Regional differences in the appearance of adult-type glycosphingolipids in the small intestine of inbred rats at weaning time

The small intestine of 15- to 33-day-old rats was cut into four segments: duodenum, proximal jejunum, distal jejunum, and ileum. Neutral glycosphingolipids and gangliosides were purified from each segment and analyzed by thin-layer chromatography in order to study the developmental appearance of adult-type glycolipids at each level of the small intestine. Type 1 A-6 glycolipid was first detected in the ileum at 15 days and subsequently in the jejunum and duodenum at 19 days of age. N-Glycolylneuraminic acid was expressed first in the ileum at 17 days, then in the proximal jejunum at 21 days, but only after 29 days in the duodenum. In each region, 6-8 days were required between first detection and full expression of N-glycolylneuraminic acid. The presence of 2-hydroxylated fatty acids in glucosylceramide was found first in the ileum at 19 days, 2-3 days before appearing in the duodenum and proximal jejunum. A period of 2-3 days was necessary to reach full adult-type level of 2-hydroxylated fatty acids in glucosylceramide. These results show that adult-type glycolipids appear earlier in the distal than in the proximal region of the rat small intestine, and that different glycolipids appear at different times and at different rates. The finding that the biochemical differentiation of the whole small intestine expands over a period of 3 days to 2 weeks, depending on the region and the glycolipid, before being fully completed indicates that, in addition to the time lag observed between the distal and the proximal region, the new cells arising from the crypt of Lieberkhün after 15 days of age are not at once fully differentiated.     

Arginine-vasopressin immunoreactive material in the gastrointestinal tract

Like many other neuropeptides, vasopressin is not confined to the hypothalamic neurohypophysial system. Furthermore, vasopressin was found to be a potent vasoconstrictor in the rat jejunum, reducing myenteric artery flow. These associations were the basis of this investigation on the presence of vasopressin in the gastrointestinal (GI) tract by both RIA and immunohistochemistry. Portions of the gastrointestinal tract and pancreatic islets of the rat were extracted with 0.1 N HCl for RIA measurements of AVP content. Similar portions from the male cat GI tract were used for immunohistochemistry studies. Acid extracts of the GI tract were found to contain immunoreactive AVP with the highest concentration (pg/mg protein) in the fundus portion of the stomach (15.0 +/- 1.6) and slightly lower values down along the antrum-pylorus portion (6.7 +/- 0.6), proximal jejunum (8.6 +/- 0.2), distal ileum (9.7 +/- 0.3) and colon (11.9 +/- 0.5). In the pancreatic islets the concentration was much higher (72.0 pg/mg protein). The extract inhibition curves showed parallelism with the appropriate standard preparation of AVP in the specific RIA. Immunohistochemical localization showed IR-AVP in the nerve fibers around the myenteric plexus of the second portion of the duodenum. It was also found in fibers starting from where the myenteric plexus goes through the layer of muscle fibers, penetrating the submucosa and duodenal mucosa, ending near the capillaries situated along the basal side of the villous epithelium cells. Similar IR-AVP activity was found in cells located in the mucosal epithelium of the duodenum, jejunum, ileum, colon and rectum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modulation of nuclear statin expression in rat thyroid follicle cell following administration of thyroid stimulating hormone.

This study was designed to examine the state of proliferation in the rat thyrocyte following the administration of thyroid stimulating hormone (TSH). An immunohistochemical technique involving the use of a monoclonal antibody to statin, a nonproliferation-specific nuclear antigen, was developed to measure the subpopulation of cells that have ceased to divide. Following the random assignment of young male Sprague-Dawley rats into various groups, the rats in the control group received a single intraperitoneal (i-p) injection of normal saline, whereas the experimental groups received single i-p injections of TSH at doses of 0.25, 0.50, and 1.0 IU, respectively. All rats were subsequently sacrificed in groups of three at 1, 2, 4, and 24 hours. The statin antibody label was readily identified within the follicle cell nucleus. Results revealed a statistically significant transient decrease in the mean percent statin-positive nuclei in the TSH-treated groups. The time- and dose-dependent effect of TSH was maximal at 2 hours and no longer discernible at 24 hours. A second experiment involving the chronic administration of TSH (i-p 0.25 IU twice daily) resulted in a cumulative response with a statistically significant progressive decrease in the mean percent of statin-positive nuclei at 5 and 10 days, returning to near normal values 5 days following the cessation of treatment. Determination of the nuclear optical density of the statin reaction product by image analysis techniques revealed that a single injection of TSH resulted in a rapid disappearance of the statin nuclear protein. This result suggests that the disappearance of statin in the nucleus appears to reflect the event of cells leaving the nondividing quiescent state to resume the cell cycle traverse following the administration of TSH. The disappearance of statin appears as an early nuclear event that parallels the earliest known cytoplasmic pinocytotic response to TSH in the rat thyroid follicle cell.     

