Greater fat oxidation with diacylglycerol oil consumption for 14 days compared with triacylglycerol oil consumption in overweight men and women.

BACKGROUND: Several studies have reported increased fat oxidation with diacylglycerol (DAG) oil consumption. However, the effects of long-term DAG oil consumption on energy metabolism remain to be investigated. OBJECTIVE: The objective of this study was to compare the effects of 14 days of either DAG or triacylglycerol (TAG) oil consumption on substrate oxidation, energy expenditure (EE) and dietary fat oxidation. DESIGN: Eight males and six females participated in this randomized, double-blind, crossover feeding study. Each patient consumed the 14-day controlled test diet containing either 10 g day(-1) of DAG or TAG oil for acclimatization before a respiratory chamber measurement, followed by a 2-week washout period between diet treatments. Substrate oxidation and EE were measured in the respiratory chamber at the end of each dietary treatment. The patients consumed test oil as 15% of total caloric intake in the respiratory chamber (mean test oil intake was 36.1+/-6.6 g day(-1)). RESULTS: Twenty-four hour fat oxidation was significantly greater with 14 days of DAG oil consumption compared with TAG oil consumption (78.6+/-19.6 and 72.6+/-14.9 g day(-1), respectively, P<0.05). There were no differences in body weight or body composition between diet treatments. Dietary fat oxidation was determined using the recovery rate of (13)CO(2) in breath, and was significantly enhanced with DAG oil consumption compared with TAG oil consumption, measured over 22 h after ingestion of (13)C-labelled triolein. Resting metabolic rate (RMR) was significantly greater with DAG oil consumption compared with TAG oil consumption (1766+/-337 and 1680+/-316 kcal day(-1), respectively, P<0.05). CONCLUSION: Consumption of DAG oil for 14 days stimulates both fat oxidation and RMR compared with TAG oil consumption, which may explain the greater loss of body weight and body fat with DAG oil consumption that has been observed in weight-loss studies.

Saliva-promoted adhesion of Streptococcus mutans MT8148 associates with dental plaque and caries experience.

Colonization of enamel surfaces by Streptococcus mutans is thought to be initiated by the attachment of bacteria to a saliva-derived conditioning film (acquired pellicle). However, the clinical relevance of the contribution of saliva-promoted S. mutans adhesion in biofilm formation has not yet been fully elucidated. The aim of this study was to correlate saliva-promoted S. mutans adhesion with biofilm formation in humans. We correlated all measurements of salivary factors and dental plaque formation in 70 healthy subjects. Dental plaque development after thorough professional teeth cleaning correlated positively with S. mutans adhesion onto saliva-coated hydroxyapatite pellets and the glycoprotein content of either parotid or whole saliva. Saliva-promoted S. mutans adhesion and glycoprotein content were also positively correlated with each other in parotid and whole saliva. By contrast, neither salivary mutans streptococci, Lactobacillus nor Candida correlated with biofilm formation. Parotid saliva-mediated S. mutans adhesion was significantly higher in 12 caries-experienced (CE) subjects than in 9 caries-inexperienced (CI) subjects. Salivary S. mutans adhesion was significantly less (p < 0.01) in the CI group than in the CE group. In conclusion, the present findings suggest the initial S. mutans adhesion, modulated by salivary protein adsorption onto the enamel surface, as a possible correlate of susceptibility to dental plaque and caries.

Statherin and histatin 1 reduce parotid saliva-promoted Streptococcus mutans strain MT8148 adhesion to hydroxyapatite surfaces.

