Administration Of L-citrulline Research Articles

Multi-dose enteral L-citrulline administration in premature infants at risk of developing pulmonary hypertension associated with bronchopulmonary dysplasia

ObjectiveInformation is needed to guide the design of randomized controlled trials (RCTs) evaluating L-citrulline therapy for premature infants with pulmonary hypertension associated with bronchopulmonary dysplasia (BPD-PH). Based on our single-dose pharmacokinetic study, we evaluated the ability of a multi-dose enteral L-citrulline strategy to achieve a target trough steady-state L-citrulline plasma concentration and its tolerability in premature infants.Study DesignPlasma L-citrulline concentrations were measured in six premature infants receiving 60 mg/kg L-citrulline every 6 h for 72 h before the first and last L-citrulline doses. L-citrulline concentrations were compared to concentration-time profiles from our previous study.ResultsTarget trough plasma L-citrulline concentrations were achieved in 2/6 subjects. No serious adverse events occurred.ConclusionsMulti-dose L-citrulline was well tolerated. These results will assist in the design of phase II RCTs evaluating L-citrulline dosage strategies to achieve target plasma L-citrulline concentrations in infants at risk for BPD-PH. Clinical trials.gov ID: NCT03542812

Enteral citrulline supplementation versus placebo on SOFA score on day 7 in mechanically ventilated critically ill patients: the IMMUNOCITRE randomized clinical trial

BackgroundRestoring plasma arginine levels through enteral administration of L-citrulline in critically ill patients may improve outcomes. We aimed to evaluate whether enteral L-citrulline administration reduced organ dysfunction based on the Sequential Organ Failure Assessment (SOFA) score and affected selected immune parameters in mechanically ventilated medical intensive care unit (ICU) patients.MethodsA randomized, double-blind, multicenter clinical trial of enteral administration of L-citrulline versus placebo for critically ill adult patients under invasive mechanical ventilation without sepsis or septic shock was conducted in four ICUs in France between September 2016 and February 2019. Patients were randomly assigned to receive enteral L-citrulline (5 g) every 12 h for 5 days or isonitrogenous, isocaloric placebo. The primary outcome was the SOFA score on day 7. Secondary outcomes included SOFA score improvement (defined as a decrease in total SOFA score by 2 points or more between day 1 and day 7), secondary infection acquisition, ICU length of stay, plasma amino acid levels, and immune biomarkers on day 3 and day 7 (HLA-DR expression on monocytes and interleukin-6).ResultsOf 120 randomized patients (mean age, 60 ± 17 years; 44 [36.7%] women; ICU stay 10 days [IQR, 7–16]; incidence of secondary infections 25 patients (20.8%)), 60 were allocated to L-citrulline and 60 were allocated to placebo. Overall, there was no significant difference in organ dysfunction as assessed by the SOFA score on day 7 after enrollment (4 [IQR, 2–6] in the L-citrulline group vs. 4 [IQR, 2–7] in the placebo group; Mann‒Whitney U test, p = 0.9). Plasma arginine was significantly increased on day 3 in the treatment group, while immune parameters remained unaffected.ConclusionAmong mechanically ventilated ICU patients without sepsis or septic shock, enteral L-citrulline administration did not result in a significant difference in SOFA score on day 7 compared to placebo.Trial registration: ClinicalTrials.gov Identifier NCT02864017 (date of registration: 11 August 2016).

The impact of L-citrulline on murine intestinal cell integrity, immune response, and arginine metabolism in the face of Giardia lamblia infection

