BACKGROUND/OBJECTIVE: This study was designed to investigate how a Portulaca oleracea L. extract (POE) stimulates insulin secretion in INS-1 pancreatic β-cells. MATERIALS/METHOD: INS-1 pancreatic β-cells were incubated in the presence of various glucose concentrations: 1.1 or 5.6, 16.7 mM glucose. The cells were treated with insulin secretagogues or insulin secretion inhibitor for insulin secretion assay using an insulin ELISA kit. In order to quantify intracellular influx of Ca2+ caused by POE treatment, the effect of POE on intracellular Ca2+ in INS-1 pancreatic β-cells was examined using Fluo-2 AM dye. RESULTS: POE at 10 to 200 µg/mL significantly increased insulin secretion dose-dependently as compared to the control. Experiments at three glucose concentrations (1.1, 5.6, and 16.7 mM) confirmed that POE significantly stimulated insulin secretion on its own as well as in a glucose-dependent manner. POE also exerted synergistic effects on insulin secretion with secretagogues, such as L-alanine, 3-isobutyl-1-methylxanthine, and especially tolbutamide, and at a depolarizing concentration of KCl. The insulin secretion caused by POE was significantly attenuated by treatment with diazoxide, an opener of the K+ ATP channel (blocking insulin secretion) and by verapamil (a Ca2+ channel blocker). The insulinotropic effect of POE was not observed under Ca2+-free conditions in INS-1 pancreatic β-cells. When the cells were preincubated with a Ca2+ fluorescent dye, Fluo-2 (acetoxymethyl ester), the cells treated with POE showed changes in fluorescence in red, green, and blue tones, indicating a significant increase in intracellular Ca2+, which closely correlated with increases in the levels of insulin secretion. CONCLUSIONS: These findings indicate that POE stimulates insulin secretion via a K+ ATP channel-dependent pathway in INS-1 pancreatic β-cells.
1-Methyl-3-isobutylxanthine ; Adenosine Triphosphate ; Alanine ; Calcium Channels ; Diabetes Mellitus ; Diazoxide ; Enzyme-Linked Immunosorbent Assay ; Fluorescence ; Glucose ; Insulin* ; Portulaca* ; Tolbutamide ; Verapamil

Management of congenital hyperinsulinemia of infancy (CHI) is challenging. A 4-month-old female infant with persistent hypoglycemia and elevated insulin levels was diagnosed with CHI. Gallium-68 DOTANOC positron emission tomography/computed tomography (PET/CT) scan (⁶⁸Ga-labeled [1,4,7,10-tetraazacyclododecane-N,N’,N’’,N’’’-tetraacetic acid]-1-NaI3-octreotide) demonstrated focal disease in the body of the pancreas. Genetic studies indicated paternal inheritance, making focal disease likely. She was started on diazoxide therapy with partial improvement in blood glucose levels. Due to a suboptimal response to diazoxide and the likelihood of focal disease amenable to surgery, a laparoscopic subtotal pancreatectomy with preservation of the head of the pancreas was performed. The biopsy demonstrated diffuse hyperplastic pancreatic islet cells on immunohistochemistry, indicative of diffuse rather than focal disease. Paternal inheritance is a recognized indicator of focal disease. Gallium-68 DOTANOC PET/CT scan is the only available imaging modality in South India as ¹⁸F-L-dihydroxyphenylalanine (DOPA) PET/CT scan is not available at present. A laparoscopic approach reduces the postoperative recovery time and morbidity in such patients. The absence of ¹⁸F-L-DOPA PET/CT scan and the limited supply of diazoxide makes the management of this complex condition more challenging in developing countries.
Biopsy ; Blood Glucose ; Congenital Hyperinsulinism* ; Developing Countries* ; Diazoxide ; Electrons ; Female ; Head ; Humans ; Hyperinsulinism ; Hypoglycemia ; Immunohistochemistry ; India ; Infant ; Insulin ; Islets of Langerhans ; Pancreas ; Pancreatectomy ; Positron-Emission Tomography and Computed Tomography ; Wills

A 2.4 kg baby boy born via Caesarian section at 35 weeks had the first onset of hypoglycemia at 2 hours of life. The infant required a glucose load of 30 mg/kg/min. Insulin level was 19.6 pmol/L (normal value 17.8-173.0) in the absence of ketosis. He was resistant to oral diazoxide but responded to octreotide infusion. The boy was found to be heterozygous for an ABCC8 nonsense mutation, p.R934*. We present our experience on the use of subcutaneous octreotide for 2 years for the treatment of diazoxide resistant congenital hyperinsulinism (CHI).

