烧伤后早期肠道营养对大鼠小肠粘膜保护作用的形态学观察

目的：为深入了解烧伤后期肠道地小肠粘膜保护作用的形态学变化。方法：采用计算机图像分析仪、透射电及冰冻蚀刻得型技术，对严重烧伤大鼠早期喂养（ＥＦ）、延迟喂养（ＤＦ）后小肠粘膜从光镜结构数量到超微结构质量的变化进行观察分析。结果：ＤＦ组空肠粘膜厚度、绒毛高度较ＥＰ组降低，电镜观察示肠上皮细胞间囊性扩张，微绒毛坏死脱落，线粒体空化、嵴断裂、冰冻刻刻复型观察示细胞间紧密连接松散紊乱，而ＥＦ组上述变化时间减     

sIgA- and IgM-containing cells in the intestinal mucosa of iron-deficient rats

The effect of iron deficiency on the jejunal mucosa was studied in postweaning rats that had received a 3-wk regimen of either iron-deficient or iron-sufficient diet (iron content 6 and 50 mg/kg diet) and in rats given the iron-sufficient diet for 1 wk after the initial 3-wk iron-deficient diet. Morphometric analysis showed little difference in villous height but a significant decrease in mitotic index of the crypt epithelial cells in the iron-deficient group. Direct immunoperoxidase studies showed that iron-deficient rats had substantially fewer sIgA- and IgM-containing cells than iron-sufficient rats. This abnormality was reversed after a 1-wk iron-sufficient diet. We conclude that iron deficiency may impair local immunity in the intestinal mucosa, sensitizing the surface epithelial cells to damage by noxious agents. Similar changes might lead to the syndrome of iron-deficiency anemia and hypoproteinemia in children.     

Developmental changes in the sucrase-isomaltase complex in rat intestinal mucosa.

Developmental changes in sucaras-isomaltase complex formation were investigated in intestinal mucosal homogenates and brush border membranes of 15-day-old, 18-day-old and adult rats using Sephadex G-200 column chromatography and polyacrylamide disc gel electrophoresis. Disaccharidases were solubilized by papain treatment. The molecular weight of the complex did not change during development, however, the activity ratio of sucrase to isomaltase increased during development. Furthermore, a significant amount of free isomaltase, which was probably not to be derived from intestinal brush border membrane, was detected before the weanling.     

Metabolic and development changes in growing rats born to dams restricted in protein and/or energy intake.

During gestation and lactation, the food intake of female rats was restricted to 50% of the ad libitum stock diet intake of controls (C). One restricted group (M1) was fed stock diet while another restricted group (M2) was fed casein-supplemented stock diet containing 66% protein. Observations were directed to their progeny. After weaning at 21 days, all progeny were fed the stock diet ad libitum for 2 weeks. Mean birth weight of M2 was lower than M1 which was lower than C. Weight gain of progeny was faster in M2 than M1 but both were less than C. At 5 weeks, M2 had normal brain weight but lower mg protein/g brain than either M1 or C. M1 had the lowest brain weight. Livers of M1 and M2 were smaller than C, and M2 had higher RNA and protein, and lower DNA per g liver than either M1 or C. Both M1 and M2 had about three-fold elevation in hepatic serine dehydratase and slightly lower phosphoglycerate dehydrogenase than C. The lower birth weight and normal brain size of M2 suggested that some of the protein consumed by M2 dams was conserved for synthesis of vital components despite energy restriction.     

Immunohistologic changes of the intestinal mucosa in chronic inflammatory bowel diseases

In the pathogenesis of inflammatory bowel disease abnormally increased immune reactions in the intestinal mucosa play a basic role. The revealing of these reactions was facilitated by the rapidly spreading immunohistological methods in last decades. This review discusses in detail the characteristic distribution of lymphocyte subsets and plasma cells in Crohn's disease and ulcerative colitis. Results indicating increased expression of adhesion molecules are also presented, as well as the different patterns of cytokine production in Crohn's disease and ulcerative colitis. The rapid epithelial turnover developing as a consequence of increased rate of proliferation and apoptosis in inflammatory bowel disease is also shown. The epithelial expression of MHC II antigen in colonic mucosa which is not observed in healthy subjects is also discussed. In addition, the pathogenetic role of lost oral tolerance in the development of inflammatory bowel is reviewed in detail.     