Giardiasis is an intestinal protozoal disease caused by Giardia lamblia (G. lamblia) which is a major worldwide health problem due to development of resistance to commonly used drugs. Therefore, it is necessary to identify an effective drug for giardiasis. This study aimed to assess the therapeutic role of L-citrulline against giardiasis in experimental animals. 40 male Swiss Albino weaned rats were used in this study, divided into four groups. Group I: normal control; group II: infected un-treated; group III: infected and treated with L-citrulline and Group IV: infected and treated with metronidazole. The efficacy was evaluated by counting Giardia trophozoites in the intestinal mucosa and cysts in the stool of infected rats. Histopathological analyses, immunohistochemistry expression of inducible nitric oxide synthase (iNOS) in the small intestine tissues were performed. Along with, serum IL6, the intestinal arginase enzyme level and giardial flavohemoglobin (flavoHb) expression were measured. L-citrulline administration reduced the mean number of G. lamblia cysts and trophozoites, serum IL-6, and intestinal arginase enzyme levels. Furthermore, the intestinal brush border was restored, with a reduction in the inflammatory infiltrate and an increase in iNOS activity. Moreover, there was a significant decrease in flavoHb gene expression in both the L-citrulline and metronidazole treated groups. Thus L-citrulline is effective in NO production therefore it has a therapeutic potential in controlling giardiasis.

Oral Administration of L-Citrulline Changes Brain Free Amino Acid and Monoamine Metabolism in Heat-Exposed Broiler Chickens

High ambient temperatures (HT) in summer are becoming more severe due to global warming, leading to severe adverse effects on poultry production. Recently, we have reported that oral administration of L-citrulline (L-Cit) can minimize hyperthermia in chickens under HT. However, whether oral L-Cit can enter the brain, the center for thermoregulation, has not been studied. We investigated the effects of oral administration of L-Cit on free amino acids and monoamines in the diencephalon region of the brain of heat-exposed broilers. Broilers were treated with L-Cit (40 mmol/20 ml/bird), then moved to a chamber at HT (30 ± 1°C) or to a thermoneutral temperature (CT: 22 ± 1°C) chamber for 2 h. Control groups were given methyl cellulose solution and placed in the CT or HT chambers. After 2 h of exposure to HT, there were increased brain concentrations of Cit in comparison with concentrations in broilers exposed to CT, whereas brain ornithine (Orn) concentrations were decreased, and arginine (Arg) concentrations were not changed. Interestingly, oral administration of L-Cit increased brain concentration of Cit, Arg, and Orn under both CT and HT. Tryptophan and its metabolite, serotonin (5-HT) concentrations were lower in the brain under HT than under CT. HT did not change brain concentrations of tyrosine, but dopamine (DA, a metabolite of tyrosine) concentrations decreased, and methoxyhydroxyphenylglycol (MHPG, a metabolite of DA) concentrations increased in comparison with CT. Oral administration of L-Cit decreased brain concentrations of both tryptophan and tyrosine under CT and HT without changing 5-HT; however, DA levels declined under HT. Moreover, MHPG concentrations increased. In conclusion, these results suggest that metabolism of amino acids and metabolism of DA can be enhanced in the brain by oral administration of L-Cit. Metabolic changes in the brain in response to oral administration of L-Cit may influence the thermoregulatory center in the brain, leading to a reduction in body temperature and conferring thermotolerance in heat-exposed broiler chickens.

Administration of L-citrulline prevents Plasmodium growth by inhibiting/ modulating T-regulatory cells during malaria pathogenesis.

Malaria affects around 228 million people all over the globe. Malaria causing parasite Plasmodium infection leads to activation of immune responses. The growth of parasite and immune activation requires semi essential amino acids like L-arginine. Malaria infection leads to condition of hyperargininemia and low availability of nitric oxide. However, the effect of L-arginine supplementation in malaria infected mice has not been explored in in-vivo studies. In this study we have compared the effect of oral supplementation of nitric oxide donor, L-arginine and L-citrulline, in malaria infected mice Methods: To examine the effect of oral supplementation of L-arginine and L-citrulline, Plasmodium berghei infected mice were divided in different groups and respective groups were fed with L- arginine and L-citrulline, parasitemia was measured on different days. Mice was sacrificed and immunophenotyping was done on 10 days post infection. our results show that supplementation of L-arginine induces conducive environment for Plasmodium growth due to which the infected mice dies earlier than control wild type infected mice whereas L-citrulline supplementation inhibits parasite growth and mice survives for longer period of time. Flow cytometric analysis shows that supplementation of L-arginine increases cTLA-4 on T cell population, increases Treg cells leading to immunosuppression while supplementation of L-citrulline does not have effect on T cells population and number of Treg cell decrease compared to P. berghei infected mice. our results show that L-citrulline can be a better alternative than L-arginine because of lower expression of inhibitory molecules and lower parasitemia as well as increased survival of infected mice.

