The Role of L‐Arginine and Inducible Nitric Oxide Synthase in Intestinal Permeability and Bacterial Translocation

Background: Arginine has been shown to have several immunological and trophic properties in stressful diseases. Its metabolites, nitric oxide (NO) and polyamines, are related to arginine's effects. Thus, the aim of this study was to determine the effects of the NO donor L‐arginine and the role of inducible NO synthase (iNOS) on intestinal permeability and bacterial translocation in a model of intestinal obstruction (IO) induced by a simple knot in the terminal ileum. Material and Methods: Male C57BL6/J wild‐type (WT) and iNOS knockout (iNOS–/–) mice were randomized into 6 groups: Sham and Sham–/– (standard chow), IO and IO–/– (standard chow +IO), and Arg and Arg–/– (standard chow supplemented with arginine + IO). After 7 days of treatment with standard or supplemented chows, IO was induced and intestinal permeability and bacterial translocation were evaluated. The small intestine and its contents were harvested for histopathological and morphometric analysis and the determination of polyamine concentration. Results: Pretreatment with arginine maintained intestinal permeability (P > .05; Arg and Arg–/– groups vs Sham and Sham–/– groups), increased polyamine concentration in intestinal content (P < .05; Arg vs IO group), and decreased bacterial translocation in WT animals (Arg group vs IO and IO–/– groups). Absence of iNOS also presented a protective effect on permeability but not on bacterial translocation. Conclusion: Arginine supplementation and synthesis of NO by iNOS are important factors in decreasing bacterial translocation. However, when intestinal permeability was considered, NO had a detrimental role.     

Pretreatment and Treatment With L‐Arginine Attenuate Weight Loss and Bacterial Translocation in Dextran Sulfate Sodium Colitis

Background: Imbalances in a variety of factors, including genetics, intestinal flora, and mucosal immunity, can contribute to the development of ulcerative colitis and its side effects. This study evaluated the effects of pretreatment or treatment with arginine by oral administration on intestinal permeability, bacterial translocation (BT), and mucosal intestinal damage due to colitis. Methods: C57BL/6 mice were distributed into 4 groups: standard diet and water (C: control group), standard diet and dextran sodium sulfate (DSS) solution (Col: colitis group), 2% L ‐arginine supplementation for 7 days prior to DSS administration and during disease induction (PT: pretreated group), and 2% L ‐arginine supplementation during disease induction (T: treated group). Colitis was induced by administration of 1.5% DSS for 7 days. After 14 days, intestinal permeability and BT were evaluated; colons were collected for histologic analysis and determination of cytokines; feces were collected for measurement of immunoglobulin A (IgA). Results: The Col group showed increased intestinal permeability (C vs Col: P < .05) and BT (C vs Col: P < .05). In the arginine‐supplemented groups (PT and T), this amino acid tended to decrease intestinal permeability. Arginine decreased BT to liver during PT (P < .05) and to blood, liver, spleen, and lung during T (P < .05). Histologic analysis showed that arginine preserved the intestinal mucosa and tended to decreased inflammation. Conclusions: Arginine attenuates weight loss and BT in mice with colitis.     

Enteral Arginine Partially Ameliorates Parenteral Nutrition–Induced Small Intestinal Atrophy and Stimulates Hepatic Protein Synthesis in Neonatal Piglets

