Dietary N-carbamylglutamate and rumen-protected L-arginine supplementation during intrauterine growth restriction in undernourished ewes improve fetal thymus development and immune function

The significance of N-carbamoylglutamate in ruminant production

Improving the efficiency and production of grazing ruminants to support food and fiber production, while reducing the environmental footprint and meeting the welfare needs of the animals, is important for sustainable livestock production systems. Development of new technologies that can improve the efficiency of nitrogen (N) utilization in ruminants, and that are effective and safe, has important implications for ruminant livestock production. N-carbomoylglutamate (NCG) is a functional micronutrient that stimulates endogenous synthesis of arginine, which can improve survival, growth, lactation, reproductive performance, and feed efficiency in mammals. There is a growing body of evidence to support the potential of dietary NCG supplementation to improve the productive capacity and N utilization efficiency of ruminants. This review summarizes the current literature on the effects of dietary supplementation with NCG in ruminants and impacts on production and potential to reduce the environmental footprint of farmed ruminant livestock. The current literature highlights the potential for commercial application in ruminant livestock to improve productivity and N utilization efficiency.

Autophagy attenuates placental apoptosis, oxidative stress and fetal growth restriction in pregnant ewes

Bisphenol A (BPA)-induced oxidative stress (OS) and its potentially associated autophagy and apoptosis have not been studied previously in pregnant ewes. Accordingly, this study investigated the underlying mechanisms of BPA-induced autophagy and apoptosis in the placenta and primary trophoblasts of pregnant ewes exposed to BPA both in vivo and in vitro. In vivo experiment, pregnant Hu ewes (n = 8) were exposed to 5 mg/kg/d of BPA compared to control ewes (n = 8) receiving only corn oil from day 40 through day 110 of gestation. Exposure to BPA during gestation resulted in placental insufficiency, fetal growth restriction (FGR), autophagy, endoplasmic reticulum stress (ERS), mitochondrial dysfunction, OS, and apoptosis in type A placentomes. Regarding in vitro model, primary ovine trophoblasts were exposed to BPA, BPA plus chloroquine (CQ; an autophagy inhibitor) or BPA plus rapamycin (RAP; an autophagy activator) for 12 h. Data illustrated that exposure to BPA enhanced autophagy (ULK1, Beclin-1, LC3, Parkin, and PINK1), ERS (GRP78, CHOP10, ATF4, and ATF6) and apoptosis (Caspase 3, Bcl-2, Bax, P53) but decreased the antioxidant (CAT, Nrf2, HO-1, and NQO1)-related mRNA and protein expressions as well as impaired the mitochondrial function. Moreover, treatment with CQ exacerbated the BPA-mediated OS, mitochondrial dysfunction, apoptosis, and ERS. On the contrary, RAP treatment counteracted the BPA-induced trophoblast dysfunctions mentioned above. Overall, the findings illustrated that BPA exposure could contribute to autophagy in the ovine placenta and trophoblasts and that autophagy, in turn, could alleviate BPA-induced apoptosis, mitochondrial dysfunction, ERS, and OS. These results offer new mechanistic insights into the role of autophagy in mitigating BPA-induced placental dysfunctions and FGR.

Developmental Programming of Fertility in Cattle-Is It a Cause for Concern?