Oral administration of l-citrulline alters the vascular delivery of substances to rat skeletal muscles

Vascular endothelial function deteriorates with age and disease, and the production of vasodilator factors like nitric oxide (NO) decreases. The free amino acid l-citrulline increases vasodilation and blood flow through increased NO production. We examined the effects of oral l-citrulline administration on vascular delivery of substances to skeletal muscles. In Experiment 1, following oral l-citrulline administration and subsequent intravenous Evans blue dye (EBD) administration to rats, EBD levels delivered to skeletal muscles were measured after 60 min. In Experiment 2, plasma concentrations of amino acids and NOx, an indicator of vasodilation, were measured over time after oral l-citrulline administration. In Experiment 3, we measured EBD levels in skeletal muscles of streptozotocin-induced type 1 diabetic rats following l-citrulline administration. In these experiments, EBD levels in the soleus muscle were higher in the l-citrulline group than in the control group (19.9 ± 0.7 vs. 22.5 ± 1.9 μg/g tissue, p < 0.05). Plasma l-arginine, l-citrulline, and NOx levels were increased within 30 min after l-citrulline administration. EBD levels in the soleus and gastrocnemius muscles were higher in diabetic rats with l-citrulline administration (18.7 ± 2.2 vs. 25.0 ± 4.3 μg/g tissue, p < 0.05 and 8.0 ± 0.5 vs. 9.2 ± 0.8 μg/g tissue, p = 0.05, respectively). These data suggest that oral l-citrulline administration may increase the level of substances delivered to skeletal muscles by increasing the NO production in both normal and vascular endothelial dysfunction models.

L-Citrulline ameliorates the attenuation of acetylcholine-induced vasodilation of retinal arterioles in diabetic rats

In our previous study, we found that the vasodilation of retinal arterioles induced by acetylcholine and BMS-191011, a large-conductance Ca2+-activated K+ (BKCa) channel opener, were diminished in diabetic rats. Currently, few agents ameliorate the impaired vasodilator responses of retinal blood vessels. Our recent finding that the intravenous infusion of L-citrulline dilated retinal arterioles, suggests that L-citrulline could be a potential therapeutic agent for circulatory disorders of the retina. In this study, we determined the effect of an oral L-citrulline treatment on impaired acetylcholine- and BMS-191011-induced vasodilation in the retinal arterioles of diabetic rats. To induce diabetes, rats were administered an intravenous dose of streptozotocin (65 mg/kg) and a 5% D-glucose solution as drinking water. The L-citrulline (2 g/kg/day) and L-arginine (2 g/kg/day) treatments commenced either 15 days before or just after the streptozotocin injection and continued throughout the experimental period. A 29-day treatment with L-citrulline, but not L-arginine, significantly ameliorated the impaired acetylcholine- and BMS-191011-induced retinal vasodilation in diabetic rats without affecting their plasma glucose levels. The 2-week L-citrulline treatment tended to ameliorate the dysfunction of the acetylcholine-induced retinal vasodilation in diabetic rats. In conclusion, these results showed that the retinal blood vessel dysfunction induced by diabetes mellitus could be prevented by the long-term administration of L-citrulline and suggest that the latter could play a potentially prophylactic role in diabetic retinopathy.

Oral administration of L-citrulline changes the concentrations of plasma hormones and biochemical profile in heat-exposed broilers.

