The incretin effect in cats: comparison between oral glucose, lipids, and amino acids

Incretin hormones are secreted from the intestines in response to specific nutrients. They potentiate insulin secretion and have other beneficial effects in glucose homeostasis. We aimed to study the incretin effect in cats and to compare the effect of oral glucose, lipids, or amino acids on serum concentrations of insulin, total glucose-dependent insulinotropic peptide (GIP) and total glucagon-like peptide 1 (GLP-1). Ten healthy cats were used in a repeated measures design. Glucose, lipid, or amino acids were administered through nasoesophageal tubes on separate days. Blood glucose (BG) concentrations were matched between experiments by measuring BG every 5 min and infusing glucose intravenously at a changing rate. Intravenous glucose infusion with no prior treatment served as control. The incretin effect was estimated as the difference in insulin area under the curve (AUC) after oral compared with intravenous glucose. Temporal changes and total amount of hormone secretions were compared between treatment groups with the use of mixed models. Total glucose infused (TGI) at a mean dose of 0.49 g/kg resulted in slightly higher BG compared with 1 g/kg oral glucose (P = 0.038), but insulin concentrations were not significantly different (P = 0.367). BG and the TGI were not significantly different after the 3 oral challenges. Total GIP AUC was larger after lipids compared with amino acids (P = 0.0012) but GIP concentrations did not increase after oral glucose. Insulin and GIP concentrations were positively correlated after lipid (P < 0.001) and amino acids (P < 0.001) stimulations, respectively, but not after oral glucose stimulation. Total GLP-1 AUC was similar after all three oral stimulations. Insulin and GLP-1 concentrations were positively correlated after glucose (P = 0.001), amino acids (P < 0.001), or lipids (P = 0.001) stimulations. Our data indirectly support an insulinotropic effect of GIP and GLP-1. Potentiation of insulin secretion after oral glucose is minimal in cats and is mediated by GLP-1 but not GIP.     

Distribution of 5-hydroxytryptamine,Ghrelin or Glucagon-like Peptide-1 Immunopositive Cells in the Gastrointestinal Tract of Meihua Pig

In order to analyze the distributions and densities of endocrine cells in the gastrointestinal tract of Meihua pig (an elite native breed of Guangdong province, China), 6 healthy piglets weaned at 30 days of age were fed with the same diet till 65 days of age. At 65 days of age, different sections of the gastrointestinal tract of each piglet were collected, and the features and densities of 5-hydroxytryptamine (5-HT), ghrelin and glucagon-like peptide-1 (GLP-1) immunopositive cells were detected by immunohistochemistry. The results showed that the 5-HT positive cells distributed at the epithelial layer throughout the intestinal tract (duodenum, jejunum, ileum and colon) with a variety of features (e.g. cone, round, spindle), and they could be classified into either open-shape or closed-shape type, the density of 5-HT positive cells in duodenum was highest; The ghrelin positive cells were located along the gastrointestinal tract (gastric glands, pylorus, duodenum and jejunum) with both open-shape and closed shape, and its density decreased along the tract with most cells in gastric glands; The GLP-1 positive cells were observed along the intestinal tract, but its density increased from duodenum to ileum and then decreased in colon. This study might provide supporting data for further study of the gastrointestinal physiology of Meihua pig.     