Effect of Weaning on Small Intestinal Structure and Function in the Piglet

Fifty-four piglets were selected from 12 litters weaned at 17 (Treatment 1), 21 (Treatment 2), 28 (Treatment 3) and 35 (Treatment 4) days old, respectively, to determine the effect of weaning age on small intestinal villus morphology, immunology and histochemistry. From proximal duodenum, proximal jejunum, distal jejunum and middle ileum, intestinal samples with three replicates (piglets) in each treatment were taken at 18, 22, 28 and 36; 22, 28, 36 and 43; 28, 36, 43, and 50; and 18, 22, 28, 36, 43 and 50d of age in Treatment 1, 2, 3 and 4, respectively. This was equivalent to 12h, 3d, 1 week, 2 week postweaning in Treatment 1; 12h, 1 week, 2 week, 3 week postweaning in Treatment 2 and 3, and all the same age in Treatment 4 as in Treatment 1, 2, 3, respectively. The results showed that villous height of duodenum and proximal jejunum decreased significantly in Treatment 1 and 3. Crypt depth in the duodenum, proximal jejunum and ileum also decreased significantly in Treatment 1. Date had significant effect on villous height of the duodenum, distal jejunum and ileum with the shortest on day 29 and crypt depth of all positions increased with piglet age except the crypt depth in proximal jejunum decreased on day 50. Weaning age and day of age had significant effects on intraepithelial lymphocyte (IEL) number and goblet cell (GC) number at all positions of small intestinal mucosa in piglets. The number of IEL at all segments of small intestinal mucosa in Treatment 3 increased significantly compared to those in other treatments, but IEL number at all locations of small intestinal mucosa in Treatment 2 decreased significantly compared to those in other treatments. The number of GC in small intestinal mucosa increased significantly in early-weaned (< day 21) piglets. It appears that providing fluid milk replacer for a few days postweaning could dramatically reduce the negative impact of weaning on villous morphology and digestive and absorptive function, especially in pigs weaned prior to 3 week of age. Finally, as weaning age was reduced, GC had a greater role in intestinal duct protection.     

Absorption of iron in rats with experimental enteritis*

Inflammatory conditions of the gastrointestinal tract and iron-deficiency anemia are very common in humans. Acute intestinal inflammation was pathologically established in rats by intraluminal administration of acetic acid into the duodenum and the proximal jejunum. The study included two control groups of intact (untreated) rats and sham-operated (saline-treated) rats for each intestinal segment. A third group of rats received acetic acid. The acetic acid-induced inflammatory process was established histopathologically and biochemically. Two days after treatment, iron absorption was measured using ligated 10-cm loops of proximal jejunum or ligated duodenum in which ⁵⁹Fe was injected intraluminally (n=6 in each group). In another four control groups (intact and sham-operated for each intestinal segment) and two acetic acid-treated groups, serosal-luminal secretion of ⁵⁹Fe was measured after intravenous injection (n=5 in each group). ⁵⁹Fe transfer from the lumens of the duodenum and jejunum to the portal system was significantly lower in those rats in whom inflammation was induced by acetic acid. There was no apparent serosal-luminal secretion of intravenously injected ⁵⁹Fe in any of the studied groups. We conclude that acetic acid-induced intestinal inflammation significantly reduces iron absorption by the duodenum and the proximal jejunum.     

