Sodium-glucose cotransporter-2 inhibitor-associated euglycemic diabetic ketoacidosis in COVID-19-infected patients: A systematic review of case reports

BACKGROUND Diabetic ketoacidosis(DKA)manifests as hyperglycemia,metabolic acidosis,and ketosis.However,euglycemic DKA(eu-DKA)conceals severe DKA with glucose levels below 200 mg/dL.Sodium-glucose cotransporter-2(SGLT2)inhibitors can induce eu-DKA in diabetic patients.Notably,coronavirus disease 2019(COVID-19)-infected individuals with diabetes using SGLT2 inhibitors face an augmented risk of eu-DKA due to the direct toxic impact of the virus on pancreatic islets.This study aims to comprehensively investigate the association between SGLT2 inhibitors and eu-DKA in COVID-19 patients through meticulous case report analysis.Additionally,we endeavor to examine the outcomes and treatment approaches for COVID-19-infected diabetics receiving SGLT2 inhibitors,providing indispensable insights for healthcare professionals managing this specific patient population.AIM To investigate the connection between SGLT2 inhibitors and euglycemic DKA in COVID-19 patients through a meticulous analysis of case reports.METHODS We conducted an exhaustive search across prominent electronic databases,including PubMed,SCOPUS,Web of Science,and Google Scholar.This search encompassed the period from December 2019 to May 2022,incorporating published studies and pre-prints.The search terms employed encompassed“SGLT2 inhibitors”,“euglycemic DKA”,“COVID-19”,and related variations.By incorporating these diverse sources,our objective was to ensure a thorough exploration of the existing literature on this subject,thereby augmenting the validity and robustness of our findings.RESULTS Our search yielded a total of seven case reports and one case series,collectively comprising a cohort of twelve patients.These reports detailed instances of eu-DKA in individuals with COVID-19.Crucially,all twelve patients were utilizing SGLT2 as their primary anti-diabetic medication.Upon admission,all oral medications were promptly discontinued,and the patients were initiated on intravenous insulin therapy to effectively manage the DKA.Encouragingly,eleven patients demonstrated a favorable outcome,while regrettably,one patient succumbed to the condition.Subsequently,SGLT2 were discontinued for all patients upon their discharge from the hospital.These findings provide valuable insights into the clinical management and outcomes of eu-DKA cases associated with COVID-19 and SGLT2,underscoring the critical importance of prompt intervention and vigilant medication adjustments.CONCLUSION Our study sheds light on the possibility of diabetic patients developing both drug-related and unrelated DKA,as well as encountering adverse outcomes in the context of COVID-19,despite maintaining satisfactory glycemic control.The relationship between glycemic control and clinical outcomes in COVID-19 remains ambiguous.Consequently,this systematic review proposes that COVID-19-infected diabetic patients using SGLT2 should contemplate alternative treatment protocols until their recovery from the disease.

Sodium-glucose co-transporter-2 inhibitor-associated euglycemic diabetic ketoacidosis that prompted the diagnosis of fulminant type-1 diabetes:A case report

Fulminant type 1 diabetes mellitus(FT1DM)is a subtype of type 1 diabetes mellitus characterized by an abrupt onset and a rapid and complete functional loss of isletβcells.It is a very rare disease generally associated with ketoacidosis and the absence of circulating pancreatic islet-related autoantibodies.Diabetic ketoacidosis with normal blood glucose levels has been reported during sodiumglucose co-transporter 2(SGLT2)inhibitor therapy.CASE SUMMARY The patient was a 43-year-old woman that consulted a medical practitioner for malaise,thirst,and vomiting.Blood analysis showed high blood glucose levels(428 mg/dL),a mild increase of hemoglobin A1c(6.6%),and increased ketone bodies in urine.The patient was diagnosed with type 2 diabetes mellitus.The patient was initially treated with insulin,which was subsequently changed to an oral SGLT2 inhibitor.Antibodies to glutamic acid decarboxylase were negative.Four days after receiving oral SGLT2 inhibitor,she consulted at Mie University Hospital,complaining of fatigue and vomiting.Laboratory analysis revealed diabetic ketoacidosis with almost normal blood glucose levels.The endogenous insulin secretion was markedly low,and the serum levels of islet-related autoantibodies were undetectable.We made the diagnosis of FT1DM with concurrent SGLT2 inhibitor-associated euglycemic diabetic ketoacidosis.The patient's general condition improved after therapy with intravenous insulin and withdrawal of oral medication.She was discharged on day 14 with an indication of multiple daily insulin therapy.CONCLUSION This patient is a rare case of FT1DM that developed SGLT2 inhibitor-associated diabetic ketoacidosis with almost normal blood glucose levels.This case report underscores the importance of considering the diagnosis of FT1DM in patients with negative circulating autoantibodies and a history of hyperglycemia that subsequently develop euglycemic diabetic ketoacidosis following treatment with a SGLT2 inhibitor.

