Sodium Glucose Cotransporter 1 mRNA Research Articles

Intestinal Morphology and Glucose Transporter Gene Expression under a Chronic Intake of High Sucrose.

Sucrose is a disaccharide that is degraded into fructose and glucose in the small intestine. High-sucrose and high-fructose diets have been reported, using two-dimensional imaging, to alter the intestinal morphology and the expression of genes associated with sugar transport, such as sodium glucose co-transporter 1 (SGLT1), glucose transporter 2 (GLUT2), and glucose transporter 5 (GLUT5). However, it remains unclear how high-fructose and high-sucrose diets affect the expression of sugar transporters and the intestinal morphology in the whole intestine. We investigate the influence of a chronic high-sucrose diet on the expression of the genes associated with sugar transport as well as its effects on the intestinal morphology using 3D imaging. High sucrose was found to increase GLUT2 and GLUT5 mRNA levels without significant changes in the intestinal morphology using 3D imaging. On the other hand, the delay in sucrose absorption by an α-glucosidase inhibitor significantly improved the intestinal morphology and the expression levels of SGLT1, GLUT2, and GLUT5 mRNA in the distal small intestine to levels similar to those in the proximal small intestine, thereby improving glycemic control after both glucose and sucrose loading. These results reveal the effects of chronic high-sugar exposure on glucose absorption and changes in the intestinal morphology.

Abstract 14127: The Role of Sodium Glucose Co-Transporter 1 in Hyperglycemia Ischemia Reperfusion Injury

Introduction: Hyperglycemia is a common finding in ACS patients in both diabetic and non-diabetic, it is considered a powerful predictor of prognosis and mortality. The role of hyperglycemia in ischemia-reperfusion injury is not fully understood, whether the Sodium Glucose Co-Transporter 1(SGLT1) plays a role in increase injury, before and/or after reperfusion, remains to be elucidated. SGLT2 inhibitors clinical trials have shown significant improvements in cardiovascular outcomes in diabetic and non-diabetic, yet the mechanism is not fully understood and whether SGLT1 plays a role in infarct augmentation remains to be elucidated. Hypothesis: High glucose at reperfusion leads to excess myocardial injury and the increased injury is mediated through the activity of SGLT1. Methods: RT-PCR and in-situ hybridization (RNAScope) combined with Immunofluorescence integrated co detection with different cell marker techniques were used to detect SGLT1 mRNA expression in Sprague-Dawley whole myocardium and Zucker diabetic rats. An Ex-vivo Langendorff ischemia-reperfusion perfusion model was used to study the effect of high glucose on myocardium at reperfusion. Canagliflozin a non-selective SGLT inhibitor (1μmoL/L to block the SGLT1 and SGLT2 transporter and 5nmol/L to block only the SGLT2 transposer) and Mizagliflozin a selective SGLT1 inhibitor (100nmol/L) was introduced following ischemia at two different glucose concentration concentrations at reperfusion and its effect on infarct size measured using triphenyltetrazolium chloride (TTC) staining. Results: Our data reveal that SGLT1 is homogenously expressed throughout the myocardium and is particularly evident within the vasculature. We have also demonstrated that high-glucose mediated injury in the isolated, perfused heart model and it is abrogated through the administration of both mixed SGLT2/SGLT1 inhibitor, canagliflozin, at a dose that inhibits both SGLT2 and SGLT1, and through the administration of novel specific SGLT1 inhibitor, Mizagliflozin. Conclusions: We have shown that SGLT1 is present in the myocardium. Hyperglycemia appears to augment myocardial infarction and inhibition of SGLT1 attenuates this increase.