Background: Arginine is an indispensable amino acid in neonates; de novo synthesis of arginine occurs in the small intestine (SI) but is reduced during parenteral nutrition (PN), limiting the arginine available to the mucosa. We assessed the effects of route of intake and dietary concentration of arginine on protein synthesis, superior mesenteric artery (SMA) blood flow, and SI morphology. Methods: Piglets (n = 18, 14–17 days old) were given complete PN for 3 days to induce SI atrophy, then switched to 1 of 3 treatments: arginine‐free PN plus an intragastric (IG) infusion of high arginine (1.6 g·kg^?1·d^?1, IG‐H Arg) or low arginine (0.6 g·kg^?1·d^?1, IG‐L Arg) or complete high‐arginine PN (1.6 g·kg^?1·d^?1, IV‐H Arg). Results: Enteral arginine, irrespective of amount provided, stimulated hepatic protein synthesis compared with intravenous delivery of arginine (P = .01). SMA blood flow declined for all groups following the initiation of PN. After 48 hours on the test diets, all groups reached low constant levels, but the IV‐H group was significantly higher than both IG groups (P < .05). Despite greater blood flow, the SI morphological characteristics in IV‐H Arg pigs were not significantly improved over the other groups. IV‐H Arg pigs had higher plasma concentrations of indispensable amino acids (tyrosine, isoleucine, and valine) compared with IG‐H Arg, despite identical amino acid intakes. Conclusions: Intravenous delivery of arginine sustained the best SMA blood flow, whereas even a moderate amount of enteral arginine stimulated liver protein synthesis and maintained SI growth, independent of blood flow.     

Cranberry Proanthocyanidins Improve the Gut Mucous Layer Morphology and Function in Mice Receiving Elemental Enteral Nutrition

Background: Lamina propria Th2 cytokines, interleukin (IL)‐4 and IL‐13, stimulate goblet cell (GC) proliferation and MUC2 production, which protect the intestinal mucosa. Elemental enteral nutrition (EEN) reduces tissue IL‐4 and impairs barrier function. Proanthocyanidins (PACs) stimulate oral mucin levels. We hypothesized that adding PAC to EEN would maintain Th2–without stimulating Th1–cytokines and preserve luminal MUC2 vs EEN alone. Materials and Methods: Seventy mice were randomized to 5 diet groups–standard chow, intragastric EEN, or EEN with lowPAC, midPAC (50 mg), or highPAC (100 mg PAC/kg BW)–for 5 days, starting 2 days after gastric cannulation. Ileal tissue was analyzed for histomorphology and the cytokines IL‐4, IL‐13, IL‐1β, IL‐6, and TNF‐α by enzyme‐linked immunosorbent assay. MUC2 was measured in intestinal washes. Results: EEN lowered IL‐13 (P < .05) compared with standard chow, whereas IL‐4 was not significant (P < .07). LowPAC and midPAC increased IL‐13 (P < .05), whereas highPAC increased both IL‐4 and IL‐13 (P < .05) compared with EEN. All EEN diets reduced (P < .05) crypt depth compared with the chow group. Compared with standard chow, GC numbers and luminal MUC2 were reduced with EEN (P < .05). These effects were attenuated (P < .05) with midPAC and highPAC. No changes were observed in tissue Th1 cytokines. Conclusions: Adding PACs to EEN reverses impaired intestinal barrier function following EEN by improving the gut mucous layer and function through increased GC size and number as well as levels of MUC2 and ileal IL‐4 and IL‐13.     

Systemic arginine depletion after a murine model of surgery or trauma

Background: Arginine metabolism and availability after surgery or trauma (ST) is an important modulator of immune responses. Arginine levels are significantly depleted in human trauma patients. Diets containing arginine administered to surgery patients have restored immune function. We hypothesized an arginase‐dependent depletion of arginine in a murine model of ST. In addition, we hypothesized a systemic arginase release in human trauma patients. Methods: Male mice were anesthetized and a laparotomy with bowel manipulation was used as a model of ST. Plasma was collected after ST for analysis of arginase activity and arginine, ornithine, and citrulline. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in plasma were measured after ST. Also, arginase activity was determined in human plasma from 4 healthy controls and 8 trauma patients. Results: Arginase activity increased maximally at 2–4 hours after ST, and arginine was significantly reduced after ST. Citrulline was significantly decreased at 8 and 12 hours after ST. Plasma AST and ALT did not significantly vary from control mice after ST. In addition, on day 1 after intensive care unit admission, human trauma patients exhibited a significant increase in arginase activity. Conclusions: The biological consequences of arginine depletion remain incompletely understood. These data are consistent with data showing that patients given arginine‐containing diets experience reduced morbidity. Understanding of arginine metabolism after ST may lead to therapies aimed at improving clinical outcome after ST.     

