Intestinal Glucose Research Articles

BMAL1 controls glucose uptake through paired-homeodomain transcription factor 4 in differentiated Caco-2 cells.

The transcription factor aryl hydrocarbon receptor nuclear translocator-like protein-1 (BMAL1) is an essential regulator of the circadian clock, which controls the 24-h cycle of physiological processes such as nutrient absorption. To examine the role of BMAL1 in small intestinal glucose absorption, we used differentiated human colon adenocarcinoma cells (Caco-2 cells). Here, we show that BMAL1 regulates glucose uptake in differentiated Caco-2 cells and that this process is dependent on the glucose transporter sodium-glucose cotransporter 1 (SGLT1). Mechanistic studies show that BMAL1 regulates glucose uptake by controlling the transcription of SGLT1 involving paired-homeodomain transcription factor 4 (PAX4), a transcriptional repressor. This is supported by the observation that clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated endonuclease Cas9 (Cas9) knockdown of PAX4 increases SGLT1 and glucose uptake. Chromatin immunoprecipitation (ChIP) and ChIP-quantitative PCR assays show that the knockdown or overexpression of BMAL1 decreases or increases the binding of PAX4 to the hepatocyte nuclear factor 1-α binding site of the SGLT1 promoter, respectively. These findings identify BMAL1 as a critical mediator of small intestine carbohydrate absorption and SGLT1.

Impairments in Protein Digestion and Absorption Attenuate the Anabolic Response to Feeding in Patients with Congestive Heart Failure (FS09-03-19)

ObjectivesGastrointestinal symptoms are prevalent extracardiac systemic manifestations of Congestive Heart Failure (CHF). We developed a comprehensive panel of methods to unravel gut dysfunction in CHF and its impact on the anabolic response to feeding. MethodsWe recruited 14 clinically stable CHF patients (ejection fraction: 33.9 ± 2.1, NYHA class: 2.3 ± 0.2) and 17 healthy controls matched for age and gender. Stable tracers of L-phenylalanine (PHE)-[ring-2H5] and L-tyrosine (TYR)-[13C9,15 N] were administered intravenously for 5 hours via primed constant and continuous infusion. After 2 hours, participants ingested a complete high protein meal containing L-PHE-[1–13C] and spirulina-[U-15 N]. We sampled blood throughout the study to analyze enrichments by LC-MS/MS. We calculated the anabolic response to feeding before and after correction for changes in protein digestion and absorption, assessed by spirulina degradation ratio (L-PHE-[15 N]/[1–13C]). Moreover, we measured small intestinal membrane integrity and active carrier-mediated glucose transport by urinary recovery of the orally ingested inert sugars lactulose, rhamnose, and 3-O-methyl-glucose. Disease severity was assessed by medical chart and history. Statistical analysis was performed by unpaired t-tests. Data are expressed as mean ± SEM. ResultsIn CHF patients, protein digestion and absorption were reduced (0.66 ± 0.04 vs. 0.82 ± 0.04, P < 0.01), which further attenuated the anabolic response to feeding (28.3 ± 3.8 vs. 54.0 ±5.5 μmol/kg FFM/meal, P < 0.001). Disturbances in protein digestion and absorption as well as anabolic response in CHF were independent of disease severity. Small intestinal permeability and active carrier-mediated glucose transport did not differ between the groups indicating a preserved enterocyte function in CHF patients. ConclusionsWe hypothesize that enhancing protein digestion and absorption in patients with CHF can improve the availability of nutrients and protein anabolism. Funding SourcesNational Institutes of Health

Anthocyanin Improves Glucose Homeostasis in Obese Mice via Beneficial Regulation of Intestinal Microbiota and Barrier Function (OR34-08-19)