Cattle fertility remains sub-optimal despite recent improvements in genetic selection. The extent to which an individual heifer fulfils her genetic potential can be influenced by fetal programming during pregnancy. This paper reviews the evidence that a dam's age, milk yield, health, nutrition and environment during pregnancy may programme permanent structural and physiological modifications in the fetus. These can alter the morphology and body composition of the calf, postnatal growth rates, organ structure, metabolic function, endocrine function and immunity. Potentially important organs which can be affected include the ovaries, liver, pancreas, lungs, spleen and thymus. Insulin/glucose homeostasis, the somatotropic axis and the hypothalamo-pituitary-adrenal axis can all be permanently reprogrammed by the pre-natal environment. These changes may act directly at the level of the ovary to influence fertility, but most actions are indirect. For example, calf health, the timing of puberty, the age and body structure at first calving, and the ability to balance milk production with metabolic health and fertility after calving can all have an impact on reproductive potential. Definitive experiments to quantify the extent to which any of these effects do alter fertility are particularly challenging in cattle, as individual animals and their management are both very variable and lifetime fertility takes many years to assess. Nevertheless, the evidence is compelling that the fertility of some animals is compromised by events happening before they are born. Calf phenotype at birth and their conception data as a nulliparous heifer should therefore both be assessed to avoid such animals being used as herd replacements.

Integration of transcriptomic and metabolomic analysis of the mechanism of dietary N-carbamoylglutamate in promoting follicle development in yaks

Yak is the main livestock in the highlands of China. The low reproductive rate of yaks is a serious constraint on their production and utility. N-carbamylglutamate (NCG) can increase arginine synthesis in mammals and has been shown to improve reproductive performance. Twelve multiparous and simutaneous anoestrous female yaks were randomly divided into two groups, one of which was fed the basal diet (Control, n = 6), and the other was fed the basal diet supplemented with NCG at 6 g/day/yak (NCG, n = 6). All yaks were slaughtered on the 32nd day (the time predicted for the selection of the last wave of dominant follicles), and their ovarian tissues were collected and follicles were classified. NCG supplementation increased the number of large ovarian follicles (diameter > 10 mm), as well as caused significant changes in the transcriptional and metabolic levels in yak ovaries which due to the differential expression of 889 genes and 94 metabolites. Integrated analysis of the transcriptomics and metabolomics data revealed that the differentially expressed genes and differential metabolites were primarily involved in the process of energy metabolism, amino acid metabolic pathways, carbohydrate metabolic pathways, and lipid metabolic pathways. The highlighted changes were associated with amino acid synthesis and metabolism, ovarian steroid hormone synthesis, the pentose phosphate pathway, and the tricarboxylic acid cycle, suggesting that NCG supplementation may promote estrogen synthesis and help regulate follicular development by altering the pathways associated with glucose catabolism. The results present important clues for understanding the mechanisms by which NCG supplementation promotes follicular development in yaks. The findings of this study provide a basis for the development and application of NCG in optimizing animal reproduction, including yak reproductive performance, which may help optimize livestock management and uplift the pastoral economy.

Prenatal interventions for fetal growth restriction in animal models: A systematic review

Fetal growth restriction (FGR) in human pregnancy is associated with perinatal mortality, short- and long-term morbidities. No prenatal therapy is currently established despite decades of research. We aimed to review interventions in animal models for prenatal FGR treatment, and to seek the next steps for an effective clinical therapy. We registered our protocol and searched MEDLINE, Embase, and The Cochrane Library with no language restrictions, in accordance with the PRISMA guideline. We included all studies that reported the effects of any prenatal intervention in animal models of induced FGR. From 3257 screened studies, 202 describing 237 interventions were included for the final synthesis. Mice and rats were the most used animals (79%) followed by sheep (16%). Antioxidants (23%), followed by vasodilators (18%), nutrients (14%), and immunomodulators (12%) were the most tested therapy. Two-thirds of studies only reported delivery or immediate neonatal outcomes. Adverse effects were rarely reported (11%). Most studies (73%), independent of the intervention, showed a benefit in fetal survival or birthweight. The risk of bias was high, mostly due to the lack of randomization, allocation concealment, and blinding. Future research should aim to describe both short- and long-term outcomes across various organ systems in well-characterized models. Further efforts must be made to reduce selection, performance, and detection bias.

