Sodium-Glucose Cotransporter-2 Inhibitors: Who, When & How? Guidance for Use from a Multidisciplinary Practical Approach

Sodium-glucose cotransporter-2 inhibitors (SGLT-2 inhibitors) have transformed diabetes management by targeting renal glucose reabsorption. Designed initially as antidiabetic agents, their ability to lower blood glucose levels independently of insulin is well-documented. Beyond glycemic control, emerging research has unveiled their profound cardiorenal benefits. By inhibiting SGLT-2 protein, these drugs enhance glucose excretion in urine, reducing blood glucose levels. This mechanism has translated into significant cardiovascular and renal protection, establishing SGLT-2 inhibitors as pivotal in managing not only diabetes but also cardiovascular and renal diseases. Recent studies have illuminated the broader therapeutic potential of SGLT-2 inhibitors beyond diabetes. Evidence indicates their efficacy in managing heart failure, chronic kidney disease (CKD), and cardiovascular complications in individuals with or without diabetes. This expanded therapeutic landscape has catalyzed a paradigm shift in SGLT-2 inhibitor use, positioning them as key agents in the cardiorenal metabolic continuum. Moreover, their role in the secondary prevention of cardiovascular events and slowing CKD progression in T2DM patients has garnered considerable attention. This consensus-based review aims to offer practical guidance in an algorithmic approach to primary care healthcare professionals to optimize SGLT-2 inhibitors utilization and maximize their benefits. The review seeks to empower clinicians to effectively manage patients who may benefit from SGLT-2 inhibitor therapy by addressing common initiation barriers and optimizing treatment strategies. Additionally, it aims to raise awareness among primary care physicians regarding the multifaceted benefits of these medications and overcome clinical inertia in their adoption into routine clinical practice.

Heterogeneity in cardiorenal protection by Sodium glucose cotransporter 2 inhibitors in heart failure across the ejection fraction strata:Systematic review and meta-analysis

BACKGROUND Gliflozins or Sodium glucose cotransporter 2 inhibitors(SGLT2i)are relatively novel antidiabetic medications that have recently been shown to represent favorable effects on patients’cardiorenal outcomes.However,there is shortage of data on potential disparities in this therapeutic effect across different patient subpopulations.AIM To investigate differential effects of SGLT2i on the cardiorenal outcomes of heart failure patients across left ventricular ejection fraction(LVEF)levels.METHODS Literature was searched systematically for the large randomized double-blind controlled trials with long enough follow up periods reporting cardiovascular and renal outcomes in their patients regarding heart failure status and LVEF levels.Data were then meta-analyzed after stratification of the pooled data across the LVEF strata and New York Heart Associations(NYHA)classifications for heart failure using Stata software version 17.0.RESULTS The literature search returned 13 Large clinical trials and 13 post hoc analysis reports.Meta-analysis of the effects of gliflozins on the primary composite outcome showed no significant difference in efficacy across the heart failure subtypes,but higher efficacy were detected in patient groups at lower NYHA classifications(I2=46%,P=0.02).Meta-analyses across the LVEF stratums revealed that a baseline LVEF lower than 30%was associated with enhanced improvement in the primary composite outcome compared to patients with higher LVEF levels at the borderline statistical significance(HR:0.70,95%CI:0.60 to 0.79 vs 0.81,95%CI:0.75 to 0.87;respectively,P=0.06).Composite renal outcome was improved significantly higher in patients with no heart failure than in heart failure patients with preserved ejection fraction(HFpEF)(HR:0.60,95%CI:0.49 to 0.72 vs 0.94,95%CI:0.74 to 1.13;P=0.04).Acute renal injury occurred significantly less frequently in heart failure patients with reduced ejection fraction who received gliflozins than in HFpEF(HR:0.67,95%CI:51 to 0.82 vs 0.94,95%CI:0.82 to 1.06;P=0.01).Volume depletion was consistently increased in response to SGLT2i in all the subgroups.CONCLUSION Heart failure patients with lower LVEF and lower NYHA sub-classifications were found to be generally more likely to benefit from therapy with gliflozins.Further research are required to identify patient subgroups representing the highest benefits or adverse events in response to SGLT2i.