Manganese-induced biochemical changes in growing versus adult rats

Manganese chloride was administered daily intraperitoneally to growing and adult rats for a period of 30 days to compare certain biochemical parameters in both groups of animals. Marked alterations in the levels of dopamine and norepinephrine in the brain was observed in manganese-treated growing rats. Furthermore, the contents of tyrosine, tryptophan in blood, liver, and brain have been significantly altered in these animals. Identical manganese administration to adult rats had no effect on the contents of tyrosine in liver and brain, nor tryptophan, and dopamine in the brain. Some of the parameters which were altered in the adult rats were less in magnitude compared to the growing animals. The experiments indicated higher susceptibility of the growing rats to the toxic effects of this metal.     

Long-term cysteine fortification impacts cysteine/glutathione homeostasis and food intake in ageing rats

Purpose

Healthy ageing is associated with higher levels of glutathione. The study aimed to determine whether long-term dietary fortification with cysteine increases cysteine and glutathione pools, thus alleviating age-associated low-grade inflammation and resulting in global physiological benefits.

Methods

The effect of a 14-week dietary fortification with cysteine was studied in non-inflamed (NI, healthy at baseline) and in spontaneously age-related low-grade inflamed (LGI, prefrail at baseline) 21-month-old rats. Fifty-seven NI rats and 14 LGI rats received cysteine-supplemented diet (4.0 g/kg of free cysteine added to the standard diet containing 2.8 g/kg cysteine). Fifty-six NI rats and 16 LGI rats received a control alanine-supplemented diet.

Results

Cysteine fortification in NI rats increased free cysteine (P < 0.0001) and glutathione (P < 0.03) in the liver and the small intestine. In LGI rats, cysteine fortification increased total non-protein cysteine (P < 0.0007) and free cysteine (P < 0.03) in plasma, and free cysteine (P < 0.02) and glutathione (P < 0.01) in liver. Food intake decreased over time in alanine-fed rats (r ² = 0.73, P = 0.0002), whereas it was constant in cysteine-fed rats (r ² = 0.02, P = 0.68). Cysteine fortification did not affect inflammatory markers, mortality, body weight loss, or tissue masses.

Conclusion

Doubling the dietary intake of cysteine in old rats increased cysteine and glutathione pools in selected tissues. Additionally, it alleviated the age-related decline in food intake. Further validation of these effects in the elderly population suffering from age-related anorexia would suggest a useful therapeutic approach to the problem.     

Protein malnutrition and the function and fluidity of the intestinal microvillus membrane in growing rats

The effect of protein malnutrition on the function, fluidity and composition of the intestinal microvillus membrane was studied in growing rats. Weanling male rats were fed diets containing 10% protein derived from either wheat gluten (experimental diet) or casein (control diet). Intestinal microvillus membranes were isolated after a 7-wk feeding period. The functionality of the membranes, as assessed by the level of activity of the four enzymes alkaline phosphatase, gamma-glutamyl transpeptidase, leucine aminopeptidase and maltase, showed no difference between the membranes derived from the experimental and the control animals. Similar Arrhenius plot patterns of alkaline phosphatase activity (13-50 degrees C) and of the fluorescence anisotropy parameter (8-40 degrees C) were observed for both types of membranes with respect to the transition temperatures and energies of activation. In addition, the similarity between the membranes derived from the experimental and the control animals was also manifested in the cholesterol and phospholipid content. The study demonstrates that despite the extreme nutritional stress exerted on the gluten-fed rats, the integrity and functionality of the intestinal microvillus membrane was adequately maintained.     

