Effects Of Dietary Arginine Supplementation Research Articles

Effects of dietary arginine supplementation on reproductive performance and immunity of sows

Arginine (Arg) is considered to have beneficial effects on placental development and function, as well as reproductive performance. The well-developed placenta is highly required in late gestation for rapid fetal growth, however, it is unknown if there is a crucial role of Arg in late gestation. Likewise, the immunological response of sows to Arg needs to be determined. Therefore, this study is designed to investigate the effects of dietary Arg supplementation on reproductive performance and immunity of sows. At day 30 of gestation, sixty sows (Landrace × Large White) were allocated to 3 groups receiving corn and soybean-based control diet (control group, n = 20), control diet supplemented with 1% l-arginine HCl until day 90 of gestation (Arg90 group, n = 20), and control diet supplemented with 1% l-arginine HCl until day 114 of gestation (Arg114 group, n = 20), respectively. Litter performance was recorded at parturition. Blood samples (n = 6) collected at days 30, 90, and 110 of gestation were measured for metabolic and immunological parameters. At parturition, total litter size was not affected by dietary Arg supplementation. As a result of less pigs born dead, however, sows in Arg114 group had more pigs born alive than sows in control group (+1.6 pigs, P < 0.05), total and live litter weights were increased (+1.6~2.1 kg, P < 0.05) in Arg114 group relative to both control and Arg90 groups. Compared with control group, dietary Arg supplementation increased (+12~110%, P < 0.05) plasma levels of ornithine, proline, and arginine at either day 90 (Arg90 and Arg110 groups) or day 110 of gestation (Arg110 group). Moreover, immune response was enhanced in Arg-supplemented sows, as indicated by the increased levels of serum immunoglobulin and porcine reproductive and respiratory syndrome virus (PRRSV) antibody. These findings indicate dietary Arg supplementation can improve litter performance and immune response, and the beneficial effect of Arg on fetal growth is evident in late gestation.

Effects of dietary arginine supplementation on broiler breeder egg production and hatchability

This study investigated the effects of arginine (Arg) supplementation on broiler breeder egg production and egg quality. Male (30) and female (360) Ross® breeders, totaling 390 birds, were studied. A completely randomized design with five Arg levels (0.943%, 1.093%, 1.243%, 1.393%, 1.543% digestible Arg) and six replicates of 12 females and one male per experimental unit was applied. The following performance and egg quality were evaluated: lay percentage, albumen and yolk contents, average egg weight, egg specific gravity, and eggshell percentage and thickness. Hatchability and and embryo mortality were also determined. The applied dietary digestible Arg levels quadratically influenced egg production (p<0.05), with the highest production obtained when 1.262% digestible Arg was supplemented. Egg weight linearly increased (p<0.05) with digestible Arg dietary level; however, egg specific gravity linearly decreased (p<0.05). Hatchability was not affected (p<0.05) by digestible Arg level. The supplementation of broiler breeder diets with Arg improved egg production and egg weight without any effect on hatchability. Further research is needed to determine the effect of dietary Arg supplementation on the performance of the progeny.

Protective effects of dietary arginine supplementation against oxidative stress in weaned piglets

Oxidative stress is detrimental to animals. Previous studies have indicated that arginine (Arg) may function as a potential substance against oxidative stress. The present study was conducted to explore the potential mechanisms behind the Arg-induced protective effects against oxidative stress in piglets. A total of thirty-six piglets were randomly allocated to six groups with six replicates per group. Piglets were subjected to three dietary treatments (namely two groups per treatment) in week 1 and fed with a basal diet (ArgL) or the basal diet supplemented with 0.8% (ArgM) or 1.6% (ArgH) L-Arg, respectively. On day 8, piglets were injected intraperitoneally either with diquat (10 mg/kg body weight) or sterile saline. The whole trial lasted 11 d. Results showed that dietary Arg supplementation did not affect growth performance in week 1. Oxidative stress significantly decreased the growth performance of piglets (P < 0.05). However, ArgH attenuated the negative effects of oxidative stress on feed intake and significantly increased the total antioxidant capacity in the liver under oxidative stress (P < 0.05). Both ArgM and ArgH enhanced the activities of plasma glutathione peroxidases and superoxide dismutases and decreased the IL-6 and TNF-a mRNA level in the liver under oxidative stress (P < 0.05). The present study not only shows that Arg can function as a potential nutrient to alleviate oxidative stress responses through the enhancement of antioxidant capacity, and inhibition of the expression of inflammatory cytokines, but the results also suggest that alleviation of oxidative stress responses using dietary nutrient components deserves further attention in the future.

