals received intraperitoneal injections of 150 μg/kg human recombinant EGF 30 min prior to the mesenteric ischemia/reperfusion. Mesenteric ischemia/reperfusion caused degeneration of the intestinal mucosa, inhibition of cell proliferation, stimulation of apoptosis and oxidative stress in the small intestine of rats. In the ischemia/reperfusion group, lipid peroxidation was stimulated accompanied by increased intestinal catalase and glutathione peroxidase activities, however, glutathione levels and superoxide dismutase activities were markedly decreased. EGF treatment to rats with ischemia/reperfusion prevented the ischemia/reperfusion-induced oxidative injury by reducing apoptosis and lipid peroxidation, and by increasing antioxidant enzyme activities. These results demonstrate that EGF has beneficial antiapoptotic and antioxidant effects on intestinal injury induced by ischemia/reperfusion in rats.

Chard (Beta vulgaris L. var. cicla) extract ameliorates hyperglycemia by increasing GLUT2 through Akt2 and antioxidant defense in the liver of rats

Chard is a plant used as an alternative hypoglycemic agent by diabetic people in Turkey. The aim of this study was to examine the molecular mechanism of hypoglycemic effects of chard extract. Male Sprague-Dawley rats (6-7 months old) were divided into five groups for this investigation: (1) control, (2) hyperglycemic, (3) hyperglycemic+chard, (4) hyperglycemic+insulin, (5) hyperglycemic+chard+insulin. Fourteen days after animals were rendered hyperglycemic by intraperitoneal injection of 60 mg/kg streptozotocin, the chard water extract (2 g/kg/day) or/and insulin (6 U/kg/day) was administered for 45 days. Hypoglycemic effect of chard extract was demonstrated by a significant reduction in the fasting blood glucose and increased glycogen levels in liver of chard extract-treated hyperglycemic rats. Moreover, activity of adenosine deaminase, which is suggested as an important enzyme for modulating the bioactivity of insulin, was decreased by chard treatment. Immunostaining analysis showed increased nuclear translocation of Akt2 and synthesis of GLUT2 in the hepatocytes of chard or/and insulin-treated hyperglycemic rats. The oxidative stress was decreased and antioxidant defense was increased by chard extract or/and insulin treatment to hyperglycemic rats according to the decreased malondialdehyde formation, the activities of catalase, superoxide dismutase, myeloperoxidase and increased glutathione levels. These findings suggest that chard extract might improve glucose response by increasing GLUT2 through Akt2 and antioxidant defense in the liver.

Regulation of oxidative stress and somatostatin, cholecystokinin, apelin gene expressions by ghrelin in stomach of newborn diabetic rats

The aim of the study was to determine whether ghrelin treatment has a protective effect on gene expression and biochemical changes in the stomach of newborn streptozotocin (STZ) induced diabetic rats. In this study, four groups of Wistar rats were used: control, ghrelin control, diabetic and diabetic+ghrelin. The rats were sacrificed after four weeks of treatment for diabetes. The gene expressions of: somatostatin, cholecystokinin, apelin and the altered active caspase-3, active caspase-8, proliferating cell nuclear antigen, were investigated in the pyloric region of the stomach and antioxidant parameters were measured in all the stomach. Although ghrelin treatment to diabetic rats lowered the stomach lipid peroxidation levels, the stomach glutathione levels were increased. Exogenous ghrelin caused an increased activities of stomach catalase, superoxide dismutase, glutathione reductase and glutathione peroxidase in diabetic rats. Numbers of somatostatin, cholecystokinin and proliferating cell nuclear antigen immunoreactive cells decreased in the diabetic+ghrelin group compared to the diabetic group. Apelin mRNA expressions were remarkably less in the diabetic+ghrelin rats than in diabetic rats. The results may indicate that ghrelin treatment has a protective effect to some extent on the diabetic rats. This protection is possibly accomplished through the antioxidant activity of ghrelin observed in type 2 diabetes. Consequently exogenous ghrelin may be a candidate for therapeutic treatment of diabetes.