Thiol/disulfide redox status is oxidized in plasma and small intestinal and colonic mucosa of rats with inadequate sulfur amino acid intake

Low molecular weight thiol/disulfide redox pools are dependent upon extracellular cysteine (Cys) availability. We determined whether dietary sulfur amino acid (SAA) deficiency induces oxidative stress in vivo, as determined by redox state of major thiol/disulfide couples in plasma [Cys/cystine (CySS)] and intestinal mucosa [glutathione (GSH)/glutathione disulfide (GSSG)]. Rats were fed isocaloric, isonitrogenous semipurified diets: either SAA-adequate (control), SAA-deficient, or SAA-supplemented, pair-fed to intake of the SAA-deficient group. Reference rats consumed standard rat food ad libitum. After 7 d, plasma and gut mucosal samples were analyzed for Cys, CySS, GSH and GSSG, and the redox potentials of Cys/CySS and GSH/GSSG were determined. Mean daily food intake in the pair-fed rats was similar (approximately one-half of reference-rat intake). Body weight decreased in all pair-fed groups, but rats fed the SAA-deficient diet lost significantly more body weight. Dietary SAA deficiency decreased GSH concentrations in both plasma and gut mucosa, increased plasma GSSG, and oxidized plasma and gut mucosal GSH/GSSG redox and plasma Cys/CySS redox. SAA supplementation resulted in a more reducing plasma Cys/CySS redox potential. Reference rats exhibited similar tissue and plasma GSH/GSSG redox as rats that ate semipurified SAA-adequate rat food, which provided similar net SAA intake. Our in vivo data show that inadequate dietary SAA intake oxidizes the thiol/disulfide redox status in rat-gut mucosa and plasma. Such oxidation of redox pools is associated with oxidative stress and the onset or progression of several pathological conditions. Thus, dietary SAA deficiency could contribute to the progression of disease by causing an oxidation of these components.     

Nutrition disorder and immunologic parameters: study of the intestinal villi in growing rats

OBJECTIVE: The aim of the present work was to study how a diet in which cereals were the only protein source would affect B and T lymphocytes and a cell population positive for thymus-expressed chemokine (TECK) in the intestinal villi of growing rats. METHODS: Wistar rats were fed a 6.5% precooked maize protein diet for 18-20 d (M group). An age-matched control group received stock diet (C group). Body weight (grams) was determined, ponderal growth rate (grams per day per 100 g) was calculated, and intestines were removed and processed by Saint-Marie's technique. Tissue sections were studied by indirect immunofluorescence. CD5(+) T cells and the T-cell subsets TCRalphabeta(+), TCRgammadelta(+), CD4(+), CD8alpha(+), and CD8beta(+) in the lamina propria (LP) and intraepithelium, in addition to immunoglobulin A-positive B cells in the LP were determined (n cells/30 fields were read). In addition, the presence of the TECK(+) cell population was qualitatively assessed. RESULTS: The M versus C group showed statistically significant differences in body weight and ponderal growth rate. The number of immunoglobulin A-positive B cells in the LP and the CD5(+) T cells and CD4(+), CD8alpha(+), CD8beta(+), TCRalphabeta(+), and TCRgammadelta(+) T-cell subpopulations of the M group in the LP and intraepithelium of the gut villi were significantly decreased compared with the C group (P < 0.001). The M group also showed differences in the size and cellularity of the gut villi and in the distribution of TECK. CONCLUSION: The results show that intake of a low concentration of a low-quality dietary protein as the only source of protein produces an important disorder in the mucosal immunity of experimental rats.     

Self-selection of histidine and arginine intake and the requirements for these amino acids in growing rats

The regulation of histidine and arginine intake in rats was investigated using the self-selection feeding method. The usefulness of the self-selection feeding technique for the determination of amino acid requirements is also discussed. When weanling rats were offered a choice of two diets differing only in histidine or arginine content for 2 weeks, they chose diets to support maximal growth, with the exception of some groups that did not grow to the maximum level. Histidine and arginine intake of the self-selecting rats ranged from 0.25% to 2.22% and from 0.43% to 2.43% of the diets ingested. These results demonstrate clearly that rats have the ability to consume a minimum amount that satisfies histidine and arginine needs for maximal growth. Previous and the present results suggest that the self-selection feeding method is a useful technique for the determination of amino acid requirements in growing rats.     