Dietary N-carbamylglutamate or L-arginine improves fetal intestinal amino acid profiles during intrauterine growth restriction in undernourished ewes

Our previous studies demonstrated that prenatal in utero growth restriction impairs postnatal intestinal function. Thus, improving postpartal intestinal absorption capacity and growth by manipulating the maternal diet prepartum is of importance. This work was conducted to determine whether supplementation of N-carbamylglutamate (NCG) or rumen-protected L-arginine (RP-Arg) increased fetal intestinal amino acid (AA) profiles in intrauterine growth retardation (IUGR) fetuses. On d 35 of gestation, Hu ewes (n = 32) carrying twin fetuses were randomized into 4 groups (8 ewes and 16 fetuses in each group), where diets were as follows: 100% of nutrient requirements recommended by National Research Council (NRC, 2007) (CON); 50% of nutrient requirements recommended by NRC (2007) (RES); RES + RP-Arg (20 g/d), (RES + ARG); and RES + NCG (5 g/d), (RES + NCG). On d 110 of gestation, both fetal and maternal tissues were collected and weighed. Compared with RES, solute carrier family 1, member 5 (SLC1A5) was upregulated (P < 0.05) within fetal jejunum, duodenum and ileum when supplementing NCG and RP-Arg. Relative to RES, RP-Arg or NCG supplementation to RES resulted in upregulation (P < 0.05) of peptide transporter 1 protein abundance within the fetal ileum. NCG or RP-Arg supplementation to RES also upregulated phosphorylated mechanistic target of rapamycin (pmTOR)-to-mTOR ratio in the fetal ileum induced by IUGR (P < 0.05). As a result, during IUGR, supplementation of Arg or NCG affected intestinal AA profiles in the fetus in part through controlling mTOR signal transduction as well as AA and peptide transport. Future studies should be conducted to understand the role (if any) of the placenta on the improvement of growth and AA profiles independent of the fetal intestine. This would help demonstrate the relative contribution of intestinal uptake in fetal life.

L-Arginine Nutrition and Metabolism in Ruminants

L-Arginine (Arg) plays a central role in the nitrogen metabolism (e.g., syntheses of protein, nitric oxide, polyamines, and creatine), blood flow, nutrient utilization, and health of ruminants. This amino acid is produced by ruminal bacteria and is also synthesized from L-glutamine, L-glutamate, and L-proline via the formation of L-citrulline (Cit) in the enterocytes of young and adult ruminants. In pre-weaning ruminants, most of the Cit formed de novo by the enterocytes is used locally for Arg production. In post-weaning ruminants, the small intestine-derived Cit is converted into Arg primarily in the kidneys and, to a lesser extent, in endothelial cells, macrophages, and other cell types. Under normal feeding conditions, Arg synthesis contributes 65% and 68% of total Arg requirements for nonpregnant and late pregnany ewes fed a diet with ~12% crude protein, respectively, whereas creatine production requires 40% and 36% of Arg utilized by nonpregnant and late pregnant ewes, respectively. Arg has not traditionally been considered a limiting nutrient in diets for post-weaning, gestating, or lactating ruminants because it has been assumed that these animals can synthesize sufficient Arg to meet their nutritional and physiological needs. This lack of a full understanding of Arg nutrition and metabolism has contributed to suboptimal efficiencies for milk production, reproductive performance, and growth in ruminants. There is now considerable evidence that dietary supplementation with rumen-protected Arg (e.g., 0.25-0.5% of dietary dry matter) can improve all these production indices without adverse effects on metabolism or health. Because extracellular Cit is not degraded by microbes in the rumen due to the lack of uptake, Cit can be used without any encapsulation as an effective dietary source for the synthesis of Arg in ruminants, including dairy and beef cows, as well as sheep and goats. Thus, an adequate amount of supplemental rumen-protected Arg or unencapsulated Cit is necessary to support maximum survival, growth, lactation, reproductive performance, and feed efficiency, as well as optimum health and well-being in all ruminants.