ObjectivesAnthocyanin (ACN) is a natural polyphenol with anti-diabetic effects. However, intact anthocyanin has low bioavailability and largely arrives unmetabolized in the colon, its mechanisms of action remain unclear. The intestinal microbiota dysbiosis and leaky gut contribute to the development of diet-induced type 2 diabetes. Therefore, we aim to investigate whether the anti-diabetic effects of anthocyanin were related to changes in the gut microbiota and epithelial barrier function. MethodsMale C57Bl/6 N mice were randomly assigned into 4 groups and pair-fed either a chow or high fat/high sugar diet (HFHS, 45 kcal% fat, 17 kcal% sucrose) +/- 1.0% anthocyanin for 8 weeks. Indices of systemic inflammation, parameters of glucose homeostasis and intestinal barrier function were determined. The composition of the gut microbiota was assessed by analysing 16S rRNA gene sequences with Illumina pyrosequencing. To ascertain the involvement of the gut microbiota in the anti-diabetic effects of anthocyanin. A separate cohort of HFHS-fed C57Bl/6 N mice were oral gavage administered with fecal microbiota from chow-fed donors, HFHS-fed donors, HFHS + ACN-fed donors and heat-killed fecal microbial from HFHS + ACN-fed donors (HK-ACN) for 8 weeks, followed by the same examination. ResultsRelative to vehicle controls, ACN ingestion attenuated several effects of HFHS feeding, including glucose intolerance, insulin resistance and serum inflammatory markers. ACN ingestion reduced intestinal permeability and metabolic endotoxemia. These beneficial effects of ACN were associated with increased expression of genes involved in epithelial barrier function (ZO-1, occludin) and decreased inducible NO-synthase (iNOS) protein levels in ileum and colon of HFHS-fed mice. Gut microbiota analysis revealed that ACN ingestion induced profound alterations in the gut microbiome of HFHS-fed mice. Transplantation of the gut microbiome from ACN-fed mice, but not HFHS-fed or HK-ACN-fed mice, was sufficient to recapitulate the improvement in intestinal epithelial barrier function, systemic inflammation and glucose homeostasis observed with oral ACN treatment. ConclusionsThese findings indicate that ACN-mediated changes in the gut microbiota and epithelial barrier function may play a predominant role in the mechanism of action of anthocyanin. Funding SourcesThe State Key Program of National Natural Science Foundation of China [grant number 81730090].

2005-P: Transgenic Overexpression of Human Chimeric Intestinal Alkaline Phosphatase (IAP) Improves Plasma Lipid Profile and Attenuates Western Diet (WD)-Induced Atherosclerosis in LDLR-/- Mice

IAP represents the first layer of the intestinal barrier and detoxifies bacterial endotoxin LPS in the gut lumen. Reduced levels of IAP are associated with diabetes and heart disease. We developed intestine specific IAP transgenic mice (IAPTg) and demonstrated attenuation of WD-induced intestinal barrier dysfunction and glucose intolerance. In this study, we crossed the IAPTg mice into LDLR-/- background to examine the effects on atherosclerosis. Panel A shows significant reduction in plasma total cholesterol (TC) and triglyceride (TG) in LDLR-/-IAPTg mice. There was a small but statistically non-significant improvement in glucose tolerance (Panel B). Enface analyses (Panel C) showed significant reduction in arch and total aortic lesions (Panel D). Expression of IAP was observed along the entire length of the GI tract including colon (Panel E). Expression of Muc-2, major protein of the mucin or the second layer of the intestinal barrier was enhanced in colon of IAPTg mice. Increased expression of GLP-1 was also noted in the ileum of IAPTg mice. These data suggest that in addition to limiting LPS-mediated intestinal inflammation, IAP also improves intestinal barrier function by increasing Muc-2 expression and IAP-modulated increase in ileal GLP-1 expression may contribute to the improved glucose tolerance. Disclosure S.S. Ghosh: None. J. Wang: None. P.J. Yannie: None. Y.K. Sandhu: None. S. Ghosh: None. Funding American Diabetes Association (1-16-IBS-105 to S.G.)

Effects of Acute Swimming Exercise on Pancreatic Enzyme Activity and Intestinal Glucose Transporters in Rats

