Biological roles of L-carnitine in perinatal metabolism

Changes in Lipid Profiles with the Progression of Pregnancy in Black Women

Background/Objectives: Lipid metabolism plays an important role in maternal health and fetal development. There is a gap in the knowledge of how lipid metabolism changes during pregnancy for Black women who are at a higher risk of adverse outcomes. We hypothesized that the comprehensive lipidome profiles would show variation across pregnancy indicative of requirements during gestation and fetal development. Methods: Black women were recruited at prenatal clinics. Plasma samples were collected at 8-18 weeks (T1), 22-29 weeks (T2), and 30-36 weeks (T3) of pregnancy. Samples from 64 women who had term births (≥37 weeks gestation) were subjected to "shotgun" Orbitrap mass spectrometry. Mixed-effects models were used to quantify systematic changes and dimensionality reduction models were used to visualize patterns and identify reliable lipid signatures. Results: Total lipids and major lipid classes showed significant increases with the progression of pregnancy. Phospholipids and glycerolipids exhibited a gradual increase from T1 to T2 to T3, while sphingolipids and total sterol lipids displayed a more pronounced increase from T2 to T3. Acylcarnitines, hydroxy acylcarnitines, and Lyso phospholipid levels significantly decreased from T1 to T3. A deviation was that non-esterified fatty acids decreased from T1 to T2 and increased again from T2 to T3, suggestive of a potential role for these lipids during the later stages of pregnancy. The fatty acids showing this trend included key fatty acids-non-esterified Linoleic acid, Arachidonic acid, Alpha-linolenic acid, Eicosapentaenoic acid, Docosapentaenoic acid, and Docosahexaenoic acid. Conclusions: Mapping lipid patterns and identifying lipid signatures would help develop intervention strategies to reduce perinatal health disparities among pregnant Black women.

Low serum carnitine level is associated with increased urinary carnitine excretion in late pregnancy

BACKGROUND

Carnitine is essential for fatty acid metabolism. Free carnitine (FCA) is excreted in the urine in the glomerulus, but is partly reabsorbed by a carnitine transporter. The mechanism underlying the decrease in serum carnitine level during pregnancy is unclear.

OBJECTIVE

To investigate whether low carnitine level is associated with increased renal excretion in pregnant women.

METHODS

We recruited 43 healthy pregnant and 25 non-pregnant women. Total carnitine (TCA) and FCA levels were measured using the enzymatic cycling method, and the acylcarnitine (ACA) level was calculated. Fractional excretion (FE) was calculated as carnitine clearance divided by creatinine clearance.

RESULTS

The mean TCA, FCA, and ACA levels were lower at 12 weeks of gestation in pregnant than non-pregnant women (P < .001); the levels decreased further at 36 weeks, reaching 39%, 36%, and 52% of those in non-pregnant women, respectively (P < .001). The FEs were 3-4-fold higher in pregnant women than non-pregnant women. Pregnant women had a lower serum FCA/TCA ratio than non-pregnant women (0.788 ± 0.098 vs 0.830 ± 0.074, respectively; P < .05), whereas the urine FCA/TCA ratio was similar between the groups.

CONCLUSION

Low carnitine level is associated with increased renal excretion during late pregnancy.

Effects of in ovo injection of the L-carnosine on physiological indexes of neonatal broiler chicken

