Effects of propofol on lipopolysaccharide-induced expression and release of HMGB1 in macrophages

This study aimed to determine the effects of different concentrations of propofol (2,6-diisopropylphenol) on lipopolysaccharide (LPS)-induced expression and release of high-mobility group box 1 protein (HMGB1) in mouse macrophages. Mouse macrophage cell line RAW264.7 cells were randomly divided into 5 treatment groups. Expression levels of HMGB1 mRNA were detected using RT-PCR, and cell culture supernatant HMGB1 protein levels were detected using enzyme-linked immunosorbent assay (ELISA). Translocation of HMGB1 from the nucleus to the cytoplasm in macrophages was observed by Western blotting and activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in the nucleus was detected using ELISA. HMGB1 mRNA expression levels increased significantly in the cell culture supernatant and in cells after 24 h of stimulating RAW264.7 cells with LPS (500 ng/mL). However, HMGB1 mRNA expression levels in the P2 and P3 groups, which received 500 ng/mL LPS with 25 or 50 μmol/mL propofol, respectively, were significantly lower than those in the group receiving LPS stimulation (P<0.05). After stimulation by LPS, HMGB1 protein levels were reduced significantly in the nucleus but were increased in the cytoplasm (P<0.05). Simultaneously, the activity of NF-κB was enhanced significantly (P<0.05). After propofol intervention, HMGB1 translocation from the nucleus to the cytoplasm and NF-κB activity were inhibited significantly (each P<0.05). Thus, propofol can inhibit the LPS-induced expression and release of HMGB1 by inhibiting HMGB1 translocation and NF-κB activity in RAW264.7 cells, suggesting propofol may be protective in patients with sepsis.

Risk factors associated with the transmissionof Brazilian spotted fever in the Piracicaba river basin, State of São Paulo, Brazil

INTRODUCTION : Brazilian spotted fever (BSF) is a disease transmitted by ticks for which the etiological agent is Rickettsia rickettsii. The present essay evaluates the risk factors associated with the transmission of cases of BSF in the time period between 2003 and 2013 in the Piracicaba river basin, state of São Paulo. METHODS : This essay presents a retrospective study to identify the factors associated with the transmission of cases of BSF among all suspected cases identified by the System for Epidemiological Surveillance of São Paulo (CVE). After the description of temporal distribution (onset of symptoms) and the environmental and demographic variations of the confirmed and discarded cases, a multiple logistic regression model was applied. RESULTS : We searched 569 probable locations of infection (PLI) with 210 (37%) confirmed cases of BSF and 359 (63%) discarded cases. The associated variables for the confirmation of BSF in the multiple logistic model using a confidence interval (CI) of 95% were age (OR = 1.025 CI: 1.015-1.035), the presence of Amblyomma sculptum in the environment (OR = 1.629 CI: 1.097-2.439), the collection of ticks from horses (OR = 1.939 CI: 0.999-3.764), the presence of capybaras (OR = 1.467 CI: 1.009-2.138), an urban environment (OR = 1.515 CI: 1.036-2.231), and the existence of a dirty pasture (OR = 1.759 CI: 1.028-3.003). CONCLUSIONS : The factors associated with the confirmation of BSF cases included an urban environment, age, presence of the A. sculptum vector, the collection of ticks from horses, the presence of a capybara population, and a dirty pasture environment. .

Baseline micronuclei and nuclear abnormalities frequencies in native fishes from the Paraná River (Argentina) / Frequências basais de micronúcleos e anormalidades nucleares em peixes nativos do Rio Paraná (Argentina)

This work aims to establish baseline frequencies of micronuclei (MN) and nuclear abnormalities (NA) in native fish species collected in situ from the Paraná River. For this purpose, the micronucleus test was applied in peripheral blood erythrocytes from specimens obtained from samplings collected at two localities (Posadas and Candelaria, Misiones, Argentina) during the period 2007-2010. The results were statistically analyzed using the Kruskal Wallis test. Data from nine fish species were obtained, among which Steindachnerina brevipinna (Characiformes) revealed the highest baseline frequency of MN and NA, showing statistically significant differences with regard to the other analyzed species. These results are the first report of baseline MN and NA frequencies for native fish species studied and could be useful for future comparisons with data of fishes belonging to other environments.

