OBJECTIVETo investigate the protective effect of losartan against angiotensin II (AngII)-induced beta cell (RIN-m) impairment and explore its mechanism.

METHODSIn vitro cultured RIN-m cells were divided into control group, 100 nmol/L AngII group and losartan pretreatment group. After cell incubation with the corresponding agents for 24 h, the amount of basal (3.3 mmol/L) and glucose-stimulated (16.7 mmol/L) insulin secretion (GSIS) was detected by radioimmunoassay, and the cellular reactive oxygen species (ROS) was assayed by flow cytometry with DCFH-DA staining; the mRNA and protein expressions of uncoupling protein 2 (UCP2) were determined by RT-PCR and Western blotting, respectively.

RESULTSThe basal insulin secretion showed no significant differences between the 3 groups (P>0.05). The GSIS in 100 nmol/L AngII group was significantly lower than that of the control group (P<0.001), but losartan pretreatment markedly restored the insulin secretion function to a level comparable to that of the control group (P<0.05). Compared with the control group, 100 nmol/L AngII significantly increased the cellular ROS level and the mRNA and protein expressions of UCP2 (P<0.05), and these changes were eliminated by losartan pretreatment.

CONCLUSIONSLosartan pretreatment offers protective effect against AngII-induced impairment of the GSIS of beta cells possibly by antagonizing the effects of AngII that causes increased ROS level and UCP2 expressions in beta-cells.

Angiotensin II ; adverse effects ; antagonists & inhibitors ; Animals ; Antihypertensive Agents ; pharmacology ; Cell Line, Tumor ; Insulin-Secreting Cells ; drug effects ; physiology ; Insulinoma ; pathology ; Ion Channels ; genetics ; metabolism ; Losartan ; pharmacology ; Mitochondrial Proteins ; genetics ; metabolism ; Protective Agents ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Uncoupling Protein 2

Apoptosis is a programmed, physiologic mode of cell death that plays an important role in tissue homeostasis. As for the central nervous system, ischemic insults can induce pathophysiologic cascade of apoptosis in neurophils. Impairment of astroctye functions during brain ischemia can critically influence neuron survival by neuronglia interactions. We aimed to elucidate the protective effect of ketamine on apoptosis by energy deprivation in astrocytes. Ischemic insults was induced with iodoacetate/ carbonylcyanide mchlorophenylhydrazone (IAA/CCCP) 1.5 mM/ 20 micrometer or 150 micrometer/2 micrometer for 1 hr in the HTB-15 and CRL-1690 astrocytoma cells. Then these cells were reperfused with normal media or ketamine (0.1 mM) containing media for 1 hr or 24 hr. FITC-annexin-V staining and propidium iodide binding were determined by using flow cytometry. Cell size and granularity were measured by forward and side light scattering properties of flow cytometry system, respectively. An addition of keta-mine during reperfusion increased the proportion of viable cells. Ketamine alleviated cell shrinkage and increased granularity during the early period, and ameliorated cell swelling during the late reperfusion period. Ketamine may have a valuable effect on amelioration of early and late apoptosis in the astrocytoma cells, even though the exact mechanism remains to be verified.
Anesthetics, Dissociative/*pharmacology ; Annexin A5/pharmacology ; Apoptosis ; Astrocytes/metabolism ; Astrocytoma/*drug therapy/pathology ; Brain/pathology ; Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology ; Cell Line, Tumor ; Cell Size ; Cell Survival ; Central Nervous System/drug effects/pathology ; Enzyme Inhibitors/pharmacology ; Flow Cytometry/*methods ; Humans ; Indicators and Reagents/pharmacology ; Iodoacetates/pharmacology ; Ischemia/pathology ; Ketamine/metabolism/*pharmacology ; Light ; Neurons/metabolism/pathology ; Neutrophils/metabolism ; Perfusion ; Propidium/pharmacology ; Scattering, Radiation ; Time Factors ; Uncoupling Agents/pharmacology

This study was aimed to detect the effect of genipin and Vitamin E (VitE) on non-alcoholic fatty liver disease. L02 cells were divided into five groups:control group, palmic acid treated group, VitE treated group, genipin treated group, and a combination group. All treatments were terminated at the end of 72 hours. Pathological changes of L02 cells were observed. Mitochondrial membrane potential changes were detected by flow cytometry. MDA, SOD, ALT, AST, GGT, TG in culture medium and expression of UCP2 mRNA and protein in L02 cells were detected. We also studied the effects of genipin and VitE on UCP2 and other related factors such as NF-kappaB and TNF-alpha on the L02 cell model of non-alcoholic fatty liver disease. In combination group, the degree of adipose degeneration of L02 cells mitigated significantly; mitochondrial membrane potential and the level of SOD activity increased; the level of MDA, ALT, AST, GGT, TG and the expression of UCP2, NF-kappaB,TNF-alpha in L02 cells decreased. The use of genipin in combination with VitE can increase mitochondrial membrane potential and markedly relieve the adipose degeneration of liver cells.
Cell Line ; Drug Synergism ; Fatty Liver ; metabolism ; Humans ; Ion Channels ; genetics ; metabolism ; Iridoid Glycosides ; pharmacology ; Iridoids ; Liver ; cytology ; Membrane Potential, Mitochondrial ; Mitochondrial Proteins ; genetics ; metabolism ; NF-kappa B ; genetics ; metabolism ; Non-alcoholic Fatty Liver Disease ; Protective Agents ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; genetics ; metabolism ; Uncoupling Protein 2 ; Vitamin E ; pharmacology

