Urinary excretion in mice after impairment of extracellular sugar detection. Metabolic and electrolyte levels in 24-h urine samples from wild-type (WT) or transgenic mice fed a standard or a glucose-rich diet. Values are presented as means±S.E.M. (n = 6 per group). Statistical differences between wild-type and transgenic mice are indicated as *P<0.05 ns non significant, nd indicates not determined.

<p>Urinary excretion in mice after impairment of extracellular sugar detection. Metabolic and electrolyte levels in 24-h urine samples from wild-type (WT) or transgenic mice fed a standard or a glucose-rich diet. Values are presented as means±S.E.M. (n = 6 per group). Statistical differences between wild-type and transgenic mice are indicated as *P<0.05 ns non significant, nd indicates not determined.</p

Kidney function in mice after impairment of extracellular sugar detection.

<p>A: Effect of a glucose-rich diet on gene expression in the kidney of transgenic (Tg) and wild-type (WT) mice fasted for 48 h and refed for 15 h. Levels of mRNA were analyzed by real-time PCR. Values are presented as means±S.E.M. (n = 3 to 4 mice/group). Statistical differences between refed and fasted mice are indicated as *P<0.05, **P<0.01 and ns non significant. B: GLUT2 protein levels in total membrane preparations of kidney from mice fed with a glucose-rich diet for five days. C: Structure, size and weight of kidneys from wild-type and transgenic mice shown by ultrasonic image (transverse cross section). D: Urine and blood glucose concentrations during an oral glucose tolerance test in fasted wild-type and transgenic mice (n = 3 mice per group). Statistical differences between transgenic and wild-type mice are indicated as **P<0.01 (two-way ANOVA) for the areas under the curves. E: Levels of SGLT mRNA were analyzed by real-time PCR. Values are presented as means±S.E.M. (n = 3 to 4 mice/group). Statistical differences between refed and fasted mice are indicated as **P<0.01 and ns non significant.</p

Generation of GLUT2-loop transgenic mice.

<p>A: Quantification of the transgene copy number in genomic DNA from independent lines of mice (Tg G, P, B and W) to the reference gene Apolipoprotein A1 (ApoA1). B: RT-PCR analysis of transgene and L19 control mRNA levels in various tissues. C: Immunoprecipitation and immunoblot analysis showing the presence of GLUT2 loop in liver homogenate from transgenic mice.</p

Impairment of extracellular sugar detection in GLUT2-expressing tissues in transgenic mice.

<p>Effect of a glucose-rich diet on gene expression in liver (A) and adipose tissue (C). Transgenic (Tg) and wild-type (WT) mice were fasted for 48 h and refed for 15 h before liver and epididymal fat pad biopsies. Levels of mRNA were analyzed by real time PCR. Values are presented as means±S.E.M. (n = 3 to 5 mice/group). Statistical differences between refed and fasted mice are indicated by *P<0.05, **P<0.01, and ns non significant. B: GLUT2 protein levels in total membrane preparations from the liver of mice fed a glucose-rich diet for five days. D: Blood glucose concentrations during an insulin tolerance test in wild-type and transgenic mice. Values are presented as means±S.E.M (n = 8 to 10 mice/group).</p

Pancreatic function in mice after impairment of extracellular sugar detection.

<p>A: Effect of a glucose-rich diet on gene expression in the pancreas of wild-type (WT) and transgenic (Tg) mice fasted for 48h and refed for 15 h. Levels of mRNA were analyzed by real-time PCR. Values are presented as means±S.E.M. (n = 3 to 4 mice/group). Statistical differences between refed and fasted mice are indicated as **P<0.01 and ns non significant. B: GLUT2 protein levels in total membrane preparations of pancreas from mice fed a glucose-rich diet for five days. C: Left panel: Blood glucose concentrations during an oral glucose tolerance test in wild-type and transgenic mice fasted for 24 h (n = 17 for wild-type mice, n = 2 to 5 for transgenic mice). Statistical differences between transgenic and wild-type mice are indicated as ***P<0.001, *P<0.05 and ns non significant (two-way ANOVA) for the areas under the curves. Right panel: Blood glucose concentrations in wild-type and transgenic mice in the fasted state or 6 h after being refed with a glucose-rich diet. Values are presented as means±S.E.M. (n = 4 to 8 mice/group). D: Upper panel: Plasma insulin concentrations during an oral glucose tolerance test in fasted wild-type and transgenic mice (n = 10 to 13 mice/group). Statistical differences between transgenic and wild-type mice are indicated as ***P<0.001 (two-way ANOVA) for the areas under the curves. Lower panel: Pancreatic insulin content in mice 6h after being refed a standard diet. Values are presented as means±S.E.M. (n = 5 mice/group). Statistical differences between transgenic and wild-type mice are indicated as *P<0.05. E: Upper panel : Representative immunostaining with antibody against insulin of pancreatic sections from wild-type and transgenic mice. Arrows indicate small islets. The bar corresponds to 100 µm. Lower panel: Histomorphometric comparisons of islet number, size and ß-cell mass. Proportion of small islets (<25 µm) to total number of islets is statistically different indicated as *P<0.03 between transgenic and wild-type mice.</p

Remodeling of the Residual Gastric Mucosa after Roux-En-Y Gastric Bypass or Vertical Sleeve Gastrectomy in Diet-Induced Obese Rats