Distribution and heterogeneity of immunoreactive cholecystokinin (CCK) in the mucosa of the porcine gastrointestinal tract

The concentration and molecular nature of cholecystokinin-like immunoreactivity (CCK-LI) in extracts of porcine intestinal mucosa were determined using sequence-specific radioimmunoassays. Highest CCK concentrations were measured in duodenal mucosa (258 +/- 60 pmol/g in the distal duodenum) followed by jejunal mucosa (204 +/- 36 pmol/g in the proximal jejunum) and pylorus (51 +/- 9 pmol/g). All other gastrointestinal regions proximal to the pylorus and distal to the jejunum contained less than 20 pmol/g. Pancreas contained less than 1 pmol/g. Gel chromatography in 6 M urea revealed four immunoreactive forms and this was confirmed by reverse-phase high-pressure liquid chromatography (HPLC). The predominant molecular form in acid extracts of duodenal mucosa resembled CCK-33 although high concentrations of the larger CCK form ('CCK-58') and of the form intermediate in size between CCK-33 and CCK-8 were measured. A molecular form resembling CCK-8 was the principal form in neutral extracts of the duodenum.     

Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--II. Copper accumulation in the ileum and distal jejunum

High concentrations of copper were demonstrated histochemically in the enterocytes lining the ileum and distal jejunum of suckling rats. Copper was not detected in cells from the duodenum or proximal jejunum of these rats or from any region of the small intestine of rats in which "closure" had taken place. X-Ray microanalysis demonstrated copper, in equi-atomic association with sulphur, within discrete vesicles in the supranuclear cytoplasm of the enterocytes. Despite the high concentrations of these two elements no biochemical evidence was found for the presence of significant amounts of copper-binding metallothionein. The highest concentrations of copper (226 +/- 48 mg atoms/kg dry wt: +/- SD) were found in vesicles adjacent to the nucleus, which did not accumulate particulate tracers, or calcium from the lumen of the intestine. These vesicles probably result from the coalescence of Golgi-derived primary lysosomes followed by fusion with endocytic vacuoles. They may provide a mechanism of copper excretion from the neonatal rat.     

Endogenous ghrelin and 5-HT regulate interdigestive gastrointestinal contractions in conscious rats

Endogenous ghrelin causes interdigestive contractions of the stomach in rats. In contrast, previous studies showed that 5-HT(3) and 5-HT(4) receptors were involved in regulating intestinal interdigestive contractions. We studied the possible role of endogenous ghrelin and 5-HT regulating interdigestive gastrointestinal (GI) contractions in rats. Four strain gauge transducers were implanted on the antrum, duodenum, and proximal and distal jejunum. After an overnight fast, GI contractions were recorded in freely moving conscious rats and ghrelin receptor antagonists [(d-lys3)GHRP6; 1 micromol/kg], 5-HT(3) antagonists (Ondansetron; 0.5 mg/kg) and 5-HT(4) antagonists (GR 125,487; 1 mg/kg) were administered (bolus iv). To evaluate the relationship between the luminal concentrations of 5-HT and phase III-like contractions of the duodenum, duodenal juice was collected via the intraduodenal catheter. 5-HT content of the duodenal juice was measured by HPLC. (d-lys3)GHRP6 significantly attenuated the occurrence and amplitude of phase III-like contractions of the antrum, but not the duodenum and jejunum. 5-HT(4) antagonists significantly reduced spontaneous phase III-like contractions of the jejunum, without affecting those of the antrum and duodenum. In contrast, 5-HT(3) antagonists did not affect phase III-like contractions in GI tract. Luminal concentration of 5-HT at the phase III-like contraction (36.0 +/- 13.3 ng/ml, n = 9) was significantly higher than that at the phase I-like contractions of the duodenum (4.9 +/- 1.6 ng/ml, n = 9, P < 0.05). It is suggested that released ghrelin from the gastric mucosa mediates gastric phase III-like contractions, whereas 5-HT released from enterochromaffin cells of the duodenal mucosa mediates intestinal phase III-like contractions via 5-HT(4) receptors.     