Saudi Consensus on the Usage of Sodium-Glucose Cotransporter-2 Inhibitors on the Management of Chronic Kidney Diseases

According to recent epidemiological data, chronic kidney diseases (CKDs) affect approximately 10% of the global population. Like many countries, CKD is a significant public health issue in Saudi Arabia. The prevalence of CKD in Saudi Arabia is estimated to be around 4.5% of the adult population, with a higher prevalence in older age groups. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are a class of oral medications used to treat type 2 diabetes mellitus (T2DM). In addition to their glucose-lowering effects, SGLT2i have been shown to have beneficial effects on kidney function in patients with or without T2DM. Therefore, a Saudi task force gathered to develop an explicit, evidence-based consensus on SGLT2i use in CKD Saudi patients. A panel of 14 experts made up a task force. An initial concept proposal was obtained. The proposal was divided into several topics discussed on 24 May 2023. A literature review was carried out. The literature search was completed on 3rd June 2023. A drafted report was distributed to the entire panel. Approval of the recommendations required consensus, defined as a majority approval (i.e. above 75%). The recommendations were revised to accommodate any differences of opinion until a consensus was reached. Recommendations were finally formulated on 21st June 2023. Subsequently, the panel reviewed and discussed the supporting rationale of the revised recommendations. This article presents these practical recommendations.

Ipragliflozin: A novel sodium-glucose cotransporter 2 inhibitor developed in Japan

Sodium-glucose cotransporter 2(SGLT2) inhibition induces glucosuria and decreases blood glucose levels in diabetic patients and lowers hypoglycemic risk. SGLT1 is expressed in the kidney and intestine; SGLT1 inhibition causes abdominal symptoms such as diarrhea and reduces incretin secretion. Therefore, SGLT2 selectivity is important. Ipragliflozin is highly selective for SGLT2. In type 2 diabetes mellitus(T2DM), urinaryglucose excretion increased to 90 g/24 h after 28 d of treatment with ipragliflozin 300 mg/d. Twelve weeks of ipragliflozin 50 mg/d vs placebo reduced glycated hemoglobin and body weight by 0.65% and 0.66 kg, respectively, in Western T2 DM patients, and by 1.3% and 1.89 kg, respectively, in Japanese patients. Ipragliflozin(highly selective SGLT2 inhibitor) improves glycemic control and reduces body weight and lowers hypoglycemic risk and abdominal symptoms. Ipragliflozin can be a novel anti-diabetic and antiobesity agent.

Sodium glucose cotransporter 2 inhibitors:New horizon of the heart failure pharmacotherapy

Sodium-glucose cotransporter 2(SGLT2)inhibitors have gained momentum as the latest class of antidiabetic agents for improving glycemic control.Large-scale clinical trials have reported that SGLT2 inhibitors reduced cardiovascular outcomes,especially hospitalization for heart failure in patients with type 2 diabetes mellitus who have high risks of cardiovascular disease.Accumulating evidence has indicated that beneficial effects can be observed regardless of the presence or absence of type 2 diabetes mellitus.Accordingly,the Food and Drug Administration approved these agents specifically for treating patients with heart failure and a reduced ejection fraction.It has been concluded that canagliflozin,dapagliflozin,empagliflozin,or ertugliflozin can be recommended for preventing hospitalization associated with heart failure in patients with type 2 diabetes and established cardiovascular disease or those at high cardiovascular risk.In the present review,we explore the available evidence on SGLT2 inhibitors in terms of the cardioprotective effects,potential mechanisms,and ongoing clinical trials that may further clarify the cardiovascular effects of the agents.

Mechanism Underlying Increase of the Serum Magnesium Concentration Observed Following Treatment with Sodium-Glucose Cotransporter 2 Inhibitors

Aim: The EMPA-REG OUTCOME study reported that the sodium-glucose cotransporter 2 inhibitor (SGLT2-i) suppressed cardiovascular (CV) events in patients with type 2 diabetes;we recently suggested that increase of the serum magnesium (Mg) by SGLT2-i’s can, in part, explain this reduction. The objective of this study was to elucidate the mechanism underlying the elevation of the serum Mg level induced by treatment with SGLT2-i’s. Methods: We analyzed the data of 37 patients with type 2 diabetes who underwent clinical evaluation and laboratory assessment at baseline and the end of 3 months. To investigate the relationship between the changes in the serum Mg concentrations during 3 months’ treatment (ΔMg) and other variables, we carried out simple linear regression analysis and multiple linear regression analysis. Results: Three months’ treatment with the SGLT2-i resulted in a significant improvement of the body weight (BW), BMI, hemoglobin A1c (HbA1c), and fasting plasma glucose levels. The serum Mg increased significantly. Simple linear regression analysis revealed an association between the ΔMg and the serum triglyceride, serum Mg at baseline, change of the BW (ΔBW), and change of the HbA1c. Multiple linear regression analysis revealed a significant association between the ΔMg and the serum Mg level at the baseline (r = -0.55, P Conclusion: Our study revealed that a lower serum Mg level at the baseline and BW reduction were significantly associated with an increase in the serum Mg following 3 months’ treatment with SGLT2-i’s.