Effects of dietary arginine supplementation on growth, protein optimization and innate immune response of channel catfishIctalurus punctatus(Rafinesque 1818)

Juvenile channel catfish Ictalurus punctatus were fed casein–gelatin-based semi-purified test diets with graded amounts of arginine (ARG, 0.5%, 1%, 2% and 4% of dry diet) for a 6-week period, to evaluate the effects of dietary ARG supplementation on performance indicators, levels of plasma ARG, ornithine, citrulline, glutamine and glutamate, as well as selected innate immune parameters. Incremental dietary ARG resulted in significant improvements in weight gain, feed efficiency and protein efficiency ratios, protein retention, protein deposition and arginine deposition. Fish fed the 4% ARG diet had significantly higher values for all performance indicators, although these values were not different from those of fish fed the 2% ARG diet with the exception of protein retention, protein deposition and arginine deposition. Conversely, fish fed the 0.5% ARG diet had significantly lower values for all analysed plasma amino acids. Similarly, both phagocyte superoxide anion production and neutrophil respiratory burst were significantly decreased in fish fed the 0.5% ARG diet. These results demonstrate that the indispensability of dietary ARG is not only related to optimized protein utilization for growth but also its supplementation to fish diets may significantly impact several aspects of the immune system, including phagocyte function and thus improve overall fish health.

Effect of Dietary L-Arginine Supplementation on Fetoplacental Vegfr2 Gene Activity and Reproductive Performance in a Bioluminescent Murine Pregnancy Model.

Arginine is a conditionally essential amino acid for mature mammals, yet it is considered to be essential for young, developing mammals. Regarded as one of the most versatile amino acids, arginine serves as a precursor for many molecules and has been reported to improve the reproductive performance of rats and pigs. While the mechanism is still unclear, arginine has been proposed to alter angiogenesis during pregnancy. To this end, the objective of this study was to determine whether the beneficial effect that dietary arginine supplementation has on reproductive performance is associated with an alteration of fetoplacental vascular endothelial growth factor receptor-2 (Vegfr2) transcription activity. Homozygous FVB/N-Tg(Vegfr2-luc)-Xen transgenic male mice (Vegf2-luc), genetically modified with a cloned murine Vegfr2 promoter upstream to firefly luciferase, were purchased from Caliper Life Sciences, Inc. (Hopkinton, MA, USA). Eighteen wild-type FVB/N females were bred to Vegfr2-luc males so that only the fetoplacental tissues would possess the Vegfr2-luc transgene. Once bred, females (n=6 per diet) received a control diet (Con) or the diet supplemented with either 2.0% (wt:wt) L-arginine (+Arg), or 4.1% (wt:wt) alanine (+Ala) which served as an isonitrogenous control for the +Arg diet. Body weight and total feed intake were recorded during gestation. Pregnant mice were imaged daily from day 12 to day 18 of gestation to detect luciferase activity as an indicator of Vegfr2 gene expression using the IVIS 100 imaging system (Caliper Life Sciences, Inc.). Number of pups and litter weight were recorded at birth, and the number of placental attachments was determined three weeks postpartum. All data were analyzed using ANOVA followed by Fisher's LSD test for pairwise comparison. The threshold of significance was fixed at P ≤ 0.05 and a tendency at P ≤ 0.10. Total feed intake did not differ significantly between groups; however, animals in the +Arg group consumed more arginine than others (P < 0.05). Arginine supplementation increased weight gain during the latter third of gestation (day 12 to day 18), total litter size, number of pups born alive, number of placental attachment sites, litter birth weight, and litter weight of pups born alive (P < 0.05). Conversely, individual birth weights of pups born alive was less (P < 0.05) in those born to arginine supplemented dams. There was a tendency (P = 0.07) for average total fetoplacental Vegfr2 gene activity to differ between groups, and this effect was significantly greater in the arginine supplemented animals when compared to the animals receiving the isonitrogenous alanine supplemented diet (P < 0.05). When corrected for fetoplacental mass, Vegfr2 gene activity did not significantly differ between groups; however, animals supplemented with arginine displayed an earlier rise in Vegfr2 gene activity. In conclusion, our results demonstrate that the beneficial effect of dietary arginine supplementation on mammalian reproduction is associated with an earlier increase in Vegfr2 transcription activity in fetoplacental tissues. This research was supported by the USDA-ARS Biophotonics Initiative #58-6402-3-0120. (platform)