Innate Mucosal Immune System Response of BALB/c vs C57BL/6 Mice to Injury in the Setting of Enteral and Parenteral Feeding

Background: Outbred mice exhibit increased airway and intestinal immunoglobulin A (IgA) following injury when fed normal chow, consistent with humans. Parenteral nutrition (PN) eliminates IgA increases at both sites. Inbred mice are needed for detailed immunological studies; however, specific strains have not been evaluated for this purpose. BALB/c and C57BL/6 are common inbred mouse strains but demonstrate divergent immune responses to analogous stress. This study addressed which inbred mouse strain best replicates the outbred mouse and human immune response to injury. Methods: Intravenously cannulated mice received chow or PN for 5 days and then underwent sacrifice at 0 or 8 hours following controlled surgical injury (BALB/c: n = 16–21/group; C57BL/6: n = 12–15/group). Bronchoalveolar lavage (BAL) was analyzed by enzyme‐linked immunosorbent assay for IgA, tumor necrosis factor–α (TNF‐α), interleukin (IL)–1β, and IL‐6, while small intestinal wash fluid (SIWF) was analyzed for IgA. Results: No significant increase in BAL IgA occurred following injury in chow‐ or PN‐fed BALB/c mice (chow: P = .1; PN: P = .7) despite significant increases in BAL TNF‐α and SIWF IgA (chow: 264 ± 28 vs 548 ± 37, P < .0001; PN: 150 ± 12 vs 301 ± 17, P < .0001). Injury significantly increased mucosal IgA in chow‐fed C57BL/6 mice (BAL: 149 ± 33 vs 342 ± 87, P = .01; SIWF: 236 ± 28 vs 335 ± 32, P = .006) and BAL cytokines. After injury, PN‐fed C57BL/6 mice exhibited no difference in BAL IgA (P = .9), BAL cytokines, or SIWF IgA (P = .1). Conclusions: C57BL/6 mice exhibit similar airway responses to injury as outbred mice and humans, providing an appropriate model for studying mucosal responses to injury. The BALB/c mucosal immune system responds differently to injury and does not replicate the human injury response.     

Lack of enteral nutrition delays nuclear factor kappa B activation in peritoneal exudative cells in a murine glycogen-induced peritonitis model

Background: Early enteral nutrition is associated with a lower incidence of intraabdominal abscess in severely injured patients than parenteral nutrition (PN). We explored the underlying mechanisms by examining the influence of nutrition route on nuclear factor κB (NFκB) activation in peritoneal exudative cells (PECs) and peritoneal cytokine levels. Methods: Thirty male Institute Cancer Research mice were randomized to chow (n = 10), IV PN (n = 10), or intragastric (IG) PN (n = 10) and fed for 5 days. PECs were harvested at 2 or 4 hours after intraperitoneal injection of 2 mL of 1% glycogen. Intranuclear NFκB activity in PECs was examined by laser scanning cytometry. Cytokine (tumor necrosis factor‐α [TNF‐α], macrophage inflammatory protein‐2 [MIP‐2], interleukin‐10 [IL‐10]) levels in peritoneal lavaged fluid were determined by enzyme‐linked immunosorbent assay. Results: Intranuclear NFκB at 2 hours was significantly higher in the chow and IG‐PN groups than in the IV‐PN group. TNF‐α and IL‐10 levels of the chow group were significantly higher than those of IV‐PN mice at 2 hours, whereas those of IG‐PN mice were midway between those of the chow and IV‐PN groups. MIP‐2 was significantly higher in the chow group than in the IG‐PN and IV‐PN mice at 2 hours. TNF‐α levels correlated positively with intranuclear NFκB activity in PECs. Conclusions: Enteral nutrition may improve peritoneal defense by preserving early NFκB activation in PECs and cytokine responses.     

