Dietary starch is weight reducing when distally digested in the small intestine

Nowadays, carbohydrate-based foods have a negative consumer connotation and low carb diets have become a popular way to lose weight. Here, we show how digestible starch and flavonoids can be used as a dietary approach to manage food intake and weight gain through elevation of glucagon-like peptide-1 (GLP-1) secretion for gut-brain axis communication. This was achieved by extending the digestion of cooked starch to the distal small intestine using luteolin or quercetin as α-amylase-specific inhibitors with competitive inhibition mechanism. In a mouse model, extended and complete digestion produced a signature blunted glycemic profile that induced elevation of GLP-1 and positive regulation of hypothalamic neuropeptides with significantly reduced food intake and weight gain (p < 0.05). These findings represent a shift in paradigm of dietary carbohydrates from weight increasing to reducing, and have implications for industry and public health related to the design of carbohydrate-based foods/ingredients for managing obesity and diabetes.

Intragastric Administration of Casein Leads to Nigrostriatal Disease Progressed Accompanied with Persistent Nigrostriatal-Intestinal Inflammation Activited and Intestinal Microbiota-Metabolic Disorders Induced in MPTP Mouse Model of Parkinson's Disease

Gut microbial dysbiosis and alteration of gut microbiota composition in Parkinson's disease (PD) have been increasingly reported, no recognized therapies are available to halt or slow progression of PD and more evidence is still needed to illustrate its causative impact on gut microbiota and PD and mechanisms for targeted mitigation. Epidemiological evidence supported an association between milk intake and a higher incidence of Parkinson's disease (PD), questions have been raised about prospective associations between dietary factors and the incidence of PD. Here, we investigated the significance of casein in the development of PD. The mice were given casein (6.75 g/kg i.g.) for 21 days after MPTP (25 mg/kg i.p. × 5 days) treatment, the motor function, dopaminergic neurons, inflammation, gut microbiota and fecal metabolites were observed. The experimental results revealed that the mice with casein gavage after MPTP treatment showed a persisted dyskinesia, the content of dopamine in striatum and the expression of TH in midbrain and ileum were decreased, the expression of Iba-1, CD4, IL-22 in midbrain and ileum increased continuously with persisted intestinal histopathology and intestinal barrier injury. Decreased intestinal bile secretion in addition with abnormal digestion and metabolism of carbohydrate, lipids and proteins were found, whereas these pathological status for the MPTP mice without casein intake had recovered after 24 days, no significant differences were observed with regard to only treated with casein. Our study demonstrates that intestinal pathologic injury, intestinal dysbacteriosis and metabolism changes promoted by casein in MPTP mice ultimately exacerbated the lesions to dopaminergic neurons.

C. A. Hop C. Inter-individual and inter-regional variations in enteric drug metabolizing enzyme activities: Results with cryopreserved human intestinal mucosal epithelia (CHIM) from the small intestines of 14 donors

We have previously reported successful isolation and cryopreservation of human intestinal mucosa (CHIM) with retention of viability and drug metabolizing enzyme activities. Here we report the results of the quantification of drug metabolizing enzyme activities in CHIM from different regions of the small intestines from 14 individual donors. CHIM were isolated from the duodenum, jejunum, and ileum of 10 individuals, and from 10 consecutive 12-inch segments starting from the pyloric sphincter of human small intestines from four additional individuals. P450 and non-P450 drug metabolizing enzyme activities (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A, UGT, SULT, FMO, MAO, AO, NAT1, and NAT2) were quantified via incubation with pathway-selective substrates. Quantifiable activities were observed for all pathways except for CYP2A6. Comparison of the duodenum, jejunum, and ileum in 10 donors shows jejunum had higher activities for CYP2C9, CYP3A, UGT, SULT, MAO, and NAT1. Further definition of regional variations with CHIM from ten 12-inch segments of the proximal small intestine shows that the segments immediately after the first 12-inch segment (duodenum) had the highest activity for most of the drug metabolizing enzymes but with substantial differences among the four donors. Our overall results demonstrate that there are substantial individual differences in drug metabolizing enzymes and that jejunum, especially the regions immediately after the duodenum, had the highest drug metabolizing enzyme activities.