The objective of the present investigation was to ascertain the impact of in ovo administration of L-carnosine on physiological indicators in neonatal broiler chickens. A total of 280 viable broiler eggs were allocated to 7 distinct groups: control, Sham in ovo injection of sterile water on d 7 of incubation. Groups 3 and 4 were subjected to in ovo injections of L-carnosine (25 and 50 µg) on d 7 of incubation. Group 5, functioning as a sham in ovo, received an injection of sterile water on d 18 of incubation. Groups 6 and 7 were in ovo injected with L-carnosine (25 and 50 µg) on d 18 of incubation. All eggs were subjected to incubation, and the hatching rate and body weight were measured post-hatch. Subsequently, blood samples were collected, and the levels of biochemical constituents in the serum were determined. Based on the outcomes, the administration of L-carnosine (50 µg) on d 7 of incubation led to a significant increase in post-hatch body weight compared to the control group (P < 0.05). The in ovo injection of L-carnosine (25 and 50 µg) on d 7 and 18 of incubation resulted in a significant decrease in the levels of serum glucose, triglyceride (TG), low-density lipoprotein (LDL), phosphorus (P), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine transaminase (ALT) in the newly hatched chickens (P < 0.05). Furthermore, the in-ovo injection of L-carnosine (25 and 50 µg) on d 7 and 18 of incubation led to a significant increase in the levels of serum high-density lipoprotein (HDL), calcium, and total protein (TP) in the newly hatched chickens (P < 0.05). Nonetheless, L-carnosine did not have a significant effect on the levels of serum IgY and IgA in the newly hatched chickens (P > 0.05). These findings indicate that the in ovo administration of L-carnosine yielded favorable outcomes in neonatal broiler chickens.

Molecular pathways and nutrigenomic review of insulin resistance development in gestational diabetes mellitus

Gestational diabetes mellitus is a condition marked by raised blood sugar levels and insulin resistance that usually occurs during the second or third trimester of pregnancy. According to the World Health Organization, hyperglycemia affects 16.9% of pregnancies worldwide. Dietary changes are the primarily alternative treatment for gestational diabetes mellitus. This paper aims to perform an exhaustive overview of the interaction between diet, gene expression, and the metabolic pathways related to insulin resistance. The intake of foods rich in carbohydrates can influence the gene expression of glycolysis, as well as foods rich in fat, can disrupt the beta-oxidation and ketogenesis pathways. Furthermore, vitamins and minerals are related to inflammatory processes regulated by the TLR4/NF-κB and one carbon metabolic pathways. We indicate that diet regulated gene expression of PPARα, NOS, CREB3L3, IRS, and CPT I, altering cellular physiological mechanisms and thus increasing or decreasing the risk of gestational diabetes. The alteration of gene expression can cause inflammation, inhibition of fatty acid transport, or on the contrary help in the modulation of ketogenesis, improve insulin sensitivity, attenuate the effects of glucotoxicity, and others. Therefore, it is critical to comprehend the metabolic changes of pregnant women with gestational diabetes mellitus, to determine nutrients that help in the prevention and treatment of insulin resistance and its long-term consequences.

Stachydrine, N-acetylornithine and trimethylamine N-oxide levels as candidate milk biomarkers of maternal consumption of an obesogenic diet during lactation

We aimed to evaluate whether improving maternal diet during lactation in diet-induced obese rats reverts the impact of western diet (WD) consumption on the metabolome of milk and offspring plasma, as well as to identify potential biomarkers of these conditions. Three groups of dams were followed: control-dams (CON-dams), fed with standard diet (SD); WD-dams, fed with WD prior and during gestation and lactation; and reversion-dams (REV-dams), fed as WD-dams but moved to SD during lactation. Metabolomic analysis was performed in milk at lactation days 5, 10, and 15, and in plasma from their male and female offspring at postnatal day 15. Milk of WD-dams presented, throughout lactation and compared to CON-dams, altered profiles of amino acids and of the carnitine pool, accompanied by changes in other polar metabolites, being stachydrine, N-acetylornithine, and trimethylamine N-oxide the most relevant and discriminatory metabolites between groups. The plasma metabolome profile was also altered in the offspring of WD-dams in a sex-dependent manner, and stachydrine, ergothioneine and the acylcarnitine C12:1 appeared as the top three most discriminating metabolites in both sexes. Metabolomic changes were largely normalized to control levels both in the milk of REV-dams and in the plasma of their offspring. We have identified a set of polar metabolites in maternal milk and in the plasma of the offspring whose alterations may indicate maternal intake of an unbalanced diet during gestation and lactation. Levels of these metabolites may also reflect the beneficial effects of implementing a healthier diet during lactation.

