Effects of high dietary cellulose on the large intestinal microflora and short-chain fatty acids in rats

Wistar rats fed diets containing different contents of cellulose or 5% transgalactosylated oligosaccharides (TOS) for 7 weeks were examined for faecal microflora and caecal short-chain fatty acids. High (15%) cellulose diet showed remarkable increases in concentrations of faecal bifidobacteria and caecal butyrate with a reduced concentration of propionate as compared with the other diets. TOS-fed rats showed strikingly increased concentrations of bifidobacteria and acetate. A comparison of pH values between the caecal contents and faeces suggested more fermentation of cellulose in the distal than proximal part of the large bowel of rats.     

The effect of dietary mannitol on the caecal microflora and short-chain fatty acids in rats

Wistar rats fed 5%-mannitol diet showed significant decreases of viridans streptococci and bifidobacteria, and a remarkable increase of butyric acid concentration and a decrease of acetic acid in the caecal contents compared with the sucrose and basal diet groups. Stocky fusiform bacteria were increased in concentration in the rats on mannitol compared with the other groups.     

THE EFFECT OF DIETARY HISTIDINE LEVEL ON THE CARNOSINE CONCENTRATION OF RAT OLFACTORY BULBS

Young adult male rats were fed purified diets supplying the maintenance level of the essential amino acids or the same diet devoid of histidine. Animals were sacrificed after 2, 4, 6 and 8 weeks on these diets and olfactory bulbs, whole brains and breast muscle removed for analysis of free histidine and histidinecontaining dipeptides. There was an immediate and sharp drop in the level of carnosine in the olfactory bulb of rats on the histidine-free diet. By 8 weeks only very small amounts of this dipeptide remained. The carnosine concentration in the olfactory bulbs of the rats receiving the maintenance level of histidine also decreased in comparison with the level maintained on the stock diet; this is believed to reflect the much reduced amount of histidine in the former as compared to the latter diet. Homocarnosine disappeared completely from whole brains of rats within 2 weeks on the histidine-free diet. Muscle carnosine decreased in both absolute terms and relative to the controls. Anserine was lower relative to the controls, but actually increased in absolute value. Histidine deficiency may be used to study the role of carnosine in olfactory function.     

The effects of pyridoxine deficiency and of caloric restriction on lipids in the developing rat brain

Abstract— The effects of dietary deficiency of pyridoxine upon the contents of lipids in the brain were determined at several times after birth for three groups of rats. The mothers of the nursing pups were fed one of the following dietary regimes: pyridoxine-deficient diet ad lib., pyridoxine-supplemented diet ad lib., or pyridoxine-supplemented diet in restricted amounts. At 7 and 14 days of postnatal age there were no significant differences between supplemented and deficient animals for any of the cerebral lipids studied. At 21 days the content of sphingomyelin in the brains of deficient animals was significantly lower than that in brains from the supplemented or calorically restricted animals in terms of percentage of total lipid and phospholipid phosphorus or tissue weight. On a per brain basis the content of sphingomyelin in the brains of calorically-restricted rats was significantly lower than in the brains of rats fed the supplemented diet ad lib. The contents of cerebrosides but not of sulphatides or ceramides were also significantly lower in brains of the deficient group than in brains from the other two groups. The contents of pyridoxine in brains and in livers of the deficient animals were considerably lower than the contents found in the same organs of the other dietary groups. The results suggest that one reason for the abnormal development of the brains of rats on a pyridoxine-deficient diet during the early postnatal period may be due to decreased quantities of sphingolipids.     

Development changes to gut microflora metabolism in mice.

Developmental changes in the activities of bacterial nitrate reductase, nitroreductase and beta-glucuronidase and their response to fermentable dietary fibre, were investigated in caecal contents from suckling mice (2-week-old) and in mice aged 4-24 weeks fed either a purified fibre-free diet or that diet supplemented with 5% (w/w) pectin. There was no apparent age-related trend common to the three enzymes studied. Nitrate reductase activity in the mice fed the fibre-free diet did not markedly alter with age. Pectin administration, however, was associated with a significant increase in nitrate reductase activity, particularly in 4-week-old mice. Nitroreductase activity exhibited an overall upward trend in mice from 2 to 12 weeks and thereafter decreased. Caecal beta-glucuronidase activity in mice increased sharply between 2 weeks and 4 weeks of age, thereafter not changing significantly until the 24th week. Pectin feeding had no consistent effect on activities either of nitroreductase or beta-glucuronidase. The changes in enzyme activities with age were not related to the concentration of bacteria in the caecum, which was highest in the 2-week-old mice. We conclude that the weaning is a period in which marked changes in caecal bacterial enzyme activities can occur.     