梅花猪胃肠道5-羟色胺、胃饥饿素和胰高血糖素样肽-1免疫阳性细胞分布特征研究

为了解中国优良地方猪种梅花猪胃肠道内分泌细胞的分布与形态特征,本试验选取6头30日龄断奶健康梅花仔猪,在相同条件下饲养至65日龄,所有仔猪饲喂相同日粮,自由采食饮水。试验结束时,收集仔猪胃肠道各段组织样品,应用免疫组织化学方法观察3种胃肠道内分泌激素5-羟色胺（5-HT）、胃饥饿素（ghrelin）和胰高血糖素样肽-1（GLP-1）免疫阳性细胞的分布及形态特征,并对阳性细胞密度进行分析。结果显示,梅花猪的肠道不同部位（十二指肠、空肠、回肠和结肠）均存在5-HT阳性细胞,主要位于肠上皮组织中,呈锥形、圆形、梭形等形态,可分为开放型和闭合型,其中十二指阳性细胞肠密度显著高于其他肠段（P<0.05）;梅花猪的胃肠道不同部位均有Ghrelin阳性细胞,阳性细胞密度也是随胃肠道走向递减,胃腺体部密度最高;梅花猪的肠道不同部位均有GLP-1阳性细胞,阳性细胞密度沿肠道走向呈抛物线分布,其中回肠数量最多。本试验结果为进一步探究梅花猪胃肠道生理奠定了基础。     

The small intestine of the adult New Hampshire chicken: an immunohistochemical study

The presence and distribution of glucose-dependent insulinotropic polypeptide or gastric inhibitory polypeptide (GIP), gastric-releasing peptide (GRP) and glucagon immunoreactivity were studied in the small intestine of the New Hampshire chicken using immunohistochemistry. This is the first report of the presence of GIP-immunoreactive (ir) cells in avian small intestine. GIP, GRP and glucagon immunoreactivity was localized in the epithelium of the villi and crypts of the duodenum, jejunum and ileum. In particular, both in the duodenum and in the jejunum immunoreactive endocrine cells to GIP, GRP and glucagon were observed. In the ileum, we noticed GIP-ir and glucagon-ir cells. GRP-ir was found in nerve fibres of all three segments of the small intestine. The distribution of these bioactive agents in the intestinal tract of the chicken suggests that GIP and glucagon may play a role in the enteropancreatic axis in which intestinal peptides modulate pancreas secretion.     

CCK and GLP-1 release in response to proteinogenic amino acids using a small intestine ex vivo model in pigs

The impact of individual amino acids (AA) on gut hormone secretion and appetite regulation in pigs remains largely unknown. The aim of the present study was to determine the effect of the 20 proteinogenic AA on the release of the anorexigenic hormones cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) in postweaning pigs. Six 25-d-old male piglets (Domestic Landrace × Large White; body weight = 6.94 ± 0.29 kg) were humanely killed for the collection of intestinal segments from the duodenum, jejunum, and ileum. Tissue samples from the three intestinal segments were used to determine which of the regions were more relevant for the analysis of gut peptides. Only the segments with the highest CCK and GLP-1 secretion and expression levels were evaluated with the 20 individual AA. Tissue segments were cut open, cleaned, and stripped of their muscle layer before identical circular samples were collected and incubated in 24-well plates for 1 h (37 °C, 5% v/v CO₂). The culture broth consisted of a glucose-free KRB buffer containing no added AA (control) or with the addition of 10 mM of 1 of the 20 proteinogenic AA. Following incubation, tissues and supernatant were collected for gene expression and secretion analysis of CCK and GLP-1 levels. CCK secretion and mRNA expression were higher (P < 0.05) in duodenum when compared with proximal jejunum or ileum, whereas GLP-1/proglucagon levels were higher in ileum vs. duodenum (P < 0.05) and jejunum (P < 0.05, for GLP-1 only) in postweaning pigs. Based on these results, the effect of AA on CCK and GLP-1 secretion was studied in the duodenum and ileum, respectively. None of the AA tested stimulated both anorexigenic hormones. Of all the essential AA, Ile, Leu, Met, and Trp significantly (P < 0.05) stimulated GLP-1 from the ileum, while only Phe stimulated CCK from the duodenum. Of the nonessential AA, amide AA (Gln and Asn) caused the release of CCK, while Glu and Arg increased the release of GLP-1 from the ileum. Interpreting the results in the context of the digestion and absorption dynamics, non-bound AA are quickly absorbed and have their effect on gut peptide secretion limited to the proximal small intestine (i.e., duodenum), thus, mainly CCK. In contrast, protein-bound AA would only stimulate CCK release from the duodenum through feedback mechanisms (such as through GLP-1 secreted mainly in the ileum).     