FEATURES OF HISTOCHEMICAL CHANGES IN THE ACTIVITY OF SUCCINATE DEHYDROGENASE OF ARTIFICIAL BLADDER IN DYNAMICS (EXPERIMENTAL STUDY)

The gold standard for the treatment of invasive bladder cancer recognized throughout the world is radical cystectomy with orthotopic ileocystoplasty using the ileal intestinal tract. The study of the effect of urine on the adaptation of the mucosa of the artificial bladder continues for the last twenty years. According to the researchers, the results are quite contradictory, as some scientists note the hypersecretion of sulphomucins, sialomucins, progressive atrophy of microvilli, adenomatous hyperplasia and dysplasia. The aim of investigation to study the features of the histochemically revealed activity of succinate dehydrogenase in the wall of the artificial bladder and ileum in experimental animals. The material of the present study were the results obtained from the study of 18 female mini-pigs aged 4-5 months and weighing 8-10 kg. The modeling of the artificial bladder was performed in experimental animals, by cystectomy and subsequent ileo-cystoplasty. Experimental animals with a bladder model in groups of 6 animals were withdrawn from the experiment 3, 6 and 12 months after operational modeling. As for the wall of the official bladder, the changes in the activity of the studied enzymes were significant and showed not only possible changes in the activity of the Krebs cycle, but also about periodic displacements of the accents of substrate maintenance. These changes, in our view, are related to the transformation processes in the structural elements of the ileum wall, from which an unproblem has been formed to fulfill new functional duties. Signs of a violation of energy metabolism indicate the processes of hypoxia in the tissue of the artificial bladder and require further study and observation.

Evaluation of an insect meal of the Black Soldier Fly (Hermetia illucens) as soybean substitute: Intestinal morphometry, enzymatic and microbial activity in laying hens

This research investigated the ileum morphometry and enzymatic activity, the caecal volatile fatty acid production and the apparent nutrient digestibility in laying hens fed a Hermetia illucens larvae meal (HILM) as a complete replacement of diet soybean meal (SBM). The hens fed HILM exhibited a lower live weight (P<0.05) and a higher incidence of the full digestive tract (P<0.05) than the SBM group. In the duodenum, the maltase exhibited a higher (P<0.05) activity in the HILM group while the intestinal alkaline phosphatase (IAP) had a higher (P<0.05) activity in the SBM group. In the ileum, the maltase and saccarase had a higher activity in the HILM hens (P≤0.01) while the IAP and ɤ glutamil transferase had a higher activity in the SBM group (P<0.05 and P<0.01, respectively). The HILM group showed a higher (P<0.05) villi height in the duodenum, while the opposite happened in the jejunum and the ileum. Only in the ileum the crypt depth resulted higher (P<0.05) in the HIML group than in the SBM. The higher production of acetate (P<0.05) and butyrate (P<0.01) affected the total production of volatile fatty acids of the HILM group. The coefficient of apparent digestibility of dry and organic matter as well as of crude protein was higher (P<0.05) in SBM group. The total replacement of SBM with HILM in laying hens diet from 24 to 45weeks of age resulted in a higher caecal production of butyric acid while the enzymatic activities of brush border membrane were partially reduced.

Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na⁺/K⁺-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes

Background: Beneficial effects of Resveratrol (RSV) have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min) in Ussing chambers (functional studies) and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs)). Results: RSV reduced alanine and glucose-induced short circuit currents (ΔI_sc) and influenced forskolin-induced ΔI_sc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1), AMP-activated protein kinase (AMPK), protein kinase A substrates (PKA-S) and liver kinase B1 (LKB1) increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1) and (phosphorylated) Na⁺/H⁺-exchanger 3 (NHE3) did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP) levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.

High altitude increases the expression of hypoxia-inducible factor 1α and inducible nitric oxide synthase with intest-inal mucosal barrier failure in rats

BACKGROUND

The failure of intestinal mucosal barrier may induce multiple organ dysfunction and systemic inflammatory response syndrome, but little work has been done on whether hypobaric hypoxia related to the failure of intestinal mucosal barrier.

AIMS

To study the expression of hypoxia-inducible factor 1α (HIF-1α), inducible nitric oxide synthase (iNOS) and morphological changes of intestinal mucosa in albino rats at different altitude.

