Pyy Expression Research Articles

Globular adiponectin, acting via AdipoR1, regulates food intake of Siberian sturgeon (Acipenser baerii) in a mTOR dependent manner

Adiponectin (AdipoQ) is a hormone that regulates food intake and energy homeostasis in mammals. The globular adiponectin (gAd) has been reported involved in the regulation of appetite, but the regulatory role and mechanism in fish remains unelucidated. Using Siberian sturgeon as a model of Chondrostei, the recombinant gAd protein of Siberian sturgeon (SsgAd) was produced by Escherichia coli expression system and verified using western blotting. Intraperitoneal injection of recombinant SsgAd protein at 100 ng/g BW suppressed food intake 1 h after administration. Peripheral injection of SsgAd protein caused the upregulation of anorexigenic pyy expression in the valvula intestine, but did not affect cck expression in the valvula intestine and orexigenic ghrelin expression in the stomach. The SsgAd administration significantly increased the hypothalamic expressions of pomc and decreased npy, agrp, and cart expression. In addition, SsgAd recombinant protein promoted adipor1, ampkα2, akt, and mtor mRNA expressions within the hypothalamus, whereas inhibited ampkβ1, ampkβ2 and ampkγ2 mRNA expression, suggesting AMPK and mTOR signaling pathways might be related to SsgAd protein-mediated anorexia activity. Furthermore, the injection of an mTOR antagonist (rapamycin) reversed the reduced food intake and npy, agrp, and cart expression due to the peripheral injection of SsgAd, as well as the increased pomc expression induced by SsgAd, which were not observed after AMPK antagonist (dorsomorphin) treatment. In summary, the current study, for the first time, suggest that the anorexigenic function of SsgAd might bind with AdipoR1 and activate the mTOR signal pathway to affect the expression of hypothalamic appetite factors in Siberian sturgeon. This study provides new insight into the molecular mechanism of AdipoQ in feeding regulation in fish, and a basis for further exploration on physiological function of AdipoQ.

RYGB surgery has modest effects on intestinal morphology and gut hormone populations in the bypassed biliopancreatic limb but causes reciprocal changes in GLP-2 and PYY in the alimentary limb.

Roux-en-Y gastric-bypass (RYGB) induced alterations in intestinal morphology and gut-cell hormone expression profile in the bypassed biliopancreatic-limb (BPL) versus the alimentary-limbs (AL) are poorly characterised. This pilot study has therefore explored effects following RYGB in high-fat-diet (HFD) and normal-diet (ND) rats. Female Wistar rats (4-week-old) were fed HFD or ND for 23-weeks prior to RYGB or sham surgeries. Immunohistochemical analysis of excised tissue was conducted three-weeks post-surgery. After RYGB, intestinal morphology of the BPL in both HFD and ND groups was unchanged with exception of a small decrease in villi width in the ND-RYGB and crypt depth in the HFD-RYGB group. However, in the AL, villi width was decreased in ND-RYGB rats but increased in the HFD-RYGB group. In addition, crypt depth decreased after RYGB in the AL of HFD rats. GIP positive cells in either limb of both groups of rats were unchanged by RYGB. Similarly, there was little change in GLP-1 positive cells, apart from a small decrease of numbers in the villi of the BPL in HFD rats. RYGB increased GLP-2 cell numbers in the AL of ND-RYGB rats, including in both crypts and villi. This was associated with decreased numbers of cells expressing PYY in the AL of ND-RYGB rats. The BPL appears to maintain normal morphology and unchanged enteroendocrine cell populations despite being bypassed in RYGB-surgery. In contrast, in the AL, villi area is generally enhanced post-RYGB in ND rats with increased numbers of GLP-2 positive cells and decreased expression of PYY.

Roseburia intestinalis Modulates PYY Expression in a New a Multicellular Model including Enteroendocrine Cells.