O presente trabalho tem como objetivo estabelecer frequências basais de micronúcleos (MN) e anormalidades nucleares (AN) em espécies nativas de peixes obtidas in situ no Rio Paraná. Para este efeito, o teste do micronúcleo foi aplicado em eritrócitos de sangue periférico de espécimes provenientes de amostragens efetuadas em duas localidades (Posadas e Candelaria, Misiones, Argentina) durante o período 2007-2010. Os resultados foram analisados estatisticamente empregando o teste de Kruskal Wallis. Foram coletados dados de nove espécies e dentre estas Steindachnerina brevipinna (Characiformes) revelou a maior frequência basal de MN e AN, mostrando diferenças estatisticamente significativas com respeito às outras espécies analisadas. Estes resultados são o primeiro relatório de frequências basais de MN e AN para espécies nativas de peixes estudadas e poderiam ser úteis para futuras comparações com dados de peixes pertencentes a outros ambientes.

Rhamnogalacturonan II is a Toll-like receptor 4 agonist that inhibits tumor growth by activating dendritic cell-mediated CD8+ T cells

We evaluated the effectiveness of rhamnogalacturonan II (RG-II)-stimulated bone marrow-derived dendritic cells (BMDCs) vaccination on the induction of antitumor immunity in a mouse lymphoma model using EG7-lymphoma cells expressing ovalbumin (OVA). BMDCs treated with RG-II had an activated phenotype. RG-II induced interleukin (IL)-12, IL-1beta, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) production during dendritic cell (DC) maturation. BMDCs stimulated with RG-II facilitate the proliferation of CD8+ T cells. Using BMDCs from the mice deficient in Toll-like receptors (TLRs), we revealed that RG-II activity is dependent on TLR4. RG-II showed a preventive effect of immunization with OVA-pulsed BMDCs against EG7 lymphoma. These results suggested that RG-II expedites the DC-based immune response through the TLR4 signaling pathway.

Time- and concentration-dependent cytotoxicity of antibiotics used in endodontic therapy

OBJECTIVE: New drugs have to be assessed in endodontic therapy due to the presence of microorganisms resistant to therapeutic procedures. Thus, this study evaluated the time- and concentration-dependent cytotoxicity of different antibiotics used in endodontic therapy. MATERIAL AND METHODS: Human gingival fibroblasts were treated and divided into the following experimental groups: Group I - control; Group II - ciprofoxacin hydrochloride; Group III - clyndamicin hydrochloride; and Group IV - metronidazole. Each drug was used at concentrations of 5, 50, 150, and 300 mg/L for 24, 48, 72, and 96 h. Cytotoxicity was evaluated by the MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and spectrophotometric reading of ELISA plates. The results were analyzed by BioEstat 4.0 software using Kruskal-Wallis and Dunn's tests at a signifcance level of 5 percent. Cell viability was assessed for the different concentrations and times. RESULTS: All drugs presented dose-dependent cytotoxicity. Concentrations of 5 and 50 mgjL produced viable fibroblasts at all experimental times in all groups. CONCLUSIONS: Cell viability at 24 h was greater than in the other experimental times. Comparison between the same concentrations of antibiotics at different times showed that metronidazole presented the highest cell viability at 72 and 96 h compared to the other antibiotics, whereas clyndamicin hydrochloride showed higher cell viability at 72 h than ciprofoxacin hydrochloride.

2-Deoxy-D-glucose regulates dedifferentiation through beta-catenin pathway in rabbit articular chondrocytes

2-deoxy-D-glucose (2DG) is known as a synthetic inhibitor of glucose. 2DG regulates various cellular responses including proliferation, apoptosis and differentiation by regulation of glucose metabolism in cancer cells. However, the effects of 2DG in normal cells, including chondrocytes, are not clear yet. We examined the effects of 2DG on dedifferentiation with a focus on the beta-catenin pathway in rabbit articular chondrocytes. The rabbit articular chondrocytes were treated with 5 mM 2DG for the indicated time periods or with various concentrations of 2DG for 24 h, and the expression of type II collagen, c-jun and beta-catenin was determined by Western blot, RT-PCR, immunofluorescence staining and immunohistochemical staining and reduction of sulfated proteoglycan synthesis detected by Alcain blue staining. Luciferase assay using a TCF (T cell factor)/LEF (lymphoid enhancer factor) reporter construct was used to demonstrate the transcriptional activity of beta-catenin. We found that 2DG treatment caused a decrease of type II collagen expression. 2DG induced dedifferentiation was dependent on activation of beta-catenin, as the 2DG stimulated accumulation of beta-catenin, which is characterized by translocation of beta-catenin into the nucleus determined by immunofluorescence staining and luciferase assay. Inhibition of beta-catenin degradation by inhibition of glycogen synthase kinase 3-beta with lithium chloride (LiCl) or inhibition of proteasome with z-Leu-Leu-Leu-CHO (MG132) accelerated the decrease of type II collagen expression in the chondrocytes. 2DG regulated the post-translational level of beta-catenin whereas the transcriptional level of beta-catenin was not altered. These results collectively showed that 2DG regulates dedifferentiation via beta-catenin pathway in rabbit articular chondrocytes.