Value of glucose transport protein 1 expression in detecting lymph node metastasis in patients with colorectal cancer

BACKGROUND There are limited data on the use of glucose transport protein 1(GLUT-1)expre-ssion as a biomarker for predicting lymph node metastasis in patients with colorectal cancer.GLUT-1 and GLUT-3,hexokinase(HK)-II,and hypoxia-induced factor(HIF)-1 expressions may be useful biomarkers for detecting primary tumors and lymph node metastasis when combined with fluorodeoxyglucose(FDG)uptake on positron emission tomography/computed tomography(PET/CT).AIM To evaluate GLUT-1,GLUT-3,HK-II,and HIF-1 expressions as biomarkers for detecting primary tumors and lymph node metastasis with 18F-FDG-PET/CT.METHODS This retrospective study included 169 patients with colorectal cancer who underwent colectomy and preoperative 18F-FDG-PET/CT at Chungbuk National University Hospital between January 2009 and May 2012.Two tissue cores from the central and peripheral areas of the tumors were obtained and were examined by a dedicated pathologist,and the expressions of GLUT-1,GLUT-3,HK-II,and HIF-1 were determined using immunohisto-chemical staining.We analyzed the correlations among their expressions,various clinicopathological factors,and the maximum standardized uptake value(SUVmax)of PET/CT.RESULTS GLUT-1 was found at the center or periphery of the tumors in 109(64.5%)of the 169 patients.GLUT-1 positivity was significantly correlated with the SUVmax of the primary tumor and lymph nodes,regardless of the biopsy site(tumor center,P<0.001 and P=0.012;tumor periphery,P=0.030 and P=0.010,respectively).GLUT-1 positivity and negativity were associated with higher and lower sensitivities of PET/CT,respectively,for the detection of lymph node metastasis,regardless of the biopsy site.GLUT3,HK-II,and HIF-1 expressions were not significantly correlated with the SUVmax of the primary tumor and lymph nodes.CONCLUSION GLUT-1 expression was significantly correlated with the SUVmax of 18F-FDG-PET/CT for primary tumors and lymph nodes.Clinicians should consider GLUT-1 expression in preoperative endoscopic biopsy in interpreting PET/CT findings.

Antihypertensive Effect of Sodium-Glucose Cotransporter 2 Inhibitors and Glucagon-like Peptide 1 Receptor Agonists

An increasing body of evidence shows that new antidiabetic drugs—particularly sodium-glucose cotransporter 2(SGLT2)inhibitors and glucagon-like peptide 1(GLP-1)receptor agonists—have a beneficial effect on cardiovascular outcome.The majority of these studies have been performed in patients with heart failure and the results have shown first positive effect on blood pressure(BP)reduction.These effects are more pronounced with SGLT2 inhibitors than with GLP-1 receptor agonists.However,the reasons and mechanisms of action inducing BP reduction are still not sufficiently clear.Proposed mechanisms of SGLT2 inhibitors involve the natriuretic effect,modification of the renin-angiotensin-aldosterone system,and/or the reduction in the sympathetic nervous system.GLP-1 receptor agonists have several mechanisms that are related to glycemic,weight,and BP control.Current data show that SGLT2 inhibitors have a stronger antihypertensive effect than GLP-1 receptor agonists,which is mainly related to their renal effect.Briefly,SGLT2 inhibitors increase the response to diuretics and decrease the meal-related antinatriuretic pressure by lowering post-prandial hyperglycemia and hyperinsulinemia and prevent proximal sodium reabsorption.SGLT2 inhibitors can be used as second-line therapy in patients with diabetes mellitus or heart disease and concomitant hypertension.This article aims to summarize current knowledge regarding the antihypertensive effect of SGLT2 inhibitors and GLP-1 receptor agonists.