Dietary rumen-protected L-arginine or N-carbamylglutamate attenuated fetal hepatic inflammation in undernourished ewes suffering from intrauterine growth restriction

This study aimed to explore whether dietary rumen-protected L-arginine (RP-Arg) or N-carbamylglutamate (NCG) supplementation to feed-restricted pregnant ewes counteracts fetal hepatic inflammation and innate immune dysfunction associated with intrauterine growth retardation (IUGR) in ovine fetuses. On d 35 of pregnancy, twin-bearing Hu ewes (n = 32) were randomly assigned to 4 treatment groups (8 ewes and 16 fetuses per group) and fed diets containing 100% of the NRC requirements (CON), 50% of the NRC requirements (RES), RES + RP-Arg (20 g/d) (RESA), or RES + NCG (5 g/d) (RESN). At 08:00 on d 110 of gestation, fetal blood and liver tissue samples were collected. The levels of triglyceride, free fatty acid, cholesterol and β-hydroxybutyrate in the fetal blood of RESA and RESN groups were lower (P < 0.05) than those of the RES group, but were higher (P < 0.05) than those of the CON group. The interleukin (IL)-6 and IL-1 levels in fetal blood and liver tissue as well as the myeloid differentiation primary response 88 (MyD88), transforming growth factor β (TGFβ), and nuclear factor kappa B (NF-κB) mRNA levels in the fetal liver were decreased (P < 0.05) by the NCG or RP-Arg supplementation compared to the RES treatment. Similarly, the toll-like receptor (TLR)-4, MyD88, TGFβ, and p-c-Jun N-terminal kinase (JNK) protein levels in the fetal liver were reduced (P < 0.05) in the NCG and RP-Arg -supplemented groups compared to the RES group. These results showed that dietary supplementation of RP-Arg or NCG to underfed pregnant ewes could protect against IUGR fetal hepatic inflammation via improving lipid metabolism, down-regulating the TLR-4 and the inflammatory JNK and NF-κB signaling pathways, and decreasing cytokine production in ovine fetal blood and liver tissue.

Effect of supplementation of unprotected or protected arginine to prolific ewes on maternal amino acids profile, lamb survival at birth, and pre- and post-weaning lamb growth

This research determined the effects of dietary supplementation with rumen-protected arginine (Pro-Arg) on metabolites and amino acids in maternal plasma and lamb survival rate at birth (LSRAB) in prolific Afec-Assaf ewes. The hypothesis was that Pro-Arg, the precursor for nitric oxide and polyamines, would increase placental development and vascularity, uteroplacental blood flow, and nutrient transport and reduce oxidative stress to increase LSRAB. Ewes were fed either their basal diet, basal diet with Pro-Arg, or basal diet with unprotected arginine (Unp-Arg; 18 g/head/d). The supplemental arginine was about 1% of the dry matter intake from day 40 or 60 of gestation until parturition. Ninety-two of 98 ewes produced live lambs. Ewes fed Pro-Arg had greater (P = 0.002) concentrations of arginine and other amino acids in plasma, whereas Unp-Arg did not affect concentrations of arginine, but decreased (P < 0.05) concentrations of some amino acids. There was no effect of treatments on gestation length (144 ± 2 d), prolificacy (2.65 lambs born per ewe), LSRAB (0.80), body weight (88.8 ± 10.8 kg), and body condition score (2.8 ± 0.6) of ewes, or birth weight and crown-rump length of lambs. The GI (BW/CRL1.5) was affected by sex of lamb (P = 0.008), parity of ewe (P = 0.002), litter size (P = 0.0001), and lamb status (P = 0.003). Of 229 lambs born, 32 were dead and 16 died before 5 mo of age, leaving 181 lambs with records on weights at birth and 5 mo of age. Interestingly, lambs born to ewes fed the Unp-Arg and Pro-Arg weighed 3.6 kg less at postnatal day 150 than lambs from control ewes.

l-Arginine Inhibits Apoptosis of Ovine Intestinal Epithelial Cells through the l-Arginine-Nitric Oxide Pathway

BACKGROUND

In nonruminants, many of the biological roles of l-arginine (Arg) at the intestinal level are mediated through the Arg-nitric oxide (Arg-NO) pathway. Whether the Arg-NO pathway is involved in controlling the immune response and viability in ovine intestinal epithelial cells (IOECs) is unclear.