The gut microbiota contributes to human health and disease; however, the mechanisms by which commensal bacteria interact with the host are still unclear. To date, a number of in vitro systems have been designed to investigate the host-microbe interactions. In most of the intestinal models, the enteroendocrine cells, considered as a potential link between gut bacteria and several human diseases, were missing. In the present study, we have generated a new model by adding enteroendocrine cells (ECC) of L-type (NCI-H716) to the one that we have previously described including enterocytes, mucus, and M cells. After 21 days of culture with the other cells, enteroendocrine-differentiated NCI-H716 cells showed neuropods at their basolateral side and expressed their specific genes encoding proglucagon (GCG) and chromogranin A (CHGA). We showed that this model could be stimulated by commensal bacteria playing a key role in health, Roseburia intestinalis and Bacteroides fragilis, but also by a pathogenic strain such as Salmonella Heidelberg. Moreover, using cell-free supernatants of B. fragilis and R. intestinalis, we have shown that R. intestinalis supernatant induced a significant increase in IL-8 and PYY but not in GCG gene expression, while B. fragilis had no impact. Our data indicated that R. intestinalis produced short chain fatty acids (SCFAs) such as butyrate whereas B. fragilis produced more propionate. However, these SCFAs were probably not the only metabolites implicated in PYY expression since butyrate alone had no effect. In conclusion, our new quadricellular model of gut epithelium could be an effective tool to highlight potential beneficial effects of bacteria or their metabolites, in order to develop new classes of probiotics.

Molecular cloning, expression and appetite regulation function of adiponectin in Siberian sturgeon (Acipenser baerii)

Adiponectin (AdipoQ) as an adipocytokine has the potential to regulate feeding behavior, but the information about adipoq in fish is limited. In this study, Siberian sturgeon adiponectin (Ssadipoq) gene was cloned encoding 264 amino acids. The amino acid identity of SsAdipoQ was low compared with that of mammals, birds, amphibians and teleost fishes. The expression of Ssadipoq in the hypothalamus was significantly decreased at 1 h and 3 h post feeding, and increased after 15-day fasting. The mature domain of AdipoQ (fAd) was inserted into expression vector pET32a and successfully expressed in Escherichia coli BL21 (DE3) after stimulated by isopropyl-β-d-thiogalactoside. Food intake at 1 h and 3 h post treatment with SsfAd protein decreased significantly (P < 0.05). The mRNA expression of pyy and cck in the valvula intestine was promoted and hypothalamic npy, agrp and pomc mRNA expression were inhibited after treatment with SsfAd protein. Furthermore, hypothalamic ampk subunits expression was associated with peripheral SsfAd treatment. In summary, present study indicate that SsfAd plays an important role in the regulation of food intake and appetite signals in Siberian sturgeon, which provides a basis for further study application of prokaryotic AdipoQ in feeding behavior regulation.

The role of cholecystokinin and peptide YY in feed intake in Atlantic halibut (Hippoglossus hippoglossus) larvae

Control of appetite and feed intake in fish larvae are still largely unexplored. Two of the key players in controlling vertebrate's feed intake are cholecystokinin (CCK) and peptide YY (PYY). Here we investigated the mRNA expression of pyy, cck and cck receptors (cckr) in the brain (head) and gut of Atlantic halibut larvae in response to three consecutive meals. We used Artemia nauplii cysts that are commonly ingested by halibut larvae when present as inert feed, and three water-soluble extracts as attractants to stimulate appetite. Cyst intake was not affected by the use of attractants and overall ingestion rate was low. Differences in mRNA expression of cck and pyy were observed between the halibut larvae that had eaten and those that had not despite readily available feed (cysts), supporting that mechanisms for control of feed intake are at least partly functional. All genes analysed were present in the brain and gut, however the different expression profiles between paralogues suggest potential divergent functions. In the gut, cck2 and pyyb mRNA expression was significantly higher in the larvae that ate cysts compared to larvae that decided to not eat, indicating that these genes play a satiety function in the halibut larvae similar to the general vertebrate scheme. However, cck2, cck2r1, and pyy mRNA expression in the brain were lower in the fed-filled larvae group compared to larvae before eating, which contrasts with the presumable anorectic function of these genes. Further research is required to fully evaluate how PYY and CCK affect the feeding biology in halibut larvae, contributing to formulate inert diets that can stimulate appetite and feed intake.