肾上腺嗜铬细胞瘤患者组织葡萄糖转运蛋白1和拓扑异构酶ⅡA表达与临床特征及预后的相关性分析

目的探讨葡萄糖转运蛋白1(GLUT1)和拓扑异构酶ⅡA(TOP2A)在肾上腺嗜铬细胞瘤(PPGL)患者组织中的表达与临床特征及预后的相关性。方法选取2014年3月至2020年6月于新疆维吾尔自治区人民医院行手术切除的120例PPGL组织作为实验组。另收集同期行手术切除的100例无功能肾上腺腺瘤的肾上腺组织作为对照组。采用免疫组织化学染色法检测组织中GLUT1和TOP2A表达情况。通过Cox回归分析PPGL患者预后的影响因素。结果实验组中GLUT1的低表达率和TOP2A的高表达率均高于对照组[51.7%(62/120)比14.0%(14/100)、52.5%(63/120)比19.0%(19/100)],差异均有统计学意义(χ^(2)=34.225、31.829,均P<0.001)。GLUT1、TOP2A表达水平与镜下组织浸润和Ki-67有关(均P<0.05)。预后良好组中GLUT1高表达和TOP2A低表达比例均高于预后不良组,差异均有统计学意义(均P<0.001)。单因素分析结果显示,患者镜下组织浸润、Ki-67、GLUT1、TOP2A均是影响预后的因素(均P<0.001)。Cox多因素回归分析显示TOP2A、镜下组织浸润及Ki-67均是导致PPGL患者预后不良的危险因素,GLUT1为保护因素(均P<0.001)。结论GLUT1在PPGL组织中呈低表达,TOP2A呈高表达,与患者预后不良有关。

1-甲基环丙烯缓释贴纸对模拟运输期间完熟期番茄果实品质的影响

完熟期番茄果实的成熟度高,生理代谢旺盛,不耐贮运。为了减轻高成熟度番茄果实运输过程中的损耗问题,将果实装入纸箱或泡沫箱,并添加1-甲基环丙烯(1-methylcyclopropene,1-MCP)缓释贴纸作为处理,于(30±5)℃条件下进行3 d的模拟运输试验(包含2 h的模拟振动)。以番茄果实的生理代谢、采后品质和相关酶活性为评价指标,分析1-MCP缓释贴纸和包装材料对番茄果实模拟运输期间品质的影响。结果表明,随着模拟运输时间延长,果实品质劣变加剧,包括硬度下降,形成瘀伤、伤呼吸、伤乙烯以及色泽变化。1-MCP缓释贴纸能降低果实的损伤指数、呼吸强度、乙烯生成速率、红色指数a^(*)、丙二醛含量和脂氧合酶活力,保持较高的硬度、亮度L^(*)、抗坏血酸含量,并诱导过氧化物酶和过氧化氢酶活力。此外,主成分分析表明纸箱包装更适合于贮藏环节,泡沫箱包装更适合于运输环节。综上,使用1-MCP缓释贴纸处理以及泡沫箱外包装可以更好地维持完熟期番茄果实运输期间的采后品质,为高成熟度番茄果实的物流配送及品质调控提供了技术参考。

Divalent metal transporter 1 expression and iron deposition in the substantia nigra of a rat model of Parkinson's disease

Extensive iron deposition has been observed in the midbrain substantia nigra （SN） of Parkinson＇s disease （PD） patients, but the mechanisms of iron deposition in the SN remain poorly understood. The present study investigated the relationship between dopaminergic neuronal damage, iron content changes, and divalent metal transporter 1 （DMT1） in the midbrain SN of PD rats to explore the relationship between time of iron deposition and DMT1 expression. Frozen midbrain SN sections from model rats were stained with Perls＇ iron. Results showed massive loss of tyrosine hydroxylase （TH）-positive cells in the SN and increased DMT1 expression in model group rats. No obvious iron deposition was observed in the SN during early stages after damage, but significant iron deposition was detected at 8 weeks post-injury. Results demonstrate that the loss of TH-positive cells in the SN appeared simultaneously with increased DMT1 expression. Extensive iron deposition occurred at 8 weeks post injury, which could be regarded as an early time window of iron deposition.

Up-regulation of divalent metal transporter 1 in 6-hydroxydopamine intoxication is IRE/IRP dependent