Effects of Na2S2O3 and Glucose on the Compositions of Glycerolipids and Their Fatty Acids in Synechocystis sp. PCC 6803 Cells

Compositions of glycerolipids and fatty acid compositions of glycerolipids were compared among Synechocystis sp. PCC 6803 cells grown in the BG-11 medium containing different concentrations of glucose and Na2S2O3 in this study. It was found that Na2S2O3 can effectively increase the percentage of sulphoquinovosyl diacylglycerol (SQDG) and phosphatidylglycerol (PG) to total membrane lipids and the simultaneous application of glucose with Na2S2O3 can counteract the effect of Na2S2O3. In addition, Na2S2O3 can significantly increase the percentage of palmitic acid (C, 16:0) in fatty acid composition of monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) and decrease the fatty acid unsaturation degree accordingly, and these effects can also be eliminated by glucose. These results indicate that Na2S2O3 can take as a reductant to make membrane lipids in a low unsaturated state, and the simultaneous application of glucose can decrease the reducing power of Na2S2O3. In addition, Na2S2O3 can take as a sulfur donor for the synthesis of SQDG.

Role of the Na^+/K^+/2Cl^- cotransporter NKCC1 in cell cycle progression in human esophageal squamous cell carcinoma

AIM: To investigate the role of Na+/K+/2Cl- cotransporter 1 (NKCC1) in the regulation of genes involved in cell cycle progression and the clinicopathological significance of its expression in esophageal squamous cell carcinoma (ESCC).

Na^+/HCO_3^- cotransporter is expressed on β and α cells during rat pancreatic development

AIM To determine the expression and localization of the electrogenic Na^+/HCO_3^- cotransporter(NBC1) in rat pancreas during development. METHODS The rat pancreas from postnatal and embryos removed from the uterus of pregnant rats that had been sacrificed by CO2 asphyxiation were used. Rat pancreas from embryonic day(E) 15.5 and E18.5 rat embryos was isolated under a stereomicroscope. Rat pancreas from postnatal(P) days 0, 7, 14, 21 and adult was directly isolated by the unaided eye. The RT-PCR analysis of the NBC1 specific region on rat pancreastissues from different developmental stages. The two antibodies which target the NBC1 common COOHterminal region and NH2-terminal region detected a clear band of about 145 k Da in the Western blot analysis. The localization of NBC1 was examined by immuno-fluorescence detection. RESULTS The results revealed the first peak of NBC1 expression at E18.5 and the second peak at P14. Meanwhile, the low NBC1 expression occurred at P7 and adult stages. Our results demonstrated, for the first time, the presence of NBC1 in the plasma membrane of β and α cells, as well as in the basolateral membrane of acinar cells of the rat pancreas at different stages of development. CONCLUSION The data strongly suggests that NBC1 is diversely expressed in the pancreas at different developmental stages, where it may exert its functions in pancreatic development especially islet cell growth through HCO_3^- transport and pH regulation.

Localization and vasopressin regulation of the Na^+-K^+-2Cl^- cotransporter in the distal colonic epithelium

AIM: To investigate whether Na+-K+-2Cl- cotransporter (NKCC2) is expressed in the mouse distal colonic epithelia and whether it is regulated by vasopressin in the colon.

The Physiological Model of Na⁺-Dependent Transporters for Glucose and Amino Acids in Rat and Turtle

Conditions in rat and turtle small intestine tissue where glucose and glycine transport is inhibited while glucose-induced Na+ transport is preserved are described. The generally accepted model for the Na+-dependent transporter (а single channel for the Na+ and nutrient) does not account for the data obtained from the analysis of the interaction between the transport of glucose, glycine, and Na+ at different temperatures and the effect of inhibitors оn these рroсеssеs. The phenomenon of temperature uncoupling of Na+ and nutrient transport саn best bе described bу а two-pathway model with а gate mechanism. According to this model, the Na+-dependent transporter has at least two pathways: оnе for Na+ and another for nutrients. The model рrovidеs for the passage of Na+ in both directions along а channel opened bу glucose. Experiments are carried out using the addition of glucose and glycine on backgrounds of glycine and glucose, respectively. It has been hypothesized that when all three transporters (for Na+, glucose and glycine) are unite in a single structure, then there should be “competitive relations” between short-circuit current changes on glycine and glucose for sodium ions passing through its transporter.

