O24: THE PANCREATIC EPSILON-CELLS RECOVER THE EMBRYONIC GHRELIN SECRETION IN RESPONSE TO BARIATRIC SURGERY

Introduction Many surgical techniques are employed in the treatment of obesity. A main consequence of these techniques is the severe improvement of Type 2 Diabetes mellitus. Many hypotheses had been exposed to know the intrinsic mechanism developed in this relationship. The enterohormones seems to be a definitive effector. The ghrelin is an enterohormone released for the gastric fundus and it has been related to the mentioned improvement. We hypothesized about the role of pancreatic epsilon cells, which have the capacity to release ghrelin during the embryonic stages. We studied the changes in the ghrelin immunostaining in endocrine pancreas of rats which underwent bariatric surgery. MATERIAL AND Method We employed 16 non obese euglycemic male Wistar rats, randomised in the surgical groups. These groups were the surgical techniques (Sleeve gastric –SG- and Roux en Y Gastric Bypass –RYGB-), and two controls (fasting and surgical). After three months, rats were sacrificed; the pancreas were obtained and processed for the immuno-cytochemical technique. Result We reported a significant increase of epsilon cells (ghrelin positive/mm2 pancreatic area) in the pancreas of SG versus the control groups (vs FC, P<0.01 and vs sham, P<0.05). CONCLUSION. SG and RYGB are surgical techniques broadly employed in humans and both reduce severely the fundus. Paradoxically, the serum level of ghrelin in patients are preserved. We reported that the total suppression of the fundus gastric produced the recovery of an embryonic pancreatic function. This mechanism could be related with the complex physiologic mechanism that improve T2DM after bariatric surgery. Take-home message After bariatric surgery, the pancreas release of ghrelin increased as the response to gastric reduction.

Modulation of Food Intake by Differential TAS2R Stimulation in Rat

Metabolic surgery modulates the enterohormone profile, which leads, among other effects, to changes in food intake. Bitter taste receptors (TAS2Rs) have been identified in the gastrointestinal tract and specific stimulation of these has been linked to the control of ghrelin secretion. We hypothesize that optimal stimulation of TAS2Rs could help to modulate enteroendocrine secretions and thus regulate food intake. To determine this, we have assayed the response to specific agonists for hTAS2R5, hTAS2R14 and hTAS2R39 on enteroendocrine secretions from intestinal segments and food intake in rats. We found that hTAS2R5 agonists stimulate glucagon-like peptide 1 (GLP-1) and cholecystokinin (CCK), and reduce food intake. hTAS2R14 agonists induce GLP1, while hTASR39 agonists tend to increase peptide YY (PYY) but fail to reduce food intake. The effect of simultaneously activating several receptors is heterogeneous depending on the relative affinity of the agonists for each receptor. Although detailed mechanisms are not clear, bitter compounds can stimulate differentially enteroendocrine secretions that modulate food intake in rats.

Vitamin C protects against chronic social isolation stress-induced weight gain and depressive-like behavior in adult male rats

Objective. Considering the importance of ghrelin in stress-induced hyperphagia and a role of antioxidants in decreasing body weight, in the present study, the effect of vitamin C (VitC) on ghrelin secretion and food intake following chronic social isolation (CIS) was evaluated in rats. Methods. Thirty two male Wistar rats (200–220g) were randomly divided into: control, VitC, CIS, and CIS + VitC groups. Animals received VitC (500 mg/kg/day)/saline by gavage for 3 weeks. For 24 h cumulative and post 18–20 h fasting food intake, fasting plasma ghrelin level, and body weight were measured. Gastric histopathology was also evaluated. Results. Results showed a marked increase in fasting plasma ghrelin and food intake in stressed rats compared to controls. VitC prevented the increases in stressed rats. Histological assessment indicated a positive effect of VitC on gastric glandular cells compared to control, an effect that might partially be a reason of significant increase of plasma ghrelin levels in VitC rats. Elevated plasma ghrelin in VitC group was even higher than that one in stressed group, whereas there were no significant changes in the food intake. Assessment of the percentage of changes in body weight during 21 days showed a significant increase in stressed rats compared to controls. Vitamin C treatment prevented this increase. Stressed rats also displayed depression-like behavior as indicated by sucrose test, whereas VitC ameliorated it. Conclusions. The data of the present study indicate that VitC may overcome ghrelin-induced hyperphagia and improve the abnormal feeding and depressive behavior in CIS rats.