Microtubule distribution in somatic cell nuclear transfer bovine embryos following control of nuclear remodeling type

This study was conducted to evaluate the microtubule distribution following control of nuclear remodeling by treatment of bovine somatic cell nuclear transfer (SCNT) embryos with caffeine or roscovitine. Bovine somatic cells were fused to enucleated oocytes treated with either 5 mM caffeine or 150 micrometer roscovitine to control the type of nuclear remodeling. The proportion of embryos that underwent premature chromosome condensation (PCC) was increased by caffeine treatment but was reduced by roscovitine treatment (p < 0.05). The microtubule organization was examined by immunostaining beta- and gamma-tubulins at 15 min, 3 h, and 20 h of fusion using laser scanning confocal microscopy. The gamma-tubulin foci inherited from the donor centrosome were observed in most of the SCNT embryos at 15 min of fusion (91.3%) and most of them did not disappear until 3 h after fusion, regardless of treatment (82.9-87.2%). A significantly high proportion of embryos showing an abnormal chromosome or microtubule distribution was observed in the roscovitine-treated group (40.0%, p < 0.05) compared to the caffeine-treated group (22.1%). In conclusion, PCC is a favorable condition for the normal organization of microtubules, and inhibition of PCC can cause abnormal mitotic division of bovine SCNT embryos by causing microtubule dysfunction.

Effect on histological and sperm kinetics in DBP exposed Wistar rats.

Di-n-butyl phthalate (DBP) is a ubiquitous environmental pollutant, extensively used as a softener for polyvinyl chloride resins. A study was conducted to evaluate its effect on reproductive function of Wistar rats. DBP was given orally at a dose of 500, 1000 and 1500 mg kg(-1) body weight for 7 days. Evaluating histological and fertility parameters assessed reproductive function. Significant reduction in seminiferous tubule diameter, Leydig cell nuclear diameter (except at dose 500 mg), number of primary spermatocytes, secondary spermatocytes and spermatids were observed. Caudal sperm density and viability reduced significantly. Decrease in serum testosterone was also observed. Evidence indicates that DBP exposure causes dose dependent testicular toxicity and has the potential to induce adverse effect.

Study of the Nuclear Volume of Testicular Cells of Rats Receiving Ofloxacin Through Lactation / Estudio del Volumen Nuclear de Células Testiculares de Ratas que Recibieron Ofloxacin Durante la Lactancia

Ofloxacin presents an ample spectrum of antimicrobial action, including combating Mycobacterium leprae, and is currently employed as a substitute when the use of rifampicin is impossible. The objective of this work was to study alterations in testicular cell nuclei of suckling rats, whose dams were submitted to oral application of ofloxacin, and respective control groups. The method utilized was morphometry by the karyometric technique. The main structures observed in histological preparations of the testicles were interstitial cells, spermatogonias, and sustentacular cells. 10 Wistar rats were utilized, four treated and five controls, in the period of the first 25 days of life, whose dams received ofloxacin 12 mg/ Kg of body weight / day orally, before being killed on the 25th day after birth. The karyometric study of interstitial cells and spermatogonias revealed that there were no changes in the form of their nuclei (p > 0.05). Since sustentacular cell nuclei presented increased major diameter, minor diameter, mean geometric diameter, volume, area, volume/area ratio and perimeter, as well as an augmented and statistically different eccentricity (p < 0.05) in suckling pups whose dams were administered ofloxacin, the nuclei presented larger size and more elongated form. It was concluded that the sustentacular cells were more sensitive to the ofloxacin effect at the administered dose.