The cardioprotective effect of inhibiting SGLT1 in hyperglycemia ischemia reperfusion injury

Abstract Background Diabetes clinical trials have shown SGLT inhibition improves cardiovascular outcomes, yet the mechanism is not fully understood. Hyperglycemia is a common finding in diabetic and non-diabetic patients presenting with ACS and is a powerful predictor of prognosis and mortality. The role of hyperglycemia in ischemia-reperfusion injury (IRI) is not fully understood, and whether the Sodium Glucose Co-Transporter 1 (SGLT1) plays a role in infarct augmentation, before and/or after reperfusion, remains to be elucidated. Purpose Investigate if SGLT1 is involved in a glucotoxicity injury during IRI and whether inhibiting SGLT1 with an SGLT1 inhibitor may reduce infarct size. Method RT-PCR and in-situ hybridization (RNAScope) combined with Immunofluorescence integrated co detection with different cell marker techniques were used to detect SGLT1 mRNA expression in Sprague-Dawley whole myocardium and isolated primary cardiomyocytes. An Ex-vivo Langendorff ischemia-reperfusion perfusion model was used to study the effect of high glucose (22mmol) on myocardium at reperfusion. Canagliflozin (CANA) a non-selective SGLT inhibitor (1μmoL/L to block the SGLT1 receptor and SGLT2 and 5nmol/L to block only the SGLT2 receptor) and Mizagliflozin a selective SGLT1 inhibitor (100nmol/L) was introduced following ischemia at two different glucose concentration concentrations at reperfusion and its effect on infarct size measured using triphenyltetrazolium chloride (TTC) staining. Results We showed that SGLT1 is homogenously expressed throughout the myocardium and is particularly evident within the vasculature. we demonstrate that hyperglycemia at reperfusion is injurious to myocardium with an increase of myocardial infarction. Our data reveal that glucose exacerbation of injury appears to be mediated via SGLT1. We have also demonstrated that high-glucose mediated injury in the isolated, perfused heart model is abrogated through the administration of a clinically available mixed SGLT2/SGLT1 inhibitor, canagliflozin, at a dose that inhibits both SGLT2 and SGLT1, but by the SGLT2-selective concentration. Conclusion We have shown that SGLT1 is present in the myocardium. Hyperglycemia appears to augment myocardial infarction and inhibition of SGLT1 attenuates this incre Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The government of saudi Arabia

Sodium-glucose co-transporter 1 (SGLT1) differentially regulates gluconeogenesis and GLP-1 receptor (GLP-1R) expression in different diabetic rats: a preliminary validation of the hypothesis of "SGLT1 bridge" as an indication for "surgical diabetes".

BackgroundSodium-glucose co-transporter 1 (SGLT1) may play a synergistic role in gluconeogenesis (GNG) and glucagon-like peptide-1 (GLP-1) expression. We proposed the hypothesis of a “SGLT1 bridge” as an indication for “surgical diabetes” that was preliminary validated in the present study.MethodsWe selected nonobese diabetic Goto-Kakizaki (GK) rats and Zuker diabetic fat (ZDF) rats to represent advanced and early diabetes, respectively. Based on glucose gavage with or without SGLT1 inhibitor phlorizin, the rats were divided into 4 groups: Gk-Glu, GK-P, ZDF-Glu, and ZDF-P. The expressions of SGLT1, GLP-1 receptor (GLP-1R), glucose-6 phosphatase (G6Pase), and phosphoenolpyruvate carboxykinase-1 (Pck1) were determined by immunohistochemistry (IHC) or quantitative reverse transcription polymerase chain reaction (RT-qPCR), and the effects of phlorizin were analyzed.ResultsGlucose tolerance was worse in GK rats and the homeostasis model assessment-insulin resistance (HOMA-IR) was higher in ZDF rats, indicating different pathophysiological conditions between the different diabetic rats. GK rats showed higher activity of duodenal SGLT1 (P=0.022) and jejunal SGLT1 mRNA expression (P=0.000) and lower SGLT1 mRNA expression in the liver (P=0.000) and pancreas (P=0.000). Phlorizin effectively inhibited the activity of duodenal SGLT1 in both GK rats (P=0.000) and ZDF rats (P=0.000). In ZDF rats, the expression of GLP-1R mRNA was downregulated in the jejunum (P=0.001) and upregulated in the pancreas (P=0.021) by phlorizin, but there were no regulatory effects on GLP-1R mRNA in the jejunum and pancreas of GK rats. As for the regulatory effects on GNG, phlorizin upregulated Pck1 mRNA in the duodenum (P=0.000) and the jejunum (P=0.038), whereas it downregulated hepatic G6Pase mRNA in ZDF rats (P=0.005) and Pck1 mRNA expression in GK rats (P=0.001), suggesting that SGLT1 inhibitor may have upregulated intestinal GNG in ZDF rats and downregulated hepatic GNG in both ZDF and GK rats.ConclusionsSGLT1 showed synergistic regulatory effects on the entero-insular axis (EIA) and the gut-brain-liver axis (GBLA), preliminarily validating the hypothesis of a “SGLT1 bridge”. The distinct expression of SGLT1 and its differentially regulatory effects on diabetic rats with different pathophysiological conditions may provide probable potential indications involved in the “Surgical Diabetes” that is supposed as the inclusion for diabetic surgery.