OBJECTIVES

The current study aimed to examine the role of the Arg-NO pathway in apoptosis, antioxidant capacity, and mitochondrial function of IOECs.

METHODS

The IOECs were incubated in Arg-free DMEM supplemented with 150 μM Arg (CON) or 300 μM Arg (ARG) alone or with 350 μM Nw-nitro-l-arginine methyl ester hydrochloride (l-NAME) (CON + NAME, ARG + NAME) for 24 h. The reactive oxygen species (ROS) concentration, antioxidant capacity, and cell apoptotic percentage were determined.

RESULTS

Arg supplementation decreased (P < 0.05) the ROS concentration (38.9% and 22.7%) and apoptotic cell percentage (57.2% and 54.8%) relative to the CON and CON + NAME groups, respectively. Relative to the CON and ARG treatments, the l-NAME administration decreased (P < 0.05) the mRNA abundance of superoxide dismutase 2 (32% and 21.3%, respectively) and epithelial NO synthase (36% and 29.1%, respectively). Arg supplementation decreased (P < 0.05) the protein abundance of apoptosis antigen 1 (FAS) (52.0% and 43.9%) but increased (P < 0.05) those of nuclear respiratory factor 1 (31.3% and 22.9%) and inducible NO synthase (35.2% and 41.8%) relative to the CON and CON + NAME groups, respectively.

CONCLUSIONS

The inhibition of apoptosis in IOECs due to the increased supply of Arg is associated with the mitochondria- and FAS-dependent pathways through the activity of the Arg-NO pathway. The findings help elucidate the role of the Arg-NO pathway in IOEC growth and apoptosis.

Ruminal microbes of adult sheep do not degrade extracellular l-citrulline

This study determined whether extracellular citrulline is degraded by ruminal bacteria of sheep. In the first experiment, whole rumen fluid (3 mL) from six adult Suffolk sheep was incubated at 37 °C with 5 mM l-glutamine (Gln), l-glutamate (Glu), l-arginine (Arg), or l-citrulline (Cit) for 0, 0.5, 1, and 2 h or with 0, 0.5, 2, or 5 mM Gln, Glu, Arg, or Cit for 2 h. An aliquot (50 µL) of the incubation solution was collected at the predetermined time points for amino acids (AA) analyses. Results showed extensive hydrolysis of Gln into Glu and ammonia, of Arg into l-ornithine and l-proline, but little or no degradation of extracellular Cit or Glu by ruminal microbes. In the second experiment, six adult Suffolk sheep were individually fed each of three separate supplements (8 g Gln , Cit, or urea) on three separate days along with regular feed (800 g/animal). Blood (2 mL) was sampled from the jugular vein prior to feeding (time 0) and at 0.5, 1, 2, and 4 h after consuming the supplement. Plasma was analyzed for AA, glucose, ammonia, and urea. The concentrations of Cit in the plasma of sheep consuming this AA increased (P < 0.001) by 117% at 4 h and those of Arg increased by 23% at 4 h, compared with the baseline values. Urea or Gln feeding did not affect (P > 0.05) the concentrations of Cit or Arg in plasma. These results indicate that Cit is not metabolized by ruminal microbes of sheep and is, therefore, absorbed as such by the small intestine and used for the synthesis of Arg by extrahepatic tissues.