PURPOSE: It has been reported that long-term endurance exercise training increases pancreatic amylase activity in rats, suggesting that chronic exercise training enhances the carbohydrate digestive capacity. To clarify whether an acute bout of endurance exercise can also induce the pancreatic adaptation and affect glucose transport capacity in small intestine as well, we evaluate the effects of acute swimming exercise with different duration on pancreatic amylase activity and intestinal glucose transporter contents in rats. METHODS: Male Sprague-Dawley rats performed acute bout of swimming exercise for 1 h (Ex-1h group) or 6 h (Ex-6h group, two 3-h bouts separated by 1h of rest). Sedentary rats were used as a control (Con group). Immediately and 24 h after the exercise, pancreas and small intestine (jejunum) were dissected out and amylase activity and glucose transporters (GLUT2 and SGLT1) content were measured, respectively. RESULTS: While no significant difference in total pancreatic amylase activity was observed between the Con and Ex-1h groups, the Ex-6h group had significantly lower total amylase activity compared with the Con group in both immediately (1233 ± 229 vs. 2088 ± 205 U, p < 0.05) and 24 h after the exercise (1295 ± 112 vs. 1954 ± 227 U, p < 0.05). There were no significant differences in GLUT2 and SGLT1 protein contents among the three groups. CONCLUSIONS: These results suggest that acute bout of prolonged exercise for longer time (~6 h) may decrease the carbohydrate digestive capacity in the rat pancreas through the diminished amylase activity, although it has little effect on intestinal glucose transporters content.

In Vitro Effects of Zinc Oxide Nanoparticles on Electrophysiological Indices and Sodium-Dependent Glucose Transport Across Jejunal Mucosa in Laying Hens

SUMMARY As nanoparticles (NPs) are readily absorbed across gastrointestinal tract, it is hypothesized that Zinc oxide nanoparticles (ZnO-NPs) will not interfere with intestinal glucose transport. The current study aims to investigate the in vitro effects of ZnO-NPs on Na linked glucose transport across jejunal mucosa in laying hens. A total of 12 White Leghorn laying hens (1.73 ± 0.176 kg), 40 wk of age, housed in individual cages were killed and mid-jejunum was divided into 4 segments to be mounted on the Ussing chambers. The mucosal side of jejunum was bathed with either no ZnO, ZnO (70 μM), ZnO-NPs (70 μM), or ZnO-NPs (35 μM) followed by addition of D-glucose (10 mM) mucosally in all the 4 experimental groups. Peak electrical response was measured 2 min after the addition of D-glucose. Results demonstrate that there was a decrease (P

Active transport of glucose across the jejunal epithelium decreases with age in broiler chickens

Intestinal glucose absorption varies with growth; however, the dynamics of these variations has not been yet fully elucidated in broiler chickens. The present study aimed to compare jejunal glucose uptake and maltose digestion in broilers of 2 different ages, i.e., 1- vs. 5 wk old. Oral D-maltose gavage, everted sac, and Ussing chamber experiments were carried out to investigate intestinal glucose absorption and mRNA expression of glucose-transport-related genes as well as jejunal maltase activity. Upon gavage, glucose concentrations peaked at 10min post-administration in 1-wk-old chicks, while they peaked at 40min in 5-wk-old chickens. Glucose concentrations at 10min were significantly higher in the 1-wk-old chicks (P = 0.010). Using the everted sacs experimental setup, 5 intestinal regions i.e., duodenum, proximal jejunum, distal jejunum, proximal ileum, and distal ileum, were targeted to examine D-maltose digestion and glucose transport across the intestinal mucosa. In the distal and proximal ileum, glucose concentrations were found to be significantly higher in the serosal compartment of the 1-wk-old chicks upon incubation with D-maltose (25mM) (P < 0.05), while in the mucosal compartment the levels were significantly higher in the 5-wk-old chickens (P < 0.05). An Ussing chamber setup was employed to measure glucose-induced short-circuit current (ΔIsc) in the mucosal epithelium of the jejunum. In response to the addition of D-maltose (10mM) into the mucosal compartment, ΔIsc was significantly higher in the 1-wk-old chicks (P = 0.018). Furthermore, no variations in jejunal maltase activity were observed between the 2 age groups. While jejunal glucose absorption was lower in the 5-wk-old chickens, the mRNA expression levels of jejunal SGLT1, GLUT2, and Na+/K+-ATPase did not show any significant differences between the 2 age groups. Our results suggest that the active transport of glucose across the jejunal epithelium decreases upon growth in broiler chickens but is not accompanied by any variations in maltase activity or in the expression of glucose-absorption-related genes.

Crassocephalum rubens, a leafy vegetable, suppresses oxidative pancreatic and hepatic injury and inhibits key enzymes linked to type 2 diabetes: An ex vivo and in silico study.