Dietary carbohydrate modifies the density of L cells in the chicken ileum

Glucagon-like peptides (GLPs) are secreted from intestinal L cells and stimulate various physiological functions in the gastrointestinal tract. The secretion of GLPs is influenced by macronutrient ingestion. This study aims to clarify the effects of dietary carbohydrate (CHO) on L cells in the chicken ileum. Six-week-old, male White Leghorn chickens were divided into three groups: control, low-CHO and CHO-free, with five chickens in each group. Paraffin sections were made from the proximal and distal ileum of each animal and subjected to immunohistochemistry for GLP-1 and GLP-2 peptides and in situ hybridization for proglucagon (PG) mRNA. A significant reduction of GLP-1- and GLP-2-immunoreactive cells was observed in the two experimental groups compared with that in the control. A reduction of cells expressing PG mRNA was observed in the proximal and distal ileum of the CHO-free group compared with that in the control. The ratio of GLP-1-immunoreactive cells showing Ki-67 immunoreactivity was significantly lower in the distal ileum of the CHO-free group than that in the control group. These data suggest that dietary CHO is an effective stimulator for modifying L cell density in the chicken ileum.     

Oxyntomodulin attenuates exendin-4-induced hypoglycemia in cattle

Oxyntomodulin (OXM), glucagon, glucagon-like peptide-1 (GLP-1), and exendin-4 (Ex-4) are peptide hormones that regulate glucose homeostasis in monogastric and ruminant animals. Recently, we reported that the insulin-releasing effects of OXM and glucagon in cattle are mediated through both GLP-1 and glucagon receptors. The purpose of this study was to examine the mechanisms of the glucoregulatory actions induced by Ex-4, GLP-1, OXM, and glucagon and the interrelationships among these hormones in cattle. Two experiments were performed in Holstein cattle. In Experiment 1, we initially assessed the effects of intravenous (iv) bolus injection of 0, 0.25, 1, and 2 μg/kg body weight (BW) of Ex-4, GLP-1, and OXM on insulin and glucose concentrations in 3-mo-old intact male Holstein calves. In Experiment 2, we studied insulin and glucose responses to iv coinjection of 0.25 μg of Ex-4 or GLP-1/kg BW with 2 μg of OXM or glucagon/kg BW in 4-mo-old Holstein steers. Administration of peptides and blood sampling were done via a jugular catheter. Plasma was separated and the concentrations of peptides and glucose in plasma were analyzed using radioimmunoassay and enzymatic methods, respectively. Results showed that the potent glucoregulatory action of Ex-4 in 4-mo-old steers was delayed and attenuated when Ex-4 was coinjected with OXM. The decline in plasma glucose concentrations began at 5 min in the Ex-4-injected group (P < 0.05) vs 15 min in the Ex-4 + OXM–injected group (P < 0.05). Plasma concentrations of glucose at 30 min were reduced 26% from basal concentrations in the Ex-4-injected group and 13% in the Ex-4 + OXM–injected group (P < 0.001). Results also showed that the glucose concentrations initially increased in the Ex-4 + glucagon–treated group, but declined to a relatively hypoglycemic condition by 90 to 120 min. In contrast, the glucose concentrations at specific time points between the GLP-1 + OXM–injected group and the OXM-injected group did not differ. Similarly, the glucose concentrations in the GLP-1 + glucagon–injected group did not differ from those in the glucagon-injected group. Because OXM and glucagon mediate glucose concentrations via the glucagon receptor, it is suggested that the potent glucose-lowering action of Ex-4 might include the glucagon receptor antagonistic action of Ex-4.     