Runting Stunting Syndrome in Broiler Chickens Is Associated with Altered Intestinal Stem Cell Morphology and Gene Expression.

Runting stunting syndrome (RSS) in broiler chickens is characterized by altered intestinal morphology and gene expression and stunted growth. The objective of this study was to conduct a retrospective study of gene expression in stem and differentiated cells in the small intestine of RSS chicks. Two different models of RSS were analyzed: broiler chicks that were experimentally infected and broiler chicks that were naturally infected. Experimentally infected chicks were exposed to litter from infected flocks (RSS-litter chicks) or infected with astrovirus (RSS-astrovirus chicks). Intestinal samples from naturally infected chicks showing clinical signs of RSS were acquired from commercial farms in Georgia and were brought into a poultry diagnostic lab (RSS-clinical-GA) and from farms in Brazil that had a history of RSS (RSS-clinical-BR). The RSS-clinical-BR chicks were separated into those that were positive or negative for gallivirus based on DNA sequencing. Intestinal morphology and intestinal cell type were identified in archived formalin-fixed, paraffin-embedded tissues. In situ hybridization for cell-specific mRNA was used to identify intestinal stem cells expressing olfactomedin 4 (Olfm4), proliferating cells expressing Ki67, absorptive cells expressing sodium glucose cotransporter 1 (SGLT1) and peptide transporter 1 (PepT1), and goblet cells expressing mucin 2 (Muc2). RSS-litter and RSS-clinical-GA chicks showed 4% to 7.5% cystic crypts, while gallivirus-positive RSS-clinical-BR chicks showed 11.7% cystic crypts. RSS-astrovirus and gallivirus-negative RSS-clinical-BR chicks showed few cystic crypts. RSS-litter and gallivirus-positive RSS-clinical-BR chicks showed an increase in crypt depth compared to control or gallivirus-negative chicks, respectively. There was no expression of Olfm4 mRNA in the stem cells of RSS-litter and RSS-clinical-GA chicks, in contrast to the normal expression of Olfm4 mRNA in RSS-astrovirus and RSS-clinical-BR chicks. All chicks regardless of infection status showed normal expression of Ki67 mRNA in crypt cells, Muc2 mRNA in goblet cells, and SGLT1 or PepT1 mRNA in enterocytes. These results demonstrate that RSS, which can be induced by different etiologies, can show differences in the expression of the stem cell marker Olfm4.

Oral administration of Lactococcus lactis-expressed recombinant porcine epidermal growth factor stimulates the development and promotes the health of small intestines in early-weaned piglets.