A High Amylose Wheat Diet Improves Gastrointestinal Health Parameters and Gut Microbiota in Male and Female Mice.

High amylose wheat (HAW) contains more resistant starch than standard amylose wheat (SAW) and may have beneficial effects on gastrointestinal health. However, it is currently unclear whether these effects differ according to the level of HAW included in the diet or between males and females. Male and female C57BL/6 mice (n = 8/group/sex) were fed SAW65 (65% SAW; control), HAW35 (35% HAW), HAW50 (50% HAW) or HAW65 (65% HAW) diet for eight weeks. Female but not male, mice consuming any amount of HAW exhibited accelerated gastric emptying compared to SAW65 group. In both sexes, relative colon weights were higher in the HAW65 group compared to SAW65 group and in females, relative weights of the small intestine and cecum were also higher in the HAW65 group. In females only, colonic expression of Pyy and Ocln mRNAs were higher in the HAW65 group compared to HAW35 and HAW50 groups. In both sexes, mice consuming higher amounts of HAW (HAW50 or HAW65) had increased fecal bacterial load and relative abundance of Bacteroidetes phylum and reduced relative abundance of Firmicutes compared to SAW65 group. These data are consistent with a beneficial impact of HAW on gastrointestinal health and indicate dose-dependent and sex-specific effects of HAW consumption.

Cholecystokinin 1 and 2 in red seabream Pagrus major: molecular cloning, response to feeding, and a potential indicator of dietary protein source quality

Cholecystokinin (Cck) and peptide YY (Pyy) play important roles in digestive regulation in fish, but their function in red seabream (Pagrus major) remains obscure. Two cck complementary DNAs (cck-1 and cck-2) in red seabream were identified, and tissue distribution analysis of the genes revealed that cck and pyy were expressed throughout the digestive tract, except for stomach cck-2. After feeding, cck-1 expression significantly increased in the stomach and pyloric caeca, cck-2 expression significantly increased in the pyloric caeca and hindgut, and pyy expression increased in the pyloric caeca of red seabream. After oral administration of dietary protein, i.e., high-quality fish meal (HQFM), soy protein concentrate (SPC), or low-quality FM (LQFM), only HQFM significantly increased stomach cck-1 expression. To assess the growth of red seabream in response to different sources of dietary protein, three isonitrogenous and isoenergetic diets were formulated: HQFM, SPC with a low percentage of HQFM, and LQFM. Mean body weight was highest in the HQFM group after 6 weeks. The stomach cck-1 response to HQFM may explain the high growth in the HQFM group. Our data suggest that cck-1, cck-2, and pyy are involved in digestion. Furthermore, stomach cck-1 may be a valuable tool for evaluating the quality of dietary protein sources for red seabream.

Effects of potential climate change -induced environmental modifications on food intake and the expression of appetite regulators in goldfish

Climate changes due to global warming result in part from the release of gases such as carbon dioxide (CO2) and methane into the atmosphere and results in warming and acidification of water bodies, and changes precipitation and wind patterns, which might in turn affect water currents, turbulence and turbidity. These changes might affect feeding and its endocrine control. Feeding is regulated by central and peripheral hormones that either stimulate (e.g. orexin, ghrelin) or inhibit (e.g. irisin, cocaine and amphetamine regulated transcript – CART, cholecystokinin – CCK and peptide YY -PYY) food intake. In this study we examined the effects of four climate change-related environmental factors (i.e. temperature, pH, turbulence and turbidity) on food intake and the hypothalamic and intestinal expressions of appetite regulators in fish, using goldfish as a model. High temperatures increased food intake and the brain expression of orexin, and decrease brain CART 1 and intestinal CCK, PYY and ghrelin. Low pHs decreased feeding and increased the expressions of CART1 and CART2 in the hypothalamus and CCK and PYY in the intestine. Turbulence (waves) induced an increase in food intake and a decrease in mRNA expression levels of both CART1 and CART2 in the hypothalamus and both CCK and PYY in the intestine. Turbidity (low visibility) did not affect food intake but increased locomotion and the time taken to reach satiation, while increasing brain orexin and intestinal PYY expression levels and lowering CART1 hypothalamic expression. The results of this study suggest that environmental stress affects feeding physiology of goldfish and bring new insights on how fish might respond to climate changes.