Obesity and Insulin Resistance: Associations with Chronic Inflammation, Genetic and Epigenetic Factors

Background: Obesity is known to be a multifactorial disease. In its pathogenesis, different factors such as chronic inflammation, oxidative stress, insulin resistance, genetic factors, environmental effects, vegetative disturbance, and unbalanced nutrition play a significant role. Methodology: This study describes the association of obesity and insulin resistance with chronic inflammation, genetic, and epigenetic factors. Previous literature has been reviewed to explain the relation of obesity with those factors involved in chronic low-grade inflammation and insulin. Results: Obesity is associated with a decrease in ghrelin secretion, elevated plasma leptin levels, oxidative stress, increased macrophage phagocytic activity, and the induction of pro-inflammatory synthesis of cytokines and interferon-gamma. Obesity is linked to decreased levels of cytochrome P450 (CYP) enzymes and impaired detoxification processes. Deficiency of vitamins and minerals can also play a significant role in the development of oxidative stress and chronic inflammation in obesity. There is evidence of associations between a genetic predisposition to obesity in children with elevated levels of certain miRNAs. Conclusion: The purpose of the present review is an analysis of the multiple factors associated with obesity.

NKX2-2 Mutation Causes Congenital Diabetes and Infantile Obesity With Paradoxical Glucose-Induced Ghrelin Secretion

Context NKX2-2 is a crucial transcription factor that enables specific β-cell gene expression. Nkx2-2(–/–) mice manifest with severe neonatal diabetes and changes in β-cell progenitor fate into ghrelin-producing cells. In humans, recessive NKX2-2 gene mutations have been recently reported as a novel etiology for neonatal diabetes, with only 3 cases known worldwide. This study describes the genetic analysis, distinctive clinical features, the therapeutic challenges, and the unique pathophysiology causing neonatal diabetes in human NKX2-2 dysfunction. Case Description An infant with very low birth weight (VLBW) and severe neonatal diabetes (NDM) presented with severe obesity and developmental delay already at age 1 year. The challenge of achieving glycemic control in a VLBW infant was unexpectedly met by a regimen of 3 daily doses of long-acting insulin analogues. Sanger sequencing of known NDM genes (such as ABCC8 and EIF2AK3) was followed by whole-exome sequencing that revealed homozygosity of a pathogenic frameshift variant, c.356delG, p.P119fs64*, in the islet cells transcription factor, NKX2-2. To elucidate the cause for the severe obesity, an oral glucose tolerance test was conducted at age 3.5 years and revealed undetectable C-peptide levels with a paradoxically unexpected 30% increase in ghrelin levels. Conclusion Recessive NKX2-2 loss of function causes severe NDM associated with VLBW, childhood obesity, and developmental delay. The severe obesity phenotype is associated with postprandial paradoxical ghrelin secretion, which may be related to human β-cell fate change to ghrelin-secreting cells, recapitulating the finding in Nkx2-2(–/–) mice islet cells.

The Effect of High-Fat Diet-Induced Obesity on the Expression of Nutrient Chemosensors in the Mouse Stomach and the Gastric Ghrelin Cell

The stomach is the primary source of the orexigenic and adiposity-promoting hormone, ghrelin. There is emerging evidence on the nutrient-mediated modulation of gastric ghrelin secretion. However, limited information is available on gastric nutrient-sensing mechanisms in high-fat diet (HFD)-induced obesity. This study investigated the impact of HFD-induced obesity on the expression of nutrient chemosensors in mouse stomach, particularly ghrelin cells. Male C57BL/6 mice were fed either a standard laboratory diet (SLD) or HFD for 12 weeks. The expression of ghrelin, enzymes involved in ghrelin production (PC1/3, GOAT) and nutrient chemosensors (CD36, FFAR2&4, GPR93, CaSR, mGluR4 and T1R3) was determined by quantitative RT-PCR in the mouse corpus and antrum. Immunohistochemistry assessed the protein expression of CaSR and ghrelin in the corpus and antrum. Antral mRNA levels of CaSR and PC1/3 were increased in HFD compared to SLD mice, while mRNA levels of all other nutrient chemosensors examined remained unchanged. CaSR immunolabelling was observed in the gastric antrum only. Nearly 80% of antral ghrelin cells expressed CaSR, with a similar cell density and co-expression in SLD and HFD mice. In conclusion, HFD-induced obesity increased CaSR mRNA expression in mouse antrum. However, the high antral co-expression of CaSR and ghrelin was unaltered in HFD compared to SLD mice.