We previously generated Lactococcus lactis-expressed recombinant porcine epidermal growth factor (LL-pEGF), and demonstrated improved growth performance in early-weaned piglets. This study investigates the effect of LL-pEGF on the development and expression of genes that maintain the structural integrity and function of the small intestine in early-weaned piglets. The mitogenic effect of porcine epidermal growth factor (pEGF) was tested in vitro with the 5-Bromodeoxyuridine (BrdU) incorporation assay in fibroblast cells. In the in vivo study, 40 weaned piglets were randomly allocated to control, antibiotic control, Lc. lactis-expressing empty vector (LL-EV) and LL-pEGF treatment groups. Cells treated with LL-pEGF had higher BrdU-positive stained cells than those in the control and the LL-EV treatments (P < 0·05). Scanning electron microscope and histological examination demonstrated that the small intestinal villi treated with LL-pEGF were higher (P < 0·05) than in the other treatments. LL-pEGF increased the messenger RNA (mRNA) expression levels of the intestinal structural integrity proteins trefoil factor 3, claudin 1 (CLDN1), occludin and zonula occludens 1 (ZO-1), the digestive enzymes sucrose, aminopeptidase A, and aminopeptidase N, and the nutrient transporters sodium/glucose cotransporter 1 (SGLT1), glucose transporter 2, and peptide transporter 1 (PEPT1) as compared with the control (P < 0·05) in the small intestine. Meanwhile, the mRNA levels of CLDN1 in the jejunum and ZO-1 in the ileum were higher in the LL-EV group than in the control group (P < 0·05). LL-EV and the antibiotic control increased SGLT1 mRNA in the jejunum and PEPT1 mRNA in the ileum compared with the control (P < 0·05). Recombinant pEGF promotes cell mitosis. Oral administration of Lc. lactis-expressing pEGF stimulated intestinal development by upregulating the gene expression of the intestinal structural integrity proteins, the digestive enzymes and the nutrient transporters. The combination of epidermal growth factor and genetically modified micro-organisms may be used as dietary supplements to reduce intestinal stress in animals and even humans.

Abord supra-tentoriel dans le cadre des adénomes hypophysaires : indications, résultats, complications, intérêts et inconvénients. À propos d’une série rétrospective de 17 cas

Aspergillus niger-fermented Ginkgo biloba leaves (FR) and its comparative effect with non-fermented G. biloba leaves (NF) were investigated on growth performance, small intestinal structure and function of broiler chicks. A total of 300 d-old Arbor Acress broilers were randomly allocated into 5 dietary treatments, which were then denoted as the control group (basal diet), and the NF group (containing 0.35% and 0.7% NF in the starter and grower diets, respectively), FR1, FR2 and FR3 groups containing 0.2%, 0.35% and 0.5% FR in the starter diets and 0.4%, 0.7% and 1.0% FR in the grower diets, respectively. The results showed that, compared with the control and NF groups, reduced (P<0.05) feed/gain ratio of FR2 group and higher (P<0.05) mucosal alkaline phosphatase (AKP) activities in duodenum and jejunum of groups FR2 and FR3 were observed. Villous height of duodenum and jejunum was improved (P<0.05) as increased FR levels, while crypt depth of jejunum was decreased (P<0.05). FR supplementation led to an increase in the protease activities in pancreas, duodenum and jejunum, as well as amylase activity in the duodenum and jejunum (P<0.05 or P<0.01, respectively). In addition, the sodium glucose co-transporter 1 (SGLT1) mRNA level in duodenum was increased in birds fed with FR2 and FR3 diets. Furthermore, birds supplemented with FRs had increased (P<0.05) plasma d-xylose levels. Whereas compared with the control, broilers had lower (P<0.05) serum urea nitrogen (SUN) levels when they were provided with the FR2 and FR3 diets. The present study may indicate that the improved feed efficiency and intestinal functions in the group supplemented with FR are directly connected with physiological mechanisms such as the regulation of the SGLT1 mRNA expression.