TLR ligands and butyrate increase Pyy expression through two distinct but inter-regulated pathways.

The intestinal epithelium is an active barrier separating the host from its microbiota. It senses microbial compounds through expression of a wide range of receptors including the Toll-like receptors (TLRs). TLRs have been shown to regulate epithelium permeability or secretion of defensin by Paneth cells. However, the expression and function of TLRs in enteroendocrine L-cells, a specific subtype of intestinal cells secreting PYY and GLP-1, have not yet been assessed. PYY and GLP-1 are implicated in regulation of gut motility, food intake and insulin secretion, and are of great interest regarding obesity and type 2 diabetes. Using a cellular model of human L-cells and a reporter system for NF-κB activation pathway, we reported functional expression of TLRs in these cells. Stimulation with specific TLR-agonists increased expression of Pyy but not Proglucagon in an NF-κB-dependent manner. Moreover, the effect of TLR stimulation was additive to butyrate, a product of bacterial fermentation, on Pyy expression. Additionally, butyrate also increased Tlr expression, including Tlr4, and the NF-κB response to TLR stimulation. Altogether, our results demonstrated a role of TLRs in the modulation of Pyy expression and the importance of butyrate, a product of bacterial fermentation in regulation of microbial TLR-dependent sensing.

Potential Role of PYY in Skeletal Muscle Cells?

PYY is characteristically considered an appetite hormone with identified roles in metabolism, inflammation, and proliferation. The expression of PYY and its receptors has been demonstrated in the skeletal muscle; however, the role of PYY in the skeletal muscle is unknown.ObjectiveTo investigate the role of PYY on proliferating and differentiating/differentiated skeletal myoblasts and to determine the effect of PYY on inflammatory and metabolic signaling pathways.MethodsExpression of the PYY gene was determined in cultured murine C2C12 cells incubated in growth or differentiation media (GM and DM, respectively) using quantitative PCR. Additionally, changes in proteins of interest were determined from C2C12 cells that were cultured in DM for 96 h then switched to DM containing 0.1 mM palmitate for 72 h, followed by exposure to 500 pM murine PYY3‐36 for 6 h prior to lysis.ResultsPYY gene expression, which was identified in proliferating C2C12 cells, decreased in differentiating cells. Relative to myotubes that received only palmitate, the presence of PYY decreased phosphorylation of STAT3 (signal transducer and activator of transcription 3) serine‐727 (‐37%, p = 0.03) and tyrosine‐705 (‐33%, p = 0.01). There was no change in the total STAT3 protein, the ratio of phospho‐STAT3 to total STAT3, or NF‐kB‐p65 levels.ConclusionsThese results indicate that the PYY gene is not only detectable in mouse myoblasts, but it also changes with different physiological states (i.e. proliferating vs. differentiating). Additionally, PYY appears to play a role in skeletal muscle STAT3 signaling. Follow‐up research is necessary to confirm these results and identify downstream targets of PYY through the STAT3 pathway and functional outcomes. Support: NIDDK P30DK056336