Expression of monocarboxylate transporter 1 (MCT1) in the dog intestine

In this study, the expression and distribution of monocarboxyolate transporter 1 (MCT1) along the intestines (duodenum, jejunum, ileum, cecum, colon and rectum) of dogs were investigated at both the mRNA and protein levels. The expression of MCT1 protein and its distribution were confirmed by Western blotting and immunohistochemical staining using the antibody for MCT1. We identified mRNA coding for MCT1 and a 43-kDa band of MCT1 protein in all regions from the duodenum to the rectum. Immunoreactive staining for MCT1 was also observed in epithelial cells throughout the intestines. MCT1 immunoreactivity was greater in the large intestine than in the small intestine. MCT1 protein was predominantly expressed on the basolateral membranes along intestinal epithelial cells, suggesting that MCT1 may play an important role in lactate efflux and transport of short-chain fatty acids (SCFAs) to the bloodstream across the basolateral membranes of the dog intestine.     

Expression and localisation of calbindin D28k in all intestinal segments of the laying hen

1. The aim of the present study was to investigate expression and localisation of a 28-kDa calcium-binding protein (CaBP-D28k) related to active calcium (Ca) absorption, in the entire intestine of egg-laying hens. 2. Western blotting analysis showed that the entire intestine expressed CaBP-D28k to the following degree: duodenum > jejunum > caecum > ileum > colon. Immunohistochemistry showed strong CaBP-D28k localisation in enterocytes along the villus tip-crypt axis in the duodenum and in villus tips in the caecum and colon. The jejunum and ileum had moderate localisation with respect to the number of immunoreactive cells and staining intensity. 3. These results suggest that laying hens actively absorb Ca in both the large and small intestines.     

Glucagon-like peptide 2 function in domestic animals

Glucagon-like peptide 2 (GLP-2) is a member of family of peptides derived from the proglucagon gene expressed in the intestines, pancreas and brain. Tissue-specific posttranslational processing of proglucagon leads to GLP-2 and GLP-1 secretion from the intestine and glucagon secretion from the pancreas. GLP-2 and GLP-1 are co-secreted from the enteroendocrine L-cells located in distal intestine in response to enteral nutrient ingestion, especially carbohydrate and fat. GLP-2 secretion is mediated by direct nutrient stimulation of the L-cells and indirect action from enteroendocrine and neural inputs, including GIP, gastrin-releasing peptide (GRP) and the vagus nerve. GLP-2 is secreted as a 33-amino acid peptide and is rapidly cleaved by dipeptidylpeptidase IV (DPP-IV) to a truncated peptide which acts as a weak agonist with competitive antagonistic properties. GLP-2 acts to enhance nutrient absorption by inhibiting gastric motility and secretion and stimulating nutrient transport. GLP-2 also suppresses food intake when infused centrally. The trophic actions of GLP-2 are specific for the intestine and occur via stimulation of crypt cell proliferation and suppression of apoptosis in mucosal epithelial cells. GLP-2 reduces gut permeability, bacterial translocation and proinflammatory cytokine expression under conditions of intestinal inflammation and injury. The effects of GLP-2 are mediated by a G-protein-linked receptor that is localized to the intestinal mucosa and hypothalamus. The intestinal localization of the GLP-2R to neural and endocrine cells, but not enterocytes, suggests that its actions are mediated indirectly via a secondary signaling mechanism. The implications of GLP-2 in domestic animal production are largely unexplored. However, GLP-2 may have therapeutic application in treatment of gastrointestinal injury and diarrheal diseases that occur in developing neonatal and weanling animals.     