We examined the effects of oral administration of L-citrulline (L-Cit) on plasma metabolic hormones and biochemical profile in broilers. Food intake, water intake, and body temperature were also analyzed. After dual oral administration (20 mmol/head/administration) of L-Cit, broilers were exposed to a high ambient temperature (HT; 30 ± 1°C) chamber for 120 min. Oral administration of L-Cit reduced (p < .001) rectal temperature in broilers. Food intake was increased (p < .05) by heat stress, but it was reduced (p < .05) by L-Cit. Plasma levels of 3,5,3'-triiodothyronine, which initially increased (p < .0001) due to heat stress, were reduced (p < .01) by oral administration of L-Cit. Plasma insulin levels were increased by heat exposure (p < .01) and oral L-Cit (p < .05). Heat stress caused a decline (p < .05) in plasma thyroxine. Plasma lactic acid (p < .05) and non-esterified fatty acids (p < .01) were increased in L-Cit-treated heat-exposed broilers. In conclusion, our results suggest that oral L-Cit can modulate plasma concentrations of major metabolic hormones and reduces food intake in broilers.

Protective Effect of Citrulline on the methotrexate - induced cardiac muscle toxicity in male albino rats: Histological and immunohistochemical study

Background and Objectives: Methotrexate (MTX) is a worldwide drug used to treat neoplastic and non-neoplastic diseasesdespite its severe side-effects. The present study aimed to throw more light on the MTX effects on cardiac muscle of adult malealbino rats and the possible protective role of L-citrulline.Materials and Methods: Thirty Adult male albino rats were used and equally divided into three Groups: Group I: control,Group II (MTX treated), Group III (MTX and L-citrulline treated). Left ventricular specimens were prepared for H and E,Mallory trichrome staining, immunohistochemical analysis for TLR2 and electron microscope examination.Results: Cardiac muscles of MTX treated rats (Group II) showed histological, ultrastructural and histochemical changes suchas dark stained nuclei, vacuolation, pyknotic nuclei, loss of striations and interrupted intercalated disc. Increased collagenfibers were also found. Minimal changes were observed in Group III (MTX and L-citrulline treated).Conclusion: MTX has a deleterious effect on rat cardiac muscle and administration of L-citrulline has a protective effect.

The Potency of Oral Administration of L-Citrulline as Anti Heat Stress Agent in KUB Chickens.

The Potency of Oral Administration of L-Citrulline as Anti Heat Stress Agent in KUB Chickens.

Oral Administration of Watermelon Rind Extract to Induce Hypothermia in Chicks.

Oral administration of l-citrulline (l-Cit) caused hypothermia, but l-Cit is not recommended in poultry diets in Japan. Watermelon is a natural source of l-Cit. The objective of this study is to examine the effect of watermelon waste, i.e., watermelon rind (WR) on the body temperature and plasma free amino acids of chicks. In Experiment 1, 14-day-old chicks were subjected to acute oral administration of WR extract (WRE) (2 ml) under control thermoneutral temperature (CT). In Experiment 2, 15-day-old chicks were orally administered 1.6 ml of either WRE, lowdose l-Cit (7.5 mmol/10 ml), or high-dose l-Cit (15 mmol/10 ml) under CT. In both experiments, rectal temperature (RT) and plasma free amino acids were analyzed. In Experiment 3, after dual oral administration of (1.6 ml) WRE or l-Cit (15 mmol/10 ml), 15-day-old chicks were exposed to high ambient temperature (HT; 35±1°C, 2 h) to monitor changes in RT. Acute oral administration of WRE significantly reduced RT under CT. The degree of RT reduction by WRE was similar to that by high l-Cit. Moreover, RT was significantly low at HT owing to the oral administration of WRE. However, the reduced RT was difficult to explain by the content of Cit in WRE alone. In conclusion, WRE could be used as a dietary ingredient to reduce body temperature for imparting thermotolerance in chicks.

47 Oral administration of L-citrulline, but not L-glutamine, to adult sheep increases the concentrations of L-citrulline and L-arginine in plasma.

47 Oral administration of L-citrulline, but not L-glutamine, to adult sheep increases the concentrations of L-citrulline and L-arginine in plasma.

Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study.

