Effects of galacto-oligosaccharide ingestion on the mucosa-associated mucins and sucrase activity in the small intestine of mice

BACKGROUND

Galacto-oligosaccharides (GOS) are non-digestible oligosaccharides with short galactosyl chain units produced by lactose fermentation which are considered as prebiotics. Only few studies have investigated the effects of GOS medium-term ingestion on the small intestinal epithelium characteristics.

AIM OF THE STUDY

In this study, we evaluated the consequences of GOS ingestion on small intestinal mucosal morphology, on brush-border membrane enzyme activities and on mucin content in BALB/c mice.

METHODS

Mice received the experimental diets for 4 weeks and then the small intestine was collected to measure sucrase, lactase and alkaline phosphatase activities, to study the villus heights in the jejunum mucosa and to determine mucosal mucin content as well as MUC-2 and MUC-4 mRNAs expression by qRT-PCR.

RESULTS

Our results showed that GOS has no detectable effect on the intestine villus height but increased the total protein content by twofold. Sucrase activity was significantly increased in the intestinal mucosa recovered from animals fed the GOS diet without any detectable modification of lactase and phosphatase activities. Interestingly, GOS was also able to increase sucrase activity in cultured Caco-2 cells raising the view that they likely act directly on these cells. Furthermore, GOS was found to markedly increase O-linked glycoproteins associated with the intestinal mucosa without modifying MUC-2, MUC-4 mRNAs expression. Lastly, TNF-alpha mRNA expression was also not modified after GOS ingestion.

CONCLUSIONS

These results suggest that, in BALB/c mice, 4-week GOS ingestion is able to increase the small intestinal mucosa-associated mucin content and enterocyte-associated sucrase activity without modifying villus height.

Effects of Streptococcus thermophilus TH-4 on intestinal mucositis induced by the chemotherapeutic agent, 5-Fluorouracil (5-FU)

Beneficial bacteria (probiotics) and probiotic-derived factors have the potential to ameliorate disorders of the intestine. The aim of this study was to compare live Streptococcus thermophilus TH-4 (TH-4), dead TH-4 and TH-4 supernatant in rats treated with 5-Fluorouracil. Rats were randomly allocated to five treatment groups (n=8-10): Saline+Water; 5-FU+Skim Milk; 5-FU+Live TH-4; 5-FU+Supernatant TH-4; and 5-FU+Dead TH-4. 5-FU (150mg.kg(-1)) was administered by a single intraperitoneal injection on day 0; animals were killed on day 4. Treatments were administered daily from days -2 to 3 via oro-gastric gavage. Metabolic parameters were measured daily. Blood was obtained by cardiac puncture, and intestinal tissues removed for quantitative and qualitative histological assessment, including: villous height and area; crypt depth and area, mitotic count and crypt fission; biochemical determination of sucrase and myeloperoxidase (MPO) activity; and disease severity scoring. One-way ANOVA statistical analyses were conducted for the majority of outcome measures. Live TH-4 significantly reduced disease severity score by 13% (p< 0.05), and partially normalised mitotic counts compared with 5-FU+Skim milk controls. Live and supernatant TH-4 reduced crypt fission by 69% and 48% (p< 0.05), respectively, compared to 5-FU+Skim Milk controls. No significant differences (p> 0.05) in the occurrence of bacteraemia were evident across all groups. Live TH-4 partially normalised mitotic count and histological severity score in 5-FU treated rats. The inhibitory effect of live TH-4 and TH-4 supernatant on crypt fission suggests therapeutic utility in the prevention of disorders characterised by increased crypt fission, such as colorectal carcinoma.

Alpha-glucosidase inhibitor from Kothala-himbutu (Salacia reticulata WIGHT)

A polyhydroxylated cyclic 13-membered sulfoxide (1) was isolated from an aqueous extract of Kothala-himbutu ( Salacia reticulata WIGHT). The structure of compound 1 was elucidated by 1D and 2D NMR and APCI-MS methods. The alpha-glucosidase inhibitory activity of compound 1 (IC 50: maltase, 0.227 microM; sucrase, 0.186 microM; isomaltase, 0.099 microM) was much greater than the inhibitory activity of salacinol and kotalanol, which were previously isolated from Kothala-himbutu.