Immunohistochemical distribution of glucagon-like peptide 1 in the digestive system of different aquatic vertebrates

The distribution of glucagon-like peptide 1 (GLP-1)-positive cells in digestive tracts and pancreases of aquatic vertebrates was investigated by immunohistochemical staining method. The results suggested that GLP-1-positive cells were distributed in the columnar mucous epithelium and tubular glands of lamina propria in the digestive system. However, GLP-1-positive cells were also found in subepithelial lamina propria of the mucosae and muscularis in each segment of the digestive tract of Rana nigromaculata. The distribution densities of these cells reached peaks in the stomachs, and the middle or end segments of small intestines of Chinese softshell turtle, Bufo gargarizans, R. nigromaculata and catfish, and there was the third distribution density peak in the rectum of catfish. The total amount or overall density of GLP-1-positive cells varied a lot in the digestive tracts of different animal species. The distribution density was relatively low in the digestive tract of chub and reached the maximum in the digestive tracts of snakehead and catfish, but no GLP-1-positive cells were found in the digestive tract of bighead carp. GLP-1-positive cells were densely distributed in the pancreases of Chinese softshell turtle, B. gargarizans and R. nigromaculata. These cells spread over the superficial layers of islets or scattered in exocrine pancreas in the pancreas of B. gargarizans, spread in the endocrine cells or scattered in the pancreas of Chinese softshell turtle, scattered in the pancreas of R. nigromaculata and distributed in the superficial layers of islets in the pancreas of catfish.     

Numbers and distribution of immune cells in the tunica mucosa of the small and large intestine of full-thickness biopsies from healthy pet cats

In this study, CD3(+) T lymphocytes and IgA(+) , IgG(+) and IgM(+) plasma cells were quantified in the tunica mucosa of the intestinal tract of 12 pet cats without gastrointestinal diseases. The study included full-thickness biopsies of the duodenum, jejunum, ileum and colon. The distribution and quantification of CD3(+) T cells, IgA(+) , IgG(+) and IgM(+) plasma cells within the intestinal tunica mucosa was performed by using immunohistochemical methods and computer-aided morphometry. CD3(+) T cells were significantly prominent in the villi and their numbers increased from duodenum to ileum but decreased towards the colon. The predominant type of plasma cells was IgA(+) cells, followed by IgM(+) cells. The number of IgG(+) cells was generally low compared to the other plasma cell types investigated. The results of the vertical distribution showed that IgA(+) and IgM(+) plasma cells were most numerous in the lower crypt areas, whilst IgG(+) plasma cells accumulated in the upper crypt region with a decline towards the villi and the lower crypt areas of control cats. All types of plasma cells showed a general decline from the duodenum towards the caudal sections of the intestinal tract regarding the horizontal distribution of plasma cells. This study provides a comprehensive overview on the vertical and horizontal distribution and the number of CD3(+) T cells and IgA(+) , IgG(+) and IgM(+) plasma cells in the intestinal tunica mucosa of pet cats.     

Population pharmacokinetics for danofloxacin in the intestinal contents of healthy and infected chickens

Avian pathogenic Escherichia coli could cause localized and systemic infection in the poultry, and danofloxacin is usually used to treat avian colibacillosis through oral administration. To promote prudent use of danofloxacin and reduce the emergence of drug‐resistant E. coli strains, it is necessary to understand the population pharmacokinetics (PopPK) of danofloxacin in chicken intestines. In this study, reversed‐phase high performance liquid chromatography (HPLC) with fluorescence detection was used to detect the concentrations of danofloxacin in the contents of duodenum, jejunum, and ileum of the healthy and infected chickens after single oral administration (5 mg/kg body weight). Then, the PopPK of danofloxacin in intestines were analyzed using NONMEM software. As a result, a two‐compartment PK model best described the time‐concentration profile of duodenal, jejunal, and ileal contents. Interestingly, absorption rate (K_a), distribution volume (V), and clearance (CL) for danofloxacin from duodenal, jejunal to ileal contents were sequentially decreased in the healthy chickens. However, the trend of K_a, V, and CL of danofloxacin was changed dramatically in the intestine of infected chickens. K_a and V of danofloxacin in the jejunum were higher than in the ileum and duodenum. Compared with healthy chickens, K_a and V of danofloxacin in the duodenum decreased significantly, while increased in jejunum, respectively. It has been noted that K_a decreased and V increased in the ileum of infected chickens. Besides, CL in the duodenum, jejunum, and ileum of infected chickens was, respectively, lower than those of healthy chickens. Interestingly, the relative bioavailability (F) of danofloxacin in the ileum was relatively higher in both healthy and infected chickens. In addition, F in the duodenal, jejunal, and ileal contents of infected chickens was respectively higher than healthy chickens. In summary, the PopPK for danofloxacin in infected chicken intestines was quite different from healthy chickens. The absorption, distribution, and clearance of danofloxacin in healthy chickens decreased from duodenum to jejunum and to ileum. Moreover, the pharmacokinetic characteristics in the intestine of infected chickens changed significantly, and the pharmacokinetic characteristics in the ileum can be used as a representative of all intestinal segments.     