Enterohormones Down-Regulated in High-Fat Diet

Introduction: To investigate the role of microbes upon the regulation of enteroendocrine hormones. Methods: Germ-free and specific pathogen-free (SPF) mice were caged under a 12-hour light-dark cycle and fed a high- or low-fat diet for 10 weeks. Animals were then humanely anesthetized with a mixture of ketamine and xylazine. Then, ileal mucosal scrapes were collected for RNA. cDNA was synthesized and qRT-PCR was performed with GiP, PYY, CCK primers, and normalized to GAPDH as a housekeeping gene. Results: More than 1/3 of U.S. adults are obese, and evidence suggests that inappropriate responsiveness to the intestinal microbiome plays a role. Obesity is a multivariable disease resulting in prolonged imbalance of energy input and energy expenditure. Since evidence suggests that changes in the gut microbiome influence energy metabolism and play an important role in the pathogenesis of obesity, we hypothesized that microbes influence enteroendocrine hormones in the intesitne. CCK is produced by I cells, and was the first gut hormone identified to regulate appetite. GiP is produced by K cells and is an incretin that regulates fatty acid metabolism. PYY is produced by L cells and regulates appetite and gastric emptying. Our results show that CCK, GiP, and PYY expression is unchanged in germ-free animals regardless of the diet (high-fat vs low-fat). However, in SPF animals, high-fat diets significantly up-regulate CCK by twofold and GiP by three-fold compared with animals on low-fat diet. No changes were observed in PYY expression in SPF regardless of the diet. In addition, no diurnal patterns were observed when examining CCK or GIP in circadian time, suggesting feeding patterns do not drive the changes in expression. Conclusion: Under germ-free conditions, diet has no influence upon CCK, GiP, or PYY expression in the small intestine. In SPF mice, CCK and GiP are up-regulated in the ileum under high fat diet. It appears microbes are required for the dietary regulation of CCK and GiP expression. There is no circardian variation of CCK and GiP ileal expression in animals fed with high-fat versus low-fat diet. Therefore, the effect of the different diets is not due to diurnal variation. Our study will add to our mechanistic insight into the regulation of obesity by the microbiome and further elucidate how changes in the microbiome lead to obesity.

Enhanced transcription of pancreatic peptide YY by 1α-hydroxyvitamin D3 administration in streptozotocin-induced diabetic mice

Peptide YY (PYY) is a peptide hormone secreted from L cells in the intestine in response to food intake that regulates appetite and gastrointestinal function. PYY is also produced in the pancreatic islets. The vitamin D receptor (VDR) is a nuclear receptor for the active form of vitamin D3 that regulates numerous physiological processes. VDR is expressed in the pancreatic islets and pharmacological VDR activation increases PYY expression in mouse peripheral islet cells. Although VDR is present in insulin-producing β cells as well as non-β cells, the role of β cell VDR in Pyy transcription remains unknown. We treated mice with streptozotocin to ablate β cells in the pancreas. Pancreatic Vdr mRNA expression was decreased in streptozotocin-induced diabetic mice. Interestingly, streptozotocin-treated mice exhibited increased basal Pyy expression and 1α-hydroxyvitamin D3 treatment further increased expression. Moreover, 1α-hydroxyvitamin D3 increased mRNA expression of pancreatic polypeptide and decreased that of neuropeptide Y in streptozotocin-induced diabetic mice but not in control mice. 1α-Hydroxyvitamin D3 slightly increased mRNA expression of insulin but transcript levels were nearly undetectable in the pancreas of streptozotocin-treated mice. Thus, VDR in non-β islet cells is involved in Pyy expression in the mouse pancreas. The findings from this β cell ablation study suggest a hormone transcription regulatory network composed of β cells and non-β cells.

Effects of fasting and feeding on the brain mRNA expressions of orexin, tyrosine hydroxylase (TH), PYY and CCK in the Mexican blind cavefish (Astyanax fasciatus mexicanus)

The effects of fasting and feeding on the brain expression of orexin (OX), tyrosine hydroxylase (TH), peptide Y (PY) and cholecystokinin (CCK) were examined in the blind cavefish Astyanax fasciatus mexicanus. A 10-days fasting period induced increases in both OX and TH brain mRNA expression but had no effect on PYY and CCK expression. Periprandial changes in expression were seen for OX, TH and PYY but not for CCK. OX brain expression peaked 1h prior to a scheduled meal and decreased 1h post feeding in fed fish. A peak in TH expression was seen 1h post feeding in unfed fish whereas a peak in PYY expression was seen 1h post feeding in fed fish. Our result indicates that brain OX, TH and PYY might be involved in the central regulation of feeding of blind cavefish.