Crassocephalum rubens falls under the wild edible, under-cultivated traditional leafy vegetables (TLV) in Africa; it is used by locals in managing diabetes mellitus among other diseases. This study investigated the in vitro, ex vivo antioxidant and antidiabetic potentials of different extracts of C. rubens. The ameliorative effects of the extracts on Fe2+ -induced oxidative injury was investigated ex vivo together with the effects of the aqueous extract on intestinal glucose absorption and muscle glucose uptake in freshly harvested tissues from normal rats. The aqueous extract was subjected to Liquid Chromatography-Mass Spectrometry (LC-MS) analysis to identify possible bioactive compounds which were then docked with the tested enzymes through in silico modeling. The extracts exhibited antioxidant activity, inhibited α-glucosidase and lipase enzyme activities, intestinal glucose absorption and enhanced muscle glucose uptake compared to controls. Sanguisorbic acid dilactone identified through LC-MS analysis showed a high binding affinity for catalase and lipase enzymes. PRACTICAL APPLICATIONS: The results of this study suggest that the aqueous extract of C. rubens possesses better antioxidant and possible antidiabetic potentials compared to other extracts which could be associated to the synergistic action of its identified bioactive compounds.

Raffia palm (Raphia hookeri) wine: Qualitative sugar profile, functional chemistry, and antidiabetic properties

The effects of short-term fermentation on the sugar quality, functional chemistry, antioxidant and antidiabetic properties of Raffia palm (Raphia hookeri) wine were investigated. Palm wine samples were subjected to open air fermentation for 24 and 48 h. The samples showed significant (p < 0.05) antioxidant activities with little or no differences between the unfermented and fermented samples. There was a dose-dependent inhibitory effect on α-glucosidase, α-amylase and intestinal glucose absorption with increasing fermentation time. Both non-fermented and 24 h fermentation led to increased muscle glucose uptake in a dose-dependent manner. 1H NMR spectroscopy showed the presence of allose, cellobiose, d-tagatose, fructose, galactitol, gluconic acid, rhamnose, sucrose, xylose and β-N-acetylglucosamine in the samples. FTIR spectroscopy showed the presence of alcohols, phenols, 1° and 2° amines and aromatics functional groups in all samples. Fermentation led to the addition of the functional group, bend alkenes. These results suggested that un-fermented and fermented Raffia palm wine may have antioxidant and antidiabetic properties.

Enterococcus faecalis YM0831 suppresses sucrose-induced hyperglycemia in a silkworm model and in humans

Hyperglycemia caused by excessive intake of sucrose leads to lifestyle-related diseases such as diabetes. Administration of a lactic acid bacterial strain to mice suppresses sucrose-induced hyperglycemia, but evidence for a similar effect in humans is lacking. Here we show that Enterococcus faecalis YM0831, identified using an in vivo screening system with silkworms, suppressed sucrose-induced hyperglycemia in humans. E. faecalis YM0831 also suppressed glucose-induced hyperglycemia in silkworms. E. faecalis YM0831 inhibited glucose uptake by the human intestinal epithelial cell line Caco-2. A transposon insertion mutant of E. faecalis YM0831, which showed decreased inhibitory activity against glucose uptake by Caco-2 cells, also exhibited decreased inhibitory activity against both sucrose-induced and glucose-induced hyperglycemia in silkworms. In human clinical trials, oral ingestion of E. faecalis YM0831 suppressed the increase in blood glucose in a sucrose tolerance test. These findings suggest that E. faecalis YM0831 inhibits intestinal glucose transport and suppresses sucrose-induced hyperglycemia in humans.

Su1096 – Calcium Signaling in the Regulation of Small Intestinal Glucose Absorption

Su1096 – Calcium Signaling in the Regulation of Small Intestinal Glucose Absorption

Daily expression of sodium-dependent glucose cotransporter-1 protein in jejunum during rat ontogeny.

It is widely known that intestinal capacities such as the enzymatic hydrolysis of carbohydrates, lipids and proteins, and the subsequent absorption of the hydrolyzed products, are evolutionary matched to dietary loads and feeding behaviors. In this study, we demonstrate that the protein expression of apically located sodium-dependent glucose cotransporter-1 (SGLT-1) throughout rat ontogeny is daily adjusted to afford glucose uptake when the load of this metabolically essential monosaccharide in the intestinal lumen is maximum. The jejunal expression of SGLT-1 protein in 14 one-day-old suckling pups was found to increase at dark and early light phase (P < 0.05), when they have a better access to mother milk. In weaning 21-d-old and juvenile 28-d-old rats, the cotransporter expression was high throughout the entire day (P < 0.05). Finally, adult 90-d-old rats showed a well-developed circadian rhythm for SGLT-1 protein (P < 0.05), whose expression increased at late light and dark phase when the highest intestinal glucose load was achieved. To our knowledge, these results are the first reporting the daily profile of SGLT-1 expression during rat early developmental stage and may contribute to understand the biological significance of a well-established molecular capacity to deal with the crucial increase of glucose load in the diet during the weaning process.