Effect of feeding Aspergillus niger-fermented Ginkgo biloba-leaves on growth, small intestinal structure and function of broiler chicks

Aspergillus niger-fermented Ginkgo biloba leaves (FR) and its comparative effect with non-fermented G. biloba leaves (NF) were investigated on growth performance, small intestinal structure and function of broiler chicks. A total of 300d-old Arbor Acress broilers were randomly allocated into 5 dietary treatments, which were then denoted as the control group (basal diet), and the NF group (containing 0.35% and 0.7% NF in the starter and grower diets, respectively), FR1, FR2 and FR3 groups containing 0.2%, 0.35% and 0.5% FR in the starter diets and 0.4%, 0.7% and 1.0% FR in the grower diets, respectively. The results showed that, compared with the control and NF groups, reduced (P<0.05) feed/gain ratio of FR2 group and higher (P<0.05) mucosal alkaline phosphatase (AKP) activities in duodenum and jejunum of groups FR2 and FR3 were observed. Villous height of duodenum and jejunum was improved (P<0.05) as increased FR levels, while crypt depth of jejunum was decreased (P<0.05). FR supplementation led to an increase in the protease activities in pancreas, duodenum and jejunum, as well as amylase activity in the duodenum and jejunum (P<0.05 or P<0.01, respectively). In addition, the sodium glucose co-transporter 1 (SGLT1) mRNA level in duodenum was increased in birds fed with FR2 and FR3 diets. Furthermore, birds supplemented with FRs had increased (P<0.05) plasma d-xylose levels. Whereas compared with the control, broilers had lower (P<0.05) serum urea nitrogen (SUN) levels when they were provided with the FR2 and FR3 diets. The present study may indicate that the improved feed efficiency and intestinal functions in the group supplemented with FR are directly connected with physiological mechanisms such as the regulation of the SGLT1 mRNA expression.

Effects of an early lipopolysaccharide challenge on growth and small intestinal structure and function of broiler chickens

Hu, X. F., Guo, Y. M., Li, J. H., Yan, G. L., Bun, S. and Huang, B. Y. 2011. Effects of an early lipopolysaccharide challenge on growth and small intestinal structure and function of broiler chickens. Can. J. Anim. Sci. 91: 379–384. Two experiments were conducted to determine the effect of early exposure to lipopolysaccharide (LPS) on small intestinal structure and function of broiler chickens. Seven-day-old birds were randomly allotted to two equal treatments: an LPS-injected treatment in which the birds were injected intraperitoneally with LPS 500 µg kg−1 body weight (dissolved in 1 mL saline) on 8, 10, 12, 15, 17, and 19 d of age, i.e., on days 1, 3, and 5 d for 2 continuous weeks, and a control treatment (CTRL) in which the birds were similarly injected with 1 mL saline as a placebo. In exp. 1, food intake and weight gain were monitored over the 2 wk, the weight of the small bowel was determined at 14 and 21 d of age and duodenal and jejunal villus height and crypt depth, D-xylose uptake were also measured at 21 d. In exp. 2, additional measurements of the intestinal peristalsis ratio and the BrdU-labeling index and duodenal sodium-glucose co-transporter-1 (SGLT1) mRNA level were made at 21 d of age. The results showed that LPS challenge decreased feed intake, daily gain, duodenal and jejunal villus height and crypt depth, plasma D-xylose concentration and intestinal BrdUrd-labeling index, respectively (P&lt;0.05) as well as small bowel weight at 14 and 21 d of age (P&lt;0.05). Conversely, LPS injection increased SGLT1 mRNA level in the small intestine (P&lt;0.05) and the small intestinal relative weight at 14 (P&lt;0.05) and 21 d of age (P=0.063). Following LPS injection there were non-significant changes in feed conversion ratio and intestinal peristalsis ratio (P&gt;0.05). In conclusion, early LPS challenge delayed the growth of intestine and impaired small intestinal structure and absorptive function.

Feeding Rats Dietary Resistant Starch Shifts the Peak of SGLT1 Gene Expression and Histone H3 Acetylation on the Gene from the Upper Jejunum toward the Ileum.