Alterations in kidney tissue following zinc supplementation to STZ-induced diabetic rats

Diabetes mellitus is a chronic disease characterized by anomalies forming in carbohydrate, lipid, protein metabolisms and the incidence of this disease varies widely throughout the world. Zinc is an important element which is essential for life and is present in nature. In this study, the animals were divided into four groups. These groups were named as untreated; zinc sulfate; streptozotocin (STZ); STZ and zinc sulfate. STZ (65 mg/kg) was dissolved in a freshly prepared 0.01 M pH 4.5 citrate buffer and given with intraperitoneal injection in a single dose. Zinc sulfate (100mg/kg) was dissolved in distilled water and given to the animals by gavage at a daily dose for 60 days. The rats were sacrificed under ether anesthesia. This study was aimed to investigate histological and biochemical changes of zinc supplementation on the kidney tissue in STZ-induced diabetic rats. In the current study, histological and histochemical observations showed that the occurred degenerative changes decreased after giving zinc in the kidney tissue of diabetic group. Kidney glutathione (GSH) levels decreased and lipid peroxidation (LPO), nonenzymatic glycosylation (NEG), urea and creatinine levels increased in diabetic rats. GSH levels increased, while LPO, NEG, urea and creatinine levels decreased in the kidney with administration of zinc to diabetic rats. As a result, we observed curative effects of zinc given to diabetic rats. We can say that zinc may be an important antioxidant for the treatment of secondary complications of diabetes in kidney tissue.

Teduglutide, a glucagon-like peptide 2 analogue: a novel protective agent with anti-apoptotic and anti-oxidant properties in mice with lung injury

Teduglutide is a long-acting synthetic analogue of human glucagon-like peptide-2 (GLP-2). GLP-2 regulates cell proliferation and apoptosis as well as normal physiology in the gastrointestinal tract. In the present study, possible cytoprotective and reparative effects of teduglutide were analyzed on a mouse model with lung injury induced by tumor necrosis factor-alpha (TNF-α) and actinomycin D (Act D). BALB/c mice were divided into six groups: control mice (I), mice injected intraperitoneally with 15 μg/kg TNF-α (II), 800 μg/kg Act D (III), Act D 2 min prior to TNF-α administration with the same doses (IV), mice injected subcutaneously with 200 μg/kg teduglutide every 12h for 10 consecutive days (V), and mice given Act D 2 min prior to TNF-α administration on day 11 after receiving teduglutide for 10 days (VI). The TNF-α/Act D administration made the lung a sensitive organ to damage. Mice lung subjected to TNF-α/Act D were characterized by the disruption of alveolar wall, induced pulmonary endothelial/epithelial cell apoptosis and expression of active caspase-3. These mice exhibited an increase in lipid peroxidation, glutathione levels, and activities of myeloperoxidase, superoxide dismutase, catalase, glutathione peroxidase and xanthine oxidase, as well as reduced tissue factor and sodium-potassium/ATPase activities. Teduglutide pretreatment regressed the structural damage, cell apoptosis and oxidative stress by reducing lipid peroxidation in mice received TNF-α/Act D. GLP-2 receptors were present on the cell membrane of type II pneumocytes and interstitial cells. Thus, teduglutide can be suggested as a novel protective agent, which possesses anti-apoptotic and anti-oxidant properties, against lung injury.

The relation among NGF, EGF and insulin is important for triggering pancreatic β cell apoptosis

BACKGROUND

Nerve growth factor (NGF) is a well-known mediator for maintaining the survival of neurons, while recent studies report that its absence induces apoptosis in cultured β cells of humans and rats. However, its relationship with other growth factors that have important roles in the survival and function of β cells such as epidermal growth factor (EGF) has not yet been elucidated. The aim of this study was to investigate the effects of NGF withdrawal on the synthesis and secretion of EGF, insulin with respect to β cell apoptosis in hyperglycemic rats.

METHOD

β cells were isolated from euglycemic and streptozotocin-induced hyperglycemic rats and treated with NGF neutralizing antibody for withdrawal of NGF in culture medium. NGF, EGF and insulin levels in cell lysates and secretion samples were measured by enzyme-linked immunosorbent assay, and their gene expressions were determined by real-time reverse transcription polymerase chain reaction assay. Apoptosis was quantitatively determined by cytoplasmic histone-associated DNA fragments.