El ofloxacin presenta un amplio espectro de acción antimicrobiana, incluyendo el combate a.Mycobacterium leprae, y es frecuentemente empleado como un sustituto cuando el uso de la rifampicina es imposible. El objetivo del trabajo fue estudiar las alteraciones en el núcleo de las células testiculares en ratas que se encontraban amamantando y que fueron sometidas a la aplicación oral de ofloxacin. El método utilizado fue la técnica morfométrica de la cariometría. Las principales estructuras observadas en las preparaciones histológicas fueron las células intersticiales, espermatogenias y células sustentaculares. Se utilizaron 10 ratas Wistar, cinco fueron el grupo control y cinco sometidas al tratamiento, cuyas madres recibieron ofloxacin en dosis oral diaria de 12 mg/Kg de peso corporal los primeros 25 días de vida, para luego ser sacrificadas al día 25 después del nacimiento. El estudio cariométrico de las células intersticiales y de la espermatogénesis revelaron que no hubo cambios en la forma de sus núcleos (p > 0,05). Las células sustentaculares presentaron un incremento en su diámetro mayor, diámetro menor, diámetro geométrico promedio, volumen, área, razón volumen/área y perímetro, también hubo aumento con una diferencia de la excentricidad estadísticamente significativa (p < 0,05) en las crías amamantadas, a las cuales se les administró ofloxacin. Los núcleos presentaron un gran tamaño y una forma más alargada. Esto concluye que las células sustentaculares son más sensibles al efecto de la administración de ofloxacin.

Effects of cadmium on photoreceptors and ganglionic cells of retinal layer in mice embryo--an ultrastructural study.

Cadmium (Cd) is one of the environmental contaminant and because of its non-decomposable character, it can damage nature. In this study, TEM was used in order to assess the ultrastructural effects of Cd on photorececptor and ganglionic cells of mouse retinal layer. Apoptotic nuclei, heterochromatic nuclei, deletion of nucleus membrane, invisible nucleolus, and apoptotic cells with mitochondrial changes were observed in mice embryo (days 15 of gestation) following CdCl2 injection to mothers on day 9 of gestation. Cadmium exposure caused apoptotic changes both in photoreceptors and ganglionic cells.

Differential role of MAP kinase isoforms in malachite green transformed Syrian hamster embryo fibroblasts in culture.

Malachite green (MG) induces DNA damage and malignant transformation of Syrian hamster embryo (SHE) cells in primary culture. In the present study, we have studied the role of all the three isoforms of mitogen activated protein (MAP) kinases i.e. ERK (extracellular regulated kinase), JNK (JUN- N- terminal kinase) and p38 kinase during transformation of SHE cells by MG. The results showed that transformed cells were associated with a decreased expression of phosphoactive ERK and JNK and increased expression of p38 kinase as evident from the Western blot, immunofluorescence and flow cytometry studies. Also, a persistent nuclear localization of p38 kinase was observed in the transformed cells. The present study indicated that p38 kinase was present at higher levels and seemed to be associated with transformation, which suggested that inhibitors of p38 kinase could serve in general as potential agents for selective cancer therapy.

Centrosome amplification and multinuclear phenotypes are Induced by hydrogen peroxide

Multinucleated cells resulted from mitosis defect have been noted in pathophysiological states of the cells such as inflammation, senescence and cancer. Since oxidative stress has been known to correlate with these pathophysiological conditions, we tested the effect of H2O2 on the cell cycle progression and formation of multinucleated cells. H2O2 induced a significant delay in cell cycle progression in Chang liver cells. Interestingly, H2O2 actively induced hyperamplification of centrosomes (> or =3) and multipolar spindle formation during mitosis and subsequently increased the generation of multinucleated cells. A significant increase of the phospho-ERK level was observed upon H2O2 treatment but PD98059, an MEK1/2 inhibitor, didn't reduce the frequency of cells with hyperamplified centrosomes. On the other hand, treatment of either H2O2 or adriamycin increased intracellular ROS levels and multinucleated cells, which were significantly suppressed by antioxidants, N-acetylcysteine and PDTC. Thus, our results suggest that oxidative stress can trigger centrosome hyperamplification and multinucleated cell formation, which may promote pathophysiological progression.