EFFECTS OF N-METHYLAMINOETHANOL, AND N,N-DIMETHYL-AMINOETHANOL IN THE DIET OF PREGNANT RATS ON NEONATAL RAT BRAIN CHOLINERGIC AND PHOSPHOLIPID PROFILE

Abstract— Pregnant rats were fed for 15 days predelivery until 15 days postpartum a choline (Ch)-deficient diet (CD diet) or a CD diet supplemented with 0.8% Ch-CI (CS), 1% N -methylaminoethanol (MME) or 1% N,N -dimethylaminoethanol (DME). Gestation and parturition of the pregnant rats proceeded normally. However, all the pups born of dams fed the MME diet, and most of those born of dams fed the DME diet, died within 36 h of birth. No histological or cytological alterations were detected in the brain of the pups. Levels of Ch and acetylcholine (ACh) were elevated in the brain of pups born of dams fed the MME and DME diets, but not the CS diet. The content of total phospholipids in the brain of the pups was not altered by the diet fed to the dams. However, the phosphatidyl-Ch and phosphatidylaminoethanol (PAE) contents in the brain of the MME- and DME-exposed pups were markedly reduced. At the same time, significant amounts of DME, phosphatidyl-N-monomethylaminoethanol (PMME) and of phosphatidyl- N,N -dimethylaminoethanol (PDME) were present in the same brain areas. These results are evaluated and discussed in terms of providing a cause for the death of the MME- and DME-exposed neonatal rats.     

Variation of mucin distribution in the rat intestine, caecum and colon: effect of the bacterial flora.

The influence of the intestinal microflora on mucin types was studied in the small intestine, caecum and colon of conventional (CV) rats as compared to germ-free (GF) rats. A colorimetric method was used on purified water-soluble mucin extracted from mucosal scrapings and contents. Variations occurred between the three anatomical sites both in the mucosas and intestinal contents of GF rats. In CV rats, the presence of the bacterial flora led to different effects depending on the intestinal site: in the small intestinal mucosa, neutral and sulphomucins values were higher whereas sialomucin was much lower. Conversely, sialomucin was higher in the caecal and colonic mucosas and contents whereas sulphated mucins were decreased significantly in caecal contents and caecal and colonic mucosas. These variations in the contents may reflect the bacterial mucolytic activity and the effect of bacterial metabolites on the mucosa.     

Effects of age and mannanoligosaccharides supplementation on production of volatile fatty acids in the caecum of rabbits

This trial studied the effect of including mannanoligosaccharides (MOS, Bio-Mos^®, Alltech Inc., USA) in the diet on the caecal volatile fatty acids (VFA) and pH of rabbits from 34 to 90 days of age. Three experimental diets were compared: control diet, zinc bacitracin (ZnBac) diet (control diet with 0.1 g ZnBac/kg feed) and MOS diet (control diet with 2.0 g MOS/kg feed). Rabbits were slaughtered at 34, 48, 69 and 90 days of age and caecal contents were collected and analyzed for dry matter, pH and VFA concentration. The empty caecum and caecal contents weights relative to live weight were also determined.Age affected (P<0.0001) VFA concentration and pH values in the caecum. The pH decreased with age whereas VFA concentration increased. Rabbits fed MOS had higher (P<0.05) VFA and tended (P=0.098) to had lower pH in the caecum than rabbits fed ZnBac and control diets. Acetic, propionic and butyric acids concentrations in the caecum increased with MOS but its molar proportions were similar among diets. Diet had no effect on empty caecum weight and caecal contents weight and dry matter concentration. There was no interaction effect between diet and age. From 34 to 90 days of age, VFA production was higher (P<0.05) in the caecum of rabbits fed MOS than in those fed ZnBac diet and control diet.The addition of MOS to the diet increased the VFA concentration in the caecum of growing rabbits from 34 to 90 days of age.     