Iron plays a key role in Parkinson＇s disease （PD）. Increased iron content of the substantia nigra （SN） has been found in PD patients, and divalent metal transporter 1 （DMT1） has been shown to be up-regulated in the SN of both MPTP-induced PD models and PD patients. However, the mechanisms underlying DMT1 up-regulation are largely unknown. In the present study, we observed that in the SN of 6-hydroxydopamine （6-OHDA）-induced PD rats, DMT1 with the iron responsive element （IRE, DMTI＋IRE）, but not DMT1 without IRE （DMTI-IRE）, was up- regulated, suggesting that increased DMTI＋IRE expression might account for nigral iron accumulation in PD rats. This possibility was further assessed in an in vitro study using 6-OHDA-treated and DMTl＋IRE-over-expressing MES23.5 cells. In 6-OHDA-treated MES23.5 cells, increased iron regulatory protein （IRP） 1 and IRP2 expression was observed, while silencing of IRPs dramatically diminished 6-OHDA-indueed DMTI＋IRE up-regulation. Pre- treatment with N-acetyl-L-cysteine fully suppressed IRPs up-regulation by inhibition of 6-OHDA-indueed oxidative stress. Increased DMTI＋IRE expression resulted in increased iron influx by MES23.5 cells. Our data provide direct evidence that DMTI＋IRE up-regulation can account for IRE/IRP-dependent 6-OHDA-induced iron accumulation initiated by 6-OHDA-induced intracellular oxidative stress and that increased levels of intracellular iron result in ag- gravated oxidative stress. The results of this study provide novel evidence supporting the use of anti-oxidants in the treatment of PD, with the goal of inhibiting iron accumulation by regulation of DMT1 expression.

Neuroprotective effects of cromakalim on cerebral ischemia-reperfusion injury in rats Correlation with hippocampal metabotropic glutamate receptor 1 alpha and glutamate transporter 1

BACKGROUND：Studies have reported that potassium channel openers exhibit a protective effect on cerebral ischemia-reperfusion injury and inhibit glutamate excitotoxicity in rats.However,the effects of the glutamate receptor 1α and glutamate transporter 1 remain poorly understood.OBJECTIVE：To investigate the prophylactic use of the adenosine triphosphate-sensitive potassium channel opener cromakalim on neurological function and cerebral infarct size,as well as glutamate receptor 1α and glutamate transporter 1 expression,in rats with cerebral ischemia-reperfusion injury,and to explore action mechanisms underlying reduced glutamate excitotoxicity and neuroprotection in rats.DESIGN,TIME AND SETTING：Randomized,controlled,animal experiment was performed at the Brain Institute,Qingdao University Medical College,Between July 2008 and April 2009.MATERIALS：Cromakalim was purchased from Sigma,USA; rabbit anti-glutamate receptor 1α polyclonal antibody was offered by Wuhan Boster,China; rabbit anti-glutamate transporter 1 polyclonal antibody was offered by Santa Cruz Biotechnology,USA.METHODS：Sixty male,Wistar rats,aged 6 months,were randomly assigned to three groups （n =20）：sham-surgery,model,and cromakalim.Intraluminal thread methods were used to establish middle cerebral artery occlusion in rats from the model and cromakalim groups.Rats from the sham-surgery group were subjected to exposed common carotid artery,external carotid artery,and internal carotid artery,without occlusion.Cromakalim （10 mg/kg） was administered 30 minutes prior to middle cerebral artery occlusion,but there was no intervention in the model and sham-surgery groups.MAIN OUTCOME MEASURES：At 24 hours post-surgery,neurological behavioral functions were evaluated using Bederson＇s test,cerebral infarction volume was determined following tetrazolium chloride staining,and glutamate receptor 1a and glutamate transporter 1 expressions were detected using immunohistochemistry.RESULTS：Following cerebral ischemia-reperfusion injury,neurological behavioral malfunctions were obvious in all mice.Focal cerebral infarction was detected in ischemic hemispheres,glutamate receptor 1α expression increased,and glutamate transporter 1 expression decreased in the ischemic hemisphere （P〈 0.05）.Compared with the model group,neurological behavioral functions significantly improved,cerebral infarction volume was significantly reduced （P〈 0.05）,glutamate receptor 1α expression was significantly decreased,and glutamate transporter 1 expression was increased in the cromakalim group （P 〈 0.05）.CONCLUSION：Improved neurological function and reduced cerebral infarction volume in rats through the preventive use of cromakalim could be related to decreased glutamate receptor 1α expression and enhanced glutamate transporter 1 expression.