Appearance of interstitial cells of Cajal in the human midgut

Several subtypes of the interstitial cells of Cajal (ICC) form networks that play a role in gastrointestinal motor control. ICC express c-kit and depend on signaling via Kit receptors for development and phenotype maintenance. At 7-8 weeks of development, c-kit-immunoreactive (c-kit-IR) cells are present in the human oesophagus, stomach and proximal duodenum wall. In the remaining small and large bowel, c-kit-IR cells appear later. The object of the present study is to determine the timing of the appearance of c-kit-IR ICC in the parts of the digestive tube originating from the midgut (distal duodenum, jejunum, ileum and proximal colon). Specimens were obtained from eight human embryos and 11 fetuses at 7-12 weeks of gestational age. The specimens were exposed to anti-c-kit antibodies to investigate ICC differentiation. The differentiation of enteric neurons and smooth muscle cells was immunohistochemically examined by using anti-PGP9,5 and anti-desmin antibodies, respectively. In the distal duodenum, jejunum and ileum, c-kit-IR cells emerged at week 9 at the level of the myenteric plexus in the form of a thin row of cells encircling the inception of the ganglia. These cells were multipolar or spindle-shaped with two long processes and corresponded to the ICC of the myenteric plexus. In the proximal colon, c-kit-IR cells emerged at week 9-10 in the form of two parallel belts of cells extending at the submucosal plexus and the myenteric plexus levels. We conclude that ICC develop following two different patterns in the human midgut.     

The thickness of the mucus layer in different segments of the rat intestine

Summary The thickness of the pre-epithelial mucus layer has been measured in different gut segments of rats kept under normal (ad libitum) feeding conditions, and after 48 h of fasting, using cryostat sections and celloidin stabilization from samples containing luminal contents. The mucus layer of the stomach, duodenum, jejunum, ileum, caecum, proximal colon, colon transversum, distal colon and rectum was studied in five groups of male rats (10, 40, 70 and 150 days of age, and older). Underad libitum feeding conditions, a distinct and continuous mucus layer, with a thickness of more than 3 μm, was only observed in the colon transversum, in the distal colon, in the rectum and in the stomach. No pre-epithelial mucus layer was observed in the duodenum and jejunum where the glycocalix from the apical membrane of the superficial cells appeared to be in a direct contact with the luminal ingesta. In the ileum, caecum and the proximal colon, the surface epithelium of the mucosa was only partly covered by a mucus layer of highly variable thickness. After 48 h of fasting, a mucus layer of 28.8 ± 25.6 μm and 93.3 ± 59.4 μm thickness, respectively, was found in the duodenum and jejunum of adult rats, but no increase in the thickness of the mucus layer was observed in the rat hind gut.     

Trefoil peptide expression and goblet cell number in rat intestine: effects of KGF and fasting-refeeding

The trefoil factor family peptides TFF1, TFF2, and TFF3 are important for gut mucosal protection and restitution. Keratinocyte growth factor (KGF) stimulates proliferation and differentiation of epithelial cells with potent effects on goblet cells. To investigate interactions between food intake and KGF, rats were fed ad libitum (control), fasted for 72 h, or fasted for 72 h and then refed for 72 h with or without KGF (3 mg. kg(-1). day(-1)). With fasting, goblet cell number in duodenum increased, TFF3 mRNA in duodenum and jejunum decreased, and TFF3 protein did not change or increased. KGF during fasting stimulated colonic growth, normalized TFF3 mRNA in duodenum and jejunum, and broadly upregulated gut goblet cell number and TFF3 protein expression. With fasting-refeeding, KGF increased small bowel and colonic mucosal growth, goblet cell number, and TFF3 protein but had variable effects on TFF3 mRNA. KGF induced TFF2 mRNA and protein in duodenum and jejunum with both nutritional regimens. We conclude that nutrient availability modifies rat intestinal goblet cell number, TFF3 mRNA, and the gut-trophic effects of KGF in a region-specific manner. KGF enhances TFF2 expression in proximal small bowel and increases goblet cell number and TFF3 protein content throughout the intestine independent of food intake.     