Effect of dietary arginine supplementation on reproductive performance of mice with porcine circovirus type 2 infection.

The objective of this study was to investigate whether supplemental dietary arginine increases reproductive performance in mice infected with porcine circovirus type2 (PCV2). A total of 50KM female mice were allotted randomly to the arginine group (0.6% arginine + gestation diet) and control group (1.22% alanine + gestation diet). All the mice began to mate after 14 days of treatment with our prepared feed and challenged with PCV2 at the dose of 100 TCID50 (50% tissue culture infection dose, TCID50) after 7 days of pregnancy. Abortion rate, litter number, litter birth weight, the daily weight gain in the first 7 days and survival rate in the first 2 weeks of the neonates were calculated. The serum progesterone, estrogen, nitric oxide and superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC) on the 14th day of pregnancy were measured. Arginine supplementation decreased the abortion rate of pregnant mice and mortality of neonates caused by PCV2 infection. Further, litter number, litter birth weight and the daily weight gain of neonates increased in the arginine group compared to the control group. Arginine supplementation increased significantly the serum progesterone (P < 0.01) and nitric oxide levels (P < 0.05), but had little effect on the serum estrogen level. SOD activity and T-AOC in the arginine group were significantly higher (P < 0.01) than the control group. In conclusion, arginine supplementation partially reversed the reproductive failure in mice caused by PCV2 infection.

Dietaryl-arginine supplementation enhances intestinal development and expression of vascular endothelial growth factor in weanling piglets

Oral administration of L-arginine has been reported to prevent gut disease in human infants. However, little is known about the effects of dietary arginine supplementation on intestinal development of weaned piglets. In the present study, twenty 21-d-old castrated piglets with 5·3 (SEM 0·13) kg body weight (BW) were weaned from sows, individually housed and randomly assigned to one of the two maize- and soyabean meal-based diets supplemented with 0 or 1% L-arginine. After consuming the diets for 7 d, six pigs were randomly selected from each group to obtain various tissues. Compared with control pigs, dietary supplementation with 1% L-arginine did not affect feed intake but enhanced (P<0·05) the relative weight of the small intestine (+33 %), daily BW gain (+38 %) and feed efficiency (+28 %). The villus height of the duodenum, jejunum and ileum in arginine-supplemented piglets was 21, 28 and 25% greater (P<0·05) than in the nonsupplemented control group. Arginine supplementation increased (P<0·05) protein levels for vascular endothelial growth factor(VEGF) in duodenal, jejunal and ileal mucosae by 14, 39 and 35 %, respectively. Compared with the control group, dietary supplementation with 1% L-arginine increased (P<0·05) plasma concentrations of arginine and insulin (+36 %), and decreased (P<0·05) plasma concentrations of cortisol (233 %), NH3 (221 %) and urea (219 %). These results indicate that arginine supplementation enhances intestinal growth, development and expression of VEGF in early-weaned pigs fed a maize- and soyabean meal-based diet. The findings may have important implications for neonatal pigs under stressful or diseased conditions.