Absence of Na^+/sugar cotransport activity in Barrett's metaplasia

AIM:To evaluate the presence of Na+-dependent, active, sugar transport in Barrett's epithelia as an intestinal biomarker, based on the well-documented, morphological intestinal phenotype of Barrett's esophagus (BE). METHODS: We examined uptake of the nonmeta- bolizable glucose analogue, alpha-methyl-D-glucoside (AMG), a substrate for the entire sodium glucose cotransporter (SGLT) family of transport proteins. During upper endoscopy, patients with BE or with uncomplicated gastroesophageal reflux disease (GERD) allowed for duodenal, gastric fundic, and esophageal mucosal biopsies to be taken. Biopsies were incubated in bicarbonate-buffered saline (KRB) containing 0.1 mmol/L 14C-AMG for 60 min at 20℃. Characterized by abundant SGLT, duodenum served as a positive control while gastric fundus and normal esophagus, known to lack SGLT, served as negative controls. RESULTS: Duodenal biopsies accumulated 249.84 ± 35.49 (SEM) picomoles AMG/μg DNA (n = 12), gastric fundus biopsies 36.20 ± 6.62 (n = 12), normal esophagus 12.10 ± 0.59 (n = 3) and Barrett's metaplasia 29.79 ± 5.77 (n = 8). There was a statistical difference (P < 0.01) between biopsies from duodenum and each other biopsy site but there was no statistically significant difference between normal esophagus and BE biopsies. 0.5 mmol/L phlorizin (PZ) inhibited AMG uptake into duodenal mucosa by over 89%, but had nosignificant effect on AMG uptake into gastric fundus, normal esophagus, or Barrett's tissue. In the absence of Na+ (all Na+ salts replaced by Li+ salts), AMG uptake in duodenum was decreased by over 90%, while uptake into gastric, esophageal or Barrett's tissue was statistically unaffected. CONCLUSION: Despite the intestinal enterocyte phenotype of BE, Na+-dependent, sugar transport activity is not present in these cells.

Metabolic disorders in prediabetes:From mechanisms to therapeutic management

Diabetes,one of the world's top ten diseases,is known for its high mortality and complication rates and low cure rate.Prediabetes precedes the onset of diabetes,during which effective treatment can reduce diabetes risk.Prediabetes risk factors include high-calorie and high-fat diets,sedentary lifestyles,and stress.Consequences may include considerable damage to vital organs,including the retina,liver,and kidneys.Interventions for treating prediabetes include a healthy lifestyle diet and pharmacological treatments.However,while these options are effective in the short term,they may fail due to the difficulty of long-term implementation.Medications may also be used to treat prediabetes.This review examines prediabetic treatments,particularly metformin,glucagon-like peptide-1 receptor agonists,sodium glucose cotransporter 2 inhibitors,vitamin D,and herbal medicines.Given the remarkable impact of prediabetes on the progression of diabetes mellitus,it is crucial to intervene promptly and effectively to regulate prediabetes.However,the current body of research on prediabetes is limited,and there is considerable confusion surrounding clinically relevant medications.This paper aims to provide a comprehensive summary of the pathogenesis of prediabetes mellitus and its associated therapeutic drugs.The ultimate goal is to facilitate the clinical utilization of medications and achieve efficient and timely control of diabetes mellitus.

Effects of glucose-lowering agents on cardiorespiratory fitness

Exercise therapy is essential for the management of type 2 diabetes(T2 D). However, patients with T2 D show lower physical activity and reduced cardiorespiratory fitness than healthy individuals. It would be ideal for clinicians to co-prescribe glucose-lowering agents that improve cardiorespiratory fitness or exercise capacity in conjunction with exercise therapy. Metformin does not improve cardiorespiratory fitness and may attenuate any beneficial effect of exercise in patients with T2 D. In contrast, thiazolidinediones appear to improve cardiorespiratory fitness in patients with T2 D. Although evidence is limited, sodium–glucose cotransporter 2(SGLT2) inhibitors may improve cardiorespiratory fitness in patients with heart failure, and the effect of glucagon-like peptide-1(GLP-1) receptor agonists on cardiorespiratory fitness is controversial. Recent clinical trials have shown that both SGLT2 inhibitors and GLP-1 receptor agonists exert a favorable effect on cardiovascular disease. It becomes more important to choose drugs that have beneficial effects on the cardiovascular system beyond glucose-lowering effects. Further studies are warranted to determine an ideal glucose-lowering agent combined with exercise therapy for the treatment of T2 D.