Pretreatment 25‐Hydroxyvitamin D Levels and Durability of Anti–Tumor Necrosis Factor–α Therapy in Inflammatory Bowel Diseases

Introduction: Emerging evidence supports an immunologic role for 25‐hydroxyvitamin D (25(OH)D) in inflammatory bowel disease (IBD). Here we examined if pretreatment vitamin D status influences durability of anti–tumor necrosis factor (TNF)–α therapy in patients with Crohn's disease (CD) or ulcerative colitis (UC). Methods: All IBD patients who had plasma 25(OH)D level checked <3 months prior to initiating anti–TNF‐α therapy were included in this retrospective single‐center cohort study. Our main predictor variable was insufficient plasma 25(OH)D (<30 ng/mL). Cox proportional hazards model adjusting for potential confounders was used to identify the independent effect of pretreatment vitamin D on biologic treatment cessation. Results: Our study included 101 IBD patients (74 CD; median disease duration 9 years). The median index 25(OH)D level was 27 ng/mL (interquartile range, 20–33 ng/mL). One‐third of the patients had prior exposure to anti–TNF‐α therapy. On multivariate analysis, patients with insufficient vitamin D demonstrated earlier cessation of anti–TNF‐α therapy (hazard ratio [HR], 2.13; 95% confidence interval [CI], 1.03–4.39; P = .04). This effect was significant in patients who stopped treatment for loss of response (HR, 3.49; 95% CI, 1.34–9.09) and stronger for CD (HR, 2.38; 95% CI, 0.95–5.99) than UC (P = NS). Conclusions: Our findings suggest that vitamin D levels may influence durability of anti–TNF‐α induction and maintenance therapy. Larger cohort studies and clinical trials of supplemental vitamin D use with disease activity as an end point may be warranted.     

Pretreatment with citrulline improves gut barrier after intestinal obstruction in mice

Background: Citrulline has been shown to be an important marker of gut function, regulator of protein metabolism, and precursor of arginine. The authors assessed the effects of citrulline on gut barrier integrity and bacterial translocation (BT) in mice undergoing intestinal obstruction. Methods: Mice were divided into 3 groups: sham, intestinal obstruction (IO), and citrulline (CIT). The CIT group received a diet containing 0.6% citrulline; the IO and sham groups were fed a standard chow diet. On the eighth day of treatment, all animals received a diethylenetriamine pentaacetic acid (DTPA) solution labeled with ^99mTechnetium (^99mTc‐DTPA) by gavage for the intestinal permeability study. Terminal ileum was ligated except the sham group, which only underwent laparotomy. After 4, 8, and 18 hours, blood was collected to determine radioactivity. Samples of ileum were removed 18 hours after intestinal obstruction for histological analysis. In another set of animals, BT was evaluated. Animals received 10⁸ CFU/mL of ^99mTc–Escherichia coli by gavage; 90 minutes later, they underwent ileum ligation. Intestinal fluid and serum were collected to measure sIgA and cytokines. Results: The CIT group presented decreased intestinal permeability and BT when compared with the IO group (P < .05). Histopathology showed that citrulline preserved the ileum mucosa. The sIgA concentration was higher in the CIT group (P < .05). The IO group presented the highest levels of interferon‐γ (P < .05). Conclusions: Pretreatment with citrulline was able to preserve barrier integrity and also modulated the immune response that might have affected BT decrease.     

Year‐long Changes in Protein Metabolism in Elderly Men and Women Supplemented With a Nutrition Cocktail of β‐Hydroxy‐β‐methylbutyrate (HMB), L‐Arginine,and L‐Lysine

Background: A major contributing factor to the loss of mobility in elderly people is the gradual and continuous loss of lean body mass. Objectives: To determine whether supplementation of an amino acid cocktail daily for 1 year could improve the age‐associated changes in protein turnover and lean body mass in elderly people. Design: Elderly (76± 1.6 years) women (n = 39) and men (n = 38) were recruited for a double‐blinded controlled study. Study participants were randomly assigned to either an isonitrogenous control‐supplement (n = 37) or a treatment‐supplement (HMB/Arg/Lys) consisting of β‐hydroxy‐β‐methylbutyrate, L‐arginine, and L‐lysine (n = 40) for the 1‐year study. Lean tissue mass was measured using both bioelectrical‐impedance analysis (BIA) and dual energy x‐ray absorptiometry (DXA). Rates of whole‐body protein turnover were estimated using primed/intermittent oral doses of ¹⁵N‐glycine. Results: In subjects taking the HMB/Arg/Lys supplement, lean tissue increased over the year of study while in the control group, lean tissue did not change. Compared with control, HMB/Arg/Lys increased body cell mass (BIA) by 1.6% (P = .002) and lean mass (DXA) by 1.2% (P = .05). The rates of protein turnover were significantly increased 8% and 12% in the HMB/Arg/Lys‐supplemented group while rates of protein turnover decreased 11% and 9% in the control‐supplemented subjects (P < .01), at 3 and 12 months, respectively. Conclusions: Consumption of a simple amino acid‐related cocktail increased protein turnover and lean tissue in elderly individuals in a year‐long study.     