Hippocampal and cortical expression of gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein in pentylenetetrazol-induced chronic epileptic rats

BACKGROUND： Gamma-aminobutyric acid transporter plays an important role in gamma-aminobutyric acid metabolism, and is highly associated with epilepsy seizures. Pathologically, astrocytes release active substances that alter neuronal excitability, and it has been demonstrated that astrocytes play a role in epileptic seizures. OBJECTIVE： To observe changes in gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein expression in the hippocampus and cortex of the temporal lobe in rats with pentylenetetrazol-induced chronic epilepsy. DESIGN, TIME AND SETTING： Randomized, controlled, animal experiment was performed at the Department of Neurobiology, Third Military University of Chinese PLA between January 2006 and December 2007. MATERIALS： Pentylenetetrazol was purchased from Sigma, USA; rabbit anti-rat gammaaminobutyric acid transporter 1 and glial fibrillary acidic protein were from Chemicon, USA. METHODS： A total of 40 Sprague Dawley rats were divided into model and control groups. Rat models of chronic epilepsy were created by pentylenetetrazol kindling, and were subdivided into 3-, 7-, and 14-day kindling subgroups. MAIN OUTCOME MEASURES： Gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein expression, as well as the number of positive cells in the hippocampus and cortex of temporal lobe of rats, were determined by immunohistochemistry and Western blot analyses. RESULTS： Compared with the control group, the number of gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein -positive cells in the hippocampus and cortex of rats with pentylenetetrazol-induced epilepsy significantly increased, gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein expression increased after 3 days of kindling, reached a peak on day 7, and remained at elevated levels at day 14 （P〈 0.05）. CONCLUSION： Astrocytic activation and gamma-aminobutyric acid transporter 1 overexpression may contribute to pentylenetetrazol-induced epilepsy.

Glutamate Transporter 1-mediated Antidepressant-like Effect in a Rat Model of Chronic Unpredictable Stress

In recent years, more attention has been paid to the role of the glutamate transporter 1 （GLT-1, EAAT2） in major depressive disorder （MDD）. However, experimental data on brain GLT-1 levels are, to some extent, inconsistent in human postmortem and animal studies, These discrepancies imply that the role of GLT-1 in the pathophysiology of MDD and the action of antidepressants remain obscure. This work was designed to study the impact of chronic unpredictable stress （CUS） for 2 ses- sions per day for 35 days and four weeks of fluoxetine （FLX） on depressive-like behaviors in rats, as well as the concomitant expression of the GLT-1 protein in the hippocampus. Behavioral changes were assessed by the sucrose preference and open field tests. GLT-1 levels were detected by immunohisto- chemistry and Western blot analysis. Our study demonstrated that the animals exposed to CUS showed depressive-like behaviors and exhibited a significant decrease in GLT-1 expression in the hippocampus. Chronic FLX treatment reversed the behavioral deficits and the CUS-induced decrease in GLT-1 levels. Taken together, our results support the reduction of GLT-1 in human postmortem studies in MDD and suggest that GLT-1 may be involved in the antidepressant activity of FLX. Our studies further support the notion that GLT-1 is an attractive candidate molecule associated with the fundamental processes of MDD and may be a potential, and novel pharmacological target for the treatment of MDD.

Transforming growth factor beta-1 upregulates glucose transporter 1 and glycolysis through canonical and noncanonical pathways in hepatic stellate cells

BACKGROUND Hepatic stellate cells(HSCs)are the key effector cells mediating the occurrence and development of liver fibrosis,while aerobic glycolysis is an important metabolic characteristic of HSC activation.Transforming growth factor-β1(TGF-β1)induces aerobic glycolysis and is a driving factor for metabolic reprogramming.The occurrence of glycolysis depends on a high glucose uptake level.Glucose transporter 1(GLUT1)is the most widely distributed glucose transporter in the body and mainly participates in the regulation of carbohydrate metabolism,thus affecting cell proliferation and growth.However,little is known about the relationship between TGF-β1 and GLUT1 in the process of liver fibrosis and the molecular mechanism underlying the promotion of aerobic glycolysis in HSCs.AIM To investigate the mechanisms of action of GLUT1,TGF-β1 and aerobic glycolysis in the process of HSC activation during liver fibrosis.METHODS Immunohistochemical staining and immunofluorescence assays were used to examine GLUT1 expression in fibrotic liver tissue.A Seahorse extracellular flux(XF)analyzer was used to examine changes in aerobic glycolytic flux,lactate production levels and glucose consumption levels in HSCs upon TGF-β1 stimulation.The mechanism by which TGF-β1 induces GLUT1 protein expression in HSCs was further explored by inhibiting/promoting the TGF-β1/mothersagainst-decapentaplegic-homolog 2/3(Smad2/3)signaling pathway and inhibiting the p38 and phosphoinositide 3-kinase(PI3K)/AKT signaling pathways.In addition,GLUT1 expression was silenced to observe changes in the growth and proliferation of HSCs.Finally,a GLUT1 inhibitor was used to verify the in vivo effects of GLUT1 on a mouse model of liver fibrosis.RESULTS GLUT1 protein expression was increased in both mouse and human fibrotic liver tissues.In addition,immunofluorescence staining revealed colocalization of GLUT1 and alpha-smooth muscle actin proteins,indicating that GLUT1 expression was related to the development of liver fibrosis.TGF-β1 caused an increase in aerobic glycolysis in HSCs and induced GLUT1 expression in HSCs by activating the Smad,p38 MAPK and P13K/AKT signaling pathways.The p38 MAPK and Smad pathways synergistically affected the induction of GLUT1 expression.GLUT1 inhibition eliminated the effect of TGF-β1 on HSC proliferation and migration.A GLUT1 inhibitor was administered in a mouse model of liver fibrosis,and GLUT1 inhibition reduced the degree of liver inflammation and liver fibrosis.CONCLUSION TGF-β1 induces GLUT1 expression in HSCs,a process related to liver fibrosis progression.In vitro experiments revealed that TGF-β1-induced GLUT1 expression might be one of the mechanisms mediating the metabolic reprogramming of HSCs.In addition,in vivo experiments also indicated that the GLUT1 protein promotes the occurrence and development of liver fibrosis.