Sodium glucose cotransporter 1 (SGLT1) participates in the incorporation of glucose from the lumen to enterocytes in the small intestine. We examined whether dietary resistant starch (RS), an autoclaved high amylose starch that is digested more slowly than regular cornstarch in the small intestine, alters SGLT1 mRNA levels along the jejunum-ileum of rats. The SGLT1 mRNA level was lower in the upper jejunum in rats fed an RS diet than in those fed a regular cornstarch diet, whereas it was higher in the lower jejunum/upper ileum. Furthermore, using chromatin immunoprecipitation (ChIP) assay, we demonstrated that histone H3 acetylation on the promoter/enhancer and transcriptional regions was reduced in the upper jejunum and elevated in the lower jejunum/upper ileum by feeding rats an RS diet. On the other hand, HNF-1 binding on the region around transcription start site of the SGLT1 gene was not altered in each jejunoileal segment by feeding rats an RS diet. Our results suggest that a shift of the expressional peak of the SGLT1 gene from the upper jejunum toward the ileum by dietary RS is associated with a change of histone H3 acetylation rather than that of HNF-1 binding on the gene.

Sensing Sugar in the Gut

Two articles provide evidence that the same receptors and pathway that allow us to taste sweet compounds (sugars and artificial sweeteners) function in the intestinal tract to sense these same compounds as they reach the gut. Jang et al . found that signaling components of the sweet taste pathway originally characterized in the tongue could be detected in enteroendocrine cells--L cells, which secrete glucagon-like peptide-1 (GLP-1), and K cells, which secrete glucose-dependent insulinotropic peptide (GIP)--of the human duodenum. In mice, the Gα subunit gustducin was present in L cells but not in K cells. A comparison of the response to glucose delivered directly into the lumen of the stomach or the duodenum (to bypass the tongue) in wild-type mice or mice lacking the gustducin gene showed that the GLP-1 secretion into the blood was absent in the gustducin-deficient animals and that the temporal pattern of insulin secretion and glucose uptake was altered. Although minced duodenal tissue from the gustducin-deficient mice showed a glucose-stimulated increase in GLP-1 release, the fold change in GLP-1 secretion was less than that for wild-type tissue. Application of glucose or artificial sweeteners directly to the human enteroendocrine L cell line NCI-H716, in which the signaling components of the sweet taste pathway were also detected, resulted in GLP-1 release, which was blocked by an antagonist of the T1R3 receptor (one subunit of the T1R2 and T1R3 G protein-coupled receptor heterodimer that forms the sugar receptor). Thus, sugar sensing in the intestinal enteroendocrine system that contributes to the regulation of glucose handling by stimulation of GLP-1 secretion appears to involve the same pathway as sweet taste sensation on the tongue. The second article, by Margolskee et al . (see commentary by Sclafani), provides evidence for a connection between glucose absorption and glucose sensing through the T1R2/3 taste receptor pathway through increased intestinal expression and abundance of the sodium-glucose cotransporter 1 (SGLT1). Wild-type mice or mice deficient in gustducin or T1R3 were fed low-carbohydrate or high-carbohydrate diets or were fed low-carbohydrate diets with artificially sweetened water, and only the wild-type mice showed an increase in SGLT1 mRNA, protein, and glucose uptake when fed the high-carbohydrate diet or exposed to the artificial sweeteners. Experiments with the mouse enteroendocrine cell line GLUTag showed that these cells release GIP and GLP-1 tonically and that the artificial sweetener sucralose stimulates the release of these hormones through a mechanism that was blocked by an antagonist of the T1R2/3 sweet taste receptor. Together these results suggest that a similar pathway to sweet taste reception in the tongue may also sense sugars in the intestine. Interestingly, artificial sweeteners appear to stimulate processes that would increase glucose uptake and insulin secretion. Whether this mechanism affects human metabolism will be interesting to evaluate. H.-J. Jang, Z. Kokrashvili, M. J. Theodorakis, O. D. Carlson, B.-J. Kim, J. Zhou, H. H. Kim, X. Xu, S. L. Chan, M. Juhaszova, M. Bernier, B. Mosinger, R. F. Margolskee, J. M. Egan, Gut-expressed gustducin and taste receptors regulate secretion of glucagon-like peptide-1. Proc. Natl. Acad. Sci. U.S.A. 104 , 15069-15074 (2007). [Abstract] [Full Text] R. F. Margolskee, J. Dyer, Z. Kokrashvili, K. S. H. Salmon, E. Ilegems, K. Daly, E. L. Maillet, Y. Ninomiya, B. Mosinger, S. P. Shirazi-Beechey, T1R3 and gustducin in gut sense sugars to regulate expression of Na + -glucose cotransporter 1. Proc. Natl. Acad. Sci. U.S.A. 104 , 15075-15080 (2007). [Abstract] [Full Text] A. Sclafani, Sweet taste signaling in the gut. Proc. Natl. Acad. Sci. U.S.A. 104 , 14887-14888 (2007). [Full Text]