IntroductionPhosphodiesterase type 5 inhibitors (PDE5i) are first-line therapy for most men with erectile dysfunction (ED). If ineffective, vacuum erection devices, intracavernous injections, and penile prosthesis implantation are suitable as second- or third-line therapies. However, very few patients select these therapies. It is critically important to improve erectile function with oral administration of effective agents. Administration of L-citrulline or transresveratrol in animal experiments has been reported to improve erectile function, but few such experiments have been performed on humans with ED.AimWe aimed to investigate the efficacy of combination therapy of L-citrulline and transresveratrol in patients with ED despite their use of PDE5i.MethodsIn this randomized, double-blind, placebo-controlled crossover pilot study, men with ED (Sexual Health Inventory for Men [SHIM] score below 16) despite on-demand use of PDE5i received a placebo for 1 month or the active treatment (L-citrulline 800 mg/day and transresveratrol 300 mg/day) for another month. Patients continued on-demand use of PDE5i.Main Outcome MeasureThe SHIM score, Erection Hardness Score (EHS), Aging Male Symptoms Scale-sexual domain (AMS-SD), and adverse events were examined.Results20 patients ages 29–78 years were enrolled, and after 6 men withdrew, 13 concluded the study without adverse events. Mean SHIM score for the active treatment increased significantly (10.96 ± 1.21) compared with baseline (8.32 ± 1.21) and placebo (8.31 ± 1.23) (both P < .05). Mean EHS score for the active treatment (2.56 ± 0.26) also increased from baseline (2.31 ± 0.26), but not significantly (P = .79). Mean AMS-SD score was not significantly different in either group.ConclusionTo our knowledge, this is the first study to show that combination therapy of L-citrulline and transresveratrol is effective for ED treatment in men with added on-demand use of PDE5i. This combination supplement may be added if PDE5i is insufficient.Shirai M, Hiramatsu I, Aoki Y, et al. Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study. Sex Med 2018;6:291–296.

L-Citrulline improves cerebral blood flow in migraine model rats

We have previously reported that intravenous injection of l-citrulline, an α-amino acid isolated from watermelon juice, prevented the decrease in cerebral blood flow (CBF) during cortical spreading depression (CSD) in rats, a widely accepted animal model of migraine aura. However it is not clear whether oral l-citrulline administration improves CBF during CSD or not. For clinical application of l-citrulline against migraine aura, we evaluated the effect of oral l-citrulline administration on the parameters of CSD. Daily oral administration of l-citrulline for 8 consecutive days increased brain concentration of l-arginine as well as l-citrulline. Moreover, l-citrulline reduced the disturbance of CBF, monitored by laser Doppler flowmetry, with less effect on mean arterial pressure and heart rate during CSD. Although l-citrulline had no effect on CSD propagation velocity, it accelerated the recovery of CBF changes. These results suggest that l-citrulline has a clinically beneficial effect on migraine aura via regulation of CBF.

335 Oral administration of l-citrulline increases plasma concentrations of l-citrulline and arginine in horses

335 Oral administration of l-citrulline increases plasma concentrations of l-citrulline and arginine in horses

The Assessment of short-term effect of L-Citrulline on endothelial function via FMD to NMD ratio in known CAD patients: A randomized, cross-over clinical trial (Clinical trial number: NCT02638727).

Recent studies have confirmed the essential and paramount role of the L-Citrulline on the nitric oxide regulation and the endothelial function improvement. In this cross-over clinical trial, thirty patients, diagnosed with coronary artery disease (CAD) and flow mediated dilation to nitroglycerin dependent vasodilation (FMD/NMD) ratio less than 1, were included. The patients were randomly divided into two groups of 15 patients and underwent treatment by L-Citrulline or placebo for 15 days, in 2 step protocol. The indicators of assessment in the current study were the ratio of the FMD/NMD and FMD value. In the current cross-over clinical trial, the mean of FMD to NMD ratio and mean FMD value of all patients before starting the protocol were 0.91 ± 0.08 and 4.04 ± 0.51 mm, respectively. The final results of study showed that following L-Citrulline administration, mean FMD to NMD ratio and mean FMD value were enhanced to: 1.03 ± 0.09 and 4.96 ± 0.72 mm, respectively, which were statistically significant (P<0.001 and P<0.001, respectively). However, following placebo administration, mean FMD to NMD ratio and mean FMD value were receded to: 0.92 ± 0.09 and 4.06 ± 0.22 mm, respectively, which were not statistically significant (P = 0.75 and P = 0.89, respectively). Moreover, the improvement of mean FMD to NMD ratio (0.12 ± 0.02) and mean FMD value (0.92 ± 0.16 mm), following L-Citrulline administration, were statistically significant in comparison with the change of mean FMD to NMD ratio (0.01 ± 0.002) and mean FMD value (0.02 ± 0.003), following placebo administration (P<0.001 and P<0.001, respectively). L-Citrulline treatment can lead to improvement of the endothelial function in patients diagnosed with CAD which are assessed via FMD to NMD ratio FMD value enhancements.