GLUT1、GLUT2介导的葡萄糖摄取对小鼠牙齿早期发育的影响

目的:探究葡萄糖转运蛋白(glucose transporter,GLUT)1、GLUT2介导的葡萄糖摄取对小鼠牙齿早期发育的影响。方法:收集胚胎13.5 d(embryonic day 0.5,E13.5)、E14.5、E16.5、E18.5和出生后1 d(postnatal day 1,P1)时期的下颌磨牙牙胚、上颌切牙牙胚;实时荧光定量聚合酶链反应(real time-quantitative polymerase chain reaction,RT-qPCR)和Western blot检测牙胚中Glut1、Glut2 mRNA和蛋白水平;免疫组织化学染色检测牙胚中GLUT1、GLUT2、Ki67、糖原水平。将下颌磨牙牙胚在无糖DMEM培养基、高糖且含不同浓度的根皮素(0、0.25、0.5 mmol/L)的DMEM培养基中培养9 d;并对其进行苏木精-伊红(hematoxylin-eosin,HE)染色。结果:(1)在E13.5时期,GLUT1在成釉器中高表达,细胞增殖活跃,糖原在牙板和牙囊中大量沉积;在E14.5、E18.5时期,GLUT1在成釉器中表达逐渐降低,细胞增殖减少,糖原在成釉器和牙乳头中大量沉积;在P1时期,GLUT1在中间层和内釉上皮中表达较多,细胞增殖增多,糖原在牙乳头中少量沉积。在整个牙胚发育阶段,GLUT2表达相对较少。(2)GLUT1在前成釉细胞、前成牙本质细胞中高表达,而在分化后的成釉细胞、成牙本质细胞中表达较少;GLUT2与GLUT1呈现相反的表达趋势。(3)0.5 mmol/L根皮素能够抑制E13.5时期外植体牙胚发育,0.25 mmol/L根皮素不抑制E13.5、E14.5时期外植体牙胚发育,但能够导致牙胚变小,且具有根皮素浓度依赖性。无糖培养基能够抑制E13.5、E14.5时期外植体牙胚发育。结论:GLUT1、GLUT2在牙齿早期发育中的表达受到精确的时空调控,由GLUT1、GLUT2介导的葡萄糖摄取在小鼠牙齿早期发育中发挥重要作用。

Baicalin protects neonatal rat brains against hypoxicischemic injury by upregulating glutamate transporter 1 via the phosphoinositide 3-kinase/protein kinase B signaling pathway

Baicalin is a flavonoid compound extracted from Scutellaria baicalensis root.Recent evidence indicates that baicalin is neuroprotective in models of ischemic stroke.Here,we investigate the neuroprotective effect of baicalin in a neonatal rat model of hypoxic-ischemic encephalopathy.Seven-day-old pups underwent left common carotid artery ligation followed by hypoxia（8% oxygen at 37°C） for 2 hours,before being injected with baicalin（120 mg/kg intraperitoneally） and examined 24 hours later.Baicalin effectively reduced cerebral infarct volume and neuronal loss,inhibited apoptosis,and upregulated the expression of p-Akt and glutamate transporter 1.Intracerebroventricular injection of the phosphoinositide 3-kinase/protein kinase B（PI3 K/Akt） inhibitor LY294002 30 minutes before injury blocked the effect of baicalin on p-Akt and glutamate transporter 1,and weakened the associated neuroprotective effect.Our findings provide the first evidence,to our knowledge that baicalin can protect neonatal rat brains against hypoxic-ischemic injury by upregulating glutamate transporter 1 via the PI3 K/Akt signaling pathway.