2,3,7,8-Tetrachlorodibenzo-p-dioxin-induced change in intestinal function and pathology: evidence for the involvement of arylhydrocarbon receptor-mediated alteration of glucose transportation

Although numerous studies have been performed to clarify the mechanism(s) underlying the toxicological responses induced by dioxins, their effect on the intestine is less well understood. To address this issue, we examined the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the pathology and function of the intestine in arylhydrocarbon receptor (AhR)-sensitive (C57BL/6J) and -less-sensitive (DBA/2J) mice. A single oral administration of TCDD (100 mug/kg) to C57BL/6J mice produced changes in villous structure and nuclear/cytoplasm ratio in the epithelial cells of the intestine. Furthermore, in an oral glucose tolerance test, the serum glucose level was significantly increased in the C57BL/6J mouse but not in the DBA/2J mouse by TCDD treatment. In agreement with this, the expression of intestinal mRNAs coding sodium-glucose co-transporter 1 (SGLT1) and glucose transporter type 2 were increased only in C57BL/6J mice by TCDD. The increase in the former transporter was also confirmed from its protein level. The glucose level in the intestinal contents is thought to be one of the factors contributing to SGLT1 induction. Concerning with this, the intestinal activity of sucrase and lactase was significantly increased only in C57BL/6J mice by TCDD. These results suggest that while TCDD produces initial damage to the intestinal epithelium, the tissues induce SGLT1 to facilitate the absorption of glucose, which is expected, at least partially, to combat the wasting syndrome induced by TCDD. The data provided here also suggest that AhR is involved in the mechanism of SGLT1 induction.

Butyrate-treated colonic Caco-2 cells exhibit defective integrin-mediated signaling together with increased apoptosis and differentiation

We previously reported that the enterocytic differentiation of human colonic Caco-2 cells correlated with alterations in integrin signaling. We now investigated whether differentiation and apoptosis of Caco-2 cells induced by the short-chain fatty acid butyrate (NaBT) was associated with alterations in the integrin-mediated signaling pathway with special interest in the expression and activity of focal adhesion kinase (FAK), of the downstream phosphatidylinositol 3'-kinase (PI 3-kinase)-Akt pathway and in the role of the nuclear factor kappaB (NF-kappaB). NaBT increased the level of sucrase. It induced apoptosis as shown by: (1) decreased Bcl-2 and Bcl-X(L) proteins and increased Bax protein; (2) activation of caspase-3; and (3) increased shedding of apoptotic cells in the medium. This effect was associated with defective integrin-mediated signaling as shown by: (1) down-regulation of beta1 integrin expression; 2) decreased FAK expression and tyrosine phosphorylation; (3) concerted alterations in cytoskeletal and structural focal adhesions proteins (talin, ezrin); and (4) decreased FAK ability to associate with PI 3-kinase. However, in Caco-2 cells, beta1-mediated signaling failed to be activated downstream of FAK and PI 3-kinase at the level of Akt. Transfection studies show that NaBT treatment of Caco-2 cells promoted a significant activation of the NF-kappaB which was probably involved in the NaBT-induced apoptosis. Our results indicate that the prodifferentiating agent NaBT induced apoptosis of Caco-2 cells probably through NF-kappaB activation together with a defective beta1 integrin-FAK-PI 3-kinase pathways signaling.

Novel alpha-glucosidase inhibitors, CKD-711 and CKD-711a produced by Streptomyces sp. CK-4416. II. Biological properties

CKD-711 and CKD-711a are aminooligosaccharide alpha-glucosidase inhibitors discovered during the bioactive material screening for antibacterial agent. Their inhibitory activities were studied and compared with those of acarbose in vitro and in vivo with animals. In in vitro study, CKD-711 showed similar effects to acarbose on porcine intestinal maltase and sucrase, IC50s of 2.5 and 0.5 microg/ml, respectively, whereas it had about 2 fold lower alpha-amylase inhibitory activity (IC50, 78.0 microg/ml) than acarbose (IC50, 36 microg/ml). CKD-711a showed less inhibitory activity than CKD-711 against all the enzymes tested. In rat fed on starch and sucrose meals, the dose of CKD-711 which reduced the postprandial blood glucose increment by 50 percent in comparison to control rats (ED50) were 3.07 and 1.15 mg/kg, respectively, and acarbose had ED50s of 1.94 and 1.15 mg/kg, respectively. CKD-711 and CKD-711a also showed antibacterial activity against Comamonas terrigena.