Vitamin D Receptor Activation Induces Peptide YY Transcription in Pancreatic Islets

Peptide YY (PYY) is a peptide hormone secreted from L cells in the intestine after food intake and regulates appetite and intestinal function. PYY is also expressed in the pancreas, but the mechanisms of regulation of pancreatic PYY expression have not been elucidated. The vitamin D receptor (VDR) is a nuclear receptor for the active form of vitamin D(3) and regulates numerous physiological processes. Because VDR is expressed in the pancreas, we investigated the role of pancreatic VDR activation and found that Pyy is a VDR target gene in the mouse pancreas. Treatment of mice with 1α-hydroxyvitamin D(3) increased plasma PYY levels. VDR activation increased mRNA and protein expression of PYY in the pancreatic islets of mice and pancreatic endocrine cell lines but did not change intestinal PYY expression. 1α-Hydroxyvitamin D(3)-dependent induction of pancreatic and plasma PYY was abolished in VDR-null mice. We identified a functional vitamin D-responsive element in the mouse Pyy promoter using chromatin immunoprecipitation assay, EMSA, and luciferase promoter assay. Thus, Pyy is a tissue-specific VDR target gene. The pancreatic VDR-PYY pathway may mediate a regulatory function of vitamin D in the neuroendocrine system.

Regulation of hindbrainPyyexpression by acute food deprivation, prolonged caloric restriction, and weight loss surgery in mice

PYY is a gut-derived putative satiety signal released in response to nutrient ingestion and is implicated in the regulation of energy homeostasis. Pyy-expressing neurons have been identified in the hindbrain of river lamprey, rodents, and primates. Despite this high evolutionary conservation, little is known about central PYY neurons. Using in situ hybridization, PYY-Cre;ROSA-EYFP mice, and immunohistochemistry, we identified PYY cell bodies in the gigantocellular reticular nucleus region of the hindbrain. PYY projections were present in the dorsal vagal complex and hypoglossal nucleus. In the hindbrain, Pyy mRNA was present at E9.5, and expression peaked at P2 and then decreased significantly by 70% at adulthood. We found that, in contrast to the circulation, PYY-(1-36) is the predominant isoform in mouse brainstem extracts in the ad libitum-fed state. However, following a 24-h fast, the relative amounts of PYY-(1-36) and PYY-(3-36) isoforms were similar. Interestingly, central Pyy expression showed nutritional regulation and decreased significantly by acute starvation, prolonged caloric restriction, and bariatric surgery (enterogastroanastomosis). Central Pyy expression correlated with body weight loss and circulating leptin and PYY concentrations. Central regulation of energy metabolism is not limited to the hypothalamus but also includes the midbrain and the brainstem. Our findings suggest a role for hindbrain PYY in the regulation of energy homeostasis and provide a starting point for further research on gigantocellular reticular nucleus PYY neurons, which will increase our understanding of the brain stem pathways in the integrated control of appetite and energy metabolism.

Postprandial effects on appetite-related neuropeptide expression in the brain of Atlantic salmon, Salmo salar

Following feeding of a single meal to Atlantic salmon, the temporal changes in the brain mRNA expression of neuropeptide y ( npy), cocaine-amphetamine regulated transcript ( cart), peptide yy ( pyy), two isoforms of agouti-related protein ( agrp), two isoforms of cholecystokinin ( cck), and four isoforms of proopiomelanocortin ( pomc) were assessed by q-PCR. In the course of 24 h post-feeding (hpf), several of the brain neuropeptides displayed changes in mRNA expression compared to an unfed control group, indicating that food intake and processing affect the regulation of expression of these genes in Atlantic salmon. Expression of cart, cck-l, pomc-a1 and pomc-b all increased within 3 h of feeding, while most of the feed was still in the stomach, suggesting that these neuropeptides play central anorexigenic roles similar to those described in higher vertebrates, including determining meal intervals. On the other hand, the npy and agrp isoforms which have been described as playing orexigenic roles in mammals, showed an opposite response in salmon and both were elevated in the first 3 h after feeding. The different isoforms of cck, agrp and pomc had different mRNA expression patterns, which indicate specific roles related to feeding regulation. The minimal effect of feeding and digestion on pyy expression in the brain indicates that PYY plays a minor role in the central control of short-term food intake in Atlantic salmon.