Immunohistochemical study on the distribution of endocrine cells in the gastrointestinal tract of the babirusa, Babyrousa babyrussa (Suidae)

The distribution and relative frequency of endocrine cells in the gastrointestinal tract of the babirusa were studied immunohistochemically using the avidin-biotin-peroxidase complex method. Thirteen types of gut endocrine cells were detected; they were immunoreactive for chromogranin, serotonin, somatostatin, gastrin, bovine pancreatic polypeptide (BPP), glucagon, secretin, cholecystokinin (CCK), methionine-enkephalin-Arg6-Gly7-Leu8 (MENK8), motilin, gastric inhibitory polypeptide (GIP) and peptide tyrosine tyrosine (PYY). Cells that were immunoreactive for chromogranin, serotonin, somatostatin and glucagon were found in all portions of the gastrointestinal tract. MENK8-immunoreactive cells were observed in the stomach and small intestine. Gastrin-immunoreactive cells were detected in the pyloric region and duodenum. PYY-immunoreactive cells were found in the small and large intestine. Cells immunoreactive for motilin, CCK, GIP, and secretin were observed in the proximal small intestine and those immunoreactive for neurotensin were found only in the ileum. Although the distribution pattern of endocrine cells in the gastrointestinal tract of babirusa was similar to those reported for pig, restricted distribution of several endocrine cells, gastrin, BPP, MENK8, motilin, CCK, GIP, secretin and neurotensin and wider distribution of glucagon and PYY were observed in the babirusa. The unexpected presence of MENK8 in all glandular regions of the stomach and PYY in the small intestine was also noted. The distribution of gut endocrine cells might be related to the regulatory characteristics of the babirusa digestive tract.     

Gastrointestinal volatile fatty acid concentrations and pH in cats

OBJECTIVE: To measure volatile fatty acid (VFA) concentrations and pH in the gastrointestinal tracts of healthy adult cats fed a commercial dry cat food. ANIMALS: 14 cats. PROCEDURE: The gastrointestinal tracts were excised immediately after euthanasia and divided into 6 sections (stomach, duodenum, jejunum, ileum, proximal portion of the colon, and distal portion of the colon). Luminal contents were collected from each segment, pH was measured, and contents were centrifuged. The supernatant was analyzed for acetate, proprionate, butyrate, isobutyrate, valerate, and isovalerate concentrations by use of gas chromatography. RESULTS: Mean total VFA concentrations were lowest in the stomach (20 mmol/L); increased through the duodenum, jejunum, and ileum (30, 29, and 41 mmol/L, respectively); and were greatest in the proximal and distal portions of the colon (109 and 131 mmol/L, respectively). Estimated mean total VFA amounts were low (<600 micromol) throughout all segments of the gastrointestinal tract; pH values increased from the stomach through the ileum and subsequently decreased in the colon. CONCLUSIONS AND CLINICAL RELEVANCE: Total VFA concentrations in the colon were comparable to values reported for the forestomach of ruminants and large intestines of monogastric animals, whereas values in the small intestine were higher than reported for other species. Total VFA amounts were low, consistent with the short, nonvoluminous gastrointestinal tract of carnivores. Luminal pH varied throughout the gastrointestinal tract in a pattern similar to other monogastric animals. Volatile fatty acids probably contribute minimal metabolic energy in cats but may be important in the maintenance of local mucosal health.     