Metformin acutely lowers blood glucose levels by inhibition of intestinal glucose transport

Metformin is currently the most prescribed drug for treatment of type 2 diabetes mellitus in humans. It has been well established that long-term treatment with metformin improves glucose tolerance in mice by inhibiting hepatic gluconeogenesis. Interestingly, a single dose of orally administered metformin acutely lowers blood glucose levels, however, little is known about the mechanism involved in this effect. Glucose tolerance, as assessed by the glucose tolerance test, was improved in response to prior oral metformin administration when compared to vehicle-treated mice, irrespective of whether the animals were fed either the standard or high-fat diet. Blood glucose-lowering effects of acutely administered metformin were also observed in mice lacking functional AMP-activated protein kinase, and were independent of glucagon-like-peptide-1 or N-methyl-D-aspartate receptors signaling. [18F]-FDG/PET revealed a slower intestinal transit of labeled glucose after metformin as compared to vehicle administration. Finally, metformin in a dose-dependent but indirect manner decreased glucose transport from the intestinal lumen into the blood, which was observed ex vivo as well as in vivo. Our results support the view that the inhibition of transepithelial glucose transport in the intestine is responsible for lowering blood glucose levels during an early response to oral administration of metformin.

The effect of intestinal glucose load on neural regulation of food craving

ABSTRACT Objectives: Excess sugar consumption, particularly in the form of sweetened beverages, has been identified as a pivotal contributor to the epidemic of obesity and associated metabolic disorders. However, the impact of sugar-sweetened beverages on food craving is still inconclusive. Therefore, the present study aimed to specifically investigate the effects of an intestinal glucose load on neural processing of food cues. Methods: Using a single-blind fMRI design, 26 normal-weight women were scanned on two occasions, after receiving either a glucose or water infusion directly into the stomach using a nasogastric tube, without being aware of the type of infusion. Participants had to either view neutral and food images, or were asked to distract themselves from these images by solving an arithmetic task. Results: In response to viewing high-caloric food cues, we observed increased activation in reward-related brain areas. During food distraction, fronto-parietal brain regions were recruited, which are commonly related to attentional deployment and hedonic valuation. Furthermore, activity in the dorsolateral prefrontal cortex showed increased functional connectivity with the insula and was correlated with subjective craving levels to food cues. Despite an increase of blood glucose levels in response to the glucose compared to the water infusion, neither subjective food craving nor neural regulation of food craving showed significant differences. Conclusions: These findings support a decreased satiation effect of sweet beverages, as intestinal glucose ingestion and signalling showed no significant effect on cortical brain circuits associated with food craving. This trial was registered at clinicaltrials.gov as NCT03075371.

OR22-5 Sotagliflozin Decreases Postprandial Glucose and Insulin by Delaying Intestinal Glucose Absorption