Metabolomic analysis of the response of growing pigs to dietary l-arginine supplementation

Arginine plays an important role regulating nutrient metabolism, but the underlying mechanisms are largely unknown. This study was conducted to determine the effect of dietary arginine supplementation on the metabolome in serum of growing pigs using (1)H nuclear magnetic resonance spectroscopy. Sixteen 120-day-old pigs (48 +/- 1 kg) were randomly assigned to one of two groups, representing supplementation with 0 or 1.0% L: -arginine to corn- and soybean meal-based diets. Serum was collected after a 46-day period of treatment. Dietary arginine supplementation decreased fat deposition and increased protein accretion in the body. Principal component analysis showed that serum concentrations of low density lipoprotein, very low density lipoprotein, and urea were lower, but concentrations of creatinine, tricarboxylic acid cycle metabolites, ornithine, lysine and tyrosine were greater in arginine-supplemented than in control pigs. Additionally, the arginine treatment affected serum concentrations of nitrogenous and lipid signaling molecules (glycerophosphorylcholine and myo-inositol) and intestinal bacterial metabolites (formate, ethanol, methylamine, dimethylamine, acetate, and propionate). These novel findings suggest that dietary arginine supplementation alters the catabolism of fat and amino acids in the whole body, enhances protein synthesis in skeletal muscle, and modulates intestinal microbial metabolism in growing pigs.

Dietary Arginine Supplementation during Early Pregnancy Enhances Embryonic Survival in Rats

Four experiments were conducted with 120 pregnant Sprague-Dawley rats to determine effects of dietary arginine supplementation on embryonic survival. Rats were fed a nonpurified diet supplemented with 1.3% (wt:wt) l-arginine-HCl or 2.2% (wt:wt) l-alanine (isonitrogenous control) throughout pregnancy (Expt. 1), between d 1 and 7 of gestation and then the nonpurified diet until parturition (Expt. 2), between d 1 and 7 of gestation for determining the number of surviving embryos on d 7 (Expt. 3), or between d 1 and 4 of pregnancy for blood sampling on d 5 after overnight food deprivation (Expt. 4). Litter size increased (P < 0.01) in response to arginine supplementation throughout pregnancy (14.5 ± 0.62 vs. 11.3 ± 0.61) or during the first 7 d of pregnancy (14.7 ± 0.33 vs. 11.3 ± 0.37). The number of surviving embryos was greater (P < 0.01) when arginine was supplemented between d 1 and 7 of pregnancy (14.7 ± 0.39 vs. 11.4 ± 0.66). Concentrations of nitric-oxide metabolites, arginine, proline, glutamine, and ornithine were higher (P < 0.05), but urea levels were lower (P < 0.05) in the serum of arginine-supplemented rats compared with the control group. The arginine treatment increased (P < 0.05) protein levels for inducible and constitutive nitric-oxide synthase at implantation sites by 35–37%. These results indicate that dietary arginine supplementation enhances embryonic survival, therefore increasing litter size by 30% at term birth. This novel finding has important implications for preventing early pregnancy loss and enhancing reproductive performance in mammals.