Expression of mRNA for proglucagon and glucagon-like peptide-2 (GLP-2) receptor in the ruminant gastrointestinal tract and the influence of energy intake

Glucagon-like peptide-2 (GLP-2) is a potent trophic gut hormone, yet its function in ruminants is relatively unknown. Experiment 1 was conducted as a pilot study to establish the presence of GLP-2 in ruminants and to ascertain whether it was responsive to increased nutrition, as in non-ruminants. Concentrations of intact GLP-2 in the blood and gut epithelial mRNA expression of proglucagon (GCG) and the GLP-2 receptor (GLP2R) were measured in 4 ruminally, duodenally, and ileally cannulated steers. Steers were fed to meet 0.75 × NE_M for 21 d, and then increased to 1.75 × NE_M requirement for another 29 d. Blood samples and ruminal, duodenal, and ileal epithelium biopsies were collected at low intake (Days −6 and −3), acute high intake (Days 1 and 3), and chronic high intake (Days 7 and 29) periods. Experiment 2 investigated the mRNA expression pattern of GCG and GLP2R in epithelial tissue obtained from the forestomachs (rumen, omasum, and abomasum) and intestines (duodenum, jejunum, ileum, and colon) of 18 forage-fed Angus steers (260 kg BW). In Experiments 1 and 2, real-time polymerase chain reaction showed that expression of GCG and GLP2R mRNA was detectable in forestomach tissues, but expression was greater (P < 0.001) in small intestinal and colon tissue. High energy intake tended (P = 0.07) to increase plasma GLP-2 during the acute period and was paralleled by a 78% increase (P = 0.07) in ileal GCG mRNA expression. After this initial adaptation, duodenal GCG mRNA expression increased (P = 0.08) during the chronic high intake period. Duodenal GLP2R mRNA expression was not affected by energy intake, but ileal GLP2R expression was increased after 29 d of high energy intake compared to both the low and acute high intake periods (P = 0.001 and P = 0.01, respectively). These data demonstrate that cattle express GCG and GLP2R mRNA primarily in small intestinal and colon tissues. Increased nutrient intake increases ileal GCG mRNA and plasma GLP-2, suggesting that GLP-2 may play a role in the trophic response of the ruminant gastrointestinal tract to increased feed intake.     

Gastrin and somatostatin enteroendocrine cells in the small intestines of ostrich (Struthio camelus var. domesticus) during pre -and post-hatching period

Studies on localization and distribution of enteroendocrine cells (EECs) are important for better understanding of their role in the ontogenetic development of intestines. Information about the distribution of the most important endocrine cells in the digestive tract of the ostrich is very limited; therefore, the aim of the present study was to identify gastrin and somatostatin EECs in the small intestine of the ostrich (Struthio camelus var. domesticus) chicks at different ages. Six embryos along with 42 ostriches of both sexes from hatching up to 60 days post-hatching, including six embryos, were obtained from an ostrich farm in Latvia. Duodenum, jejunum and ileum were investigated using routine histology and immunohistochemistry methods. Gastrin and somatostatin EECs were examined in 10 microscopic fields of the intestinal mucosa in each tissue sample. The cells were detected in all age groups as well as the embryos. The number of both types of EEC in the mucosa of the ileum was significantly lower (p < .01–.05) than in the duodenum. The present study suggested that the EEC may have a role in the development of the mucosa of the intestinal tract of ostriches with possible involvement in the development of the digestive functions.     