Progress in the Study of the Hepatoprotective Effect of SGLT2i on NAFLD Patients with T2DM

In recent years, the progress of NAFLD has become an important health problem, and the prevention or delay of progress in NAFLD is a major key point. Whether or not to combine T2MD, people are interested in the mechanisms and efficacy of SGLT2i for NAFLD. In this review, we summarized the current clinical research on SGLT2i for the combination of T2MD’s NAFLD patients, and the latest evidence of external or animal experiments. These evidences will help us to more accurately understand the protective effects of SGLT2i in NAFLD. Lifestyle changes are still essential to prevent and treat NAFLD, and for all kinds of drugs that treat NAFLD in clinical trials, SGLT2i may be one of the promising treatments.

急性盐度胁迫对斜带石斑鱼Na^+/K^+-ATP酶及血清应激指标的影响

研究了急性盐度胁迫对斜带石斑鱼幼鱼Epinephelus coioides鳃丝Na+/K+-ATP酶活性和血清应激指标的影响,将养殖于自然海水(盐度34‰)中,体重为(19.59±0.25)g的斜带石斑鱼幼鱼直接转移至盐度24‰、14‰、4‰和0‰的水体中,于转移后1、3、6、12和24h分别检测鳃丝Na+/K+-ATP酶活性和血清中血糖、天门冬氨酸氨基转移酶(AST)、溶菌酶的变化。试验表明:试验组Na+/K+-ATP酶活性变化基本一致,均在1h时达到最高值,随后下降,至6h达到稳定且均显著高于对照组(P<0.05);血糖在24‰和14‰盐度组呈下降趋势,在4‰和0‰盐度组3h时出现最低值,在6h时达到峰值,随后逐渐下降;AST水平在24‰和14‰盐度组与对照组无显著差异(P>0.05),在4‰和0‰盐度组均呈现先上升后下降的趋势,于6和12h时达到各自峰值;溶菌酶含量在试验24h时,在24‰、14‰和4‰盐度组间差异显著(P<0.05),在0‰盐度组呈现先上升后下降的趋势,至6h时达到峰值。试验显示,斜带石斑鱼幼鱼由盐度34‰的水体转移至盐度24‰和14‰的水体后,其应激强度较弱;由盐度34‰的水体转移至盐度4‰和0‰的水体后,其应激反应较大,适应盐度变化需时也较长。根据本试验结果,在对斜带石斑鱼进行应激性淡化转运时,可将其直接从34‰高盐度自然海水中转移至14‰盐度的水体后,再缓慢降至预定盐度,从而减少淡化时间。

盐碱胁迫对尼罗罗非鱼鳃Na^+/HCO_3^-共转运子、碳酸酐酶基因表达的影响

为了探讨盐碱胁迫条件下鱼类渗透生理调节机制,以尼罗罗非鱼(Oreochromis niloticus)为实验材料,PCR扩增得到了Na^(+)/3HCO^(-)共转运子(NBCe1)基因c DNA部分序列,比较了单盐(盐度10、盐度15)、单碱(1.5 g/L、3 g/L Na HCO3)、盐碱混合(盐度10,碱度1.5 g/L;盐度15,碱度3 g/L)胁迫后不同时间(0 h、6 h、12 h、24 h、48 h、72 h、96 h)血清渗透压、离子浓度(Na^(+)、K^(+)、Cl–、Ca2^(+))以及鳃碳酸酐酶(CA)活性、CA与NBCe1基因m RNA表达变化。结果显示,不同胁迫条件下,血清渗透压、离子浓度、鳃组织CA酶活、CA与NBCe1基因m RNA表达变化均与胁迫强度呈正相关。随时间推移,血清渗透压、离子浓度呈现先上升后下降的变化趋势,单盐、盐碱混合组血清渗透压值较单碱组高。单盐、单碱、盐碱混合组中,NBCe1基因m RNA在鳃中均呈略微上调,但不显著(P>0.05)。单碱组和盐碱混合组鳃CA活性较单盐组高,低盐碱胁迫(盐度10,碱度1.5 g/L)下CA活性较晚达最高值;不同胁迫条件下,CA基因m RNA表达均表现上调,单碱、盐碱混合组更为显著(P<0.05),推测CA较NBCe1对体内3HCO^(-)转运作用更为显著。研究结果为尼罗罗非鱼盐碱适应生理调节提供了基础资料。