Small salivary phosphoproteins--statherin (ST) and histatin 1 (HT1) - are found in the acquired enamel pellicle which modulates Streptococcus mutans adhesion onto dental enamel. However, their roles in S. mutans adhesion onto enamel surfaces are still undefined. The aim of this study was to investigate whether and how ST and HT1 affect (i) S. mutans adhesion and (ii) the adsorption of S. mutans adhesion-promoting salivary proteins onto hydroxyapatite (HA) in vitro. We fractionated human parotid saliva by adsorption to HA and further by gel filtration chromatography. Adhesion of [3H]-labeled S. mutans strain MT8148 onto sintered HA plates was promoted significantly (>10-fold) by high-molecular weight glycoprotein fraction (HMWGP), but not by purified ST or HT1. More interestingly, promotion of S. mutans adhesion onto HA by HMWGP was significantly reduced by adding purified ST or HT1 to HMWGP. [3H]-labeled S. mutans adhesion on HA was positively correlated to the [14C]-labeled HMWGP adsorption onto HA, which was also reduced by the addition of purified ST and HT1. Synthetic peptides corresponding to ST and HT1 reduced the parotid saliva-promoted S. mutans adhesion. However, removal of the negative charges in the N-terminal domains of ST and HT1 diminished their inhibitory effects on S. mutans adhesion promoted by parotid saliva. We conclude that ST and HT1 competitively inhibit the adsorption of salivary HMWGP, and thereby reduce S. mutans adhesion onto HA surfaces.

Reduction of diet-induced obesity by a combination of tea-catechin intake and regular swimming.

OBJECTIVE: Obesity is a metabolic disorder resulting from imbalance between metabolizable energy intake and energy expenditure. It is known to be a strong risk factor for lifestyle-related diseases. Here, we investigated the effects of long-term intake of tea catechins (Cat) in combination with regular exercise (Ex) on the development of obesity in C57BL/6 mice. DESIGN: We compared body weight, adipose tissue mass, plasma parameters and beta-oxidation activity in mice fed a low-fat diet (5% triglyceride (TG); LF), a high-fat diet (30% TG; HF), a HF diet supplemented with 0.5% (w/w) tea Cat, a HF diet in addition to swimming Ex or a HF diet plus 0.5% tea Cat in addition to swimming Ex (Cat+Ex) for 15 weeks. Oxygen consumption and respiratory quotients were measured using indirect calorimetry. RESULTS: Tea-Cat intake in combination with swimming Ex suppressed HF diet-induced body-weight gain by 18 and 22%, respectively, compared to Ex and tea-Cat intake on their own. Visceral fat accumulation and the development of hyperinsulinemia and hyperleptinemia were also reduced in the HF+Cat+Ex group. Muscular beta-oxidation activity in this group was 69 and 52% higher, respectively, than that in the HF and HF+Cat groups. Lipid oxidation, determined using indirect calorimetry, was higher in the HF+Cat+Ex group, suggesting increased lipid utilization at the individual level. CONCLUSION: These results indicate that intake of tea Cat, together with regular Ex helps to reduce diet-induced obesity. This effect might be attributed, at least in part, to the activation of whole-body energy metabolism.

Reduction of saliva-promoted adhesion of Streptococcus mutans MT8148 and dental biofilm development by tragacanth gum and yeast-derived phosphomannan.

The aim of this study was to investigate materials which reduce saliva-promoted adhesion of Streptococcus mutans onto enamel surfaces, and their potential in preventing dental biofilm development. The effects of hydroxyapatite (HA) surface pretreatment with hydrophilic polysaccharides on saliva-promoted S. mutans adhesion in vitro and de novo dental biofilm deposition in vivo were examined. Saliva-promoted adhesion of S. mutans MT8148 was significantly reduced by pretreatment of the HA surface with tragacanth gum (TG) and yeast-derived phosphoglycans. Extracellular phosphomannan (PM) from Pichia capsulata NRRL Y-1842 and TG reduced biofilm development on lower incisors in plaque-susceptible rats when administered via drinking water at concentrations of 0.5% and 0.01%, respectively. The inhibitory effect of TG on de novo dental biofilm formation was also demonstrated when administered via mouthwash in humans. It is concluded that TG and yeast-derived PM have the potential for use as anti-adherent agents and are effective in reducing de novo dental biofilm formation.