Does Citrulline Have Protective Effects on Liver Injury in Septic Rats?

Citrulline (Cit) supplementation was proposed to serve as a therapeutic intervention to restore arginine (Arg) concentrations and improve related functions in sepsis. This study explored whether citrulline had positive effects on liver injury and cytokine release in the early stages of sepsis. The cecal ligation and puncture (CLP) model was utilized in our study. Rats were divided into four groups: normal, Cit, CLP, and CLP+Cit. The CLP group and CLP+Cit group were separated into 6-, 12-, and 24-hour groups, according to the time points of sacrifice after surgery. Intragastric administration of L-citrulline was applied to rats in Cit and CLP+Cit groups before surgery. Serum AST and ALT levels and levels of MDA, SOD, NO, and iNOS in the liver tissues were evaluated. Plasma concentrations of Cit and Arg were assessed using HPLC-MS/MS. Serum concentrations of cytokines and chemokines were calculated by Luminex. Results showed SOD activities of CLP+Cit groups were significantly higher than that of CLP groups, contrasting with the MDA and NO levels which were significantly lower in CLP+Cit groups than in CLP groups. In addition, plasma concentrations of TNF-α, IL-6, and IL-1β were significantly lower in the CLP+Cit 6-hour group than in the CLP 6-hour group.

Oral Administration of L-Citrulline, but not L-Arginine or L-Ornithine, Acts as a Hypothermic Agent in Chicks

Oral Administration of L-Citrulline, but not L-Arginine or L-Ornithine, Acts as a Hypothermic Agent in Chicks

Protective Effect of Nitric Oxide Pathway in L-Citrulline Renal Ischemia-Reperfusion Injury in Rats

To observe the protective effects of L-citrulline on the renal ischemia-reperfusion (I/R) injury and elucidate the mechanisms involved. Forty-eight rats were randomized into eight groups. At the end of the reperfusion period, serum was collected and the kidneys were removed for histological and biochemical examinations. Our results showed that pretreatment with L-citrulline significantly ameliorated the renal injury caused by I/R. Moreover, L-citrulline increased the levels of NO. The I/R-induced decreases in total nitric oxide synthase (NOS) activity, inducible NOS activity and constitutive NOS activity in the renal cortex were significantly prevented. These results suggested that L-citrulline administration exhibited significant protection on renal I/R injury.

Protective effect of l-citrulline against ethanol-induced gastric ulcer in rats

We examined the protective effect of l-citrulline on ethanol-induced gastric ulcer in rats. Administration of l-citrulline at doses of 300, 600 and 900mg/kg body weight prior to ethanol ingestion protected the stomach from ulceration. The gastric lesions were significantly attenuated by all doses of l-citrulline as compared to the ethanol group. Pre-treatment with l-citrulline prevented the oxidative damage and the decrease of nitric oxide content as well as the increase of the myeloperoxidase activity. Consequently, significant changes observed included the attenuation in the elevation in total nitric oxide synthase activity and inducible nitric oxide synthase activity as well as the decrease in constitutive nitric oxide synthase activity in the gastric mucosa induced by ethanol. Analysis of serum cytokines of ethanol-induced rats showed a moderate decrease in interleukin-10 with considerable increase of interleukin-6 while l-citrulline inhibited the acute alteration of cytokines. These results suggested the gastroprotective effect of l-citrulline.