Effect of Esophageal Ligation on Small Intestinal Development in Normal and Growth‐retarded Fetal Rabbits

The uninterrupted passage of amniotic fluid through the gastrointestinal tract is hypothesized to influence both intestinal and overall fetal somatic development. The effect of in utero esophageal ligation (EL) and therefore the exclusion of AF on somatic growth, small intestinal (SI) morphology and proliferation, and the expression of the glucose transporter sodium-glucose cotransporter 1 (SGLT-1) in both normal and intrauterine growth-retarded (IUGR) fetal rabbits were evaluated. Thirteen pregnant New Zealand white rabbits underwent surgery on day 24 of their normal 31-day gestation. Ipsilateral normal and IUGR fetuses underwent EL; the contralateral normal and IUGR fetuses underwent cervical exploration only forming 4 study groups (control-normal, control-IUGR, EL-normal and EL-IUGR). Rabbits were killed on day 31. Small intestinal villus height was measured, and epithelial cell proliferation was deter mined by proliferating cell nuclear antigen staining. Sodium-glucose cotransporter 1 messenger RNA (mRNA) and protein expressions were analyzed. Statistical analysis was performed using 2-way analysis of variance. Esophageal ligation reduced fetal weight in IUGR by 15% and in normal by 10%. Villus height was significantly reduced in IUGR versus normal in both control and EL (control, P = 0.01; EL, P = 0.05). Intrauterine growth-retarded fetuses had reduced SI proliferation versus normal in both control and EL. Sodium-glucose cotransporter 1 mRNA production in EL fetuses was equal to control fetuses. Esophageal ligation-normal and EL-IUGR fetuses exhibited reduced protein levels and decreased staining for SGLT-1 in villus enterocytes. Amniotic fluid exclusion by in utero EL reduced fetal weight. Small intestinal proliferation was not affected by EL. Although SGLT-1 mRNA and protein were produced in all 4 groups, exposure of the fetal gastrointestinal tract to amniotic fluid appears necessary for proper brush border expression of nutrient transporter proteins.

Fecal Stream Is Essential for Adaptive Induction of Glucose-Coupled Sodium Transport in the Remnant Ileum After Total Proctocolectomy

Our previous studies demonstrated that sodium glucose cotransporter 1 (SGLT-1) was induced in the remnant ileum of total colectomized rats via the action of factors other than hyperaldosteronism. The aim of the present study was to clarify whether fecal stream is required for the enhancement of SGLT-1-mediated sodium transport. Twenty-seven pairs of ileal tissues were obtained from the proximal and distal side, respectively, of loop ileostomy after total proctocolectomy. Mucosae were mounted in an Ussing chamber to evaluate glucose-coupled sodium transport. Levels of SGLT-1 mRNA in proximal and distal mucosae were compared by Northern blotting. Villous height and crypt depth were measured to test for correlations between mucosal structure and SGLT-1-mediated sodium transport or mRNA expression levels. Both glucose-coupled sodium transport and expression of SGLT-1 mRNA were significantly lower in distal mucosae relative to proximal mucosae. In distal mucosae, villous height, but not crypt depth, was significantly lower than in proximal mucosae, demonstrating a positive correlation between villous height and SGLT-1 function and expression. Comparative studies of proximal and distal mucosae demonstrated that in addition to hormonal changes, fecal stream is required for full induction of the sodium transport system (which includes SGLT-1-mediated transport) in the remnant ileum following total proctocolectomy.