Effects of dietary arginine supplementation during gestation and lactation on the performance of lactating primiparous sows and nursing piglets1

A 2 x 2 factorial arrangement of treatments in a randomized block design was used to determine the effects of dietary Arg supplementation during gestation and lactation on the lactation performance of 38 first-parity sows. At 30 d of gestation, pregnant gilts were allotted based on BW to 1 of 2 diets supplemented with 1% L-Arg.HCl or 1.7% L-Ala (isonitrogenous control). After farrowing, sows were further allotted based on BW within previous gestation treatment groups to 1 of 2 lactation diets supplemented with 1% L-Arg.HCl or 1.7% L-Ala (isonitrogenous control). All gestation diets contained 3.1 Mcal/kg and 12.2% CP (as is) and were fed 2 kg/d in 2 equally sized meals, whereas all lactation diets contained 3.2 Mcal/kg and 18.6% CP (as is) and were fed ad libitum. Litter size was standardized to 10 piglets by cross-fostering within 24 h postfarrowing. On a weekly basis, BW and backfat (BF) thickness of sows, as well as piglet BW were measured, and blood and milk samples were obtained from the sows. Number of days from weaning to estrus and ADFI were also recorded. There were no differences in BW, BF thickness, ADFI, or days until return to estrus among treatment groups. There was no effect of the gestation diet or a gestation x lactation diet interaction on any parameter measured. On d 7 of lactation, plasma concentrations of Arg and insulin in sows, as well as concentrations of most AA in milk, were greater (P < 0.05) in response to Arg supplementation during lactation compared with the control. Weight gain of piglets from sows fed the Arg-supplemented diet during lactation was greater between d 0 and 7 (P < 0.01) and between d 0 and 21 (P < 0.05) of lactation compared with piglets from sows fed the control diet. Collectively, results from this study indicate the potential beneficial effects of dietary Arg supplementation in improving the lactation performance of first-parity sows.

Dietary Arginine Supplementation Enhances the Growth of Milk-Fed Young Pigs

This study was conducted to determine the effect of dietary arginine supplementation on the growth of artificially reared piglets. The pigs (n = 24; 7 d old) were removed from sows to a nursery facility and assigned randomly to 1 of the 3 treatments representing diets supplemented with 0, 0.2, or 0.4% L-arginine (on the basis of milk replacer powder). Each milk feeder was assigned to 1 dietary treatment. Fresh liquid milk replacer (18.6% dry matter) was provided daily ( approximately 0800 h) to piglets. Body weights of piglets were measured and jugular venous blood samples were obtained for metabolite analysis at d 7, 14, and 21 of age. Food intake did not differ between control and arginine-supplemented piglets [66.7 vs. 69.5 g dry matter/(kg body wt. d)]. Compared with control piglets, dietary supplementation with 0.2 and 0.4% L-arginine dose dependently increased (P < 0.05) plasma concentrations of arginine by 30 and 61%, and decreased (P < 0.05) plasma concentrations of ammonia by 20 and 35%, and those of urea by 19 and 33%, respectively. Dietary supplementation with 0.4% L-arginine also increased (P < 0.05) plasma concentrations of insulin and growth hormone by 24-27% in piglets, compared with controls. Between 7 and 21 d of age, the supplementation of 0.2 and 0.4% L-arginine to piglets enhanced (P < 0.05) average daily weight gain by 28 and 66%, and body weight by 15 and 32%, respectively, compared with control piglets. Collectively, both the metabolic and growth data demonstrate unequivocally that arginine is deficient in milk-fed young pigs and that this arginine deficiency represents a major obstacle to maximal growth in piglets.

Dietary L-Arginine Supplementation Improves the Glomerular Filtration Rate and Renal Blood Flow After 24 Hours of Unilateral Ureteral Obstruction in Rats