Sotagliflozin (Sota) inhibits sodium glucose cotransporter 2 (SGLT2; IC50=1.8 nM) and SGLT1 (IC50=36 nM). In humans, Sota improves glycemic control in part by increasing urinary glucose excretion via renal SGLT2 inhibition. Sota also lowers postprandial glucose (PPG), likely by inhibiting intestinal SGLT1 to delay the rate of appearance of oral glucose (RaO). To test the hypothesis that Sota delays SGLT1-mediated RaO, we performed a randomized, 3-period crossover study comparing effects of single doses of placebo (Pbo), Sota (400 mg) and canagliflozin (Cana, 300 mg), an SGLT2 inhibitor (IC50=4.2 nM) that inhibits SGLT1 (IC50=663 nM) with lower potency than Sota, on RaO using a dual-glucose tracer method in two cohorts of 12 healthy subjects each; plasma glucose, insulin and additional pharmacodynamic parameters were also evaluated. All subjects received a continuous [U-13C6] glucose infusion starting 5 hr before their first mixed meal (MM) test. Cohort 1 subjects had a MM breakfast containing [6,6-2H2] glucose starting 0.25 hr postdose and a MM lunch containing [1-2H1] glucose starting 5.25 hr postdose. Cohort 2 subjects had a MM breakfast containing no labeled glucose starting 0.25 hr postdose and a MM lunch containing [6,6-2H2] glucose starting 4.25 hr postdose. Plasma glucose, and labeled glucose as a fraction of plasma glucose, were measured frequently for 5 hr after any MM containing labeled glucose, while plasma levels of insulin, intestinal hormones and other analytes were measured frequently after any MM containing [6,6-2H2] glucose. For the Cohort 1 MM breakfast, Sota and Cana: 1) lowered RaO AUC[0-1 hr] and RaO AUC[0-2 hr], and also lowered AUC[0-4hr] for insulin, c-peptide and gastric inhibitory peptide (GIP), all p<0.05 vs Pbo; 2) showed trends toward lowering PPG AUC[0-4hr] vs Pbo; 3) increased AUC[0-4hr] for total glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), both p<0.05 vs Pbo; and 4) did not alter glucagon AUC[0-4hr] or the AUC[0-5hr] for RaO or endogenous glucose production (EGP). Results were similar for the Cohort 2 MM lunch starting 4.25 hr postdose, except: 1) RaO, insulin and c-peptide AUC[0-1hr] decreased more for Sota vs Cana, all p<0.05; and 2) Sota and Cana increased glucagon AUC[0-4hr] and EGP AUC[0-5hr], both p<0.05 vs Pbo. For the Cohort 1 MM lunch starting 5.25 hr postdose: 1) Sota lowered RaO AUC[0-1hr] vs Cana and Pbo, and lowered PPG AUC[0-5hr] vs Cana and Pbo, both p<0.05; and 2) Cana did not lower RaO AUC[0-1hr] or PPG AUC[0-5hr] vs Pbo. We conclude that Sota delayed RaO, resulting in lower postprandial levels of glucose and insulin. The mechanism was likely a prolonged local inhibition of intestinal SGLT1 that persisted, despite feeding, during at least the first 5 hours after oral Sota dosing. The Sota-mediated decrease in GIP levels and increases in GLP-1 and PYY levels after oral glucose challenge are consistent with local inhibition of intestinal SGLT1.

In Vitro and In Vivo Anti‐Hyperglycemic and Antioxidant Effects of Phenolic Compounds isolated from Oryza sativa L.(Keun‐nun‐Jami) Variety

Type 2 diabetes, one of the chronic diseases, is a problem in both developed and developing countries. In particular, excessive ingestion of grain, such as rice, can result in hyperglycemia and type 2 diabetes. Therefore, a Oryza sativa L. variety, Keun‐nun‐Jami (KNJM) extracts were investigated for their anti‐hyperglycemic effect using in vitro and animal models. In vitro study inhibitory activities of both ethyl alcohol extracts of bran and germ against rat intestinal sucrase and maltase were evaluated. Oxygen radical absorbance capacity (ORAC) was also investigated. Ethyl alcohol extract of KNJM bran (EKB) had the highest sucrase inhibitory activity followed by ethyl alcohol extract of KNJM germ (EKG). Taxifolin, a flavonol, was isolated from the extract of KNJM along with three unknown compounds using HPLC and semi‐prep HPLC systems. Their structures were elucidated by extensive spectroscopic analysis, including 1D and 2D NMR, and FTICR‐MS. Furthermore, post‐prandial blood anti‐hyperglycemic effect of the extacts and taxifolin were measured using SD (Sprague Dawley) rat model. Postprandial blood glucose levels were tested for 3 hr after sucrose and starch administration with or without 500 mg of EKB, EKG, and taxifolin, respectively. Similar to result in vitro study, EKB which has higher content of taxifolin than that of EKG had stronger anti‐hyperglycemic effect than that of EKG. These results indicate that taxifolin from KNJM serves to reduce post‐prandial blood glucose rise and slower absorption of glucose in the small intestine, via carbohydrate hydrolyzing enzymes inhibition. These findings suggest that EKB has better potential for this bioactivity and this observation possibly correlates with the taxifolin contents observed in both extracts. Selected variety of colored rice, KNJM may provide the potential to contribute as a dietary strategy for controlling postprandial hyperglycemia.Support or Funding InformationThis work was supported by a grant from the Next‐Generation BioGreen 21 Program (No.PJ01314003), Rural Development Administration, Republic of KoreaThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Protective Role of the Somatostatin Receptor Subtype 4 in the Indomethacin‐Induced Gastrointestinal Mucosal Injury Model