METHODS

30 male Wistar rats raised in plain for one month were randomly divided into 3 groups: Plain 500 m group (n=10), High-altitude (HA) 3842 m group (n=10) and HA4767 m group (n=10). Each group was delivered to different altitude area at the same shipping time and executed after 3 days' exposure to different altitude. Intestinal segments with the same location of all rats were removed for morphological analyses. Morphologic parameters (villous height, crypt depth, mucosal wall thickness and villous surface area) were measured by optical and scanning electron microscope. The expression of iNOS and HIF-1α were detected by immunohistochemistry.

RESULTS

Morphological indexes in higher altitude groups were exacerbated obviously compared with those of lower altitude groups. While the expression of iNOS and HIF-1α in higher altitude groups were significantly increased than those of lower altitude groups. Linear correlation analysis showed that the expression of iNOS was positively correlated with that of HIF-1α.

CONCLUSIONS

Hypobaric hypoxia increases the expression of HIF-1α and iNOS in intestinal mucosa, however exacerbates the mucous morphologic parameters with altitude increasing. HIF-1α may regulate the expression of iNOS and be involved in the damage of intestinal mucosa.

Modulation of small intestinal homeostasis along with its microflora during acclimatization at simulated hypobaric hypoxia

At high altitude (HA) hypobaric hypoxic environment manifested several pathophysiological consequences of which gastrointestinal (GI) disorder are very common phenomena. To explore the most possible clue behind this disorder intestinal flora, the major player of the GI functions, were subjected following simulated hypobaric hypoxic treatment in model animal. For this, male albino rats were exposed to 55 kPa (approximately 4872.9 m) air pressure consecutively for 30 days for 8 h/day and its small intestinal microflora, their secreted digestive enzymes and stress induced marker protein were investigated of the luminal epithelia. It was observed that population density of total aerobes significantly decreased, but the quantity of total anaerobes and Escherichia coli increased significantly after 30 days of hypoxic stress. The population density of strict anaerobes like Bifidobacterium sp., Bacteroides sp. and Lactobacillus sp. and obligate anaerobes like Clostridium perfringens and Peptostreptococcus sp. were expanded along with their positive growth direction index (GDI). In relation to the huge multiplication of anaerobes the amount of gas formation as well as content of IgA and IgG increased in duration dependent manner. The activity of some luminal enzymes from microbial origin like a-amylase, gluco-amylase, proteinase, alkaline phosphatase and beta-glucuronidase were also elevated in hypoxic condition. Besides, hypoxia induced in formation of malondialdehyde along with significant attenuation of catalase, glutathione peroxidase, superoxide dismutase activity and lowered GSH/GSSG pool in the intestinal epithelia. Histological study revealed disruption of intestinal epithelial barrier with higher infiltration of lymphocytes in lamina propia and atrophic structure. It can be concluded that hypoxia at HA modified GI microbial imprint and subsequently causes epithelial barrier dysfunction which may relate to the small intestinal dysfunction at HA.

Innate lymphoid cells regulate intestinal epithelial cell glycosylation

Fucosylation of intestinal epithelial cells, catalyzed by fucosyltransferase 2 (Fut2), is a major glycosylation mechanism of host-microbiota symbiosis. Commensal bacteria induce epithelial fucosylation, and epithelial fucose is used as a dietary carbohydrate by many of these bacteria. However, the molecular and cellular mechanisms that regulate the induction of epithelial fucosylation are unknown. Here, we show that type 3 innate lymphoid cells (ILC3) induced intestinal epithelial Fut2 expression and fucosylation in mice. This induction required the cytokines interleukin-22 and lymphotoxin in a commensal bacteria-dependent and -independent manner, respectively. Disruption of intestinal fucosylation led to increased susceptibility to infection by Salmonella typhimurium. Our data reveal a role for ILC3 in shaping the gut microenvironment through the regulation of epithelial glycosylation.

Effects of protease, phytase and a Bacillus sp. direct-fed microbial on nutrient and energy digestibility, ileal brush border digestive enzyme activity and cecal short-chain fatty acid concentration in broiler chickens