BACKGROUNDProlonged exposure of pancreatic beta-cells to fatty acids increases basal insulin secretion but inhibits glucose-stimulated insulin secretion. Rosiglitazone is a new antidiabetic agent of the thiazolidinediones. However, the relationship between thiazolidinediones and insulin secretion is highly controversial. The aim of this study is to explore the effect and mechanism of rosiglitazone on insulin secretion of islets under chronic exposure to free fatty acids (FFA).

METHODSPancreatic islets were isolated from the pancreata of male Sprague-Dawley rats by the collagenase digestion and by the dextran gradient centrifugation method. The purified islets were cultured in the presence or absence of rosiglitazone and palmitate for 48 hours. The insulin secretion was measured by radioimmunoassay. The mRNA level of peroxisome proliferator-activated receptor gamma, uncoupling protein 2 (UCP-2) and insulin were determined by real-time polymerase chain reaction (PCR). The cell cytotoxicity assay was measured by cell counting kit-8.

RESULTSIslets exposed to elevated palmitate for 48 hours showed an increased basal and a decreased glucose-stimulated insulin secretion (P < 0.01). The mRNA level of UCP-2 was increased by 3.7 fold in the 0.5 mmol/L concentration of palmitate. When islets were cultured with palmitate (0.5 mmol/L) in the presence of rosiglitazone (1.0 micromol/L), both basal and glucose-stimulated insulin secretion reversed to a pattern of control islets (P < 0.05, P < 0.01). The addition of rosiglitazone in the culture medium decreased the mRNA level of UCP-2 by 2.2 fold, having a statistically significant difference (P < 0.05) as compared with islets cultured with palmitate alone. The cell viability was not affected.

CONCLUSIONThe protective effects of rosiglitazone on insulin secretion of isolated pancreatic islets under chronic exposure to palmitate might be mediated through the downregulation of UCP-2 expression.

Animals ; Cell Survival ; drug effects ; Fatty Acids, Nonesterified ; pharmacology ; Gene Expression Regulation ; drug effects ; Hypoglycemic Agents ; pharmacology ; Insulin ; secretion ; Ion Channels ; Islets of Langerhans ; drug effects ; secretion ; Male ; Membrane Transport Proteins ; genetics ; Mitochondrial Proteins ; genetics ; PPAR gamma ; genetics ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Thiazolidinediones ; pharmacology ; Uncoupling Protein 2

Fenofibrate, an agonist for peroxisome proliferator-activated receptor alpha (PPAR-α), lowers blood pressure, but whether this action is mediated via baroreflex afferents has not been elucidated. In this study, the distribution of PPAR-α and PPAR-γ was assessed in the nodose ganglion (NG) and the nucleus of the solitary tract (NTS). Hypertension induced by drinking high fructose (HFD) was reduced, along with complete restoration of impaired baroreceptor sensitivity, by chronic treatment with fenofibrate. The molecular data also showed that both PPAR-α and PPAR-γ were dramatically up-regulated in the NG and NTS of the HFD group. Expression of the downstream signaling molecule of PPAR-α, the mitochondrial uncoupling protein 2 (UCP2), was up-regulated in the baroreflex afferent pathway under similar experimental conditions, along with amelioration of reduced superoxide dismutase activity and increased superoxide in HFD rats. These results suggest that chronic treatment with fenofibrate plays a crucial role in the neural control of blood pressure by improving baroreflex afferent function due at least partially to PPAR-mediated up-regulation of UCP2 expression and reduction of oxidative stress.
Afferent Pathways ; drug effects ; Animals ; Antihypertensive Agents ; pharmacology ; Baroreflex ; drug effects ; Blood Pressure ; drug effects ; Fenofibrate ; pharmacology ; Male ; Oxidative Stress ; drug effects ; PPAR gamma ; drug effects ; metabolism ; Rats, Sprague-Dawley ; Signal Transduction ; drug effects ; Transcriptional Activation ; drug effects ; Uncoupling Protein 2 ; drug effects ; metabolism ; Up-Regulation