Male ; Infant ; Codon, Nonsense ; Congenital Hyperinsulinism ; Diazoxide ; Glucose ; Infant ; Insulins ; Ketosis ; Octreotide ; Parturition ; Pregnancy ; Mutation

Congenital hyperinsulinism is the most frequent cause of severe, persistent hypoglycemia in infancy and childhood. It is caused by an inappropriate insulin secretion from the pancreatic beta-cells secondary to various genetic disorders. Recognition of this entity becomes important due to the fact that hypoglycemia is very severe and frequent and that it may lead to severe neurological damage in the infant manifesting as mental or psychomotor retardation or even a life-threatening events if not recognized and treated effectively in time. Hypoglycemias can be detected by seizures, fainting, or any other neurological symptoms in the neonatal period or later, usually within the first two years of life. Hypoglycemias must be rapidly and intensively treated to prevent severe and irreversible brain damages. Next, a treatment to prevent the recurrence of hypoglycemia must be set, which may include frequent and glucose-enriched feeding, diazoxide and octreotide. We report a case of congenital hyperinsulinemia in a 2 months old infant presenting as atonic seizure which has been treated with diazoxide.
Brain ; Congenital Hyperinsulinism* ; Diazoxide ; Humans ; Hyperinsulinism ; Hypoglycemia ; Infant* ; Insulin ; Octreotide ; Recurrence ; Seizures* ; Syncope

OBJECTIVES: To examine the effect of diazoxide on hypoxia-induced soluble fms-like tyrosin kinase-1 (sFlt-1) release in JEG-3 choriocarcinoma cells. METHODS: Cells were cultured under normoxia (20% O2) or hypoxia (1% O2), and expression of sFlt-1 mRNA and protein release was determined by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) assays and enzyme-linked immunosorbent assay (ELISA). RESULTS: Tumor necrosis factor-alpha (TNF-alpha) as well as hypoxia stimulated sFlt-1 release and diazoxide inhibited both of them. The selective inhibitor of mitochondrial adenosine triphosphat (ATP)-sensitive K+ channel opener (K(ATP)) 5-hydroxydecanoate (5-HD) completely reversed the diazoxide-induced inhibition of hypoxia-stimulated sFlt-1 release. qRT-PCR and Western blot analyses showed that diazoxide up-regulated the heme oxygenase-1 (HO-1) expression. In addition, the HO-1 inducer cobalt protoporphyrin (CoPP) and the metabolic product of HO-1 bilirubin mimicked diazoxide to inhibit sFlt-1 release and reactive oxygen species (ROS) production under hypoxia, whereas the HO-1 inhibitor zinc protoporphyrin IX (ZnPP IX) antagonized the effect of diazoxide. In cells transfected with the HO-1 siRNA, diazoxide did not exert any effect on sFlt-1 release and ROS production under hypoxia. CONCLUSION: These results, taken together, strongly suggest that up-regulation of the HO-1 expression is the crucial mechanism responsible for the diazoxide-induced inhibition of the sFlt-1 release and ROS production under hypoxia.
Adenosine ; Anoxia ; Bilirubin ; Blotting, Western ; Choriocarcinoma* ; Cobalt ; Diazoxide* ; Enzyme-Linked Immunosorbent Assay ; Female ; Heme Oxygenase-1 ; Humans ; Polymerase Chain Reaction ; Pregnancy ; Reactive Oxygen Species ; RNA, Messenger ; RNA, Small Interfering ; Tumor Necrosis Factor-alpha ; Up-Regulation ; Vascular Endothelial Growth Factor Receptor-1 ; Zinc