Two experiments were conducted to determine the effects of protease and phytase (PP) and a Bacillus sp. direct-fed microbial (DFM) on dietary energy and nutrient utilization in broiler chickens. In the first experiment, Ross 308 broiler chicks were fed diets supplemented with PP and DFM in a 2×2 factorial arrangement. The 4 diets (control (CON), CON + PP, CON + DFM, and CON + PP + DFM) were fed from 15–21 days of age. In Experiment 1, significant interaction (P≤0.01) between PP and DFM on the apparent ileal digestibility coefficient for starch, crude protein, and amino acid indicated that both additives increased the digestibility. Both additives increased the nitrogen retention coefficient with a significant interaction (P≤0.01). Although no interaction was observed, significant main effects (P≤0.01) for nitrogen-corrected apparent ME (AMEn) for PP or DFM indicated an additive response. In a follow-up experiment, Ross 308 broiler chicks were fed the same experimental diets from 1–21 days of age. Activities of ileal brush border maltase, sucrase, and L-alanine aminopeptidase were increased (P≤0.01) by PP addition, while a trend (P = 0.07) for increased sucrase activity was observed in chickens fed DFM, in Experiment 2. The proportion of cecal butyrate was increased (P≤0.01) by DFM addition. Increased nutrient utilization and nitrogen retention appear to involve separate but complementary mechanisms for PP and DFM, however AMEn responses appear to have separate and additive mechanisms.

Effect of cholera toxin on ATPase activities in rabbit small intestinal mucosa

Cholera toxin induced the appearance of ATPase activity in rabbit small intestinal mucosa. This enzyme significantly differed from other ATPases, including Na(+),K(+)-ATPase and HCO3(-)-ATPase in the small intestinal epithelium of rabbits, by some properties, in particular, by relation to divalent and monovalent cations and anions, pH optimum, substrate specificity, and inhibitory analysis.

[Protective effect of baicalin against LPS-induced intestinal injury]

OBJECTIVE

To investigate the protective effect of baicalin on the intestinal mucosal injury caused by endotoxin-lipopolysaccharide (LPS) and the anti-oxidative injury in colonic and ileal mucosa of rats with septicopyemia.

METHOD

Fifty healthy male BALB/c mice were randomly divided into 5 groups: the normal control group, the model group, and baicalin high-dose, medium-dose and low-dose groups. They were orally administered with double distilled water, 100 mg x kg(-1) of baicalin, 50 mg x kg(-1) of baicalin, and 25 mg x kg(-1) of baicalin respectively for three days, once a day. 1 h after the oral administration on 3 d, they were intraperitoneally injected with normal saline or LPS (17 mg x kg(-1)). At 20 h after the injection of LPS, all of the mice were sacrificed, and their colonic and ileal tissues were collected. The mental status, life state and death rate of mice in each group were observed, and the lengths of colonic were measured. Chiu's scoring method was used to assess the intestinal mucosal injury. Histopathological changes of intestinal tissues were tested by HE staining. The ultraviolet spectrophotometry was used to detect total antioxidant capacity (T-AOC), superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-PX) of intestinal homogenate. The immunohistochemical method was used to analyze the expression of PCNA in intestinal tissues of each group.

RESULT

The death of mice was observed after the intraperitoneal injection of LPS. The death rates of baicalin groups were remarkably lower than the death rate of the model group. The colons in the medium-dose baicalin group were much longer than that in the model group (P < 0.05), with a much lower intestinal mucosa injury degree than the model group. Colonic and ileal injuries in the high-dose baicalin group significantly (P < 0.05). Colonic and ileal injuries in the medium-dose baicalin group and the low-dose baicalin group significantly reduced compare with the model group (P < 0.000 1). The medium-dose baicalin group showed no significant increase in homogenate's T-AOC, T-SOD and GSH-PX compare with the model group (P < 0.05). There was no significant difference between baicalin groups and the model group in PCNA.

CONCLUSION

Baicalin can protect intestinal epithelial cells suffering from injury from oxygen radicals, and relieve the intestinal injury caused by LPS by improving the intestinal mucosa structure and functions.

Tumor necrosis factor-α mediates JNK activation response to intestinal ischemia-reperfusion injury

AIM: To investigate whether tumor necrosis factor-α (TNF-α) mediates ischemia-reperfusion (I/R)-induced intestinal mucosal injury through c-Jun N-terminal kinase (JNK) activation.

METHODS: In this study, intestinal I/R was induced by 60-min occlusion of the superior mesenteric artery in rats followed by 60-min reperfusion, and the rats were pretreated with a TNF-α inhibitor, pentoxifylline, or the TNF-α antibody infliximab. After surgery, part of the intestine was collected for histological analysis. The mucosal layer was harvested for RNA and protein extraction, which were used for further real-time polymerase chain reaction, enzyme-linked immunosorbent assay and Western blotting analyses. The TNF-α expression, intestinal mucosal injury, cell apoptosis, activation of apoptotic protein and JNK signaling pathway were analyzed.