Since gastrointestinal ulceration is still associated with high mortality despite advancements in the endoscopic and pharmacological management, precise understanding of the mucosal defensive and protective mechanisms is important. The neuropeptide somatostatin is present in the endocrine cells and sensory nerves, is analogues were shown to reduce mucosal blood flow, pepsin and gastric acid secretion. Its endocrine functions are mediated by the receptors sst2,3,5, and our group discovered that the anti‐inflammatory and analgesic actions are exerted via the sst4 receptor. Sst4 agonists are preclinically tested as novel drug candidates in theses areas. Therefore, we investigated the role of sst4 in gastrointestinal injury.Sst4 gene‐deleted (sst4 −/−) mice and wildtype counterparts (sst4 +/+) were treated s.c. with 35 mg/kg indomethacine (IDM) or its vehicle. Macroscopic and microscopic mucosal lesions in the stomach and small intestine were evaluated by the ImageJ program and semiquantitative histopathological scoring after 4 and 48 h, respectively. Small intestinal length, thymus, adrenal glands, spleen weight and plasma glucose levels were measured. Neutrophil myeloperoxidase (MPO) activity and plasma extravasation were measured by bioluminescent/fluorescent ex vivo imaging after 24 h.Macroscopic lesion area and MPO activity in the gastric mucosa were significantly greater in IDM‐treated sst4−/− mice than in wildtypes 4 h and 24 h after IDM administration, respectively. Similar tendency was observed in the duodenum and jejunum even after 48 h. However, IDM did not induce mucosal plasma extravasation in either group at the 24 h timepoint. Thymus weight was significantly less in sst4−/− mice than in sst4+/+ ones. Histopathological scores, small intestinal length, adrenal and spleen weight, and plasma glucose level were not altered by the sst4 deletion.These results provide evidence for a protective role of the sst4 receptor against chemical injury‐induced gastrointestinal mucosal damage. This shows the safety of sst4 agonist drug candidates in the gastrointestinal tract, and even highlights their potential use for gastroprotective indication.Support or Funding InformationGINOP‐2.3.2‐15‐2016‐00050 – PEPSYS, GINOP‐2.3.2 STAY ALIVE, EFOP‐3.6.2‐16‐2017‐00008, ÚNKP‐18‐3 New National Excellence Program of the Ministry of Human CapacitiesThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Portal milieu and the interplay of multiple antidiabetic effects after gastric bypass surgery.

Diabetes is a worldwide health problem. Roux-en-Y gastric bypass (RYGB) leads to rapid resolution of type 2 diabetes (T2D). Decreased hepatic insulin resistance is key, but underlying mechanisms are poorly understood. We hypothesized that changes in intestinal function and subsequent changes in portal venous milieu drive some of these postoperative benefits. We therefore aimed to evaluate postoperative changes in portal milieu. Two rat strains, healthy [Sprague-Dawley (SD)] and obese diabetic [Zucker diabetic fatty (ZDF)] rats, underwent RYGB or control surgery. After 4 wk, portal and systemic blood was sampled before and during an intestinal glucose bolus to investigate changes in intestinal glucose absorption (Gabsorp) and utilization (Gutil), and intestinal secretion of incretins and glucagon-like peptide-2 (GLP-2). Hepatic activity of dipeptidyl peptidase-4 (DPP4), which degrades incretins, was also measured. RYGB decreased Gabsorp in both rat strains. Gutil increased in SD rats and decreased in ZDF rats. In both strains, there was increased expression of intestinal hexokinase and gluconeogenesis enzymes. Systemic incretin and GLP-2 levels also increased after RYGB. This occurred without an increase in secretion. Hepatic DPP4 activity and expression were unchanged. RYGB perturbs multiple intestinal pathways, leading to decreased intestinal glucose absorption and increased incretin levels in both healthy and diabetic animals. In diabetic rats, intestinal glucose balance shifts toward glucose release. The portal vein as the gut-liver axis may integrate these intestinal changes to contribute to rapid changes in hepatic glucose and hormone handling. This fresh insight into the surgical physiology of RYGB raises the hope of less invasive alternatives. NEW & NOTEWORTHY Portal milieu after gastric bypass surgery is an underinvestigated area. Roux-en-Y gastric bypass perturbs multiple intestinal pathways, reducing intestinal glucose absorption and increasing incretin levels. In diabetic rats, the intestine becomes a net releaser of glucose, increasing portal glucose levels. The portal vein as the gut-liver axis may integrate these intestinal changes to contribute to changes in hepatic glucose handling. This fresh insight raises the hope of less invasive alternatives.