Enteral L‐Arginine Supplementation for Prevention of Necrotizing Enterocolitis in Very Low Birth Weight Neonates

Background: Necrotizing enterocolitis (NEC) is the most common acquired gastrointestinal disease in premature infants and has high mortality and morbidity. Endothelial nitric oxide is an important regulator of vascular perfusion and is synthetized from the amino acid L‐arginine. Hypoargininemia is frequently observed in preterm neonates and may predispose them to NEC. Our objective was to determine the effect of enteral L‐arginine supplementation on the incidence and severity of NEC in very low birth weight (VLBW) neonates. Materials and Methods: We conducted a parallel blind randomized pilot study, comprising VLBW neonates with birth weight ≤1500 g and gestational age ≤34 weeks. VLBW neonates were randomly assigned to receive enteral L‐arginine supplementation (1.5 mmol/kg/d bid) between the 3rd and 28th day of life or placebo. Diagnosis and classification of NEC were done according to modified Bell's criteria. Results: Eighty‐three neonates were randomized to the arginine (n = 40) or placebo (n = 43) group. No adverse effects were observed in neonates receiving L‐arginine supplementation. The incidence of NEC stage III was significantly lower in the arginine‐supplemented group (2.5% vs 18.6%, P = .030). Conclusions: Enteral L‐arginine supplementation of 1.5 mmol/kg/d bid can be safely administered in VLBW neonates from the 3rd to the 28th day of life. Enteral L‐arginine supplementation appears to reduce the incidence of stage III NEC in VLBW infants. Larger studies are needed to further evaluate the effect of L‐arginine supplementation in preventing NEC in VLBW infants.     

Oral antibiotics attenuate bowel segment reversal-induced alterations in subpopulation and function of peripheral blood leukocytes, thymocytes, and splenocytes in massive bowel-resected rats

Background: The authors previously demonstrated that oral antibiotics significantly attenuated inflammatory response, improved intestinal bacterial overgrowth, and augmented anabolic response in massive bowel‐resected rats with bowel‐segment reversal. Herein, the effects of oral antibiotics on immune functions were investigated. Methods: Male Wistar rats were subjected to a sham operation or a 70% small bowel resection with or without a 3‐cm small bowel segment reversal. Thereafter, half numbers of animals with bowel resection and reversal were orally administered clindamycin plus amoxicillin (50 plus 50 mg/kg/day) for 3 weeks. Age‐matched nonsurgical rats were included as references. Peripheral blood, spleen, and thymus were collected for analyzing immunocyte subpopulations and function.Results: Bowel resection significantly decreased weight gain, thymic weight, and splenic helper‐T, suppressor‐T, and mature‐B cells but significantly increased splenic macrophage distribution and concanvavalin A–stimulated splenocytic proliferation and cytokine production, such as tumor‐necrosis factor (TNF)‐α, interferon‐γ, and interleukin (IL)‐2 (1‐way ANOVA, P < .05). Bowel segment reversal further decreased circulating suppressor‐T cells but increased circulating natural killer cells and spontaneous splenocytic TNF‐α production. Segment reversal–induced elevations in bacterial numbers of gut content, circulating white blood cell, nitric oxide, IL‐6, splenocytic interferon‐γ and IL‐2 production, reductions in T‐thymocytic distribution, and alterations in thymocytic interferon‐γ and IL‐2 production were attenuated by oral antibiotics. Moreover, oral antibiotics significantly increased splenocytic granulocytes and spontaneous thymocytic proliferation. Conclusions: Oral antibiotics might augment the beneficial effects of bowel segment reversal on anabolism via attenuating bacterial overgrowth and inflammatory response, and restore subpopulation and function of splenocytes and thymocytes in massive bowel–resected rats.     