5-(N,N-Dimethyl)-amiloride to discriminate the Unidirectional electrolyte transports in rat small intestine and proximal colon in vivo

The effect of dimethyl-amiloride (DMA), a selective Na+/H+ exchange blocker, was studied on electrolyte net fluxes and unidirectional fluxes of Na and Cl at four levels of rat intestine in vivo in basal conditions. DMA was applied intraluminally at concentrations of 10(-4) and 10(-3) M in the model of ligated loops prepared from duodenum, proximal jejunum, distal ileum and ascending colon in fasted Sprague Dawley rats. Two iso-osmotic test solutions were used: (1) hypo-ionic: Na+ 80 mM and (2) iso-ionic: Na+ 148 mM, pH 8.2. 22Na was placed in the loop and 36Cl was given by intravenous route at the beginning of the experiment. Na+/H+ was calculated by two different means, one was based on pH variation following amiloride inhibition of Na influx, the other on the calculation of the passive Na transport. The quantitative evaluation shows that Na/H exchange largely contributes to the electroneutral absorption and luminal pH regulation. The exchanger activity decreases from duodenum, jejunum, ileum and colon where it is completed by K/H exchange to assure low colon luminal pH.     

Expression,localization and possible functions of aquaporins 3 and 8 in rat digestive system

Although aquaporins (AQPs) play important roles in transcellular water movement, their precise quantification and localization remains controversial. We investigated expression levels and localizations of AQP3 and AQP8 and their possible functions in the rat digestive system using real-time polymerase chain reactions, western blot analysis and immunohistochemistry. We investigated the expression levels and localizations of AQP3 and AQP8 in esophagus, forestomach, glandular stomach, duodenum, jejunum, ileum, proximal and distal colon, and liver. AQP3 was expressed in the basolateral membranes of stratified epithelia (esophagus and forestomach) and simple columnar epithelia (glandular stomach, ileum, and proximal and distal colon). Expression was particularly abundant in the esophagus, and proximal and distal colon. AQP8 was found in the subapical compartment of columnar epithelial cells of the jejunum, ileum, proximal colon and liver; the most intense staining occurred in the jejunum. Our results suggest that AQP3 and AQP8 play significant roles in intestinal function and/or fluid homeostasis and may be an important subject for future investigation of disorders that involve disruption of intestinal fluid homeostasis, such as inflammatory bowel disease and irritable bowel syndrome.     

Stereological studies on the small intestinal epithelium of the rat

Summary Quantitative macroscopic, light-microscopic and electron-microscopic studies were performed on the small intestine of fasted and non-fasted adult, male Sprague-Dawley rats. In non-fasted rats the small intestine was longer than in fasted rats. Due to the presence of villi the surface area in the duodenum and the jejunum was enlarged about six times. The microvilli on the villous crests caused a surface enlargement by 13 times in the duodenum (value corrected for overestimation due to section thickness), and 19 times in the jejunum of the fasted rats. At the base of the villi these values were about 50% lower. It was calculated that, in the fasted rats, the total enlargement of the luminal surface area — due to villi and microvilli — was 63 times in the duodenum and 81 times in the jejunum (corrected for section thickness).Differences between the villous crest epithelium and the villous base epithelium were also found with regard to the mean cell height, and the volume densities of the absorptive cell nuclei, the mitochondria, and the paracellular channels.Supported by grants from the Swedish Medical Research Council (Project No. 12X-2298), from the Swedish Group-Insurance Co. Förenade Liv, from Tore Nilson's Fund for Medical Research and from the Medical Faculty, University of Umeå     

Dietary alanyl-glutamine improves growth performance of weaned piglets through maintaining intestinal morphology and digestion–absorption function

Alanyl-glutamine (Ala-Gln), a highly soluble and stable glutamine dipeptide, is known to improve gut integrity and function. The aim of this study was to evaluate whether dietary Ala-Gln supplementation could improve growth performance, intestinal development and digestive-absorption function in weaned piglets. A total of 100 purebred Yorkshire piglets weaned at 21 days of age were assigned randomly to four dietary treatment groups and fed a basal diet (control group) or a basal diet containing 0.15%, 0.30% and 0.45% Ala-Gln, respectively. Compared with the control group, piglets fed the Ala-Gln diets had higher average daily gain and lower feed : gain and diarrhea rate (P < 0.05). Moreover, dietary Ala-Gln supplementation increased villous height and villous height : crypt depth ratio in duodenum and jejunum (P < 0.05), as well as the activities of maltase and lysozyme in jejunum mucosa (P < 0.05). In addition, a decrease in serum diamine oxidase activity and crypt depth in duodenum and jejunum was observed in piglets fed the Ala-Gln diets (P < 0.05). Serum cytosolic phospholipase A2 (cPLA2) concentration and gene expression of cPLA2, Na⁺-dependent glucose transporter 1, glucose transporter 2 and peptide transporter 1 in jejunum were increased by feeding Ala-Gln diets relative to control diet (P < 0.05). These results indicated that feeding Ala-Gln diet has beneficial effects on the growth performance of weaned piglets, which associated with maintaining intestinal morphology and digestive-absorption function.     