绿色荧光蛋白与人肾脏NaDC3融合基因的构建及其在肾小管上皮细胞中的定位

本文采用RT-PCR方法从人的正常肾组织中扩增出hNaDC3基因全长cDNA序列,采用基因重组技术将hNaDC3基因和绿色荧光蛋白基因融合,通过真核表达质粒-脂质体介导,导入LLG-PK1细胞系,激光共聚焦显微镜动态观察GFP-hNaDC3的定位情况。结果显示pEGFP-C3空白质粒转染的LLC-PK1细胞表达了GFP,GFP在胞内分布以核浆为主,呈均匀致密的细颗粒荧光,胞核染色强,核仁荧光稀少,界线清楚。而pEGFP-C3-hNaDC3转染细胞株的绿色荧光蛋白,转染后第1天混合分布于细胞浆和细胞膜,以粗颗粒荧光为主,两者界限不清楚,胞浆中可见未染色的圆形空洞,未见胞核染色;第3天主要聚集于细胞膜,核周的胞浆中可见粗颗粒荧光物质,胞浆和胞膜界线清楚,胞核亦未见绿色荧光蛋白;第5天清晰聚集于细胞膜,细胞膜连接呈网状。因此hNaDC3蛋白在细胞质中生成后,定位于细胞膜并稳定表达。

日本囊对虾Na-K-2Cl共同转运蛋白基因的克隆与组织表达分析

利用反转录PCR(RT-PCR)和cDNA末端快速扩增(RACE)等技术在鳃组织中获得日本囊对虾(Marsupenaeus japonicus)Na-K-2Cl共同转运蛋白(NKCC)cDNA全序列,包含14bp的5′非编码区(5′-UTR)、201bp的3′-UTR和3 183bp的开放阅读框(ORF).该ORF共编码1 060个氨基酸,预测蛋白分子质量为117.051ku,理论等电点为6.57,命名为Mj-NKCC.预测Mj-NKCC二级结构由10个跨膜区组成,跨膜区的氨基酸序列和布局均相对保守.同源对比结果显示,Mj-NKCC的氨基酸序列与夏威夷海蚀洞虾(Halocaridina rubra)的Na-K-2Cl共同转运蛋白相似度最高,为77%.系统进化分析表明Mj-NKCC与夏威夷海蚀洞虾、蓝蟹(Callinectes sapidus)等甲壳动物的NKCC聚为一支.实时荧光定量PCR(qRT-PCR)分析表明,Mj-NKCC基因在肝胰腺、鳃、胃、肠、心、眼柄、肌肉和血细胞中均有表达,鳃组织中表达量最高;在盐度骤变时,该基因表达变化显著,表明其很可能参与了对虾的渗透压调节,在对虾的渗透平衡中发挥重要作用.

木聚糖酶对尼罗罗非鱼钠葡萄糖共转运载体(SGLT_1)mRNA表达的影响

以尼罗罗非鱼[体重(106.16±16.77)g]为实验对象,小麦基础饲料为对照,小麦基础饲料中分别添加不同水平的木聚糖酶(0.05%、0.10%、0.15%)作为试验饲料。每个处理设5个重复,每个重复放养40尾雄性尼罗罗非鱼,旨在研究木聚糖酶对尼罗罗非鱼前肠和中肠钠葡萄糖共转运载体(SGLT_1)mRNA表达的影响,从分子水平揭示木聚糖酶促进尼罗罗非鱼生长的机理。饱食投喂,饲养75 d后,每饲料组分别取10尾鱼,尾静脉取血制备血清,测定血糖含量;采用离心柱型总RNA提取试剂金提取前肠和中肠总RNA,通过RT-PCR对前肠和中肠SGLT_1mRNA的表达进行相对定量。结果表明,0.05%组、0.10%组和0.15%组前肠SGLT_1 mRNA的相对表达量分别比对照组提高19.28%(P<0.05)、42.17%(P<0.01)和16.87% (P<0.05);对照组尼罗罗非鱼在摄食后2 h血糖仅为5.56 mmol·L^(-1),0.10%组极显著高于对照组(P<0.01);0.05%组和0.10%组的增重率较对照组分别提高8.29%、17.45%(P<0.01),0.15%组的增重率与对照组相比没有统计学差异(P>0.05)。研究结果表明,在小麦基础饲料中适量添加木聚糖酶能显著上调前肠SGLT_1mRNA的表达,促进葡萄糖吸收,从而提高尼罗罗非鱼的生长速度。