Effects of cellulose, carboxymethylcellulose and inulin fed to rats as single supplements or in combinations on their caecal parameters

We compared the effect of diets containing different nondigestible carbohydrates: cellulose (C), inulin (IN) and carboxymethylcellulose (CMC) as single supplements or in dietary combination on caecal physiology of rats. Sixty male Wistar rats (Rattus norvegicus) were divided into five groups and for 4 weeks were fed a casein diet with the compared carbohydrates (4% of diet) or a combination of IN+C or IN+CMC (both 4+4%). Diet intake and FCR index remained unaffected by the treatments, whereas IN improved the body weight gain of rats compared to CMC. Compared to C group, all diets containing IN and CMC decreased the caecal pH as well as enlarged the caecum, thus increasing the weights of contents and tissue, especially upon CMC treatment. Rats given carboxymethylcellulose (CMC and IN+CMC groups) had watery caecal digesta, and some of them suffered from diarrhoea. In the case of CMC, the caecal enlargement was due to tissue hypertrophy and digesta accumulation mostly in response to an increased bulk of contents. Unlike C+IN, the dietary combination of CMC- and inulin-enhanced fermentation in the caecum of rats, however the proportion of acetate, propionate and butyrate was less beneficial. Compared to CMC, inulin gave a higher concentration of SCFA, especially of butyrate and propionate. The action of inulin in the caecum of rats could be pronounced by dietary treatment combined with CMC.     

Lactulose-induced diarrhoea in rats: effects on caecal development and activities of microbial enzymes

The intake of large amounts of lactulose and other non-digestible oligosaccharides can cause diarrhoea in rats and humans. The purpose of our study was to estimate tendency and scope of changes in caecum development, amount and composition of caecal digesta and activity of caecal microbial enzymes under the influence of lactulose-rich diet evoking or not evoking diarrhoea. Male Wistar rats were fed on 8%-lactulose diet for 4 weeks. Feeding with lactulose induced enlargement of the caecum (digesta and wall) compared to the control group. However, the hypertrophy of the caecal wall in rats with diarrhoea was less than in these without that ailment. Dry matter of caecal digesta was significantly decreased in rats with diarrhoea. Diarrhoea lowered concentrations of enzymatic protein and short-chain fatty acids in the caecum, and the activity of bacterial beta-glucuronidase, alpha- and beta-galactosidase, alpha- and beta-glucosidase in caecal digesta, compared to rats without diarrhoea. The ammonia concentration in the caecum was enhanced by diarrhoea symptoms. Occurrence of diarrhoea significantly deteriorated functioning of the caecal ecosystem what in turn limited potential benefits of diet supplementation with lactulose.     

THE NORMAL INTESTINAL FLORA OF THE PIG II. QUANTITATIVE BACTERIOLOGICAL STUDIES

SUMMARY: Faecal and caecal samples from normal pigs were examined and the factors causing variations in bacterial numbers investigated by a dilution count technique. The range of variation for viable counts of faeces from normal pigs was 1.0 × 10⁸-9.9 × 10⁹/g and was in sufficiently close agreement with the results obtained with caecal contents to justify the use of faecal counts as an index of caecal numbers. The use of individually-fed pigs instead of group-fed pigs, with the consequent reduction of variations in environmental factors, appeared to reduce the variability of the counts. Changes in diet, either by incorporating grass meal or replacing all the animal protein by vegetable protein, did not affect the total numbers of organisms. The small variations in bacterial numbers regarded as significant by some of the earlier workers thus appear to be of little importance. Smears from high dilutions indicated that the predominant organisms were lactobacilli and streptococci; coli-aerogenes types were present in smaller numbers.     

Liver and blood enzyme spectra of rats with model anthracosis based on feeding a diet with additional amounts of methionine and pyridoxine

The data obtained during studies of the enzymic spectrum of the liver and blood of rats with experimental anthracosis fed the diet containing additional quota of methionine and pyridoxine are presented. It was established that introduction of additional quota of methionine and pyridoxine in the animals' diet with an optimal fat content reduced the negative manifestations on the part of the enzymic systems of the liver and blood characteristic of experimental anthracosis and thus promoted retardation of fibrous process in the lungs. Additional introduction into the diet of rats with experimental anthracosis of methionine alone appeared ineffective.     

High-moisture diet for laboratory rats: complete blood counts, serum biochemical values, and intestinal enzyme activity.