Contractile activity of duodenum, jejunum, and ileum at psychogenic stress in rabbits before and after muscarinic or nicotinic cholinoceptor blockade

In chronic experiments on rabbits, myoelectric activity (contractile activity index) in distal part of the duodenum, proximal and distal parts of the jejunum and proximal part of the ileum was studied under psychogenic stress caused by rigid fastening rabbit to a table in supine position. In duodenum, the stressor impact rendered stimulating, and in an ileum--inhibitory influence on their motility. In a jejunum the inhibition with the subsequent stimulation was observed, the latter being more expressed in a proximal part of the intestine. The proximo-distal gradient of exitatory and inhibitory influences of the psychogenic stress on contractile activity of the small bowel was revealed: in distal direction, inhibitory influences strengthen and stimulatory ones weaken. The muscarinic receptor blockade abolished increase of the duodenal and jejunal contractile activity obsereved in the control. The nicotinic cholinoceptor blockade abolished increase of the duodenal contractile activity in the 1-st phase of the stressor response and did not exclude an increase of the duodenal contractile activity in the 2-nd phase of the response. Muscarinic or nicotinic blockade did not influence the manifestation of the inhibitory reaction of proximal part of the ileum. In the period after release of the animal, the duodenal and jejunal contractile activity exeeded its initial level. This exeeding did not preserve after muscarinic cholinoceptor blockade but did preserve after nicotinic one in duodenum and proximal jejunum. The received data allow to conclude, that produced by the stress increase of the contractile activity of the distal part of duodenum, proximal and distal parts of jejunum produced by the stress, as well as exceeding the initial contractile activity level in the period after release of an animal, are mediated by cholinergic effector neurones of the enteric nervous system.     

Molecular cloning, distribution and ontogenetic expression of the oligopeptide transporter PepT1 mRNA in Tibetan suckling piglets

The gene encoding the oligopeptide transporter PepT1 (HGMW-approved gene symbol SLC15A1) from Tibetan porcine intestine was cloned. The open reading frame of this cDNA encodes 708 deduced amino acid residues that show high sequence similarity with its ovine and bovine counterparts. The putative protein has 12 putative transmembrane domains, including many structural features that are highly conserved among the vertebrate orthologs. PepT1 mRNA expression can be detected in duodenum, jejunum and ileum from Tibetan pigs at 28 days by RT-PCR. Real-time PCR analysis indicated that the jejunum had the highest expression of PepT1 when compared with the duodenum and ileum. PepT1 mRNA expression in the duodenum and proximal jejunum increases continuously from day 1 to day 14: expression was highest at day14 (P < 0.01) and then decreased gradually from day 21 to day 35. Our findings show that PepT1 mRNA expression in the distal jejunum increased gradually with age in suckling Tibetan piglet, and this may have important implications for amino acid and protein nutrition in young animals.     

In vitro fermentability and physicochemical properties of fibre substrates and their effect on bacteriological and morphological characteristics of the gastrointestinal tract of newly weaned piglets