A novel oral prodrug-targeting transporter MCT 1: 5-fluorouracil-dicarboxylate monoester conjugates

Monocarboxylate transporter 1(MCT1)is responsible for oral absorption of short-chain monocarboxylic acids from small intestine,hence,it’s likely to serve as an ideal design target for the development of oral prodrugs.However,potential application of MCT1 to facilitate the oral delivery is still unclear.Irregular oral absorption,poor permeability and bioavailability greatly limit the oral delivery efficiency of 5-fluorouracil(5-FU).Herein,we design three 5-FU-fatty acid conjugates targeting intestinal MCT1 with different lipophilic linkages.Interestingly,due to high MCT1 affinity and good gastrointestinal stability,5-FUoctanedioic acid monoester prodrug exhibited significant improvement in membrane permeability(13.1-fold)and oral bioavailability(4.1-fold)compared to 5-FU.More surprisingly,stability experiment in intestinal homogenates showed that 5-FU prodrugs could be properly activated to release 5-FU within intestinal cells,which provides an ideal foundation for the improvement of oral bioavailability.In summary,good gastrointestinal stability,high membrane permeability and appropriate intestinal cell bioactivation are the important factors for high-efficiency 5-FU oral prodrugs,and such work provides a good platform for the development of novel oral prodrugs targeting intestinal transporters.

Elevated NKCC1 transporter expression facilitates early post-traumatic brain injury seizures

As a leading cause for morbidity and mortality in young adults,traumatic brain injury（TBI）,along with the poorly understood TBI-related seizures inducing their predispositions,pose a major health and socioeconomic problem in the world（Huang,2013）.

Ipomoea batatas HKT1 transporter homolog mediates K^+ and Na^+ uptake in Saccharomyces cerevisiae

Soil salinity causes the negative effects on the growth and yield of crops. In this study, two sweet potato （Ipomoea batatas L.） cultivars, Xushu 28 （X-28） and Okinawa 100 （O-100）, were examined under 50 and 100 mmol L-1 NaCI stress. X-28 cultivar is relatively high salt tolerant than O-100 cultivar. Interestingly, real-time quantitative polymerase chain reaction （RT-qPCR） results indicated that sweet potato high-affinity K^＋ transporter 1 （IbHKT1） gene expression was highly induced by 50 and 100 mmol L-1 NaCI stress in the stems of X-28 cultivar than in those of O-100 cultivar, but only slightly induced by these stresses in the leaves and fibrous roots in both cultivars. To characterize the function of IbHKT1 transporter, we performed ion-flux analysis in tobacco transient system and yeast complementation. Tobacco transient assay showed that IbHKT1 could uptake sodium （Na^＋）. Yeast complementation assay showed that IbHKT1 could take up K^＋ in 50 mmol L^-1 K^＋ medium without the presence of NaCI. Moreover, Na^＋ uptake significantly increased in yeast overexpressing IbHKTI. These results showed that IbHKT1 transporter could have K^＋-Na^＋ symport function in yeast. Therefore, the modes of action of IbHKT1 in transgenic yeast could differ from the mode of action of the other HKT1 transporters in class I. Potentially, IbHKT1 could be used to improve the salt tolerance nature in sweet potato.

PGE_(2)通过EP4/PKA信号通路调控滑膜细胞OAT1的表达及CP-25的作用

目的明确前列腺素E2(prostaglandin E2,PGE_(2))对滑膜细胞有机阴离子转运体1(organic anion transporter 1,OAT1)膜表达的调控机制及芍药苷-6'-O-苯磺酸酯(CP-25)的作用。方法免疫荧光法检测不同浓度CP-25对PGE_(2)处理后滑膜细胞OAT1和前列腺素E受体4(prostaglandin E receptor 4,EP4)表达的影响;使用EP4激动剂(TCS2510)与拮抗剂(GW627368X),探究EP4在OAT1调节中的作用;使用CP-25和蛋白激酶A(protein kinase A,PKA)抑制剂H-89,探究CP-25和PKA对滑膜细胞OAT1表达的影响。结果PGE_(2)在0~10 min内明显下调EP4与OAT1的膜表达,20~60 min后明显上调(P<0.05);CP-25明显上调PGE_(2)处理后细胞膜OAT1和EP4的表达(P<0.05);EP4激动剂TCS2510明显上调细胞膜OAT1的表达(P<0.01);CP-25上调PGE_(2)处理的细胞中OAT1的表达,GW627368X和H-89均能下调PGE_(2)和CP-25处理的滑膜细胞中OAT1的表达(P<0.01)。结论PGE_(2)介导的EP4/PKA信号通路可以调控OAT1在滑膜细胞膜上的表达,CP-25可以通过活化EP4/PKA信号通路明显上调滑膜细胞中OAT1的膜表达。