Rats were fed an irradiated high-moisture diet (KSC-25) with or without access to a water bottle. Physiologic values were compared between these two groups and a group of rats fed a purified diet. Hematologic and serum biochemical values, urine specific gravity, and intestinal enzyme activities were determined from samples collected from the three groups of rats. Sprague Dawley rats (n = 32) fed the irradiated high-moisture diet with or without a water bottle were the test animals. Rats (n = 16) fed an irradiated purified diet and water provided via a water bottle were the control group. The purified diet formulation modified AIN-76A, is a commonly used purified diet for laboratory rodents. All rats remained alert and healthy throughout the study. A comparison of the physiologic values of rats in this study with reported normal values indicated that all of the rats in the study were in good health. Significant differences (P less than 0.05) of the physiologic values from each rat group are reported.     

饲料硒和维生素E对大鼠机体抗氧化能力的影响

 用克山病病区粮配成基础低硒饲料,补充硒和/或维生素E组成四种不同水平的饲料,饲喂雄性断乳大鼠,观察其对机体抗氧化能力的影响。评价指标是用抗坏血酸诱发的红细胞溶血率、被O~-_2(超氧阴离子)氧化的血红蛋白量和组织中的TBA值。动物饲养13周后,自尾静脉取血,测定溶血率和血红蛋白被氧化的百分率,和全血SeGSHPx(含硒谷胱甘肽过氧化物酶)活力。15周后将动物断头杀死,立即取出心脏和肝脏测定SeGSHPx活力和TBA值。结果表明在克山病病区粮的饲料中补充硒或维生素E,或者二者同时补充均明显提高组织中的SeGSHPx活力和降低组织中的TBA值。不论在硒缺乏时或硒充足时,饲料中补充维生素E显著降低抗坏血酸诱发的红细胞溶血率,对O~-_2氧化血红蛋白无保护作用。在维生素E缺乏时,仅补充硒对溶血无作用。不论饲料中维生素E缺乏或者充足,补充硒对O~-_1氧化血红蛋白均有显著保护作用。     

Evidence for the absence of participation of the microbial flora in the hypocholesterolemic effect of guar gum in gnotobiotic rats

Germ-free (GF) and heteroxenic (Hx) rats were given a hypocholesterolemic diet (Hyper) with or without 5% guar gum (GG) for 4 weeks. The GF and Hx rats fed GG diets showed a lower hepatic and plasmatic cholesterol level when compared with Hyper groups. This reduction of cholesterolemia was due to a decrease in the chylomicron + very low density lipoprotein (VLDL) fraction. The caecal and portal concentrations of propionate were 30% higher in Hx rats fed the GG diet than in Hx rats fed the Hyper diet. These results exclude the participation of the intestinal microflora in the hypocholesterolemic effect of GG, and show that guar gum nullifies the effect of the hypocholesterolemic diet in the GF rats.     

Gastrointestinal pH measurement in rats: influence of the microbial flora, diet and fasting

The pH of the rat intestinal tract was decreased by the presence of a microbial flora, but its influence in the forestomach is less clear. Stomach pH values varied according to the amount of food present at the time of measurement. Fasting increased the pH of the gastrointestinal tract in conventional rats but had little effect in germfree rats. In the conventional rat, feeding a purified diet compared with a commercial diet resulted in a lower pH in the forestomach and a higher pH in the caecal contents. Magnesium trisilicate promoted gastric emptying in conventional rats and its antacid effect was observed only in the caecum and colon.     

Caecal fermentation,putrefaction and microbiotas in rats fed milk casein,soy protein or fish meal

To clarify the effect of soy protein (SP) and fish meal (FM), compared to milk casein (MC), on the intestinal environment, we examined caecal environment of rats fed the test diets. Four-week-old rats were fed AIN-76-based diet containing 20 %, w/w MC, SP or FM for 16 days. Caecal organic acids were analysed by HPLC. Caecal putrefactive compounds (indole, phenol, H₂S and ammonia) were analysed by colorimetric assays. Caecal microflora was determined by 16S rRNA gene-DGGE and pyrosequencing with bar-coded primers targeting the bacterial 16S rRNA gene. n-Butyric and lactic acid levels were high in rats fed SP and FM, respectively. Butyrate-producing bacteria, such as Oscillibacter, and lactate-producing bacteria, such as Lactobacillus, were detected in each diet group. Also, the putrefactive compound contents were high in rats fed SP and FM. In this study, both DGGE and pyrosequencing analyses were able to evaluate the dynamics of the intestinal microbiota. The results indicate that dietary proteins can alter the intestinal environment, affecting fermentation by the intestinal microbiota and the generation of putrefactive compounds.     