SGL5213, a novel and potent intestinal SGLT1 inhibitor, suppresses intestinal glucose absorption and enhances plasma GLP-1 and GLP-2 secretion in rats

Sodium-glucose cotransporter 1 (SGLT1) is the primary transporter for glucose absorption from digested nutrients in the gastrointestinal tract. Intestinal SGLT1 inhibition reduces post-prandial hyperglycemia and enhances the increase of plasma glucagon-like peptide-1 (GLP-1) levels. SGL5213 is a novel and potent intestinal SGLT1 inhibitor. This study characterizes the pharmacological profiles of SGL5213 in rodents. Orally administered SGL5213 was hardly absorbed and its distribution was restricted to the gastrointestinal lumen. SGL5213 significantly improved post-prandial hyperglycemia in streptozotocin (STZ)-induced diabetic rats at doses of 1 mg/kg or more. After the oral administration of starch, SGL5213 increased the amount of residual glucose in the small intestine at 1–3 h and in the cecum and colon at 3–9 h by inhibiting glucose absorption and allowing the unabsorbed glucose to be delivered into the lower-gastrointestinal tract. In the vehicle group, the plasma total GLP-1 (tGLP-1) and tGLP-2 levels increased at 15 min and the plasma total glucose-dependent insulinotropic polypeptide (tGIP) level increased at 1 h after meal loading. SGL5213 at doses of 0.1 mg/kg or more enabled the plasma levels of tGLP-1 and tGLP-2 to be retained for a period of 1–6 h, compared with the vehicle group. In contrast, SGL5213 at doses of 0.3 mg/kg or more suppressed the plasma tGIP elevation after meal loading. This study demonstrated for the first time that an intestinal SGLT1 inhibitor enhanced post-prandial plasma GLP-2 secretion. These results suggest that SGL5213 might exhibit a useful pharmacological efficacy through the physiological actions of GLP-1 and GLP-2.

D-mannitol modulates glucose uptake ex vivo; suppresses intestinal glucose absorption in normal and type 2 diabetic rats

Mannitol is a widely used reduced-calorie sweetener with limited studies on its anti-hyperglycemic potential. The anti-hyperglycemic potential of mannitol was investigated using different experimental models. Mannitol inhibited α-glucosidase (IC50 = 180 ± 20% w/v) and α-amylase (IC50 = 75 ± 20% w/v) activities in a dose dependent (2.5–20% w/v) manner, in vitro, although the effective doses are not gastrointestinally tolerable. Mannitol inhibited glucose absorption (IC50 = 19 ± 3% w/v) in isolated rat jejunum in a dose dependent (2.5–20% w/v) manner, perhaps by entrapment of glucose molecules. Acute administration of 0.3 g/kg bw reduced small intestinal glucose absorption in type 2 diabetic rats, which was accompanied by reduced blood glucose. The reduced intestinal glucose absorption may be influenced by the concomitant delayed gastric emptying observed in the mannitol-treated diabetic animals. On the other hand, mannitol increased glucose uptake in a yeast cell suspension (GU50 = 4.7 ± 1.2% w/v), 3T3-L1 adipocytes (GU50 = 1.2 ± 0.4% w/v) and isolated rat muscle (GU50 = 25 ± 3% w/v) in a dose dependent manner. In silico docking suggested that GLUT-4 (binding energy = −15.5 kcal/mol) is a possible molecular target of mannitol. Data from this study suggest that mannitol may be used as a dietary supplement in controlling postprandial blood glucose increase by reducing intestinal glucose absorption and increasing muscle glucose uptake, which needs further study.