Effects of two highly monounsaturated oils on lipid composition and enzyme activities in rat jejunum

The effects of two monounsaturated fatty acid (MUFA) oils, olive oil (OO) and high-oleic sunflower oil (HOSO), with high content in oleic acid but differing in their non-fatty acid fraction, on brush-border membrane (BBM) lipid composition and fluidity and on mucosal enzyme activities of rat jejunum were studied. Animals were given semipurified diet with linoleic acid to prevent essential fatty acid deficiency (control group) or semipurified diet containing 10% of either OO or HOSO for 12 weeks. There was a significant decrease in the content of jejunal BBM phospholipids together with an increase in the level of free cholesterol in both oil-fed rats, when compared to control group. Although the increase in the BBM free cholesterol level was not statistically significant in HOSO-fed rats, a significant decrease in the phospholipid/free cholesterol ratio was found in both OO and HOSO-fed animals compared to control group. Rat jejunal BBM had a high level of free fatty acids which was increased in BBM isolated from OO and HOSO-fed animals. There was no statistical significant difference in the phospholipid distribution between the control and the OO group. However, HOSO-fed animals showed the lowest level of phosphatidylethanolamine together with the highest phosphatidylcholine content and the phosphatidylcholine/sphingomyelin ratio. The fatty acid pattern of jejunal BBM lipids was modified according to the major fatty acids in the oils. There was a decrease in both stearic acid (18:0) and linoleic acid (18:2 n-6), together with an increase in oleic acid (18:1 n-9) in jenunal BBM isolated from both oil experimental groups. All these results were accompanied by a significant increase in the BBM fluidity (as assessed by steady-state fluorescence polarization of diphenylhexatriene) isolated from oil-fed rat, when compared to control group. OO and HOSO-fed animals had the lowest activities of sucrase and maltase, while alkaline phosphatase activity only was decreased in HOSO-fed animals. The specific activity of maltase was not modified in any experimental rats. In summary, both MUFA oils induced similar effects on jejunal BBM lipid composition, fluidity, sucrase, maltase and lactase activities. Furthermore, HOSO intake resulted in a lowest alkaline phosphatase activity which was accompanied by changes in individual phospholipid composition. All these results suggest that effects of MUFA oils on jejunal BBM lipid composition and hydrolase activities are most likely due to the presence of high content of oleic acid rather than other components contained in the non-fatty acid of olive oil.

Anti-diarrhoeal and gastro-intestinal potentials of the aqueous extract of Phyllanthus amarus (Euphorbiaceae)

The anti-diarrhoeal and gastro-intestinal protective potentials of aqueous extract of leaves of Phyllanthus amarus were investigated in mice. Graded doses of the aqueous extract (100-800 mg/kg) administered orally produced a dose-related inhibition of gut meal travel distance in normal mice. The highest intestinal transit inhibition of 31.65% was obtained with 400 mg/kg. In castor oil induced diarrhoea in mice, P. amarus extract (400 mg/kg) delayed the onset of diarrhoea, reduced frequency of defecation and reduced gut meal travel distance significantly resulting in intestinal transit inhibition of 79.94% compared to 86.92% produced by morphine (100 mg/kg). In addition, the activities of some intestinal mucosa enzymes (maltase, sucrase, lactase and alkaline phosphatase) in mice pretreated with extract before castor oil were not as severely depressed as those in the control (castor oil treated mice). Phytochemical screening revealed the presence of many secondary metabolites. The results are discussed with a view to establishing the basis of the use of this plant in traditional medicine for treatment of diarrhoea and other gastrointestinal disorders.