The diagnosis and treatment of congenital hyperinsulinism (CHI) have made a remarkable progress over the past 20 years and, currently, it is relatively rare to see patients who are left with severe psychomotor delay. The improvement was made possible by the recent developments in the understanding of the molecular and pathological basis of CHI. Known etiologies include inactivating mutations of the K(ATP) channel genes (ABCC8 and KCNJ11) and HNF4A, HNF1A, HADH, and UCP2 or activating mutations of GLUD1, GCK, and SLC16A1. The understanding of the focal form of K(ATP) channel CHI and its detection by 18F-fluoro-L-DOPA positron emission tomography have revolutionized the management of CHI, and many patients can be cured without postoperative diabetes mellitus. The incidence of the focal form appears to be higher in Asian countries; therefore, the establishment of treatment systems is even more important in this population. In addition to diazoxide or long-term subcutaneous infusion of octreotide or glucagon, long-acting octreotide or lanreotide have also been used successfully until spontaneous remission. Because of these medications, near-total pancreatectomy is less often performed even for the diazoxide-unresponsive diffuse form of CHI. Other promising medications include pasireotide, small-molecule correctors such as sulfonylurea or carbamazepine, GLP1 receptor antagonists, or mammalian target of rapamycin inhibitors. Unsolved questions in this field include the identification of the remaining genes responsible for CHI, the mechanisms leading to transient CHI, and the mechanisms responsible for the spontaneous remission of CHI. This article reviews recent developments and hypothesis regarding these questions.
Asian Continental Ancestry Group ; Carbamazepine ; Congenital Hyperinsulinism* ; Diabetes Mellitus ; Diagnosis ; Diazoxide ; Glucagon ; Humans ; Hyperinsulinism ; Hypoglycemia ; Incidence ; Infusions, Subcutaneous ; Octreotide ; Pancreatectomy ; Positron-Emission Tomography ; Remission, Spontaneous ; Sirolimus

OBJECTIVETo explore the protective effects of mitochondrial ATP-sensitive potassium channel opener diazoxide on hyperoxia-induced apoptosis of type II alveolar epithelial cells (A549 cells) and possible mechanisms.

METHODSA549 cells were cultured in vitro and divided randomly into control, hyperoxia and diazoxide group. The hyperoxia group was exposed to a mixture of O2 (900 mL/L) and CO2 (50 mL/L) for 10 minutes, then cultured in a closed environment. The diazoxide group was pretreated with diazoxide of 100 μmol/L for 24 hrs before hyperxia induction. The cells were collected 12, 24 and 48 hrs after culture. The morphologic changes of A549 cells were observed under an inverted microscope. A549 cell apoptosis was detected by flow cytometry. The expression of Omi/HtrA2 in the endochylema of A549 cells was determined by immunohistochemistry.

RESULTSA549 cells were damaged and the changes in morphology of the cells were serious in the hyperoxia group. The apoptosis rate of A549 cells and the expression of Omi/HtrA2 in the endochylema increased in the hyperoxia group compared with the control group (P<0.05). The growth and the morphology of A549 cells were greatly improved and the cell injuries were obviously alleviated in the diazoxide group. The expression of Omi/HtrA2 in the endochylema and the apoptosis rate of A549 cells were significantly reduced in the diazoxide group compared with the hyperoxia group (P<0.05).

CONCLUSIONSDiazoxide as an opener of mitoKATP channel can reduce the expression of Omi/HtrA2 and the apoptosis rate of A549 cells, thus relieves the injury of A549 cells induced by hyperoxia.

Apoptosis ; Cells, Cultured ; Cytoprotection ; Diazoxide ; pharmacology ; High-Temperature Requirement A Serine Peptidase 2 ; Humans ; Hyperoxia ; complications ; Lung ; pathology ; Mitochondrial Proteins ; analysis ; Potassium Channels ; physiology ; Serine Endopeptidases ; analysis

OBJECTIVETo investigate the effect of diazoxide (DE) on the myocardial ultrastructure and opening of maitochondrial permeability transition pore (MPTP) in donor rat heart suffered from long-term hypothermic preservation.

METHODSThe Langendorff model of isolated rat heart was used. The hearts were stored in 4 degrees C Celsior solution containing different concentration of DE (15, 30, or 45 micromol/L) for 9 h followed by 60 min of reperfusion. The recovery of rate-pressure product (RPP) was observed. The opening of MPTP and myocardial mitochondria ultrastructure were also evaluated.

RESULTS(1) As compared with the celsior solution preserved group, DE (30 micromol/L) increased recovery of RPP during reperfusion and inhibited the opening of MPTP. DE also alleviated the myocardial mitochondrial ultrastucture damage induced by long-term hypothermic preservation. (2) The above effects of DE were attenuated by a mitoK(ATP) channel inhibitor 5-hydroxydecanoate and a MPTP opener atractyloside.

CONCLUSIONIn the donor rat heart, DE protects myocardial mitochondria ultrastructure against long-term hypothermic preservation injury via inhibiting the opening of MPIP.