Abstract

Fermentability of fibre has a great impact on the bacterial flora along the gastrointestinal tract of newly weaned piglets. Therefore, this parameter was determined by incubating in vitro different fibre substrates (chicory roots, sugar beet pulp, wheat bran and corn cobs) with contents of jejunum or caecum sampled from slaughtered pigs. Incubating with small intestinal contents, lactic acid was the only fermentation product. Fermentability was highest for chicory roots, followed by wheat bran and sugar beet pulp, while corn cobs were not fermented. Based on SCFA formed in the incubations with caecal contents, ranking of the fermentability of the fibre substrates was in the same order. The effect of adding different fibre substrates to diets of newly weaned piglets on bacteriological and morphological aspects of the gastrointestinal tract was also investigated. In Experiment 1 three groups of five piglets, weaned at four weeks of age, received a control feed (C), C supplemented with corn cobs (50 g/kg) or with chicory roots (20 g/kg). In Experiment 2, diet C was supplemented with sugar beet pulp (120 g/kg) or with wheat bran (75 g/kg). After three weeks animals were euthanized and digesta were sampled from stomach, proximal and distal jejunum, caecum and colon. Furthermore, mucosal scrapings were prepared and tissue samples were taken from jejunum, caecum and colon. Viscosity was determined for jejunal, caecal and colon contents. Corn cobs in the feed increased the number of total bacteria, lactobacilli and bifidobacteria in the stomach and proximal duodenum, while a decreased count of streptococci in distal jejunum contents was noted. Chicory roots increased the counts of Escherichia coli in the distal jejunum and on the mucosa, while sugar beet pulp decreased the number of lactobacilli on the mucosa only. Wheat bran seemed to increase the count of E. coli in jejunal digesta and on the mucosa, and also the number of lactobacilli in the stomach and jejunum. Bifidobacterial numbers were increased but only in the proximal part of the jejunum. Fibre substrates affected the concentration of lactate and SCFA in different parts of the intestinal tract. Feeding corn cobs increased villus length in the proximal jejunum by 13%. The number of intra-epithelial lymphocytes in the villous epithelium of proximal and distal jejunum was decreased by corn cobs and chicory roots supplementation while beet pulp and wheat bran had the opposite effect. In Experiment 1, apoptotic index of the mucosa of the distal jejunum was very low and decreased when corn cobs were fed. Mitotic index in the crypts was only affected by the wheat bran diet and a small decrease was noted. It was concluded that the fermentability of fibre was not an ideal criterion for predicting its effects on the flora. The effect of fibres on viscosity of digesta was negligible probably explaining the lack of clear and consistent influences on the intestinal mucosa.     

The effect of dietary supplementation of nitric oxide donor and inhibitor on nNOS expression in and motility of the small intestine of broilers

Abstract

We investigated the effect of dietary supplementation of sodium nitroprusside (SNP), a nitric oxide (NO) donor, and N-nitro-L-arginine methyl ester (L-NAME), a NO inhibitor, on neuronal nitric oxide synthase (nNOS) expression in and motility of small intestinum in broilers. A total of 560, one-day-old Ross 308 hybrid mixed sex broiler chicks were divided randomly into one control and seven treatment groups for a 42 day feeding trial including starter phase (0–21 days) and grower phase (22–42 days). The control group was fed a basal diet and the experimental groups were the fed basal diet supplemented with 25, 50, 100 and 200 mg/kg SNP and 25, 50 or 100 mg/kg L-NAME. Ten chickens from each group were sacrificed to collect samples on days 21 and 42. The expression patterns of nNOS immunoreactivity in nerve fibers were determined by immunohistochemistry. In the contractility studies, longitudinal isolated strips of duodenum, jejunum and ileum were treated with 10^?5 M L-arginine and 10^?4 M SNP. Immunohistochemistry revealed that nNOS expression was not detectable in the duodenum or ileum of either the control or experimental groups. On the other hand, nNOS immunoreactivity in the jejunum control group showed a strong reaction on day 21, but the reaction was weak on day 42. nNOS expression clearly was suppressed on day 21 by the diet supplemented with L-NAME, while the diet supplemented with SNP stimulated nNOS expression on day 21. Contractility experiments revealed that spontaneous contractility of isolated strips of duodenum, jejunum and ileum showed no significant difference among groups. Spontaneous contractions of all strips were inhibited by L-arginine and SNP in all groups. The percentage inhibition rate of spontaneous contractions of jejunum application on days 21 and 42 after L-arginine decreased in the group supplemented with 100 mg/kg L-NAME. The percentage inhibition rate on day 21 after SNP application decreased in both groups that received 50 and 100 mg/kg L-NAME. We demonstrated the expression pattern of nNOS in nerve fibers in jejunum of broiler chickens. Contractility studies revealed that the NOS-NO pathway may play a role in smooth muscle contraction of small intestine of chickens. Feeding strategies that supplement NO donor and NO inhibitor can be of physiological importance to small intestine motility owing to alteration of nNOS expression in the jejunum.