Preventive effects of germinated barley foodstuff on methotrexate-induced enteritis in rats

The preventive effects of the dietary germinated barley foodstuff (GBF), which increases the contents of protein, RNA and DNA in the intestinal mucosa of rats on the mucosal damage and diarrhea were examined in a methotrexate (MTX)-induced enteritis model in rats. Sprague-Dawley rats intraperitoneally injected with MTX (10 mg/kg body weight) were used as an enteritis model. After consumption of diets containing GBF, glutamine or a glutamine-rich stuff (gluten), mucosal damage, contents of mucosal protein, RNA and DNA, myeloperoxidase (MPO) activity, bacterial translocation and DNA synthetic activity in the small intestine were assessed. GBF more effectively prevented diarrhea and mucosal damages, and increased mucosal protein, DNA and RNA contents than glutamine or gluten. The bacterial trans-location and elevation of MPO activity induced by MTX were depressed only by the consumption of GBF. GBF has a potential as therapeutic diet to decrease the adverse effects of anti-cancer chemotherapy.

Alterations of male Wistar rat jejunum induced by Dodine (n-dodecylguanidine acetate)

The effect of Dodine on the intestine was studied after a single administration of 1000 mg/kg, which corresponds to the LD50 in male Wistar rats. At this dose, a significant decrease in body weight was observed, accompanied by diarrhea, which may be associated with intestinal alterations. The chemical induced a significant reduction of the protein content and in sucrase activity in the jejunum. Morphological alterations included a significant decrease in crypt height and in villus length and depth. The intestinal modifications observed in animals after Dodine administration may explain the observed loss in body weight and diarrhea.

Oral insulinlike growth factor-I stimulates intestinal enzyme maturation in newborn rats

Insulinlike growth factor-I (IGF-I) has been found in the milk of various species. To investigate if milk-borne IGF-I has any effect on postnatal gut development in neonatal animals, newborn rat pups were given orally 1 microg recombinant human IGF-I daily for 3 days. For comparison, a separate group of newborn pups was given 150 microg hydrocortisone, the hormone known to stimulate intestinal maturation in neonatal rats. Oral IGF-I treatment had no significant effect on the animal body weight nor on the weight of the stomach, small and large intestines, and pancreas. Oral administration of hydrocortisone significantly reduced body weight gain, but it had no apparent effect on internal organ weights. Both IGF-I and hydrocortisone treatments, however, significantly increased lactase, maltase and sucrase activities and hydrocortisone significantly increased aminopeptidase activity at the proximal small intestine when compared with the control. The finding supports the hypothesis that milk-borne IGF-I may play a role in regulating postnatal gut development in the suckling young.

Effects of different subchronic treatments with lindane on some brush border enzymes in rat jejunum

Subchronic lindane (gamma-HCH) intoxication by oral or s.c. injection over 7 and 15 days, induced a significant inhibition in rat jejunum maltase activity when the pesticide was administered at doses of 20 mg/kg b. wt. However, maltase levels remained unaffected in those animals injected with 10 mg/kg of lindane. A longer period of s.c. lindane exposure (30 days) at doses of 10 mg/kg induced a significant decrease in maltase activity, although the injection of 20 mg/kg over the same period did not alter this enzyme activity. When this lindane dose was s.c. injected over 20 days a significant inhibition of maltase activity was observed. However no changes in this enzyme were found in rats injected over 25 days. This fact seems to suggest that between 20-25 days of pesticide exposure the organism develops possible regulatory mechanisms to counteract the alterations induced by this dose of lindane on maltase activity. Lactase and alkaline phosphatase activities were not altered by lindane action in different treatments performed. Sucrase activity was only altered in oral injected rats at doses of 20 mg/kg over 15 days. In conclusion, maltase activity seems to be more sensitive to lindane action than other brush border enzymatic proteins; lindane effects on this enzyme depend on the injected dose and the pesticide administration period duration.