Beneficial effects of tea catechins on diet-induced obesity: stimulation of lipid catabolism in the liver.

OBJECTIVE: Obesity has increased at an alarming rate in recent years and is now a worldwide health problem. We investigated the effects of long-term feeding with tea catechins, which are naturally occurring polyphenolic compounds widely consumed in Asian countries, on the development of obesity in C57BL/6J mice. DESIGN: We measured body weight, adipose tissue mass and liver fat content in mice fed diets containing either low-fat (5% triglyceride (TG)), high-fat (30% TG), or high-fat supplemented with 0.1-0.5% (w/w) tea catechins for 11 months. The beta-oxidation activities and related mRNA levels were measured after 1 month of feeding. RESULTS: Supplementation with tea catechins resulted in a significant reduction of high-fat diet-induced body weight gain, visceral and liver fat accumulation, and the development of hyperinsulinemia and hyperleptinemia. Feeding with tea catechins for 1 month significantly increased acyl-CoA oxidase and medium chain acyl-CoA dehydrogenase mRNA expression as well as beta-oxidation activity in the liver. CONCLUSION: The stimulation of hepatic lipid metabolism might be a factor responsible for the anti-obesity effects of tea catechins. The present results suggest that long-term consumption of tea catechins is beneficial for the suppression of diet-induced obesity, and it may reduce the risk of associated diseases including diabetes and coronary heart disease.

Long-term ingestion of dietary diacylglycerol lowers serum triacylglycerol in type II diabetic patients with hypertriglyceridemia.

We examined the effect of daily consumption of dietary diacylglycerol (DG) oil on serum lipid concentrations in patients with diabetes whose serum triacylglycerol (TG) levels were persistently increased despite continuous nutritional counseling at the outpatient clinic. Patients (n = 16) were divided into DG and control groups (n = 8 each). DG was incorporated (target dose 10 g/d) by substituting DG oil (80 g DG/100 g oil) for the ordinary TG cooking oil used at home for 12 wk. The control group continued consuming ordinary TG cooking oil. Dietary records indicated that there were no differences between groups in total energy intake or percentage of energy from fat. In the DG group, TG intake decreased from 26.8 +/- 9.3 to 15.7 +/- 8.9 g/d, whereas DG intake increased from 0.3 +/- 0.1 to 10.6 +/- 3.9 g/d. No differences between groups were observed in body weight, total fat intake or total oil consumption throughout the study period. In the DG group, serum TG levels decreased 39.4% from 2.51 +/- 0.75 mmol/L to 1.52 +/- 0.28 mmol/L. Serum glycohemoglobin A(1c) (HbA(1c)) concentration also decreased 9.7%. In contrast, there were no changes in these variables in the control group. Serum total and HDL cholesterol were not affected in either group. These results indicate that DG oil may be useful as an adjunct to the standard diet therapy of fat restriction in the management of diabetics with hypertriglyceridemia.

Dynamics of postprandial remnant-like lipoprotein particles in serum after loading of diacylglycerols.

BACKGROUND: To compare the effects of diacylglycerol (DAG) on postprandial lipid metabolism with triacylglycerol (TAG), we examined the differences in the dynamics of remnant lipoproteins after loading of DAG or TAG of the same fatty acid composition. METHODS: The subjects were comprised of 6 male volunteers who orally took creamed test meals prepared with either DAG or TAG at a dose of 30 g lipid/m(2) of body surface area in the early morning after fasting for at least 12 h. Blood was taken before and 2, 3, 4, 6 and 8 h after lipid loading. To quantify the amount of remnants, as the parameters, we used concentrations of cholesterol (RLP-C) and triacylglycerol (RLP-TG) in remnant-like lipoprotein particles (RLP) of serum. RESULTS: The serum triacylglycerol concentration was markedly increased 2 h after loading of DAG and TAG. Serum triacylglycerol concentrations at 2, 3 and 8 h after loading of DAG were significantly lower than those after loading of TAG. The serum RLP-C concentration was significantly lower 2, 3 and 8 h after loading of DAG than TAG. There was a trend toward less increase in the RLP-TAG in the DAG group. The area under the curve (AUC) of serum RLP-TAG after DAG loading was significantly lower than that following TAG loading. CONCLUSIONS: DAG might reduce the risk of coronary arteriosclerotic diseases by weakening the postprandial increase of RLP that is known to be closely correlated with atherosclerosis.