Animals ; Cryopreservation ; Diazoxide ; pharmacology ; Heart ; In Vitro Techniques ; Male ; Mitochondria, Heart ; physiology ; ultrastructure ; Mitochondrial Membrane Transport Proteins ; drug effects ; metabolism ; Organ Preservation Solutions ; pharmacology ; Potassium Channels ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo determine the effects of diazoxide on oxygen free radicals and cell apoptosis in brain tissue after deep hypothermia cerebral ischemia reperfusion injury in young rats.

METHODSFifty-four 3-week-old Sprague-Dawley rats were randomly and equitably divided into sham-operated group, model group and diazoxide group respectively (n = 18). The model of hypothermia cerebral ischemia reperfusion injury was made. After 24 hours of operation, the brains of rats were removed and preserved. The content of superoxide dismutase (SOD) and malonaldehyde (MDA) in brain tissue were detected. Cytosolic C release of cytochrome was confirmed by Western Blot. The protein expression of Caspase-3 was determined by immunohistochemistry.

RESULTSIn the model group, the content of SOD was (198 +/- 41) U/mg, lower than the sham-operated group's (321 +/- 36) U/mg (P < 0.01). The content of MDA was (212 +/- 21) nmol/mg, was higher than the sham-operated group's (100 +/- 23) nmol/mg (P < 0.01), and the expressions of cytochrome C (0.72 +/- 0.09) and Caspase-3 (83 +/- 10) were all significantly higher than those in the sham-operated group (0.17 +/- 0.02 and 115 +/- 9) (P < 0.01). Compared with the model group, the content of SOD in the diazoxide group [(264 +/- 34) U/mg] was markedly increased (P < 0.05). In addition, diazoxide provided significant reductions in the content of MDA [(174 +/- 19) nmol/mg] and the expressions of cytochrome C (0.41 +/- 0.05) and Caspase-3 (99 +/- 11) (P < 0.05).

CONCLUSIONSThe neuroprotective effects of diazoxide against brain injury induced by deep hypothermia cerebral ischemia reperfusion through inhibiting oxygen free radicals and cell apoptosis. Diazoxide may become a new neuroprotective drug after infant complicated congenital cardiac operation.

Animals ; Apoptosis ; drug effects ; Brain ; metabolism ; pathology ; Brain Ischemia ; etiology ; metabolism ; pathology ; Caspase 3 ; metabolism ; Circulatory Arrest, Deep Hypothermia Induced ; adverse effects ; Cytochromes c ; metabolism ; Diazoxide ; pharmacology ; Disease Models, Animal ; Female ; Male ; Neuroprotective Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species ; metabolism ; Reperfusion ; Superoxide Dismutase ; metabolism

OBJECTIVETo investigate the effect of potassium channel opener (diazoxide) on the islet cells apoptosis and bcl-2 and bax gene expressions in diabetic rats.

METHODSIslet cell apoptosis was induced by intraperitoneal injection of streptozocin (STZ). The rats were randomly allocated into normal control group (NC group), diabetes mellitus group (DM group), and diazoxide group (DIA group), all treated with diazoxide for 4 weeks. During and after the treatment, the general state, body weight, fasting plasma glucose (FPG), food intake, and oral glucose tolerance of the rats were assessed. The expressions of Bcl-2 and Bax in rat islet cells were measured by immunohistochemistry, and the cell apoptosis was analyzed by TUNEL assay.

RESULTSCompared with the NC group, the rats in the DM group showed significantly decreased body weight (P<0.05), increased blood glucose at o and 120 min after oral glucose administration, decreased expressions of Bcl-2 (P<0.01), increased expression of Bax (P<0.01), and increased islet cell apoptosis (P<0.05). Diazoxide treatment significantly decreased the body weight (P<0.05), decreased the blood glucose, increased Bcl-2 expression (P<0.01), decreased Bax expression (P<0.05), and reduced the islet cell apoptosis (P>0.05) of the diabetic rats.

CONCLUSIONBy causing potassium channel opening, diazoxide can obviously improve the oral glucose tolerance, reduce the body weight, and up-regulate Bcl-2 and down-regulate Bax expression in diabetic rats. Diazoxide can also reduce the apoptosis of the islet cells in diabetic rats.

Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Experimental ; metabolism ; Diazoxide ; pharmacology ; Islets of Langerhans ; cytology ; drug effects ; metabolism ; Male ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; metabolism