Inhibitors of pig kidney trehalase

Trehazolin, a new trehalase inhibitor isolated from the culture broth of Micromonospora, was reported to be a highly specific inhibitor for porcine and silk worm trehalases with IC50 values of 5.5 x 10(-9) and 3.7 x 10(-9) M, respectively (O. Ando, H. Satake, K. Itoi, A. Sato, M. Nakajima, S. Takashi, H. Haruyama, Y. Ohkuma, T. Kinoshita, and R. Enokita (1991) J. Antibiot. 44, 1165-1168). We also found that trehazolin is a very powerful and quite specific inhibitor against purified pig kidney trehalase, giving an IC50 value of 1.9 x 10(-8) M. Lineweaver-Burk plots showed that this compound was a competitive inhibitor of the trehalase. However, even at concentrations of 200 micrograms/ml, trehazolin did not inhibit the rat intestinal maltase or sucrase, yeast alpha-glucosidase or almond beta-glucosidase. Validoxylamine A and validamycin A, two other trehalase inhibitors, showed potent competitive inhibition against purified pig kidney trehalase, with IC50 values of 2.4 x 10(-9) and 2.5 x 10(-4) M, respectively. On the other hand, validoxylamine A was almost inactive against rat intestinal sucrase and maltase, with some inhibition being observed at millimolar concentration. A number of other glucosidase inhibitors, such as MDL 25637, castanospermine, and deoxynojirimycin were also tested against the purified trehalase and showed reasonable inhibitory activity.

Beneficial effects of L-arginine on intestinal epithelial restitution after ischemic damage in rats

The polyamines are involved in repair processes after intestinal ischemia. Arginine and ornithine, both precursors of polyamines were therefore expected to exert beneficial effects on mucosal barrier dysfunction. Arginine may also generate NO and there is support for the view that NO may be beneficial after an ischemic insult. Male Wistar rats were given, by gavage, isonitrogenous solutions of L-arginine (0.5 g/kg) or L-ornithine (0.7 g/kg) 17 and 2 h before ischemia. Controls received an isonitrogenous solution of casein hydrolysate (1 g/kg). Transient intestinal ischemia was produced in anesthetized rats by occluding the superior mesenteric artery for 90 min. Intestinal morphology, hydrolase activities, polyamine and cGMP contents, and cell proliferation rates were determined 4 h after reperfusion. Administration of arginine or ornithine did not prevent ischemic damage but accelerated morphological repair, enhanced cell proliferation, and polyamine content was observed. Arginine was significantly more effective than ornithine. Formation of cGMP was enhanced after arginine administration. NG-nitroarginine methylester, an inhibitor of NO synthase, prevented the arginine effects on mucosal repair. We conclude that arginine-derived NO is an important mediator in the restitution of intestinal mucosa by minimizing cell injury during reperfusion.

Action of zinc on enzymatic digestion and intestinal transport of sugar in the rabbit

The aim of the present work was to study whether zinc chloride added to the drinking water of rabbits affected the intestinal absorption of D-galactose and the activity of sucrase in the jejunum. The results showed that zinc decreased D-galactose absorption in the jejunal tissue. The effect appeared to be due mainly to an action on the active transport of the sugar by the mucosal border of the intestinal epithelium, because the zinc seemed not to affect its diffusion across the intestinal epithelium. Zinc was also shown to inhibit the (Na(+)-Ka+)-ATPase activity of the enterocyte, which might explain the inhibition of the Na(+)-dependent transport of D-galactose. Nevertheless, a possible direct action of the zinc ion on the Na(+)-dependent carrier cannot be discounted. Zinc did not alter the activity of sucrase in the jejunum of the rabbit.

Effect of perfusion of oral rehydration solutions containing glucose polymers from corn on disaccharidases and mucosal morphology in rat small intestines

This study aims to determine the effect of glucose and glucose polymers (GP) from corn in oral rehydration solutions (ORS) on disaccharidases and morphometric measurements in small intestinal mucosa of rats. ORS containing standard composition of salts as in WHO ORS and 2, 5, or 10 per cent glucose or GP [initial glucose polymers, long chain (> 9 molecules) and short chain (2-9 molecules) glucose polymers] from corn were infused into the duodenum of 72 Sprague-Dawley rats (250-350 g). Six rats were sham operated as controls. The levels of lactase, sucrase, maltase, palatinase, and glucoamylase enzymes were higher in rats infused with ORS-containing glucose or GP than control rats. Villus height, villus width, and crypt height in corresponding segments of duodenum, jejunum, and ileum were not significantly different between rats perfused with ORS containing glucose polymers from corn and those with ORS containing glucose. ORS containing GP from corn have no adverse effects on small intestinal enzymes and morphometric measurements.