Sulfated polysaccharides, but not cellulose, increase colonic mucus in rats with loperamide-induced constipation.

Colonic mucus is decreased in a rat model of spastic constipation, and some types of water-insoluble dietary fiber increase colonic mucus when consumed by rats for several weeks. However, little is known about the effect of water-soluble dietary fiber on the colonic mucus. The aim of the present study was to investigate the effect of various types of water-soluble dietary fiber on colonic mucus in a rat model of spastic constipation. Oral administration of 1.5 mg/day of carrageenan and chondroitin sulfate increased the fecal excretion, epithelial mucin production, thickness of the mucous layer, and amount of luminal mucus in loperamide-administered rats. Sodium alginate, 5 mg/day, thickened the mucus layer at the fecal surface. Cellulose, 5 mg/day, increased the fecal excretion but not the colonic mucus. Carrageenan, chondroitin sulfate, and sodium alginate, but not cellulose, increased colonic mucus in the rat model of spastic constipation.

Solubilization of phytosterols in diacylglycerol versus triacylglycerol improves the serum cholesterol-lowering effect.

OBJECTIVE: This study was performed to investigate the difference in the serum-cholesterol- and triglyceride-lowering activities between phytosterols dissolved in diacylglycerol (PS/DG) and dispersed in triacylglycerol (PS/TG). The effects of the solvent on the concentrations of serum beta-sitosterol and campesterol were examined. DESIGN: The study had a randomised crossover design. SUBJECTS: Twelve healthy normocholesterolemic or moderately hypercholesterolemic men aged 29-50 y participated in this study. INTERVENTIONS: For 2 weeks before the test period (designated as the control period), all subjects consumed control mayonnaise (PS free) daily with supper and were randomly assigned to two groups for the 2 week test period; one group was given mayonnaise containing PS (500 mg/day) dissolved in DG (10 g/day), and the other mayonnaise containing PS (500 mg/day) dispersed in TG (10 g/day). After a wash out period consuming control PS-free mayonnaise for 4 weeks, the groups were reversed for 2 weeks. RESULTS: PS/TG feeding had no effect on the serum cholesterol level. In contrast, PS/DG feeding significantly reduced the total and LDL cholesterol levels from the initial value of 5.57 to 5.31 mmol/l (4.7%; P<0.05) and from 3.69 to 3.39 mmol/l (7.6%; P<0.05), respectively. Moreover, the degree of total cholesterol reduction induced by PS/DG feeding in the test period was significantly greater than that induced by PS/TG feeding (P<0.05). In addition, the serum beta-sitosterol and campesterol concentrations did not change during the PS/TG or PS/DG feeding periods. CONCLUSIONS: Dissolution of PS in DG had a better serum cholesterol lowering effect than dissolution in TG. SPONSORSHIP: Kao Corporation.

Enhancing effect of alpha-monoisostearyl glyceryl ether on the percutaneous penetration of indomethacin through excised rat skin.

The enhancing effect of alpha-monoisostearyl glyseryl ether (GE-IS) on the percutaneous penetration of indomethacin (IM) from test solutions in propylene glycol (PG) was investigated using the excised abdominal skin of rats in vitro. The percutaneous penetration of IM into diffusion cells was significantly increased in the presence of 0.2% or 1% (w/w) GE-IS compared with enhancer-free PG solution. Permeation parameters of IM, such as lag time and permeability coefficient, revealed that GE-IS significantly augmented the percutaneous penetration of IM from PG. These results strongly suggested that GE-IS functions as a penetration enhancer of IM through rat skin. To elucidate the mode of action of GE-IS as a penetration enhancer, the solubility of IM in the test solution and the percutaneous penetration of IM through damaged skin from which the stratum corneum had been stripped were investigated. The results suggested that GE-IS acts directly on the stratum corneum and alters the permeability of the skin.