Dietary Supplementation of L-Arginine and N-Carbamylglutamate Attenuated the Hepatic Inflammatory Response and Apoptosis in Suckling Lambs with Intrauterine Growth Retardation

L-arginine (Arg) is a semiessential amino acid with several physiological functions. N-Carbamylglutamate (NCG) can promote the synthesis of endogenous Arg in mammals. However, the roles of Arg or NCG on hepatic inflammation and apoptosis in suckling lambs suffering from intrauterine growth restriction (IUGR) are still unclear. The current work is aimed at examining the effects of dietary Arg and NCG on inflammatory and hepatocyte apoptosis in IUGR suckling lambs. On day 7 after birth, 48 newborn Hu lambs were selected from a cohort of 432 twin lambs. Normal-birthweight and IUGR Hu lambs were allocated randomly (n = 12/group) to control (CON), IUGR, IUGR+1% Arg, or IUGR+0.1% NCG groups. Lambs were fed for 21 days from 7 to 28 days old. Compared with CON lambs, relative protein 53 (P53), apoptosis antigen 1 (Fas), Bcl-2-associated X protein (Bax), caspase-3, cytochrome C, tumor necrosis factor alpha (TNF-α), nuclear factor kappa-B (NF-κB) p65, and NF-κB pp65 protein levels were higher (P < 0.05) in liver from IUGR lambs, whereas those in liver from IUGR lambs under Arg or NCG treatment were lower than those in IUGR lambs. These findings indicated that supplementing Arg or NCG reduced the contents of proinflammatory cytokines at the same time when the apoptosis-related pathway was being suppressed, thus suppressing the IUGR-induced apoptosis of hepatic cells.

N-carbamylglutamate and l-arginine promote intestinal function in suckling lambs with intrauterine growth restriction by regulating antioxidant capacity via a nitric oxide-dependent pathway

Data indicate that intrauterine growth restriction (IUGR) in newborns can be partly alleviated through the supply of l-arginine (Arg) and N-carbamylglutamate (NCG). The current work aimed to explore whether Arg and NCG promote intestinal function by regulating antioxidant capacity in suckling lambs with IUGR via a nitric oxide (NO)-dependent pathway. Forty eight newly born Hu lambs with normal weights at birth (CON) or suffering from IUGR were randomly divided into 4 groups (n = 12 per group), namely, the CON, IUGR, IUGR + 1% Arg, and IUGR + 0.1% NCG groups. The animals were used for experiments from the age of day 7 to 28. Compared with the lambs in the IUGR group, the lambs in the Arg or NCG group had higher (P < 0.05) final body weights. The plasma insulin, NO, and NO synthase (NOS) concentrations in the IUGR group were higher (P < 0.05) compared with those in IUGR + 1% Arg or IUGR + 0.1% NCG. The jejunal level of the tumor necrosis factor α (TNF-α) in the IUGR lambs was greater (P < 0.05) compared with that in IUGR + 1% Arg or IUGR + 0.1% NCG. The plasma and jejunal total antioxidant capacity (T-AOC) values for the IUGR + 1% Arg or IUGR + 0.1% NCG group were greater (P < 0.05) compared with those for the IUGR group. Compared with the IUGR + 1% Arg or IUGR + 0.1% NCG lambs, the IUGR lambs had lower (P < 0.05) abundance of mRNA and protein abundance of glutathione peroxidase 1 (GPx1), catalase (CAT), superoxide dismutase 2 (SOD2), nuclear factor erythroid 2-related factor 2 (Nrf2), quinone oxidoreductase 1 (NQO1), heme oxygenase (HO-1), zonula occludens-1 (ZO-1), occludin, inducible NOS (iNOS), and epithelial NOS (eNOS). Overall, the data suggest that the Arg or NCG supplementation to suckling lambs with IUGR enhances the intestinal function by regulating the oxidant status via the NO-dependent pathway.

N-Carbamylglutamate and l-Arginine Promote Intestinal Absorption of Amino Acids by Regulating the mTOR Signaling Pathway and Amino Acid and Peptide Transporters in Suckling Lambs with Intrauterine Growth Restriction

BACKGROUND

Previous studies have revealed that dietary N-carbamylglutamate (NCG) and l-arginine (Arg) improve intestinal integrity, oxidative state, and immune function in Hu suckling lambs with intrauterine growth restriction (IUGR). Whether these treatments alter intestinal nutrient absorption is unknown.