Gastrointestinal hormone concentrations associated with gastric feeding in critically ill patients

Background: Altered concentrations of ghrelin, motilin, and cholecystokinin (CCK) may contribute to gastric hypomotility. The aims of this study were to evaluate the concentrations of these hormones in patients tolerant and intolerant to gastric nutrition, assess the influence of prokinetic therapy on these hormone concentrations, determine the associations between these mediators and gastric emptying, and evaluate whether inflammation influences their concentrations. Methods: Post hoc analyses of 2 prospective studies that enrolled 20 critically ill patients with an aspirated gastric residual (GR) >150 mL while receiving gastric enteral nutrition (intolerant group) and 10 critically ill patients with minimal GR (tolerant group). Patients with intolerance were also assessed 1 day after prokinetic therapy. Fasting serum concentrations of total ghrelin, acyl ghrelin (active), des‐acyl ghrelin (inactive), motilin, CCK, and tumor necrosis factor (TNF)?α were determined. Gastric emptying was assessed concurrently using the acetaminophen absorption method. Results: Compared to the tolerant group, the intolerant group had higher total ghrelin (1324.8 ± 1204.6 vs 285.1 ± 132.5 pg/mL; P < .001), lower acyl ghrelin (70.5 ± 65.4 vs 208.5 ± 186.9 pg/mL; P < .05), and lower acyl ghrelin to des‐acyl ghrelin ratio (1.11 ± 1.35 vs 3.47 ± 3.21 pg/mL; P < .05). Concentrations of other hormones and TNF‐α were similar. Despite accelerated gastric emptying after prokinetic therapy, concentrations of all hormones and TNF‐α were similar to baseline values. Hormone concentrations were not associated with gastric emptying or TNF‐α. Conclusion: Patients intolerant to gastric nutrition generate less acyl ghrelin, which may contribute to gastric hypomotility. Intolerance is not associated with altered concentrations of other hormones. Hormone concentrations are not influenced by prokinetic therapy.     

Anti-tumor necrosis factor-α monoclonal antibody alleviates parenteral nutrition-associated liver disease in mice

Background: The authors aimed to investigate the role of anti–tumor necrosis factor (TNF)–α monoclonal antibody treatment in a mouse model of parenteral nutrition–associated liver disease (PNALD). Methods: C57BL/6J male mice (aged 6–8 weeks) were randomly assigned to 3 groups: parenteral nutrition (PN), PN with anti–TNF‐α monoclonal antibody treatment (PN + mAb), and controls. A central venous catheter was inserted for intravenous infusion of a PN solution (PN and PN + mAb groups) or saline (controls) for 7 days. Liver pathology, hepatic biochemical indicators, and serum TNF‐α concentrations were analyzed. Levels of hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA were also evaluated in each group. Results: The PN group showed significant increases in serum transaminase, direct bilirubin, and bile acids relative to the control group (P < .05). Histopathological changes in this group were consistent with early stage cholestasis. The pathological score and serum alanine aminotransferase, total bilirubin, and direct bilirubin levels were improved in the PN + mAb group relative to the PN group (P < .05). The PN group showed significantly lower hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA expression than the controls (P < .05), but these were significantly increased compared to the PN group (P < .05). Conclusions: Infliximab administered at a single dose of 5 mg/kg body weight ameliorated the progression of PNALD and improved the expression of hepatic ABC transporter genes. Therefore, anti–TNF‐α monoclonal antibody may be a beneficial therapy for patients with PNALD.     