RESULTS

Nerve growth factor neutralization triggered β cell apoptosis. In addition decreased insulin, increased NGF and EGF were observed at gene expression and protein levels by NGF neutralization. Moreover, NGF withdrawal decreased secretion of these peptides from β cells. Although the alterations seemed to be similar under euglycemic and hyperglycemic conditions, NGF withdrawal more strongly affected β cells of hyperglycemic rats.

CONCLUSIONS

These important findings indicate that NGF is an important regulator for the synthesis and secretion of EGF and insulin from the β cells. Moreover, results suggested that NGF withdrawal causes apoptosis by decreasing EGF, NGF and insulin secretion from β cells of hyperglycemic rats.

Acute effects of methiocarb on oxidative damage and the protective effects of vitamin E and taurine in the liver and kidney of Wistar rats

Methiocarb (MC) is a widely used carbamate pesticide in agriculture and health programs. Although the main molecular mechanism of carbamate toxicity involves acetylcholinesterase inhibition, studies have also implicated the induction of oxidative stress. Therefore, the present study was aimed to evaluate the effect of acute MC exposure on lipid peroxidation, antioxidant defense systems, histological changes in Wistar rats and the protective effect of pretreatment with vitamin E and taurine. A total of 48 rats were randomly divided into six groups. Rats in group I were given corn oil, while those in group III were dosed with vitamin E (100 mg/kg body weight (b.w.)) and in group V were dosed with taurine (50 mg/kg b.w.). Rats in group II were administered with MC only (25 mg/kg b.w., 1/4 of median lethal dose (LD(50))), while those in groups IV and VI were pretreated with vitamin E (100 mg/kg b.w.) and taurine (50 mg/kg b.w.) for 20 days, respectively, and then exposed to MC (25 mg/kg b.w.). The rats administered with MC showed significant increase in the levels of malondialdehyde in the liver and kidney as an index of lipid peroxidation. Levels of glutathione and activities of superoxide dismutase, catalase and glutathione peroxidase were significantly increased, while activity of glutathione reductase remained unchanged in both the tissues after MC treatment. Mild degenerative histological changes were observed in liver tissue, while the changes in kidney tissue were more severe then liver after MC treatment. Pretreatment with vitamin E and taurine resulted in a significant decrease in the lipid peroxidation and alleviating effects on antioxidant defense systems in both the tissues, while protective effects on the histological changes were shown only in kidney when compared with liver. In conclusion, the study has demonstrated that the acute MC exposure in Wistar rats caused oxidative damage on liver and kidney, which were partly ameliorated by the pretreatment of vitamin E and taurine.

Regulation of gene expression and biochemical changes in small intestine of newborn diabetic rats by exogenous ghrelin

The aim of this study was to investigate (i) the cholecystokinin, somatostatin and apelin mRNA levels, (ii) the changes in levels and localization of these peptides, (iii) relation between these peptides, (iv) antiapoptotic effects and (v) antioxidant effects of ghrelin. The rats were divided into four groups second day after birth. These groups were respectively treated with physiological saline, ghrelin (100μg/kg/day), streptozotocin (100mg/kg), ghrelin and streptozotocin. After four weeks, small intestine and blood samples were taken from rats. Cholecystokinin mRNA and peptide, somatostatin mRNA, release to duodenal lumen of apelin peptide and apelin mRNA signals decreased in ghrelin-treated diabetic rats compared to the diabetic group. There was no statistically significant difference among the four groups for somatostatin and apelin peptides. Caspase-3 signals were not observed only in diabetic group treated with ghrelin. Caspase-8 signals were increased while PCNA signals were decreased in diabetic group given ghrelin compared to diabetic group. Small intestine CAT, SOD, GP(x) and GST activities and GSH levels were decreased and LPO, PC levels were increased in diabetic rats. Administration of ghrelin to diabetic rats caused an increase in intestinal CAT, SOD, GP(x) and GST activities and GSH levels, while PC levels decreased. As a result, we observed positive changes in diabetic rats treated with ghrelin in both microscopic and biochemical studies. We can suggest that ghrelin may be an important hormone for the treatment of diabetes.