OBJECTIVE

The aim of this study was to determine the influence of dietary NCG and Arg treatment during the suckling period on intestinal amino acid (AA) absorption, alterations in the mechanistic target of rapamycin (mTOR) signaling pathway, and the abundance of AA and peptide transporters in IUGR lambs.

METHODS

On day 7 after birth, 48 newborn Hu lambs were selected from a cohort of 424 twin lambs. Normal-birth-weight and IUGR Hu lambs were allocated randomly (n = 12/group) to a control (4.09 ± 0.12 kg), IUGR (3.52 ± 0.09 kg), IUGR + 0.1% NCG (3.49 ± 0.11 kg), or IUGR + 1% Arg (3.53 ± 0.10 kg).

RESULTS

At day 28, compared with the IUGR group, the IUGR groups receiving NCG and Arg had 7.4% and 7.2% greater (P < 0.05) body weight, respectively. Compared with the IUGR group, the serum concentration of insulin was greater (P < 0.05) and the cortisol was lower (P < 0.05) in the IUGR groups receiving NCG and Arg. Compared with the IUGR group, the IUGR groups receiving NCG and Arg had 13.2%-62.6% greater (P < 0.05) serum concentrations of arginine, cysteine, isoleucine, and proline. Dietary NCG or Arg to IUGR lambs resulted in greater protein abundance (P < 0.05) of peptide transporter 1 (41.9% or 38.2%) in the ileum compared with the unsupplemented IUGR lambs, respectively. Furthermore, dietary NCG or Arg treatment normalized the IUGR-induced variation (P < 0.05) in the ileal ratio of phosphorylated mTOR to total mTOR protein.

CONCLUSION

Both NCG and Arg can help mitigate the negative effect of IUGR on nutrient absorption in neonatal lambs.

l-Arginine Protects Ovine Intestinal Epithelial Cells from Lipopolysaccharide-Induced Apoptosis through Alleviating Oxidative Stress

This research aims to explore the effect of l-arginine (Arg) upon lipopolysaccharide (LPS)-induced induction of the oxidative stress as well as subsequent apoptosis within ovine intestinal epithelial cells (IOECs). Through a 16 h incubation, cells were divided into four groups and the medium was replaced with different medium as follows: (1) control (Con), Arg-free Dulbecco's modified Eagle's F12 Ham medium (DMEM); (2) Arg treatment, Arg-free DMEM supplemented with 100 μM Arg; (3) LPS treatment, Arg-free DMEM supplemented with 10 μg/mL LPS; (4) LPS with Arg treatment, Arg-free DMEM supplemented with both 10 μg/mL LPS and 100 μM Arg. After culturing for 24 h in different mediums, some characteristics of cells in the four groups were measured. Addition of Arg increased cell viability induced with LPS compared with the LPS group ( p < 0.05). Arg significantly decreased the release of dehydrogenase (LDH) and the production of malonaldehyde (MDA) ( p < 0.05) within IOECs challenged by the LPS. Compared with the LPS group, cells treated with Arg and Arg + LPS increased ( p < 0.05) mRNA as well as protein expression of glutathione peroxidase 1 (GPx1), catalase (CAT), superoxide dismutase 2 (SOD2), B-cell lymphoma 2 (Bcl2), quinone oxidoreductase 1 (NQO1), heme oxygenase (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). IOEC treatment with Arg reduced significantly ( p < 0.05) apoptosis induced by the LPS (12.58 ± 0.79%). The results showed that Arg promoted the protein expression of Nrf2, up-regulated expression of the phase II metabolizing enzymes (NQO1 and HO-1), as well as antioxidative enzymes (GPx1, CAT, and SOD2) for alleviating oxidative injury and protected IOECs from LPS-induced apoptosis.