Effect of epidermal growth factor on small intestinal sodium/glucose cotransporter–1 expression in a rabbit model of intrauterine growth retardation

Introduction Intrauterine growth–retarded (IUGR) infants have impaired gastrointestinal function with feeding difficulties and predisposition to necrotizing enterocolitis. The rabbit provides a model of IUGR based on uterine position. Sodium/glucose cotransporter–1 (SGLT-1) is a membrane protein responsible for carbohydrate transport across the intestinal brush border membrane. Previous studies demonstrate increases in small intestinal (SI) nutrient uptake in response to amniotic fluid supplementation with epidermal growth factor (EGF). To determine whether SGLT-1 expression plays a role in the intestinal response to EGF supplementation, this IUGR rabbit model was evaluated. Methods Eight pregnant rabbits underwent placement of intraamniotic catheters into 2 normal (Nl) and 2 IUGR fetuses per mother on gestational day 24. Mini-osmotic pumps infused either EGF (300 μg/kg per day) or control solution forming 4 study groups (EGF-Nl vs Cont-Nl; EGF-IUGR vs Cont-IUGR). On gestational day 31, the fetal SI was harvested. Sodium/glucose cotransporter–1/glyceraldehyde-3-phosphate dehydrogenase messenger RNA (mRNA) densitometric band ratios were measured by reverse transcriptase polymerase chain reaction. Immunohistochemistry SGLT-1 staining was performed on middle SI. Statistical analysis was performed using the analysis of variance. Results Sodium/glucose cotransporter–1 was expressed in the gastrointestinal tract throughout the last one third of gestation. There were no native differences in SGLT-1 mRNA expression between Nl and IUGR fetuses at term. Epidermal growth factor infusion did not significantly affect SI SGLT-1 mRNA expression in either Nl or IUGR fetuses vs controls (EGF-Nl = 1.94 vs Cont-Nl = 1.94, P = .98; EGF-IUGR = 1.77 vs Cont-IUGR = 1.85, P = .74). Immunohistochemistry revealed increased SGLT-1 SI protein expression in infused IUGR fetuses. Conclusions Increases in previously documented up-regulation in SI nutrient transport after EGF infusion are independent of SGLT-1 mRNA expression. Further studies are warranted investigating SGLT-1 protein expression, localization, and functional kinetics in response to amniotic fluid supplementation with EGF.

Effect of esophageal ligation (EL) on small intestinal (SI) development in a rabbit model of intrauterine growth retardation (IUGR)

Cellini, Christina MD; Xu, Jian MD; Buchmiller-Crair, Terry L. MD, FACS Author Information

Expression of glucose transporters in lactating human mammary gland epithelial cells.

Human milk contains 60-80 g/l lactose and and oligosaccharides. To synthesize this large amount of carbohydrates, the lactating mammary gland has a high demand for precursor molecules. such as glucose and galactose. In the present study we investigated the molecular basis for the uptake of glucose and galactose into the human mammary gland. Using RT-PCR, Southern and Western blotting we analyzed the expression of SGLT1 (sodium glucose cotransporter 1) und GLUT1 (sodium independent glucose transporter) in epithelial cells isolated from fresh human milk. Southern blot analysis of the amplicions revealed the expression of SGLT1 mRNA but not of GLUT1 mRNA in milk epithelial cells. Using Western blotting, SGLT1 protein was identified in human milk cells. CONCLUSIONS. Our findings indicate that 1) the cell fraction isolated from fresh human milk is a suitable model for investigating gene expression in the human mammary gland and 2) lactating human mammary gland epithelial cells are supplied with monosaccharides mainly via SGLT1.