The potential role of combined antioxidant treatment on pancreas of STZ-diabetic mice

In diabetes, cells and tissues are damaged due to the imbalance between production of free radicals and removal of them. The effective biologic antioxidants for oxidative stress such as α-lipoic acid, vitamin E and selenium are effective in diminishing oxidative damage such as membrane lipid peroxidation. The experiment aimed to investigate the oxidative stress occurring in mitochondrial and cytoplasmic fraction of pancreatic tissues in streptozotocin-diabetic mice and the possible effects of α-lipoic acid + vitamin E + selenium combination on oxidative damage and antioxidative system by using microscopic and biochemical methods. The mice were divided into five groups. These groups were treated by citrate buffer, the solvents of the antioxidants, combined the antioxidants [α-lipoic acid (50 mg/kg), vitamin E (100 mg/kg), selenium (0.25 mg/kg)], streptozotocin (40 mg/kg × 5), combined the antioxidants and streptozotocin. The mice were sacrificed by cervical dislocation. In the experimental group given combined antioxidants following results were observed compared to diabetic group: increased percent insulin-positive cell area; decreased blood glucose levels; increased manganase superoxide dismutase activities and unsignificantly increased superoxide dismutase activities; unsignificantly decreased lipid peroxidase levels in both of fraction; unsignificantly decreased in mitochondrial fraction and unsignificantly increased in cytosolic fraction for catalase levels; not any alteration glutathione levels; not any activity in both of fraction for glutathione peroxidase. We can say that by taking the blood glucose levels and immunohistochemical results into account, the combination of triple antioxidants has a partly positive effect on diabetes. This positive effect could increase when trying different doses of combined antioxidant treatment.

4-Methlycatechol prevents NGF/p75(NTR)-mediated apoptosis via NGF/TrkA system in pancreatic β cells

In this study, it was aimed to investigate whether 4-methylcatechol (4-MC) could serve as an autocrine antiapoptotic agent by increasing nerve growth factor (NGF) in β cells of hyperglycemic rats. Rats were divided into four groups: the first group was given citrate buffer and saline, the second group was administered 4-MC, the third group received streptozotocin (STZ), and the fourth group was given both 4-MC and STZ. 4-MC (10 μg/kg) was administered by daily intraperitoneal injection for 10 days before the animals were rendered hyperglycemic by administration of STZ (75 mg/kg). With 4-MC pretreatment on hyperglycemic rats the following results were noted: (i) Increase in plasma glucose, β cell apoptosis and caspase-8 activation was prevented. (ii) Reduction of NGF+ and tyrosine receptor kinase A (TrkA)+ β cell number was blocked. (iii) p75 neurotrophin receptor (p75(NTR))+ β cell number was increased. These data suggest that 4-MC might exert its antiapoptotic actions through NGF/TrkA system which may block NGF/p75(NTR) activation in pancreatic β cells of hyperglycemic rats.

Exendin-4 improves hepatocyte injury by decreasing proliferation through blocking NGF/TrkA in diabetic mice

The hepatocytes express nerve growth factor (NGF) and its high affinity receptor tyrosine kinase A (TrkA). However, the link between NGF/TrkA system and hepatocyte proliferation in diabetic animals and the effects of exendin-4, a glucagon like peptide-1 (GLP-1) receptor agonist, on this system are not known. BALB/c male mice were divided into four groups. The first group was given citrate buffer only, the second group was administered exendin-4 alone, the third group received streptozotocin (STZ), and the fourth group was given both STZ and exendin-4. Exendin-4 (3μg/kg) was administered by subcutaneous injection daily for 30 days after the animals were rendered diabetic by administration of STZ (200mg/kg). With treatment of exendin-4 to the diabetic mice the following results were noted (i) NGF, TrkA and proliferating cell nuclear antigen positive hepatocytes were decreased; (ii) p75 neurotrophin receptor and caspase-3 positive hepatocyte could not be detected; (iii) liver alanine transaminase and aspartate transaminase activities, lipid peroxidation, protein carbonyl and myeloperoxidase levels were decreased; (iv) liver catalase, superoxide dismutase, glutathione peroxidase activities and glutathione levels were increased. These data suggest that exendin-4 might exerts its anti-proliferative action through blocking NGF/TrkA system and stimulating oxidative defense system in liver of diabetic mice.