Unilateral ureteral obstruction (UUO) results in a significant change in renal blood flow (RBF) and glomerular filtration rate (GFR) by 24 hours. The intake of L-arginine, a substrate of nitric oxide (NO) synthase (NOS), can augment NO production. NO can maintain renal function through its vasodilatory action. Therefore, we examined the effect of dietary arginine supplementation on renal function in UUO. GFR and RBF were measured by inulin and para-aminohippurate clearance, respectively, in control rats and in rats 24 hours after UUO. Rats were given arginine with or without the concomitant administration of N-nitro-L-arginine methyl ester. Urinary nitrate/nitrite (NO2/NO3) was measured by the Griess reaction and urinary cyclic guanosine monophosphate was determined by enzyme-linked immunosorbent assay. The expression of renal inducible NOS was determined by immunohistochemistry. Urinary NO2/NO3 was significantly increased after 2 weeks of arginine, confirming increased NO production. In control rats GFR and RBF were not significantly different in untreated vs arginine treated groups. In contrast, arginine treatment significantly increased GFR in the obstructed kidney (0.06 +/- 0.01 to 0.14 +/- 0.02 ml per minute per 100 gm) and the contralateral kidney compared with control UUO. RBF was also significantly increased by arginine. The increases in renal function with arginine were blunted by a NOS inhibitor in obstructed and contralateral kidneys. Inducible NOS expression was increased in obstructed and contralateral kidneys. This study demonstrates that L-arginine supplementation can improve renal function in acute UUO. This finding suggests that NO system may be a future site of pharmacological intervention for UUO.

Effects of dietary arginine supplementation on nutrient metabolism and survival rate in burned mice

This study investigated the effect of arginine (Arg) supplementation on nutrient metabolism and splenocyte response in burned mice. Also, the survival of burned mice complicated with Pseudomonas aeruginosa was evaluated. Experiment 1: Sixty male BALB/c mice were assigned to 2 groups. One group was fed with casein as the protein source, the other group was supplemented with 2.4% (w/w) Arg in addition to casein. After 4 weeks, all mice received a 30% body surface area burn injury. Mice in each group were sacrificed for 3 consecutive days after the burn with 10 mice on each respective day. Plasma blood chemistry and amino acid profiles were analyzed. Spleens were removed aseptically from mice 1 day after the burn, interferon (IFN)-γ and interleukin (IL)-4 concentrations secreted by cultured splenocytes were measured. Experiment 2: Thirty mice were divided into 2 groups as described in experiment 1. After 4 weeks, burn injury was induced, and mice were challenged with P. aeruginosa. Survival of the burned mice was observed for 7 days. In experiment 1, no differences in plasma glucose, non-esterified fatty acids, and lactic acid concentrations were observed between the 2 groups on each respective day. Arg group had higher levels of alanine and branched-chain amino acids on day 2, also, plasma Arg and glutamine levels were higher in the Arg group on days 2 and 3 after the burn than in the control group. IFN-γ concentrations in mitogen stimulated splenocyte cultures were higher in the Arg group than the control group. No difference in IL-4 concentrations was observed. In experiment 2, the survival did not differ between the 2 groups. These results suggest that Arg supplementation had no beneficial effect on glucose and lipid metabolism, nor had any effect on survival when burned mice were complicated with P. aeruginosa infection. However, Arg supplementation reduced the depletion of plasma Arg and glutamine levels at the hypercatabolic stage after the burn, and may have potential benefit on enhancing cellular immune response.

Effects of dietary arginine supplementation on antibody production and antioxidant enzyme activity in burned mice

This study investigated the effect of arginine (Arg) supplementation on specific antibody production and antioxidant enzyme activities in burned mice vaccinated with detoxified Pseudomonas exotoxin A linked with the outer membrane proteins I and F, named PEIF. Also, the survival rate of burned mice complicated with Pseudomonas aeruginosa was evaluated. Experiment 1: Thirty BALB/c mice were assigned to two groups. One group was fed a control diet with casein as the protein source, while the other group was supplemented with 2% Arg in addition to casein. The two groups were isonitrogenous. The mice were immunized twice with PEIF, and the production of specific antibodies against PEIF was measured every week. After 8 weeks, all mice received a 30% body surface area burn injury. Mice were sacrificed 24 h after the burn. The antioxidant enzyme activities and lipid peroxides in the tissues as well as the specific antibody production were analyzed. Experiment 2: Twenty-eight mice were divided into two groups and vaccinated as described in experiment 1. After the burn the mice were infected with P. aeruginosa, and the survival rate was observed for 8 days. The results demonstrated that antioxidant enzyme activities and lipid peroxides in tissues were significantly lower in the Arg group than in the control group after the burn. The production of specific antibodies against P. aeruginosa significantly increased in the Arg group at 4 and 7 weeks after immunization, and 24 h after the burn. The survival rates of vaccinated burned mice after bacterial infection did not significantly differ between the two groups. These results suggest that vaccinating mice with Arg supplementation may enhance humoral immunity and attenuate the oxidative stress induced by burn injury. However, Arg supplementation did not improve survival in vaccinated mice complicated with P. aeruginosa infection.