痛泻要方通过调控结肠TPH1、SERT及肠道菌群改善腹泻型肠易激综合征症状

目的探讨痛泻要方调控结肠色氨酸羟化酶1(TPH1)、5-羟色胺转运体(SERT)及肠道菌群对腹泻型肠易激综合征(IBS-D)大鼠症状的影响。方法将42只SD大鼠随机分为对照组(7只)和造模组(35只)。造模组大鼠采用0.45 g/L的番泻叶药液[10mL/(kg·d)]灌胃联合慢性不可预知性应激的方法建立IBS-D模型。将造模成功的35只大鼠随机分为模型组、匹维溴铵组[15mg/(kg·d)]和痛泻要方低、中、高剂量组[3.75、7.5、15 g/(kg·d),以生药量计],每组7只。各药物组灌胃相应药液,每天1次,连续10 d。分别于造模前、造模后给药前、末次药物干预后评估各组大鼠的一般情况和体重变化情况;分别于造模后给药前、末次药物干预后检测其腹泻指数、内脏敏感性,观察其结肠组织病理变化,检测其结肠组织中5-羟色胺(5-HT)水平及蛋白表达情况和TPH1、SERT蛋白及mRNA的表达水平,并分析大鼠粪便样品中肠道菌群的多样性及物种组成变化。结果各组大鼠结肠组织均未见明显病理改变。与模型组比较,各药物组大鼠一般情况改善;痛泻要方中、高剂量组大鼠的日均体重增长量显著增加,腹泻指数、内脏敏感性和结肠组织5-HT、TPH1表达均显著降低或减少,结肠组织SERT表达显著增加(P<0.05或P<0.01);痛泻要方低剂量组大鼠腹泻指数、结肠TPH1蛋白表达、结肠5-HT蛋白阳性率均显著降低,SERT mRNA表达显著增加(P<0.05);痛泻要方的干预效果有剂量依赖趋势。与模型组比较,痛泻要方高剂量组大鼠的Chao1指数、Shannon指数均显著降低(P<0.05或P<0.01),厚壁菌门、乳酸杆菌属等有益菌显著增加,变形菌门、大肠杆菌属-志贺氏杆菌属、Rikenellaceae_RC9_gut_group等致病菌显著减少(P<0.05或P<0.01)。结论痛泻要方可通过抑制结肠组织中TPH1的表达并上调SERT的表达来降低5-HT水平、改善肠道菌群紊乱,从而改善IBS-D大鼠症状。

Transcriptional activation of glucose transporter 1 in orthodontic tooth movement-associated mechanical response

The interplay between mechanoresponses and a broad range of fundamental biological processes, such as cell cycle progression,growth and differentiation, has been extensively investigated. However, metabolic regulation in mechanobiology remains largely unexplored. Here, we identified glucose transporter 1(GLUT1)—the primary glucose transporter in various cells—as a novel mechanosensitive gene in orthodontic tooth movement(OTM). Using an in vivo rat OTM model, we demonstrated the specific induction of Glut1 proteins on the compressive side of a physically strained periodontal ligament. This transcriptional activation could be recapitulated in in vitro cultured human periodontal ligament cells(PDLCs), showing a time-and dose-dependent mechanoresponse. Importantly, application of GLUT1 specific inhibitor WZB117 greatly suppressed the efficiency of orthodontic tooth movement in a mouse OTM model, and this reduction was associated with a decline in osteoclastic activities. A mechanistic study suggested that GLUT1 inhibition affected the receptor activator for nuclear factor-κ B Ligand(RANKL)/osteoprotegerin(OPG)system by impairing compressive force-mediated RANKL upregulation. Consistently, pretreatment of PDLCs with WZB117 severely impeded the osteoclastic differentiation of co-cultured RAW264.7 cells. Further biochemical analysis indicated mutual regulation between GLUT1 and the MEK/ERK cascade to relay potential communication between glucose uptake and mechanical stress response. Together, these cross-species experiments revealed the transcriptional activation of GLUT1 as a novel and conserved linkage between metabolism and bone remodelling.