Nucleotide supplements alter proliferation and differentiation of cultured human (Caco-2) and rat (IEC-6) intestinal epithelial cells

The effect of exogenous nucleotides on the proliferation and differentiation of enterocytes was comparatively studied using a human colon tumor cell line (Caco-2) and a normal rat small intestinal crypt cell line (IEC-6). Caco-2 cells exhibited more active endogenous nucleic acid metabolism than did IEC-6 cells, as evidenced by greater cellular pools of nucleotides and their metabolites. To determine the supplemental nutritional effect of nucleotides, a mixture containing equal amounts (10 mg/L) of AMP, CMP, IMP, GMP and UMP was added to the culture medium. The results showed that a nucleotide supplement under normal culture conditions did not affect proliferation and differentiation of Caco-2 cells. In contrast, nucleotide supplements under normal culture conditions promoted proliferation of IEC-6 cells. The addition of nucleotides to the culture medium also enhanced differentiation of IEC-6 cells when grown on an extracellular matrix (Matrigel). Furthermore, when glutamine levels were less than optimal (nutritional stress conditions), nucleotide supplements enhanced growth and maturation of both cell lines. We conclude that the de novo biosynthesis of nucleotides is sufficient to support proliferation of tumor Caco-2 cells but not of the normal crypt IEC-6 cells. Thus, nucleotide supplements may enhance normal enterocyte growth and maturation as well as spare the need for exogenous glutamine in cell maintenance and development.

Polydextrose and activities of brush-border membrane enzymes of small intestine in rats and glucose absorption in humans

We investigated the effect of polydextrose, one of the water-soluble non-digestible polysaccharides, on the activities of brush-border membrane enzymes of small intestine in rats and on glucose absorption with relation to the thickness of the unstirred water layer in humans. Rats were fed a 5% polydextrose-supplemented elemental diet for 2 or 4 wk. The mucosal alkaline phosphatase, maltase, and sucrase activities were measured in the upper, middle, and lower intestine. There was no significant difference between control and polydextrose groups. The potentiometric tube was inserted orally in the jejunum. Glucose absorption was measured by perfusion with the solutions with or without 5% polydextrose. There was no significant difference in the glucose absorption rate or the thickness of the unstirred water layer between control and polydextrose solutions. The increase in viscosity of the polydextrose solution was negligible. This study indicated that polydextrose had no effect on the thickness of the unstirred water layer and did not inhibit glucose absorption in humans.

Effect of erythromycin on D-galactose absorption and sucrase activity in rabbit jejunum

Erythromycin, an antibiotic used in the treatment of infectious diseases, produces gastrointestinal side effects such as diarrhea. The mechanisms by which erythromycin produces these effects are not known. However, erythromycin has been shown to increase gastrointestinal motor activity and to inhibit intestinal neutral amino acid absorption. Both effects could contribute to the gastrointestinal side effects observed. Because the intestinal systems of amino acid and sugar transport present similar characteristics, the aim of the present work was to determine whether erythromycin also alters D-galactose absorption and sucrase activity in rabbit jejunum. The results show that erythromycin diminishes intestinal D-galactose absorption. This effect seems to be due to an action mainly located on the Na(+)-dependent sugar transport of the mucosal border of the intestinal epithelium. Erythromycin also inhibits the Na(+)-K+ ATPase activity of the enterocyte, which might explain the inhibition of the D-galactose Na(+)-dependent transport. However, a direct action of the erythromycin molecule on the Na(+)-dependent carrier cannot be excluded. Erythromycin did not alter sucrase activity.

[The effect of stress on the enzyme systems of the enterocyte microvilli in rat pups and the possible mechanism of the transmission of stress effects from dam to progeny]

In suckling rats whose mothers had had an immobilisation stress or been injected HC and T4 at the last day of their pregnancy, the sucrase induction decreased in the small intestine, if the HC was injected on the 10th day of life. The hormone injection to 1-day suckling rats did not affect the induction. These effects seem to be exerted not by the direct permeation of hormone from mother to litter but to be mediated rather by a special factor "stressin". The latter is transferred from mother to litter and decreases the sensitivity of intestinal enzymes to exogenous HC, thus exerting an antistressor effect.