Morphological and functional changes in the colon after massive small bowel resection

Purpose Anecdotal evidence suggests that the colon plays an important role after small bowel resection (SBR). However, colonic changes have not previously been studied. The aim of this study was to characterize morphological and functional changes within the colon after SBR and elucidate the influence of diet complexity on adaptation. Method In study 1, 4-week-old piglets underwent a 75% SBR or sham operation and were studied at 2, 4, and 6 weeks postoperation to allow analysis of early and late adaptation responses. Piglets received a polymeric infant formula (PIF). In study 2, SBR piglets received an elemental diet and were studied at 6 weeks postoperation and compared with SBR + PIF piglets from study 1. For both studies, immunohistochemistry was used to quantitate intestinal cell types. Changes in functional proteins were measured by Western blot, enteroendocrine/peptide YY (PYY), enterocyte/liver fatty acid binding protein (L-FABP), and goblet cells/trefoil factor 3 (TFF3). Results In study 1, early and late adaptation-related changes were observed after SBR. Early adaptation included increased numbers of enterocytes ( P = .0001), whereas late adaptation included increased proliferative cell numbers ( P = .02). Enteroendocrine, goblet, and apoptotic cells numbers were significantly elevated in the resected group at all time-points studied ( P < .05). Functional changes included increased levels of L-FABP ( P = .04) and PYY ( P = .03). There was no change in TFF3 expression. In study 2, feeding with an elemental diet resulted in suboptimal adaptation as evidenced by reduced rate of weight gain and significant reductions in total cell numbers ( P = .0001), proliferative ( P = .0001) and apoptotic cells ( P = .04), enteroendocrine cells ( P = .001), and PYY expression ( P .004). Conclusion These findings indicate that significant morphological and functional changes occur in the colon after massive SBR and that these occur as early and late adaptation responses. Elemental diet was associated with suboptimal adaptation suggesting an effect of diet complexity on colonic adaptation.

W1933 Expression of PYY is Unchanged in Rat Small Intestine During a High-Fat Diet

Purpose: Aging is associated with important changes in gastrointestinal function and in the levels of intestinal hormones secreted. Enterochromaffin cells containing serotonin (5-HT) and melatonin may play a major role in maintaining gut function during aging. Our aim was to characterise the mucosal availability of 5-HT and melatonin in the ileum and colon of a mouse model of aging. Methods: Female young mice (2-5 month; n=6), aged mice (~21 months; n=6) and aged mice treated with melatonin (~21 months; n=6; 10mg/kg/day) were examined. Electrochemical methods were used to measure 5-HT and melatonin (MEL) concentrations near the mucosal surface of ileum and distal colon. Amperometry was used to record compression evoked 5-HT while cyclic voltammetry was used to identify peaks for 5-HT and MEL. Differential pulse voltammetry (DPV: 500/800mV) was used to measure 5-HT and MEL steady state levels. Exogenous 5-HT and MEL were used to calibrate the carbon fibre electrodes and convert current into concentration. Paired or unpaired data were compared with a t test or a one way ANOVA (P<0.05) using a Tukey-Kramer post-hoc test. Results: Amperometry studies showed that young mice had peak compression evoked release of 5-HT from combined colon and ileum of 4.9±1.5 μM while aged mice had a enhanced release of 8.1±2.9 μM and aged mice treated with melatonin were significally depressed compared to aged mice (4.3±1.0 μM; P=004). Steady state levels of 5-HT after compression from combined tissue were 5.7±1.8 μM in young tissue while aged mice (4.8±0.6 μM) and aged mice treated with melatonin were no different from young mice (3.2±0.6 μM). DPV studies showed that young mice had concentrations of 5-HT of 4.1±1.1 μM in the ileum and 5.9±2.4 μM in the colon. Concentrations of MEL were 5.3±1.6 μM in the ileum and 4.7±1.5 μM in the colon (all n=6). Compared to young mice, the steady state levels of 5HT and MEL were increased in aged mice (combined ileum and colon: 5-HT=144% and MEL=127% of young mice). In contrast, the melatonin-treated mice had lower steady state levels compared to young mice (5-HT=89% andMEL=74%).When aged mice were compared directly with aged mice treated with melatonin, there was a significant decrease in both 5HT and MEL in the treated combined tissues (P=0.001); however, when ileum and colon were examined separately only MEL was significantly decreased in the ileum (P=0.04; n= 6) and colon (P=0.02; n=6) of treated mice. Conclusions: Our data show that the availability of 5-HT and melatonin are increased in aged mice and that melatonin treatment suppresses natural gastrointestinal production of 5-HT and melatonin in the aged mouse intestine.