Choline Alleviates Parenteral Nutrition–Associated Duodenal Motility Disorder in Infant Rats

Background:Parenteral nutrition (PN) has been found to influence duodenal motility in animals. Choline is an essential nutrient, and its deficiency is related to PN‐associated organ diseases. Therefore, this study was aimed to investigate the role of choline supplementation in an infant rat model of PN‐associated duodenal motility disorder. Materials and Methods: Three‐week‐old Sprague‐Dawley male rats were fed chow and water (controls), PN solution (PN), or PN plus intravenous choline (600 mg/kg) (PN + choline). Rats underwent jugular vein cannulation for infusion of PN solution or 0.9% saline (controls) for 7 days. Duodenal oxidative stress status, concentrations of plasma choline, phosphocholine, and betaine and serum tumor necrosis factor (TNF)–α were assayed. The messenger RNA (mRNA) and protein expression of c‐Kit proto‐oncogene protein (c‐Kit) and membrane‐bound stem cell factor (mSCF) together with the electrophysiological features of slow waves in the duodenum were also evaluated. Results: Rats on PN showed increased reactive oxygen species; decreased total antioxidant capacity in the duodenum; reduced plasma choline, phosphocholine, and betaine; and enhanced serum TNF‐α concentrations, which were reversed by choline intervention. In addition, PN reduced mRNA and protein expression of mSCF and c‐Kit, which were inversed under choline administration. Moreover, choline attenuated depolarized resting membrane potential and declined the frequency and amplitude of slow waves in duodenal smooth muscles of infant rats induced by PN, respectively. Conclusion: The addition of choline to PN may alleviate the progression of duodenal motor disorder through protecting smooth muscle cells from injury, promoting mSCF/c‐Kit signaling, and attenuating impairment of interstitial cells of Cajal in the duodenum during PN feeding.     

ω‐3 Fatty Acids Prevent Hepatic Steatosis,Independent of PPAR‐α Activity,in a Murine Model of Parenteral Nutrition–Associated Liver Disease

Objectives: ω‐3 Fatty acids (FAs), natural ligands for the peroxisome proliferator‐activated receptor–α (PPAR‐α), attenuate parenteral nutrition–associated liver disease (PNALD). However, the mechanisms underlying the protective role of ω‐3 FAs are still unknown. The aim of this study was to determine the effects of ω‐3 FAs on hepatic triglyceride (TG) accumulation in a murine model of PNALD and to investigate the role of PPAR‐α and microsomal triglyceride transfer protein (MTP) in this experimental setting. Methods: 129S1/SvImJ wild‐type or 129S4/SvJaePparatm/Gonz/J PPAR‐α knockout mice were fed chow and water (controls); oral, fat‐free PN solution only (PN‐O); PN‐O plus intraperitoneal (IP) ω‐6 FA‐predominant supplements (PN–ω‐6); or PN‐O plus IP ω‐3 FA (PN–ω‐3). Control and PN‐O groups received sham IP injections of 0.9% NaCl. Hepatic histology, TG and cholesterol, MTP activity, and PPAR‐α messenger RNA were assessed after 19 days. Results: In all experimental groups, PN feeding increased hepatic TG and MTP activity compared with controls. Both PN‐O and PN–ω‐6 groups accumulated significantly greater amounts of TG when compared with PN–ω‐3 mice. Studies in PPAR‐α null animals showed that PN feeding increases hepatic TG as in wild‐type mice. PPAR‐α null mice in the PN‐O and PN–ω‐6 groups demonstrated variable degrees of hepatic steatosis, whereas no evidence of hepatic fat accumulation was found after 19 days of oral PN plus IP ω‐3 FAs. Conclusions: PN induces TG accumulation (steatosis) in wild‐type and PPAR‐α null mice. In PN‐fed wild‐type and PPAR‐α null mice given IP ω‐3 FAs, reduced hepatic TG accumulation and absent steatosis are found. Prevention of steatosis by ω‐3 FAs results from PPAR‐α–independent pathways.     