<div><p>Whereas the remodeling of intestinal mucosa after bariatric surgeries has been the matter of numerous studies to our knowledge, very few reported on the remodeling of the residual gastric mucosa. In this study, we analyzed remodeling of gastric mucosa after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) in rats. Diet-induced obese rats were subjected to RYGB, VSG or sham surgical procedures. All animals were assessed for food intake, body-weight, fasting blood, metabolites and hormones profiling, as well as insulin and glucose tolerance tests before and up to 5 weeks post-surgery. Remodeling of gastric tissues was analyzed by routine histology and immunohistochemistry studies, and qRT-PCR analyses of ghrelin and gastrin mRNA levels. In obese rats with impaired glucose tolerance, VSG and RYGB caused substantial weight loss and rats greatly improved their oral glucose tolerance. The remaining gastric mucosa after VSG and gastric pouch (GP) after RYGB revealed a hyperplasia of the mucous neck cells that displayed a strong immunoreactivity for parietal cell H⁺/K⁺-ATPase. Ghrelin mRNA levels were reduced by 2-fold in remaining fundic mucosa after VSG and 10-fold in GP after RYGB. In the antrum, gastrin mRNA levels were reduced after VSG in line with the reduced number of gastrin positive cells. This study reports novel and important observations dealing with the remaining gastric mucosa after RYGB and VSG. The data demonstrate, for the first time, a hyperplasia of the mucous neck cells, a transit cell population of the stomach bearing differentiating capacities into zymogenic and peptic cells.</p></div

Surgical procedures of Vertical Sleeve Gastrectomy (VSG) and Roux-en-Y Gastric Bypass (RYGB) in rats.

<p><b><i>(A</i>)</b> Photography and <b>(B)</b> contrast radiography of a rat stomach showing forestomach (rumen), fundus and antrum. In both surgeries, first step is the resection of the rumen <b>(C)</b>. In VSG: vertical resection of the fundus <b>(D, E)</b> resulted in a reduction of the gastric volume visible by opacification with gastrograffine <b>(F)</b>. In RYGB: reconstructed gastric pouch directly anastomosed to the jejunum <b>(G)</b> and verification of the gastro-jejunal anastomosis (alimentary limb) after opacification <b>(H)</b>. In RYGB: jejuno-jejunal anastomosis limb <b>(I)</b> and verification of the gastro-jejunal anastomosis after opacification <b>(J). (K)</b> Example of a fistula, the main cause of the post-operative mortality. Photography of the necropsy of one rat showing a fistula <i>(star)</i> in the remaining stomach. <i>Insert</i>: radiography imaging after opacification with gastrograffine of the gastrointestinal tract showing a fistula <i>(star)</i>.</p

Immunostaining of parietal cell H⁺/K⁺-ATPase in fundic mucosa.

<p><b>(A)</b> Overview of a representative immunostaining of parietal cell H+/K⁺-ATPase along the formalin-fixed gastric pouch anastomosed to jejunum in the alimentary limb after RYGB. Comparative immunostaining of parietal cell H+/K⁺-ATPase in fundic mucosa from sham <b>(B)</b>, residual stomach after VSG <b>(C)</b>, and GP after RYGB <b>(D)</b>. Note the enlarge parietal cells <i>(blue stars)</i> with dense H⁺/K⁺ATPase immunoreactivity as compared to sham. <b>(E)</b> Percent of H⁺/K⁺-ATPase positive cells per fundic mucosa area (μm²). Values are shown as mean ± SEM n = 5 for sham and n = 6 for VSG and RYGB. **P<0.01 and ***P<0.001 <i>vs</i>. sham.</p

Time-course of body weight after VSG and RYGB in HFD obese rats.

<p><b>(A)</b> VSG- and <b>(B)</b> RYGB-induced weight loss in HFD obese rats and in the corresponding sham-operated rats. <i>Black boxes</i> correspond to the period of post-operative care and liquid diet consumption before the animals had free access to solid ND. Results are expressed as percent of loss of body weight over preoperative weight. Two-Way ANOVA was used to compare body-weight curves.</p

Histology of gastric fundic mucosa in sham-, VSG- and RYGB- operated rats.

<p><b>Panel A.</b> Post-mortem representative macroscopic photomicrographs of stomach of sham-, VSG- or RYGB-operated rats. <i>(top)</i> normal stomach showing fundus (1) and antrum (2); <i>(middle)</i> residual stomach after VSG with fundus (1), antrum (2), duodenum (3) and, pylorus <i>(arrow)</i>; <i>(bottom)</i> excluded stomach in RYGB and gastric pouch (1) directly anastomosed to the jejunum (4). <b>Panel B:</b> representative Hematoxylin and Eosin staining (H&E) of fundic mucosa. Note the hyperplasia of mucous neck cells <i>(black arrow heads)</i> after VSG and RYGB. <b>Panel C:</b> fundic mucosa sections stained with periodic acid Schiff (PAS)/Alcian blue (AB). Mucous neck cells are PAS/AB positive <i>(black arrows)</i>. <b>Panel D:</b> immunostaining of Ki67-proliferating cells <i>(brown nuclei)</i> in formalin-fixed fundic mucosa section from sham <i>(top)</i>, remaining stomach after VSG <i>(middle)</i>, and GP after RYGB <i>(bottom)</i>.</p