RESULTS: I/R significantly enhanced expression of mucosal TNF-α at both the mRNA and protein levels, induced severe mucosal injury and cell apoptosis, activated caspase-9/caspase-3, and activated the JNK signaling pathway. Pretreatment with pentoxifylline markedly downregulated TNF-α at both the mRNA and protein levels, whereas infliximab pretreatment did not affect the expression of TNF-α induced by I/R. However, pretreatment with pentoxifylline or infliximab dramatically suppressed I/R-induced mucosal injury and cell apoptosis and significantly inhibited the activation of caspase-9/3 and JNK signaling.

CONCLUSION: The results indicate there was a TNF-α-mediated JNK activation response to intestinal I/R injury.

[Morpho-functional changes of rat ileum in ethanol intoxication]

The effect of chronic alcohol intoxication of 2, 4 and 6 months' duration on the morpho-functional state of the ileum was studied in male rats (n = 36) using histological, morphometric and histochemical methods. The results show that alcohol intoxication for a period of 2 months induced the changes in the mucous membrane of the ileum which in the form of its hypertrophy accompanied by the increase of epitheliocyte mitotic activity and goblet cell number. The activity of succinate dehydrogenase in the enterocytes and muscular tunic myocytes of the ileum wall was increased. After 4 and 6 months the changes included the inhibition of enterocyte mitotic activity. By 6 months of the experiment marked atrophy of the mucous membrane was noted. Succinate dehydrogenase activity was decreased in all the structures studied.

Application of soybean meal, soy protein concentrate and isolate differing in α-galactosides content to low- and high-fibre diets in growing turkeys

The aim of this experiment was to investigate the physiological and growth response of young turkeys (up to 8 weeks of age) to dietary replacement of soybean meal (SBM) by soy protein concentrate (PC) or protein isolate (PI). This replacement resulted in a differentiated dietary concentration of α-galactosides of over 2.5% in the SBM diet, approximately 2% with a mixture SBM and PC, 1% with a PC diet and 0.1% with a PI diet. Each treatment was applied in two ways: with lower (3.5%) or higher (5.3%) dietary crude fibre content, made by supplementation with soybean hulls. The highest and lowest body weight of turkeys was recorded both after the first and second 4-week half of the study in the PC and PI-type diets respectively. A gradual withdrawal of α-galactosides from a diet was accompanied by a decline in ileal tissue mass, ileal viscosity and activity of endogenous maltase (the latter was found to be significant at 4 weeks of age). At the same time, two-way anova revealed that an elevated level of crude fibre (HF treatment) caused an increase in ileal tissue mass (p < 0.05 after 4 weeks of feeding) as well as a decrease in activity level of intestinal sucrase and maltase. The presence of raffinose family oligosaccharides in a diet, in contrast to dietary crude fibre level, significantly affected the caecal metabolism. The rate of bacterial production of short-chain fatty acids in the caeca was distinctly diminished by dietary withdrawal of α-galactosides. In conclusion, the soy protein concentrate, in contrast to the protein isolate preparation, exerted positive effects on the turkeys' growth and gastrointestinal tract physiology and should be considered as an effective SBM substitute.

Changes in mucosal alpha-glucosidase activities along the jejunal-ileal axis by an Hm-HACS diet intake are associated with decreased lipogenic enzyme activity in epididymal adipose tissue

Heat-moisture (hm)-high-amylose corn starch (HACS), which includes a larger amount of resistant starch than HACS or regular cornstarch (CS), is more indigestible in the small intestine than HACS or CS. An hm-HACS diet was also shown to ameliorate glucose intolerance and lipid abnormalities. This study examined the effects of feeding rats an hm-HACS diet for 14 days on the activities of mucosal alpha-glucosidase along the jejunal-ileal axis and lipogenic enzymes in epididymal adipose tissue. The contents in the lumen of the cecum were increased by feeding rats the HACS and hm-HACS diets, and the cecal weight was increased by the hm-HACS diet. The HACS diet reduced the activity of alpha-glucosidase in the upper jejunal mucosa, induced its activity in the upper ileal mucosa, reduced lipogenic enzyme activity in epididymal adipose tissue, and reduced serum triglyceride levels. These effects were more pronounced with the hm-HACS than with the HACS diet. These results suggest that feeding rats the hm-HACS diet reduced the activities of lipogenic enzymes in adipose tissue and alpha-glucosidase in the jejunal mucosa and induced the activity of alpha-glucosidase in the ileal mucosa compared with the HACS diet.