Developmental changes to gut microflora metabolism in mice

W.E. BRENNAN-CRADDOCK, A.K. MALLETT, I.R. ROWLAND AND S. NEALE. 1992. Developmental changes in the activities of bacterial nitrate reductase, nitroreductase and β-glucuronidase and their response to fermentable dietary fibre, were investigated in caecal contents from suckling mice (2-week-old) and in mice aged 4–24 weeks fed either a purified fibre-free diet or that diet supplemented with 5% (w/w) pectin. There was no apparent age-related trend common to the three enzymes studied. Nitrate reductase activity in the mice fed the fibre-free diet did not markedly alter with age. Pectin administration, however, was associated with a significant increase in nitrate reductase activity, particularly in 4-week-old mice. Nitroreductase activity exhibited an overall upward trend in mice from 2 to 12 weeks and thereafter decreased. Caecal β-glucuronidase activity in mice increased sharply between 2 weeks and 4 weeks of age, thereafter not changing significantly until the 24th week. Pectin feeding had no consistent effect on activities either of nitroreductase or β-glucuronidase. The changes in enzyme activities with age were not related to the concentration of bacteria in the caecum, which was highest in the 2-week-old mice.
We conclude that the weaning is a period in which marked changes in caecal bacterial enzyme activities can occur.     

Pyridoxine and atherosclerosis: role of pyridoxine in the metabolism of lipids and glycosaminoglycans in rats fed normal and high fat, high cholesterol diets containing 16% casein

The effect of administration of low and high doses of pyridoxine on the metabolism of lipids and glycosaminoglycans has been studied in rats fed normal and high fat, high cholesterol diets. Low doses of pyridoxine (0.005 mg/100 g body weight) caused increased concentrations, of cholesterol and triglycerides in the serum and aorta in animals fed normal and high fat, high cholesterol diets. Administration of high doses of pyridoxine (5.0 mg/100 g body weight) caused decrease in the concentration of these lipids in these tissues except in the case of the aorta in the animals fed a normal diet. Low doses of pyridoxine generally caused a decrease in the concentration of many glycosaminoglycan fractions in the aorta in rats fed normal and high fat, high cholesterol diets, whilst high doses caused an increase. The activity of glucosaminephosphate isomerase (glutamine-forming) and UDPglucose dehydrogenase, both key enzymes in the biosynthetic pathway of glycosaminoglycans, decreased in rats given low doses of pyridoxine and increased in rats given high doses. The activity of many enzymes concerned with degradation of glycosaminoglycans--hyaluronoglucosidase, beta-glucuronidase, beta-N-acetylglucosaminidase, aryl sulphatase, and cathepsin D--generally increased in rats fed low doses of the pyridoxine and decreased in those given high doses. The concentration of hepatic 3'-phosphoadenosine-5'-phosphosulphate, and the activity of the sulphate-activating system and of aryl sulphotransferase decreased when the dose of pyridoxine was low and increased when the dose was high.     

Effects of a probiotic on the lipid metabolism of cocks fed on a cholesterol-enriched diet.

The effects of a probiotic (a mixture of Bacillus, Lactobacillus, Streptococcus, Clostridium, Saccharomyces and Candida) on the lipid metabolism, and caecal flora and metabolites of cocks were studied. The cholesterol level of the liver and serum was significantly decreased in the cocks fed on the cholesterol-enriched diet containing the probiotic. The distribution and frequency of occurrence of flora, and the chemical characteristics of the metabolites in the caecal content of the cocks were also affected by the inclusion of the probiotic in the basal and cholesterol-enriched diets. The Enterobacteriaceae species were significantly decreased in number, while the Bacillus, Streptococcus, Bifidobacterium and Lactobacillus species were significantly increased. The presence of yeast was observed, and the ammonia level was significantly reduced. The pH value, however, was not affected. The concentration of short-chain fatty acids in the caecal content of the cocks fed on the cholesterol-enriched diet supplemented with the probiotic was increased. It is, therefore, suggested that the incorporation of a probiotic in the diet would improve the balance of the intestinal flora and metabolites. Furthermore, it would also suppress the serum and liver cholesterol levels of cocks fed on the cholesterol-enriched diet.