Energy value and digestibility of dietary oil containing mainly 1,3-diacylglycerol are similar to those of triacylglycerol.

Diacylglycerol (DAG) is a component of various vegetable oils. Approximately 70% of the DAG in edible oils are in the configuration of 1,3-DAG. We recently showed that long-term ingestion of dietary oil containing mainly 1,3-DAG reduces body fat accumulation in humans as compared to triacylglycerol (TAG) oil with a similar fatty acid composition. As the first step to elucidate the mechanism for this result, we examined the difference in the bioavailabilities of both oils by measuring food energy values and digestibilities in rats. Energy values of the DAG oil and the TAG oil, measured by bomb calorimeter, were 38.9 and 39.6 kJ/g, respectively. Apparent digestibility expressed according to the formula: (absorbed) x (ingested)(-1) x 100 = (ingested - excreted in feces) x (ingested)(-1) x 100 for the DAG oil and the TAG oil were 96.3+/-0.4 and 96.3+/-0.3% (mean +/- SEM), respectively. The similarity in the bioavailabilities of both oils supports the hypothesis that the reduced fat accumulation by dietary DAG is caused by the different metabolic fates after the absorption into the gastrointestinal epithelial cells.

Abundant expression of uncoupling protein-2 in the small intestine: up-regulation by dietary fish oil and fibrates.

Mitochondrial uncoupling protein-2 (UCP-2) is widely expressed in various mammalian tissues, although its physiological functions are not well understood. We examined the effects of dietary fish oil on UCP-2 expression in the rat small intestine, in which UCP-2 mRNA levels are higher than in other organs. Feeding with fish oil (20%) up-regulated UCP-2 mRNA within 6 days in the small intestine as well as the liver, compared to feeding with soybean oil. This was mimicked by feeding with agonists for peroxisome proliferator-activated receptor alpha (PPARalpha) such as fenofibrate and bezafibrate, but not the PPARgamma agonist troglitazone. The bezafibrate-induced increase in UCP-2 expression was found within 2 days in the small intestine, but only after 6 days in the liver. The up-regulation of UCP-2 was also found in cultured intestinal epithelial cells (IEC-6) treated for 24 h with various long-chain fatty acids and PPARalpha agonists. These results indicated that intestinal UCP-2 is up-regulated through direct activation of PPARalpha by dietary fatty acids.

Dietary diacylglycerol suppresses high fat and high sucrose diet-induced body fat accumulation in C57BL/6J mice.

Diacylglycerol (DG) comprises up to approximately 10% of various edible oils. In the present study, we examined the effects of dietary DG consisting mainly of 1,3-species on body weight, body fat accumulation, and mRNA levels of various genes involved in energy homeostasis in obesity-prone C57BL/6J mice. Five-month feeding with the high triacylglycerol (TG) diet (30% TG + 13% sucrose) resulted in significant increases in body weight, visceral fat accumulation, and circulating insulin and leptin levels compared with mice fed the control diet (5% TG). Compared with mice fed the high TG diet, body weight gain and visceral fat weight were reduced by 70% and 79%, respectively, in those fed the high DG diet (30% DG + 13% sucrose). In addition, circulating leptin and insulin levels were reduced to the respective control levels. Compared with high TG feeding, high DG feeding suppressed the elevation of leptin mRNA expression in adipose tissue, and up-regulated acyl-coenzyme (Co)A oxidase and acyl-CoA synthase mRNA expression in the liver. These results indicate that dietary DG is beneficial for suppression of high fat diet-induced body fat accumulation. Furthermore, it is suggested that structural differences in DG and TG, but not the composition of fatty acid, markedly affect nutritional behavior of lipids. -- Murase, T., T. Mizuno, T. Omachi, K. Onizawa, Y. Komine, H. Kondo, T. Hase, and I. Tokimitsu. Dietary diacylglycerol suppresses high fat and high sucrose diet-induced body fat accumulation in C57BL/6J mice. J. Lipid Res. 2001. 42: 372--378.