The influence of zinc supplementation on the pancreas of streptozotocin-diabetic rats

The aim of this study was to investigate the effects of zinc supplementation on somatostatin and insulin peptide expressions and biochemical parameters. Six- to 6.5-month-old female Swiss albino rats weighing 150-200 g were used. The animals were divided into four groups: group I: control (intact) animals; group II: control animals given zinc sulfate; group III: streptozotocin (STZ)- induced diabetic animals; group IV: STZ-induced diabetic animals given zinc sulfate. Fasting blood glucose and glutathione levels were measured at 0, 1, 30 and 60 days. On day 60, the pancreas tissue and blood samples were taken from the animals. Zinc supplementation caused a decrease in hyperglycemia, as well as weight increase. Zinc sulfate treatment did not affect the number of somatostatin-immunoreactive cells in the pancreas. More insulin-immunoreactive cells were observed in the pancreatic islets of the diabetic+zinc sulfate group than in the diabetic group, although it was not statistically significant. The results show that zinc supplementation may prevent diabetes in experimental animals.

Exendin-4 exerts its effects through the NGF/p75NTR system in diabetic mouse pancreas

Glucagon-like peptide-1 (GLP-1) ameliorates the symptoms of diabetes through stimulation of insulin secretion. We have investigated the possible components of cellular mechanism triggered by exendin-4, a potent GLP-1 receptor agonist, in streptozotocin (STZ) induced diabetic mice pancreas. BALB/c male mice were divided into four groups for this investigation. The first group was given citrate buffer only, the second group was administered exendin-4 alone, the third group received STZ, and the fourth group was given both STZ and exendin-4. Exendin-4 (3 microg/kg) was administered by daily subcutaneous injection for 30 days after the animals were rendered diabetic by administration of STZ (200 mg/kg). With exendin-4 treatment on diabetic mice, the following results were noted: (i) exendin-4 suppressed the increase in plasma glucose and inhibited somatostatin expression induced by STZ, (ii) reduction of insulin prevalence was inhibited, while expression of p75 neurotrophin receptor (p75NTR), pancreatic nerve growth factor (NGF), and NGF-positive islet cell prevalence increased, (iii) there were no alterations in the severity of proliferated cell nuclear antigen positive or apoptotic beta cells in pancreatic islets, and (iv) pancreatic catalase, glutathione peroxidase, and superoxide dismutase activities significantly increased. In conclusion, these data suggest that exendin-4 might exert its actions through the NGF/p75NTR system and decrease somatostatin expression.

The potential role of combined anti-oxidants against cadmium toxicity on liver of rats

Cadmium (Cd), a widely distributed toxic trace metal, has been shown to accumulate in liver after long- and short-term exposure. Cd (2 mg/kg/day CdCl2) was intraperitoneally given to rats for eight days. Vitamin C (250 mg/kg/day) + vitamin E (250 mg/kg/day) + sodium selenate (0.25 mg/kg/day) were given to rats by oral means. The animals were treated by anti-oxidants one hour prior to treatment with Cd every day. The degenerative changes were observed in the groups given only Cd and anti-oxidants + Cd. Metallothionein (MT) immunoreactivity increased in cytoplasm of hepatocytes of the rats given Cd when compared with controls. In a number of cells with Cd and anti-oxidants treatment, immunoreactivity increase was more than in the group given Cd only and nuclear MT expression was also detected. Cell proliferation was assessed with proliferating cell nuclear antigen (PCNA) immunohistochemistry. PCNA expressions increased in all groups more than in the controls. Anti-oxidants treatment increased cell proliferation. In the animals administered with Cd, an increase in serum aspartate (AST) and alanine (ALT) aminotransferases, liver glutathione (GSH) and lipid peroxidation (LPO) levels were observed. On the other hand, in the rats treated with anti-oxidants and Cd, serum AST and ALT, liver glutathione and LPO levels decreased. As a result, these results suggest that combined anti-oxidants treatment might be useful in protection of liver against Cd toxicity.