Beer promotes high levels of alcohol intake in adolescent and adult alcohol-preferring rats

Previous studies suggest that high levels of alcohol consumption can be obtained in laboratory rats by using beer as a test solution. The present study extended these observations to examine the intake of beer and equivalent dilute ethanol solutions with an inbred line of alcohol-preferring P rats. In Experiment 1, male adolescent P rats and age-matched Wistar rats had access to either beer or equivalent ethanol solutions for 1 h daily in a custom-built lickometer apparatus. In subsequent experiments, adolescent (Experiment 2) and adult (Experiment 3) male P rats were given continuous 24-h home cage access to beer or dilute ethanol solutions, with concomitant access to lab chow and water. In each experiment, the alcohol content of the beer and dilute ethanol solutions was gradually increased from 0.4, 1.4, 2.4, 3.4, 4.4, 5 to 10% EtOH (vol/vol). All three experiments showed a major augmentation of alcohol intake when rats were given beer compared with equivalent ethanol solutions. In Experiment 1, the overall intake of beer was higher in P rats compared with Wistar rats, but no strain difference was found during the 1-h sessions with plain ethanol consumption. Experiment 1 also showed that an alcohol deprivation effect was more readily obtained in rats with a history of consuming beer rather than plain ethanol solutions. In Experiments 2 and 3, voluntary beer intake in P rats represented ethanol intake of 10-15 g/kg/day, among the highest reported in any study with rats. This excessive consumption was most apparent in adolescent rats. Beer consumption markedly exceeded plain ethanol intake in these experiments except at the highest alcohol concentration (10%) tested. The advantage of using beer rather than dilute ethanol solutions in both selected and nonselected rat strains is therefore confirmed. Our findings encourage the use of beer with alcohol-preferring rats in future research that seeks to obtain high levels of alcohol self-administration.     

Excess energy intake promotes the development of hypoalbuminaemia in rats fed on low-protein diets

1. A group of rats were given ad lib, a diet with a protein-energy: total energy (P:E) value of 0 . 03. Other animals received the same protein intake (g/kg body-weight per d) as this group, but had their energy consumption reduced to either 90, 80, 70, 60 or 50% of the ad lib. value. 2. The restricted growth rate of rats fed on the P:E--0 . 03 diet ad lib. has been shown to be due entirely to their insufficient protein consumption. In contrast, energy intake was far in excess of that required for maintenance and the limited amount of growth. 3. Carcass analysis demonstrated that some of the excess energy intake was stored as fat, but a greater part had been dissipated, presumably by diet-induced thermogenesis. 4. The plasma concentration of triiodothyronine (T3) was elevated in all animals consuming excess energy and was significantly related to both the total surplus and the amount of energy dissipated. 5. In the group of animals restricted to 50% of the ad lib. intake, energy rather than protein appeared to be the factor limiting growth. Energy intake was below estimated requirements for maintenance and was associated with values for plasma T3 that were lower than those found in well-fed control rats. 6. Although all the animals had similar protein intakes, plasma albumin concentration differed between the groups and was found to be inversely proportional to the energy intake. Thus it was lowest in animals receiving food ad lib. and rose to near normal values in the most-severely-restricted rats. 7. It is suggested that hypoalbuminaemia, and perhaps other features of protein deficiency, seen in animals fed on low-P:E diets may occur as an undesirable consequence of the metabolic response required to deal with excess energy consumption.     