Improvement of macromolecular clearance via lymph flow in hamster gingiva by low-power carbon dioxide laser-irradiation.

BACKGROUND AND OBJECTIVE: Although therapeutic effects of low-power laser-irradiation on periodontal disease have been reported, little is known about the biological effects of laser-irradiation in the gingiva. Recently we reported that topical warming stimulated macromolecular clearance via lymph flow in hamster gingiva. This study was conducted to investigate whether low-power laser-irradiation affects macromolecular clearance via the lymph flow in the gingiva. STUDY DESIGN/MATERIALS AND METHODS: We injected 14C-methylated albumin into the mandibular gingiva of anesthetized hamsters followed by topical carbon dioxide (CO2) laser-irradiation (30 seconds, 0.5-1.5 W). We measured the clearance of radiolabeled albumin from the gingiva and its drainage into submandibular lymph nodes during 10 minutes. RESULTS: The clearance of the radiolabeled albumin from the gingiva and the influx into the submandibular lymph nodes were increased by CO2 laser-irradiation. CONCLUSION: Low-power CO2 laser-irradiation improves macromolecular clearance via the lymph flow in hamster gingiva.

Fat-soluble vitamin status is not affected by diacylglycerol consumption.

OBJECTIVE: The objective of this study was to examine the effect of dietary diacylglycerol (DAG) on the bioavailability of fat-soluble vitamins in comparison with triacylglycerol (TAG). METHODS: We conducted a long-term administration test of DAG and TAG in 27 healthy men aged 27-47 years. After measuring baseline values, subjects were randomized into two groups, one group (n = 15) was given DAG and the other (n = 12) was given TAG. Subjects ingested 20 g of DAG or TAG either in mayonnaise or an emulsion drink of their own choice at meals once a day for 12 weeks. At 4, 8 and 12 weeks, fasting blood samples were drawn and serum levels of vitamin A, E, and D were measured. RESULTS: There were no significant changes in vitamin A levels throughout the study period. Compared to the initial values (using a Student's t test for paired values), significant differences of vitamin E and D were seen at some points during the experiment. According to a two-way repeated measures analysis of variance, however, DAG and TAG (lipid) and time had no effect on fat-soluble vitamin levels. CONCLUSIONS: Our results indicate that DAG does not affect the absorption of the fat-soluble vitamins in diets.

Relationship between covalently bound ceramides and transepidermal water loss (TEWL).

The stratum corneum, which is the outermost layer of the skin, functions as an important barrier to maintain biological homeostasis. The multilamellar structures formed by intercellular lipids present in the stratum corneum are considered to play an important role in barrier function. Most intercellular lipids are unbound and can be extracted by organic solvents, but some intercellular lipids are covalently bound to cornified envelope proteins. Decreases in unbound lipid levels reduce the barrier function of the stratum corneum, but the relationship between bound lipid and the barrier function of the stratum corneum is not well understood. In this study, we examined the relationship between the amount of covalently bound ceramide, the main bound lipid, and the barrier function of the stratum corneum. A single dose of UVB irradiation (2 x MED), or continuous UVB irradiation (0.5 x MED/day for 14 days) to the back, or feeding with an essential fatty acid-deficient (EFAD) diet for 8 weeks caused a significant elevation of TEWL and a significant reduction in covalently bound ceramides in hairless rats. Transmission electron microscopy revealed that the intercellular multilamellar structures in the stratum corneum of treated rats were incomplete (folding, defects, unclear images) compared to the structures seen in the stratum corneum of non-UVB-irradiated and non-EFAD rats. These results suggest that the amount of covalently bound ceramides is highly correlated with the barrier function of the skin, and that covalently bound ceramides play an important role in the formation of lamellar structures, and are involved in the maintenance of the barrier function of the skin.