饲粮营养限制对羔羊肠道组织形态以及血清胰岛素样生长因子-1和胰高血糖素样-2浓度的影响

本试验旨在研究饲粮营养限制对羔羊肠道组织形态及血清中胰岛素样生长因子-1(IGF-1)和胰高血糖素样-2(GLP-2)浓度的影响。选取64只17日龄湖羊羔羊随机分为4组,饲喂不同营养水平的代乳品和开食料,分别为对照(CON)组、20%蛋白质限制(PR)组、20%能量限制(ER)组、20%蛋白质+20%能量限制(BR)组,每组4个重复,每重复4只羔羊,公母各占1/2。于羔羊20日龄、40日龄和60日龄采集血清用于测定IGF-1和GLP-2的浓度,40日龄和60日龄时每组分别选取4只羔羊进行屠宰,屠宰后取十二指肠、空肠和回肠组织观察小肠组织形态结构。结果表明:1)PR组、ER组、BR组40日龄小肠重量显著低于CON组(P0.05),到60日龄仅ER组羔羊小肠重显著低于CON组(P0.05),小肠重量降低主要由于空肠重量的降低。2)PR组、ER组、BR组40日龄十二指肠、空肠绒毛高度及60日龄十二指肠绒毛高度显著低于CON组(P0.05),ER组、BR组60日龄空肠绒毛高度显著低于CON组(P0.05)。3)BR组40日龄十二指肠绒毛高度/隐窝深度显著低于CON组(P0.05)。4)ER组60日龄血清GLP-2浓度显著低于其他3组(P0.05),4组间血清IGF-1浓度无显著差异(P0.05)。综上所述,饲粮营养限制抑制了羔羊十二指肠、空肠组织形态发育,同时能量限制可降低血清GLP-2的浓度。     

Effects of Recombinant E. coli Expressing Heat-stable Enterotoxin on Intestinal Morphology and Antioxidant Capacity in Seven Days old Piglets

This experiment was conducted to investigate the effects of recombinant E.coli expressing heat-stable enterotoxin(STa) on intestinal absorption and barrier function, intestinal morphology and antioxidant capacity of 7 days old piglets. Twenty-four 7 days old piglets were allotted to four treatments:control group (artificial milk), STa group (artificial milk +2×10⁹ CFU E.coli LMG194-pBAD-STa), LMG194 group (artificial milk +2×10⁹ CFU E.coli LMG194), and K88 group (artificial milk +2×10⁹ CFU E.coli K88).The pigs were treated with E.coli on the 5th day and slaughtered on the 7th day. The results showed that, compared with the control group, villus height in jejunum, ileum and duodenum, crypt depth and villus height/crypt depth in duodenum, and small intestine villi surface area were significantly decreased in STa group (P<0.05). The activities of catalase (CAT) in ileum and colon, total nitric oxide synthase (TNOS) in serum, ileum, jejunum and colon, inducible nitric oxide synthase (iNOS) in colon were significantly decreased in STa group (P<0.05). STa group also had a higher levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in serum (P<0.05). These results suggested that recombinant E.coli expressing STa could lead to intestinal injury and oxidative stress of 7 days old piglets.     

不同锌源和锌水平对猪IPEC-J2细胞GLP-2基因表达的影响

本试验旨在探讨不同锌源及锌水平对猪小肠上皮细胞(IPEC-J2)胰高血糖素样肽2(GLP-2)表达的影响。分别以乳酸锌、硫酸锌(锌浓度分别为50、100、150、200 mg/L)作用IPEC-J2细胞,实时荧光定量RT-PCR方法检测GLP-2 mRNA表达,以β-actin mRNA水平作为内参对照。结果表明:在6、12 h检测时间点,不同锌源和水平及其互作对GLP-2 mRNA表达影响极显著(P<0.01);在24 h时不同锌源对其表达影响极显著(P<0.01),锌添加水平对其表达影响显著(P<0.05),不同锌源与锌添加水平交互作用则不显著(P<0.05);乳酸锌、硫酸锌促进GLP-2基因mRNA表达均具有正向浓度效应。乳酸锌和硫酸锌均可上调肠道细胞GLP-2基因mRNA的表达;在同等锌浓度水平下,乳酸锌促进GLP-2基因表达的效果优于硫酸锌。