Modulation of intestinal transport of 2,4-dinitrophenyl-S-glutathione, a multidrug resistance-associated protein 2 substrate, by bilirubin treatment in rats

The effect of bilirubin treatment on intestinal transport of 2,4-dinitrophenyl-S-glutathione (DNP-SG), a substrate of multidrug resistance-associated protein 2 (MRP2), after application of 1-chloro-2, 4-dinitrobenzene (CDNB), a precursor of DNP-SG, was examined in rat intestine by the in-vitro everted sac, in-situ re-circulating perfusion, and in-situ loop methods. CDNB was taken up rapidly by jejunum and ileum, and the consequent intestinal efflux of DNP-SG, a glutathione conjugated metabolite of CDNB, was significantly higher in jejunum than in ileum in the in-situ and in-vitro studies. Co-administration of bilirubin (100 μM), as well as probenecid (1 mM) or ciclosporin (100 μM), with CDNB decreased the DNP-SG efflux in jejunum significantly, but not in ileum. The suppression of DNP-SG efflux in jejunum was also observed after intravenous administration of bilirubin (85.5 μmol kg−1), in which plasma bilirubin glucuronide levels were approximately 100 μM. In the in-vitro metabolism study, bilirubin exerted no significant effect on CDNB metabolism in the intestinal S9 fraction (supernatant of 9000 g). These results suggested that the diseased states accompanied with hyperbilirubinaemia might have increased the intestinal absorption, or oral bioavailability, of MRP2 substrates by suppressing MRP2 function at the proximal intestinal region.

Delayed development of interstitial cells of Cajal in the ileum of a human case of gastroschisis

The Interstitial Cells of Cajal (ICC) are responsible for rhythmic electrical activity. A paralytic ileus is present in gastroschisis (GS), a malformation due to a defective closure of the abdominal wall through which part of the intestine herniates during pregnancy. In experimental GS, ICC morphological immaturity was shown in the rat foetus at-term but it could not be demonstrated whether differentiation is accomplished post-natally. For this purpose we morphologically investigated ICC, as well as enteric neurons and smooth muscle cells, in a case of human GS at birth and 1 month later when peristaltic activity had initiated. A 36 weeks gestation female was born by c/section with prenatal diagnosis of GS and possible volvulus of the herniated intestine. At birth, the necrotic intestine was resected and both ileostomy and colostomy were performed. The intestine continuity was restored after 4 weeks. Intestinal specimens, taken during both operations at the level of the proximal stoma, were immunostained with c-kit, neuron-specific-enolase and alpha-smooth-muscle-actin antibodies and some processed for electron microscopy. ICC were present at the myenteric plexus only. At birth, these cells were rare and ultrastructurally immature; 1 month later, when partial enteral feeding was tolerated, they formed rows or groups and many of them were ultrastructurally differentiated. Neurons and smooth muscle cells, immature at birth, had developed after 1 month. Therefore, ICC differentiation, as well as that of neurons and smooth muscle cells, is delayed at birth and this might explain the paralytic ileus in GS. One month later, differentiation quickly proceeded at all cellular levels paralleling the increasing tolerance of enteral nutrition.

5-lipoxygenase modulates the alteration of paracellular barrier function in mice ileum during experimental colitis