Improvement of macromolecular clearance via lymph flow in hamster gingiva by topical warming and massage.

The lymphatic system is very important for macromolecular clearance in various tissues, especially in the gingiva. However, the kinetics of macromolecular clearance via the lymph flow in the gingiva are poorly understood. The aim of this study was to investigate whether thermal or mechanical stimulation affects macromolecular clearance via the lymph flow in the gingiva. Carbon black suspension was injected into the mandibular gingiva of anesthetized hamsters and its drainage into cervical lymph nodes was examined. Clearance of 14C-methylated bovine albumin and tritiated water from the gingiva and their drainage into submandibular lymph nodes and blood was quantified. The effect of topical warming or massage on clearance of 14C-methylated albumin from the gingiva during a 15 min period was examined. In addition, the influence of neurochemical antagonists on the stimulatory effect of topical warming on albumin clearance was investigated. Submandibular lymph nodes were clearly delineated by carbon black 10 min after the injection. More radiolabeled albumin appeared in submandibular lymph nodes than in serum, while more tritiated water appeared in serum. Topical warming (45 degrees C, 2 min) and warming plus massage (with a silicon rubber brush, 20 s) decreased the radiolabeled albumin in the gingiva 15 min after the injection. There was less radiolabeled albumin in the gingiva after gingival warming plus massage than after warming. Previous injection of HOE140 or propranolol into the gingiva diminished the stimulatory effect of topical warming on albumin clearance. It was concluded that topical warming plus massage improves macromolecular clearance via the lymph flow in hamster gingiva.

Decreased colonic mucus in rats with loperamide-induced constipation.

Constipation is a risk factor of colorectal cancer. Mucin is a major component of lumenal mucus, which protects the colorectal mucosa against mechanical and chemical damage. The aim of this study was to evaluate mucus production and to quantitate lumen mucus in a rat model of spastic constipation. We induced constipation with loperamide (1.5 mg/kg), and histochemically evaluated mucus production and the thickness of the mucus layer at the fecal surface. We quantitated the mucus attached to the mucosal surface using colonic perfusion with N-acetylcysteine. While more feces remained in the colon, there was less fecal excretion and lower fecal water content in loperamide-administered rats than in control rats. Crypt epithelial cells contained less mucus in constipated rats than in control rats. The mucus layer at the fecal surface was thinner and less mucus was recovered from the mucosal surface in constipated rats than in control rats. Mucus production of crypt epithelial cells and mucus at the fecal and mucosal surface were reduced by loperamide-induced constipation.

Short chain fatty acids but not lactate or succinate stimulate mucus release in the rat colon.

BACKGROUND: Short chain fatty acids (SCFAs) affect various intestinal functions. Mucus is an important physiological component of the intestinal mucosal barrier. However, the effect of SCFAs or other organic acids on the intestinal mucus release is poorly understood. The aim of this study was to investigate whether lumen SCFA stimulates mucus release into the rat colon. METHODS: A solution of SCFA, lactate or succinate was infused into the colon of anesthetized rats, and we then measured the hexose content of the effluent. We also examined the influence of cholinergic antagonists on the effects of SCFA. RESULTS: A SCFA mixture (75 mM acetate, 35 mM propionate and 20 mM butyrate) or individual SCFAs (130 mM) increased the mucus release into the colon in a similar manner. The individual SCFAs, but not lactate or succinate, stimulated colonic mucus secretion in similar concentration-dependent manners. Butyrate stimulated colonic mucus secretion at 20 mM, but acetate, propionate, lactate and succinate at this concentration did not. Pretreatment with an anti-cholinergic agent diminished the stimulatory effects of SCFAs on mucus secretion. CONCLUSIONS: Lumen SCFAs, but not lactate or succinate, stimulate mucus release from the rat colon via a cholinergic nerve mechanism.