Mucosal Gene Expression of Antimicrobial Peptides in Inflammatory Bowel Disease Before and After First Infliximab Treatment

BackgroundAntimicrobial peptides (AMPs) protect the host intestinal mucosa against microorganisms. Abnormal expression of defensins was shown in inflammatory bowel disease (IBD), but it is not clear whether this is a primary defect. We investigated the impact of anti-inflammatory therapy with infliximab on the mucosal gene expression of AMPs in IBD.Methodology/Principal FindingsMucosal gene expression of 81 AMPs was assessed in 61 IBD patients before and 4–6 weeks after their first infliximab infusion and in 12 control patients, using Affymetrix arrays. Quantitative real-time reverse-transcription PCR and immunohistochemistry were used to confirm microarray data. The dysregulation of many AMPs in colonic IBD in comparison with control colons was widely restored by infliximab therapy, and only DEFB1 expression remained significantly decreased after therapy in the colonic mucosa of IBD responders to infliximab. In ileal Crohn's disease (CD), expression of two neuropeptides with antimicrobial activity, PYY and CHGB, was significantly decreased before therapy compared to control ileums, and ileal PYY expression remained significantly decreased after therapy in CD responders. Expression of the downregulated AMPs before and after treatment (DEFB1 and PYY) correlated with villin 1 expression, a gut epithelial cell marker, indicating that the decrease is a consequence of epithelial damage.Conclusions/SignificanceOur study shows that the dysregulation of AMPs in IBD mucosa is the consequence of inflammation, but may be responsible for perpetuation of inflammation due to ineffective clearance of microorganisms.

Effects of the gut microbiota on host adiposity are modulated by the short-chain fatty-acid binding G protein-coupled receptor, Gpr41

The distal human intestine harbors trillions of microbes that allow us to extract calories from otherwise indigestible dietary polysaccharides. The products of polysaccharide fermentation include short-chain fatty acids that are ligands for Gpr41, a G protein-coupled receptor expressed by a subset of enteroendocrine cells in the gut epithelium. To examine the contribution of Gpr41 to energy balance, we compared Gpr41-/- and Gpr41+/+ mice that were either conventionally-raised with a complete gut microbiota or were reared germ-free and then cocolonized as young adults with two prominent members of the human distal gut microbial community: the saccharolytic bacterium, Bacteroides thetaiotaomicron and the methanogenic archaeon, Methanobrevibacter smithii. Both conventionally-raised and gnotobiotic Gpr41-/- mice colonized with the model fermentative community are significantly leaner and weigh less than their WT (+/+) littermates, despite similar levels of chow consumption. These differences are not evident when germ-free WT and germ-free Gpr41 knockout animals are compared. Functional genomic, biochemical, and physiologic studies of germ-free and cocolonized Gpr41-/- and +/+ littermates disclosed that Gpr41-deficiency is associated with reduced expression of PYY, an enteroendocrine cell-derived hormone that normally inhibits gut motility, increased intestinal transit rate, and reduced harvest of energy (short-chain fatty acids) from the diet. These results reveal that Gpr41 is a regulator of host energy balance through effects that are dependent upon the gut microbiota.