Small intestine permeability is frequently altered in inflammatory bowel disease and may be caused by the translocation of intestinal toxins through leaky small intestine tight junctions (TJs) and adherence. Recently, it has been shown that 5-lipoxygenase (5-LO) plays an important role in the development of various inflammatory conditions like inflammatory bowel disease. In the present study, by comparing the responses in wild-type mice (5-LOWT) with those of mice lacking the 5-lipoxygenase (5-LOKO), we investigated the role played by this enzyme in the permeability and structure of small intestine TJs in an animal model of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). Four days after colitis induction by DNBS, the ileal TJs were studied by means of transmission electron microscopy using lanthanum nitrate and immunohistochemistry of occludin and ZO-1. When compared with DNBS-treated 5-LOWT mice, DNBS-treated 5-LOKO mice experienced a reduced rate of the extent and severity of the histological signs of colon injury. After administration of DNBS, 5-LOWT mice showed a significant increase of ileal permeability (88.3% +/- 1.2%) compared with sham (5.6% +/- 0.5%). In colitis, the percentage of "leaky" junctions in terminal ilea correlated positively with the macroscopic colon damage score. Distal colitis in 5-LOWT mice induces an increase of TJ permeability throughout the entire small intestine, and the extent of alterations correlates with colonic damage. On the contrary, a significant reduction of (1) the degree of colon injury, (2) the alteration of ZO-1 and occludin localization (immunohistochemistry), and (3) ileal permeability (8.1% +/- 0.7%) caused by DNBS in the colon was observed in 5-LOKO mice. Similarly, the treatment of 5-LOWT with zileuton (50 mg/kg per oral gavage twice a day), a 5-LO inhibitor, resulted in a significant reduction of all the previously described parameters. Taken together, our results clearly demonstrate that 5-LO modulates small intestinal permeability in experimental colitis through the regulation of TJ protein.

Expression of CYP3A isoforms and P-glycoprotein in human stomach, jejunum and ileum

1. CYP3A isoforms metabolise a diverse array of clinically important drugs and P-glycoprotein (P-gp), a transmembrane efflux pump, can extrude a wide variety of drugs from the cell. It has been suggested that the function of CYP3A4 is complementary to that of P-gp along the gastrointestinal (GI) tract, together forming a coordinated intestinal barrier against xenobiotics. Therefore, the expression of CYP3A4, CYP3A5, CYP3A7 and ABCB1 (P-gp) genes were quantified in five normal samples from the human stomach, seven from the jejunum and eight from the ileum by real-time reverse transcription-polymerase chain reaction and western blot analysis. 2. In the tissues examined, measurable mRNA expression of CYP3A was found in almost all samples from the stomach, jejunum and ileum. The rank order for CYP3A mRNA expression was CYP3A4 > CYP3A5 > CYP3A7 in the GI tract studied, whereas median mRNA CYP3A4 expression was highest in the small intestine and lowest in the stomach. Expression of ABCB1 mRNA was found in almost all samples and the median mRNA expression level was comparable in the jejunum and ileum, but lower in the stomach. Our data also show a significant correlation between all mRNA transcripts studied and a wide interindividual variation. 3. At the protein level, CYP3A4 was detected in all stomach and small intestine samples, the levels being substantially higher in the small intestine than in the stomach. P-Glycoprotein was detected in all GI samples, but no statistically significant difference was found along the GI tract considered. 4. Collectively, these results demonstrate that CYP3A4 is the main CYP3A expressed in the GI tract investigated, an extensive interindividual variability in the expression of the different CYP3A isoforms in all tissues examined and P-gp apoprotein levels similar in the stomach, jejunum and ileum.

A novel phosphatase upregulated in Akp3 knockout mice

Reexamination of the Akp3(-/-) mouse intestine showed that, despite the lack of intestinal alkaline phosphatase (IAP), the Akp3(-/-) gut still had considerable alkaline phosphatase (AP) activity in the duodenum and ileum. This activity is due to the expression of a novel murine Akp6 gene that encodes an IAP isozyme expressed in the gut in a global manner (gIAP) as opposed to duodenum-specific IAP (dIAP) isozyme encoded by the Akp3 gene. Phylogenetically, gIAP is similar to the rat IAP I isozyme. Kinetically, gIAP displays a 5.7-fold reduction in catalytic rate constant (k(cat)) and a 30% drop in K(m), leading to a 4-fold reduction k(cat)/K(m) compared with dIAP, and these changes in enzymatic properties can all be attributed to a crucial R317Q substitution. Western and Northern blot analyses document the expression of Akp6 in the gut, from the duodenum to the ileum, and it is upregulated in the jejunum and ileum of Akp3(-/-) mice. Developmentally, Akp3 expression is turned on during postnatal days 13-15 and exclusively in the duodenum, whereas Akp6 and Akp5 are expressed from birth throughout the gut with enhanced expression at weaning. Posttranslational modifications of gIAP have a pronounced effect on its catalytic properties. Given the low catalytic efficiency of gIAP, its upregulation during fat feeding, its sequence similarity with rat IAP I, and the fact that rat IAP I has been implicated in the upregulation of surfactant-like particles during fat intake, it appears likely that gIAP may have a role in mediating the accelerated fatty acid intake observed in Akp3(-/-) mice fed a high-fat diet.