谷氨酰胺对缺血-再灌注损伤大鼠肠黏膜炎性反应和通透性的影响

目的 研究谷氨酰胺（Gln）对缺血-再灌注损伤大鼠肠黏膜炎性反应和通透性的影响.方法 将48只SD大鼠肠系膜上动脉夹闭造成缺血后恢复血流,建立肠缺血-再灌注损伤模型,将造模后的SD大鼠按随机数字表分为对照组（n=24）和模型＋Gln组（n=24）,两组大鼠肠内营养供给量为热量125.4 kJ/ （kg·d）,氮量0.2g/ （kg·d）,模型＋Gln组喂饲肠内营养加3％ Gln,对照组大鼠喂饲肠内营养加3％大豆蛋白,造模后实验持续8d.检测造模前、造模后、实验第3天和第8天大鼠肠黏膜和血浆核因子-κB （NF-κB）、肿瘤坏死因子-α（TNF-α）、白细胞介素-6（IL-6）、Gln、D-乳酸（D-LAC）和二胺氧化酶（DAO）的变化.观察小肠黏膜形态学变化.结果 造模后对照组和模型＋ Gln组大鼠肠黏膜NF-κB表达明显高于造模前（75.0％比0.0％,P=0.013; 70.8％比0.0％,P=0.019）;肠黏膜IL-6明显高于造模前[（313.27±75.28） pg/g比（227.52 ±58.13） pg/g,P=0.023; （321.75±74.46） pg/g比（227.52±58.13） pg/g,P=0.043];肠黏膜TNF-α[（241.28±65.29） pg/g、（240.35 ±64.86） pg/g]明显高于造模前[（172.45±33.76） pg/g,P=0.036,P=0.011];血浆IL-6[（150.32±18.74） ng/L、（148.21 ±20.19） ng/L]明显高于造模前[（116.37±14.59） ng/L,P=0.032,P=0.025];血浆TNF-α[（127.62±14.24） ng/L、（123.86±13.75） ng/L]明显高于造模前[（85.18±8.84） ng/L,P=0.018,P=0.035]; D-LAC[（0.46±0.03） mmol/L、（0.51 ±0.04） mmol/L]明显高于造模前[（0.27±0.02） mmol/L,P=0.041,P=0.018]; DAO[（2.76±0.57） U/ml、（2.58±0.51） U/ml]明显高于造模前[（1.52±0.24） U/ml,P=0.015,P =0.037];而血浆Gln[（0.18±0.01） g/L、（0.21±0.01） g/L]明显低于造模前[（0.39±0.03） g/L,P =0.026,P=0.031].实验第3天和实验第8天,对照组大鼠肠黏膜NF-κB[16例（66.7％）、15例（62.5％）]显著高于造模前[0例（0.0％）,P=0.027,P=0.002];肠黏膜TNF-α[（226.23±55.35） pg/g、（214.76 ±54.82） pg/g]显著高于造模前[（172.45±33.76） pg/g,P=0.042,P=0.038];肠黏膜IL-6[（297.56±71.39） pg/g、（291.49±68.46） pg/g]显著高于造模前[（227.52±58.13） pg/g,P=0.031,P=0.012];血浆IL-6 [（147.38±17.25） ng/L、（144.65±15.32） ng/L]显著高于造模前[（116.37±14.59） ng/L,P=0.016,P=0.034];血浆TNF-α[（121.75±13.72）ng/L、（113.83±11.69） ng/L]显著高于造模前[（85.18±8.84） ng/L,P=0.025,P=0.041];D-LAC[（0.41 ±0.03） mmol/L、（0.53±0.05） mmol/L]显著高于造模前[（0.27±0.02） mmol/L,P=0.029,P=0.030]; DAO [（2.51±0.52） U/ml、（1.76±0.34） U/ml]显著高于造模前[（1.52±0.24） U/ml,P=0.034,P=0.016];但血浆Gln[（0.22±0.01） g/L、（0.21±0.03） g/L]显著低于造模前[（0.39±0.03） g/L,P=0.042,P=0.035].实验第3天模型＋Gln组肠黏膜NF-κB、TNF-α、IL-6 [14例（58.3％）、（213.78±43.76） pg/g、（293.72±69.86） pg/g]明显高于造模前（P=0.038、0.026、0.013）;血浆IL-6、TNF-α、D-LAC、DAO [（135.61 ±14.25） ng/L、（117.35±11.29）ng/L、（0.45 ±0.03） mmol/L、（2.26 ±0.43） U/ml]明显高于造模前（P=0.021、0.032、0.032、0.025）.实验第8天模型＋ Gln组肠黏膜NF-κB、TNF-α、IL-6[9例（37.5％）、（184.53 ±42.16） pg/g、（236.83 ±66.52） pg/g]明显低于造模后和对照组（P=0.024,P=0.027; P=0.026,P=0.039;P =0.013,P=0.028）;血浆IL-6、TNF-α、D-LAC、DAO[（126.35 ±12.74）ng/L、（92.76±9.42）ng/L、（0.31 ±0.02） mmol/L、（1.76 ±0.34） U/ml]明显低于造模后和对照组（P=0.021,P=0.030;P=0.032,P=0.025;P=0.024,P=0.037;P=0.022,P=0.036）,而血浆Gln水平[（0.40±0.03） g/L]明显高于造模后和对照组（P =0.028、0.032）.电镜下可见造模后绒毛、隐窝结构一定程度损害,绒毛稀疏且变短,固有膜内大量炎性细胞浸润,淋巴管扩张、水肿.实验第8天,模型＋Gln组与造模后和对照组比较小肠绒毛、隐窝结构显著恢复;对照组与造模后比较肠黏膜绒毛、隐窝结构恢复不明显,固有膜内仍有炎性细胞浸润.结论 Gln通过调节肠黏膜炎性因子的释放,抑制炎症反应,降低肠黏膜的通透性,修复缺血-再灌注后损伤的肠黏膜.     