Effect of dietary arginine supplementation and environmental temperature on sow lactation performance

The objective of this study was to investigate whether supplemental dietary arginine increases lactation performance in sows subjected to a hot environment. A total of 66 multiparous sows were allotted in a 2×3 factorial arrangement, consisting of two environments and three dietary treatments. Sows were maintained in a thermoneutral environment of 20°C (TN) or heat-stressed in a hot environment of 29.4°C (HS), starting on day 95 of gestation. From day 110 of gestation to weaning, sows were provided one of three corn–soybean meal based dietary treatments formulated to contain 0.96% arginine (1:1 arginine:lysine), 1.34% arginine (1.4:1 arginine:lysine), and 1.73% arginine (1.8:1 arginine:lysine), for control (C), medium (ME), and high (HI) dietary treatments, respectively. Respiration rate and rectal temperature increased in HS sows compared to TN sows ( P<0.01) and heart rate decreased in HS sows ( P<0.05) compared to TN sows. Arginine supplementation did not affect heart rate and respiration rate; however, it tended to decrease rectal temperature ( P<0.10) in sows fed the ME diet in the thermoneutral environment. Litter weight gain ( P<0.05) and voluntary sow feed intake ( P<0.01) decreased and sow weight loss increased ( P<0.01) in the hot environment. Dietary arginine supplementation did not improve litter weight gain ( P>0.10) for either HS or TN sows. Arginine supplementation reduced feed intake ( P<0.05) and tended to reduce body weight loss (P0.06) during lactation. In conclusion, supplemental arginine in lactating sow diets in a hot environment did not improve litter performance but reduced sow weight loss and increased sow feed efficiency.

Effects of dietary arginine supplementation on protein turnover and tissue protein synthesis in scald-burn rats

We assessed the effects of dietary arginine supplementation on protein turnover and organ protein synthesis in burned rats. Male Wistar rats weighing about 200 g underwent catheter jejunostomy and received scald burns covering 30% of the whole-body surface area. Animals were divided into a control group ( n = 9) and an arginine group ( n = 9) and continuously received total enteral nutrition for 7 d (250 kcal · kg −1 · d −1, 1.72 gN · kg −1 · d −1). Changes in body weight, plasma total protein, plasma albumin, urinary excretion of polyamines, nitrogen balance, whole-body protein kinetics, and tissue protein synthesis rates were determined. Whole-body protein kinetics and tissue fractional protein synthetic rates (Ks, percent/d) were estimated using a 24-h constant enteral infusion of 15N glycine on the last day. The changes in body weight were not different between the control and arginine groups. The urinary excretion of polyamines was higher in the arginine group than in the control group ( P < 0.01). Burned rats enterally fed arginine-supplemented diet yielded significantly greater cumulative and daily nitrogen balance on days 3 and 5 than those fed a control diet (cumulative, P < 0.05; day 3, P < 0.01; day 5, P < 0.01). Whole-body protein turnover rate was significantly elevated in the arginine group as compared to that in the control group ( P < 0.05). The Ks of rectus abdominis muscles were significantly increased in the arginine group in comparison to the control group ( P < 0.01). We have shown that dietary arginine supplementation improved protein anabolism and attenuated muscle protein catabolism after thermal injury.