Inflammation and inflammatory agents activate protein kinase C epsilon translocation and excite guinea-pig submucosal neurons

BACKGROUND & AIMS

Properties of enteric neurons are transformed by inflammation and protein kinase C (PKC) isoforms are involved both in long-term changes in enteric neurons, and in transducing the effects of substances released during inflammation. We investigated roles of PKCepsilon in submucosal neurons by studying translocation in response to inflammatory mediators, effects on neuron excitability, and the changes in PKCepsilon distribution in a trinitrobenzene sulphonate model of ileitis.

METHODS

Immunohistochemical detection and analysis of association with membrane and cytosolic fractions, and Western blot analysis of cytosolic and particulate fractions were used to quantify translocation. Electrophysiology methods were used to measure effects on neuron excitability.

RESULTS

All submucosal neurons were immunoreactive for the novel PKC, PKCepsilon, and direct PKC activators, phorbol 12,13-dibutyrate, ingenol 3,20-dibenzoate, and the PKCepsilon-specific activator, transactivator of transduction-Psiepsilon receptor for activated C kinase, all caused PKCepsilon translocation from cytoplasm to surfaces of the neurons. Electrophysiologic studies showed that the stimulant of novel PKCs, ingenol (1 micromol/L), increased excitability of all neurons. Stimulation of protease-activated receptors caused PKCepsilon translocation selectively in vasoactive intestinal peptide secretomotor neurons, whereas a neurokinin 3 tachykinin receptor agonist caused translocation in neuropeptide Y and calretinin neurons. In all cases translocation was reduced significantly by a PKCepsilon-specific translocation inhibitor peptide. Increased PKCepsilon at the plasma membrane occurred in all neurons 6-7 days after an inflammatory stimulus.

CONCLUSIONS

Major targets for PKCepsilon include ion channels near the plasma membrane. PKCepsilon is likely to have a significant role in controlling the excitability of submucosal neurons and is probably an intermediate in causing hyperexcitability after inflammation.

Characterization of protein kinase pathways responsible for Ca2+ sensitization in rat ileal longitudinal smooth muscle

We investigated the protein kinases responsible for myosin regulatory light chain (LC20) phosphorylation and regulation of myosin light chain phosphatase (MLCP) activity during microcystin (phosphatase inhibitor)-induced contraction at low Ca2+ concentrations of rat ileal smooth muscle stretched in the longitudinal axis. Application of 1 microM microcystin induced LC20 diphosphorylation and contraction of beta-escin-permeabilized rat ileal smooth muscle at pCa 9. The PKC inhibitor GF-109203x, the MEK inhibitor PD-98059, and the p38 MAPK inhibitor SB-203580 significantly reduced this contraction. These inhibitory effects were abolished when the microcystin concentration was increased to 10 muM, indicating that application of these kinase inhibitors generated an increase in MLCP activity. GF-109203x and PD-98059, but not SB-203580, significantly decreased the phosphorylation level of the myosin-targeting subunit of MLCP, MYPT1, at Thr-697 (rat sequence) during microcystin-induced contraction at pCa 9. On the other hand, SB-203580, but not GF-109203x or PD-98059, significantly reduced the phosphorylation level of the PKC-potentiated phosphatase inhibitor of 17 kDa (CPI-17). A zipper-interacting protein kinase (ZIPK) inhibitor (SM1 peptide) and a Rho-associated kinase inhibitor (Y-27632) had little effect on microcystin-induced contraction at pCa 9. In conclusion, PKC, ERK1/2, and p38 MAPK pathways facilitate microcystin-induced contraction at low Ca2+ concentrations by contributing to the inhibition of MLCP activity either through phosphorylation of MYPT1 or CPI-17 [probably mediated by integrin-linked kinase (ILK)]. ILK and not ZIPK is likely to be the protein kinase responsible for LC20 diphosphorylation during microcystin-induced contraction of rat ileal smooth muscle at pCa 9, similar to its recently described role in vascular smooth muscle. The negative regulation of MLCP by PKC and MAPKs during microcystin-induced contraction at pCa 9, which is not observed in vascular smooth muscle, may be unique to phasic smooth muscle.