Fructooligosaccharide consumption enhances femoral bone volume and mineral concentrations in rats

We examined whether the enhanced mineral absorption resulting from fructooligosaccharide (FOS) consumption affects femoral bone structure and mineral concentrations, using histomorphometrical and X-ray microanalysis. Male Wistar rats (n = 16; 42 d old) were divided into two groups, a control group (n = 8) and a FOS group (5 g/100 g FOS in the diet, n = 8). After a 3-d adaptation period, constant amounts of calcium (95 mg/d) and magnesium (8 mg/d) were fed to the rats in each group, using a pair-feeding protocol. At age 60 d, a 3-d metabolic study was initiated. Calcium and magnesium absorptions were calculated. The rats were then killed, and the right femur was embedded in polyester resin. The distal metaphysis was sagittal-sectioned, and the middle of the diaphysis and neck were cross-sectioned. Calcium, magnesium and phosphorus concentrations in the three samples were then measured. Calcium and magnesium absorptions were significantly greater in FOS-fed rats. Trabecular bone volume at the metaphysis and bone volume at the neck of the femur in FOS-fed rats were also significantly greater than those in control rats. The mineral concentration (Ca, Mg and P) in each region of the bone surface was greater in FOS-fed rats. There was a significant relationship between absorbed calcium and calcium concentrations in bone (r = 0.722, P < 0.001), and a similar relationship was found for magnesium (r = 0.720, P < 0.001). These results suggest that the enhanced calcium and magnesium absorption due to FOS consumption might enhance femoral bone volume and mineral concentrations.     

慢性饮酒对大鼠胃缺血再灌注损伤影响

目的 探讨酒精对大鼠胃缺血再灌注损伤的影响机制.方法 制备胃缺血再灌注及慢性饮酒大鼠模型,实验分为6组:假手术、饮酒假手术、胃缺血再灌注1、2 h组、饮酒胃缺血再灌注1、2 h组,每组6只;记录各组胃黏膜损伤指数并检测胃黏膜丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性;缺口末端标记法(TUNEL)检测胃黏膜细胞凋亡情况.结果 缺血再灌注1、2h后胃黏膜损伤指数分别为(106.0±12.0)和(74.4±11.0),黏膜细胞凋亡率分别为(73.2±6.5)%和(54.0±7.4)%,明显高于假手术组(P＜0.05);与假手术组比较,缺血再灌注1h后胃黏膜MDA含量(7.98±2.1)nmol/mgprot]明显增加,SOD活性[(141±16.1)U/mgprot]明显降低;饮酒可引起胃黏膜轻微损伤(损伤指数为9.2±0.7),但饮酒并未加剧缺血再灌注带来的胃黏膜损伤,仅使机体自身修复能力降低.结论 饮酒可导致SOD活性下降,加剧机体内氧化和抗氧化平衡失调,使胃黏膜自身修复损伤能力降低.