Catechol inhibits FADH2-linked respiration in rat liver mitochondrial fraction

OBJETIVO: Testar a hipótese do catecol inibir a respiração basal associada ao FADH2 em frações mitocondriais hepáticas de rato. Além disso, estudou-se também a capacidade do catecol de induzir peroxidação de biomoléculas nas frações nucleares. MÉTODOS: Os homogeneizados de fígado de ratos foram incubados com catecol a 1 mM em pH fisiológico. Depois disso, as frações mitocondriais foram isoladas por centrifugação diferencial. O consumo basal de oxigênio foi medido com um eletrodo do tipo Clark após injeção de succinato a 10 mM. Frações nucleares foram incubadas com catecol por 17 horas à temperatura ambiente e a peroxidação de biomoléculas foi investigada pela reação com o ácido tiobarbitúrico e mensurada espectrofotometricamente. RESULTADOS: O catecol induziu uma inibição parcial da respiração basal mitocondrial associada ao FADH2 de forma dependente do tempo, contudo essa substância não induziu peroxidação direta das biomoléculas presentes nas frações nucleares hepáticas. CONCLUSÃO: O catecol produz inibição da respiração basal associada ao FADH2 em mitocôndrias isoladas de fígado, o que pode levar à toxicidade, produção de espécies reativas e morte celular.

Epigallocatechin-3-gallate Suppresses Galactose-alpha1,4-galactose-beta1,4-glucose Ceramide Expression in TNF-alpha Stimulated Human Intestinal Epithelial Cells Through Inhibition of MAPKs and NF-kappa B

Intestinal epithelial cells (IECs) have been known to produce galactose-alpha1,4-galactose-beta1,4-glucose ceramide (Gb3) that play an important role in the mucosal immune response. The regulation of Gb3 is important to prevent tissue damage causing shiga like toxin. Epigallocatechin-3-gallate (EGCG) has been studied as anti-carcinogenic, anti-oxidant, anti-angiogenic, and anti-viral activities, and anti-diabetic. However, little is known between the expressions of Gb3 on IECs. The aim of this study was to examine the inhibitory effect of EGCG, a major ingredient of green tea, on Gb3 production via mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-kappa B) in the TNF-alpha stimulated human colon epithelial cells, HT29. To investigate how Gb3 is regulated, ceramide glucosyltransferase (CGT), lactosylceramide synthase (GalT2), and Gb3 synthase (GalT6) were analyzed by RT-PCR in HT 29 cells exposed to TNF-alpha in the presence or absence of EGCG. EGCG dose-dependently manner, inhibits TNF-alpha induced Gb3 expression by blocking in both the MAPKs and NF-kappaB pathways in HT29 cells. TNF-alpha enhanced CGT, GalT2 and GalT6 mRNA levels and EGCG suppressed the level of these enzymes enhanced by TNF-alpha treatment.

Ultrastructural changes in cauda epididymidal epithelial cell types of Azadirachta indica leaf treated rats.

To assess if cauda epididymis is a target for the effect of A. indica leaves, Wistar strain male albino rats were administered (po) A. indica leaves (100 mg/rat/day for 24 days). Transmission electron microscopic analysis revealed that in the cauda epididymal epithelium the nuclei of principal cells were enlarged and the number of coated micropinocytotic vesicles of the apical cytoplasm decreased. Microvilli were missing and mitochondrial cristae and Golgi complex were highly disrupted. The cytoplasm was abounding with lysosomal bodies. The clear cells increased in perimeter and their nuclei increased in size and contained lesser chromatin. The nuclear membrane bulged out. The cytoplasm was vacuolized. Further, there was decrease in size of the lipid droplets, mitochondria, Golgi complex, endoplasmic reticulum and there was accumulation of lysosomal bodies. The changes in the principal and clear cells appear to be due to the effect of the hypoandrogen status caused by treatment with A. indica leaves and a direct action on the epididymal epithelium.

Ultrastructural effects of two phthalocyanines in CHO-K1 and HeLa cells after laser irradiation

The effects of Photodynamic Therapy using 2nd generation photosensitizers have been widely investigated aiming clinical application treatment of solid neoplasms. In this work, ultrastructure changes caused by the action of two 2nd generation photosensitizers and laser irradiation on CHO-K1 and HeLa (neoplastic) cells were analyzed by transmission electron microscopy. Aluminum phthalocyanine chloride, aluminum phthalocyanine tetrasulfonate chloride and radiation from a semiconductor laser at a fluency of 0.5 J/cm2 (Power=26 mW; lambda=.670 nm) were used. The results showed induction of apoptosis. Such alterations where observed in HeLa but not in CHO-K1 cells after Aluminum phthalocyanine tetrasulfonate chloride (AlPcS4, photodynamic treatment. The Aluminum phthalocyanine chloride (AlPc) photodynamic treatment induced necrosis on the neoplastic cell line, and cytoplasm and nuclear alterations on the normal cell line.