Pretreatment with arginine preserves intestinal barrier integrity and reduces bacterial translocation in mice

ObjectiveTo evaluate the effects of arginine on intestinal barrier integrity and bacterial translocation (BT) in mice undergoing intestinal obstruction.MethodsMice were divided into 3 groups, treated for 7 d before surgical intervention with isocaloric and isoprotein diets. The ARG group received a diet containing 2% arginine, the IO (intestinal obstruction) and Sham groups, standard chow diet. On the eighth day of treatment, all animals received diethylenetriamine pentaacetic acid (DTPA) solution labeled with ^99mTechnetium (^99mTc-DTPA) by gavage for intestinal permeability analysis. After 90 min, the animals were anesthetized and the terminal ileum ligated. The Sham group only underwent laparotomy. After 4, 8, and 18 h, blood was collected for radioactivity determination. Samples of ileum were collected 18 h after surgery for histological analysis. In another set of animals, BT was evaluated. After 7 d of treatment, all animals received 10⁸ CFU/mL of ^99mTc-E.coli by gavage; 90 min later they were submitted to the surgical procedure described above. BT was determined by the uptake of ^99mTc-E.coli in blood, mesenteric lymph nodes, liver, spleen, and lungs, assessed 18 h after the surgery.ResultsThe intestinal permeability and BT were higher in the IO group when compared with the Sham group (P < 0.05). Arginine supplementation reduced intestinal permeability and BT to physiologic levels. Histological analysis showed mucosal ileum preservation in animals treated with arginine.ConclusionArginine was able to preserve barrier integrity, thus reducing BT.     

Arginine enhances In vivo immune responses in young, adult and aged mice

Arginine supplementation enhances in vitro lymphocyte proliferation in healthy adult humans and in rodent models. Studies examining the effect of arginine supplementation on in vivo immune responses are lacking. The purpose of this study was to determine whether arginine supplementation could enhance in vivo immune responses in adult mice and reverse known age-associated alterations in immune function of young and aged mice. Mice (1, 10 and 33 mo old) were fed a 2% arginine or an isonitrogenous diet for 2 wk. Delayed-type hypersensitivity to 2,4-dinitrofluorobenzene-challenged ears and changes in popliteal lymph node weights to injected sheep red blood cells were measured. The mean percentage of increase in ear thickness in challenged vs. unchallenged ears was 27, 35 and 24% with arginine supplementation and 7, 12 and 0% with the isonitrogenous diet in the 1-, 10- and 33-mo-old mice, respectively (P 相似文献   

Oral Citrulline Mitigates Inflammation and Jejunal Damage via the Inactivation of Neuronal Nitric Oxide Synthase and Nuclear Factor–κB in Intestinal Ischemia and Reperfusion

Background: Intestinal ischemia and reperfusion (I/R) is a life‐threatening emergency accompanied by inflammation and organ damage. We compared the mechanisms and the effects of arginine, citrulline, and glutamine on inflammation and intestinal damage. Materials and Methods: Male Wistar rats underwent 60 minutes of superior mesenteric artery occlusion and either 3 (I/R3) or 24 (I/R24) hours of reperfusion and were orally administered vehicle, arginine, citrulline, or glutamine 15 minutes before reperfusion and at 3, 9, and 21 hours of reperfusion. Results: I/R3 rats experienced jejunal damage and apoptosis, and I/R24 rats had liver dysfunction compared with normal rats (one‐way ANOVA, P < .05). Arginine and citrulline administrations improved jejunal morphology, and citrulline and glutamine administrations alleviated the loss of jejunal mass in I/R3 rats. I/R3‐increased circulating nitrate/nitrite (NOx), tumor necrosis factor–α, and interleukin‐6 were significantly decreased by citrulline, glutamine and citrulline, and arginine, glutamine, and citrulline, respectively. These amino acids decreased plasma NOx and interferon‐γ in I/R24, decreased jejunal neuronal nitric oxide synthase (NOS) protein in I/R3 rats, and alleviated jejunal apoptosis in I/R3 and I/R24 rats. In addition, the jejunal phosphorylated to total nuclear factor–κB (NF‐κB) ratio was decreased by arginine and citrulline in I/R24 rats. Conclusion: Oral administration of arginine, citrulline, and glutamine may alleviate systemic inflammation, jejunal apoptosis, and neuronal NOS in intestinal I/R. Citrulline may further attenuate jejunal damage by preserving jejunal mass, partially via the inactivation of NOS and the NF‐κB pathway. In conclusion, oral citrulline may have more benefits than arginine and glutamine in mitigating intestinal ischemia and reperfusion‐induced adverse effects.