The Effects of[formula omitted]-Arginine on Crypt Cell Hyperproliferation in Colorectal Cancer

Background.Colonic crypt cell hyperproliferation characterizes malignant and premalignant conditions of the colon and may be modified by dietary manipulation. This study compared the effect of dietary arginine supplementation on colonic crypt cell proliferation during the initiation and promotion stages of colorectal carcinogenesis.Materials and Methods.One hundred and twenty male Wistar rats were divided into 5 groups of 24 animals each. Groups D, DA, FA, and LA received subcutaneous injections of 1,2-dimethylhydrazine for 20 weeks. Group D received no arginine supplement.l-arginine was given as a 1% solution instead of drinking water to Group DA for 22 weeks, to Group FA for the first 10 weeks, and to Group LA for the last 12 weeks. EDTA animals were given subcutaneous injections of EDTA for 20 weeks. Colonic crypt cell proliferation was assessed in 6 animals from each of the five groups and in 6 normal rats not given DMH or EDTA.Results.The BrdUrd-labeling index and proliferative zone were significantly decreased in all arginine groups (DA, FA, LA). The greatest reduction was evident in Group FA in which tumor incidence and tumor size were also significantly lowered.Conclusions.When given during the initiation phase of carcinogenesisl-arginine significantly reduced colorectal tumor production and crypt cell hyperproliferation.

Beneficial effects of dietary arginine supplementation in methicillin-resistant Staphylococcus aureus infected mice

To determine any potential benefits of feeding increased amounts of arginine to septic mice, 45 BALB/c mice were randomized into 3 groups. Group A mice were fed 20% casein diet (control), whereas the mice in Groups B and C were given 20% casein diet supplemented with 2% and 4% arginine, respectively. The diets were isonitrogenous and isocaloric. On the 10th day on these diets, each mouse was challenged with 2.0×10 8 colony forming units (CFU) of methicillin-resistant Staphylococcus aureus (MRSA) organisms intravenously and mortality noted for 20 days. The final survival rate in Group A (20%) tended to be lower than the rates in Group B (60%) and Group C (46%) but without significant difference (p>0.05). Of the surviving mice 20 days post inoculation, in Group B, 7 out of 9 (77%) eliminated the organisms as compared to 1 out of 4 (25%) in Group A, and 3 out of 7 (43%) in Group C. The surviving mice in Group B had significantly heavier splenic weight (140±30mg) as compared to Group A mice (90±10mg). The present data suggest that 2% dietary arginine supplementation may be beneficial in offering protection to the mice following MRSA challenge.

Metabolic and immune effects of dietary arginine supplementation after burn.

The effect of supplemental dietary arginine on metabolism and immunity was studied in 36 burned guinea pigs (30% of total body surface area) with previously placed catheter gastrostomies. The animals were randomized into four groups. After an initial three-day adaptation period, all groups received continuous isonitrogenous, isocaloric (175 kcal [735 kJ]/kg/d), and isovolemic intragastric tube feedings until postburn day (PBD) 14. Groups A, B, C, and D received 0%, 1%, 2%, and 4%, respectively, of total energy intake as arginine given in the form of crystalline arginine hydrochloride with 22%, 21%, 20%, and 18%, respectively, of total energy as whey protein. The average body weight after burn decreased equally in all groups. Resting metabolic expenditure on PBD 6 was higher in groups B (151% +/- 6% of preburn) and C (156% +/- 7%) than in groups A (131% +/- 4%) and D (136% +/- 3%). Ear-thickness response to dinitrofluorobenzene challenge on PBD 12 showed the best response in group C. The mortality rates of groups A, B, C, and D were 56%, 29%, 22%, and 56%, respectively. This study suggests that oral dietary arginine supplementation up to 2% of energy intake may be beneficial after burn injury.