Effect of propriety herbal formulation against chronic carbon tetrachloride induced hepatotoxicity.

Efficacy of propriety herbal formulation (PHF) against carbon tetrachloride (CCl4) induced liver damage was investigated in adult rats. Administration of CCl4 (0.2 ml/kg; i.p.) twice a week for 12 weeks resulted in significant elevation in serum transaminases activity. Level of reduced glutathione was significantly decreased. On the contrary, significant elevation was found in the hepatic lipid peroxidation level. Proliferation of fibroblast replaced the hepatic parenchyma cells in focal areas. Cell organelles like mitochondria, endoplasmic reticulum and nucleus showed severe degeneration after CCl4 exposure. PHF was effective in restoring the CCl4 induced biochemical and histological ultrastructural changes.

Effect of enrofloxacin on AgNOR counts in chick bone marrow nuclei.

The mAgNOR and pAgNOR counts reflecting the number of rDNA genes being transcribed, showed a highly significant increase from control values following administration of 5X, 10X, 15X doses of enrofloxacin in chicken. The maximum increase for both, mAgNOR and pAgNOR was shown by birds receiving 15X dose, sacrificed 48 hr after the last drug injection. The increase of pAgNOR at 5X (24 hr) was not significant relative to control values. After 72 hr time interval, AgNOR counts were not feasible due to poor differentiation. Values at 15X (24 hr) showed a decrease in number of AgNOR counts (non-significant) relative to 10X, probably due to depression of transcriptional activity of rDNA genes, which, however, is removed at 48 hr. The general increase in mAgNOR and pAgNOR with dose reflects hypertranscription of rDNA genes so that the birds can cope up with the drug induced toxicity.

Dual effect of oxidative stress on NF-kappaB activation in HeLa cells

Reactive oxygen species (ROS) has been implicated as an inducer of NF-kappaB activity in numbers of cell types where exposure of cells to ROS such as H2O2 leads to NF-kappaB activation. In contrast, exposure to oxidative stress in certain cell types induced reduction of tumor necrosis factor (TNF)-induced NF-kappaB activation. And various thiol-modifying agents including gold compounds and cyclopentenone prostaglandins inhibit NF-kappaB activation by blocking IkappaB kinase (IKK). To understand such conflicting effect of oxidative stress on NF-kappaB activation, HeLa cells were incubated with H2O2 or diamide and TNF-induced expression of NF-kappaB reporter gene was measured. NF-kappaB activation was significantly blocked by these oxidizing agents, and the inhibition was accompanied with reduced nuclear NF-kappaB and inappropriate cytosolic IkappaB degradation. H2O2 and diamide also inhibited IKK activation in HeLa and RAW 264.7 cells stimulated with TNF and lipopolysaccharide, respectively, and directly blocked IKK activity in vitro. In cells treated with H2O2 alone, nuclear NF-kappaB was induced after 2 h without detectible degradation of cytosolic IkBa or activation of IKK. Our results suggest that ROS has a dual effect on NF-kappaB activation in the same HeLa cells: it inhibits acute IKK-mediated NF-kappaB activation induced by inflammatory signals, while longer-term exposure to ROS induces NF-kappaB activity through an IKK-independent pathway.

Protective mechanism of glucose against alloxan-induced beta-cell damage: pivotal role of ATP

Glucose prevents the development of diabetes induced by alloxan. In the present study, the protective mechanism of glucose against alloxan-induced beta-cell damage was investigated using HIT-T 15 cell, a Syrian hamster transformed beta-cell line. Alloxan caused beta-cell damages with DNA fragmentation, inhibition of glucose-stimulated insulin release, and decrease of cellular ATP level, but all of these beta-cell damages by alloxan were prevented by the presence of 20 mM glucose. Oligomycin, a specific inhibitor of ATP synthase, completely abolished the protective effects of glucose against alloxan-induced cell damage. Furthermore, treatment of nuclei isolated from HIT-T15 cells with ATP significantly prevented the DNA fragmentation induced by Ca2+. The results indicate that ATP produced during glucose metabolism plays a pivotal role in the protection of glucose against alloxan-induced beta-cell damage.