Maternal supplementation of L-Carnosine improves Reflexive Motor Behaviors in Mice Offspring

This study aimed to investigate the effect of maternal supplementation of L-carnosine on improved reflexive motor behaviors in mice offspring. Forty pregnant female NMRI mice were allocated into four groups. In the control group, mice received water, while in groups 2-4, female mice received supplementation of the L-carnosine (0.001, 0.01, or 0.1 mg/kg) at gestation days (G.D.) 5, 8, 11, 14, and 17. Newborn male pups were selected, and reflexive motor behaviors were analyzed on days 5, 7, 10, and 10-15, respectively. Serum malondialdehyde(MDA), superoxide dismutase(SOD), glutathione peroxidase(GPx) and total antioxidant status(TAS) of was determined in offspring's. According to findings, prenatal supplementation of the L-carnosine significantly increased ambulation score, surface righting, hind-limb suspension score, grip strength, front-limb suspension time, and negative geotaxis in mice offspring (P<0.05). Hind-limb foot angle decreased in mice offspring by maternal supplementation of the L-carnosine (P<0.05). Prenatal supplementation of the L-carnosine significantly decreased the MDA and increased the SOD, GPx, and TAS levels in offspring (P<0.05). These results suggested maternal supplementation of the L-carnosine improved reflexive motor behaviors and antioxidant status in mice offspring.

Gut Microbial Succession Patterns and Metabolic Profiling during Pregnancy and Lactation in a Goat Model

The maternal gut microbiome affects the duration of pregnancy, delivery, and lactation. It also coordinates the stability of maternal metabolism by regulating and modulating inflammatory cytokines and reproductive hormones. This has been shown in several species; however, the situation in ruminants remains a black box. Here, we aimed to elucidate the relationship between the hindgut microbiota, metabolism, and reproductive hormones in domestic goats (Capra hircus) during nonpregnancy, pregnancy, and lactation stages. The hindgut microbiota was altered during these three stages, with a drastic decrease in the abundance of Family_XIII_AD3011_group in the second and third trimesters of pregnancy. Additionally, a decline in the abundance of Christensenellaceae_R-7_group and Turicibacter was observed from the nonpregnancy stage to late gestation. Family_XIII_AD3011_group and Paeniclostridium were strongly correlated with decreased fecal estradiol and progesterone. Furthermore, we generated a metabolome atlas of the gut and serum from nonpregnancy to lactation to reveal the specific metabolic fingerprints of each physiological stage. Several specific gut metabolites, including carnitine C8:1, γ-aminobutyric acid, and indole-3-carboxylic acid, were negatively correlated with the fecal and serum estradiol concentrations. In contrast, 2'-deoxyinosine, deoxyadenosine, and 5'-deoxyadenosine were positively correlated with the fecal and serum estradiol concentrations. The levels of 2'-deoxyinosine, deoxyadenosine, and 5'-deoxyadenosine in fecal samples were positively correlated with Family_XIII_AD3011_group. Other serum metabolites, such as (±)12-HEPE (hydroxy eicosapentaenoic acid), (±)15-HEPE, (±)18-HEPE, cytidine, uracil, and 5-hydroxyindole-3-acetic acid, were negatively correlated with the serum concentrations of estradiol and progesterone. Finally, Corynebacterium and Clostridium_sensu_stricto_1 in the fecal samples were positively correlated with the abundance of 11,12-EET (epoxy-eicosatrienoic acid), (±)18-HEPE, (±)15-HEPE, and (±)12-HEPE in the serum. IMPORTANCE Our findings revealed that the activity of Family_XIII_AD3011_group and Corynebacterium is strongly correlated with the beneficial regulation of physiological hormones and metabolic changes during pregnancy and lactation. These findings are key for guiding targeted microbial therapeutic approaches to modulate microbiomes in gestating and lactating mammals.

A Study of the Metabolic Pathways Affected by Gestational Diabetes Mellitus: Comparison with Type 2 Diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) remains incompletely understood and increases the risk of developing Diabetes mellitus type 2 (DM2). Metabolomics provides insights etiology and pathogenesis of disease and discovery biomarkers for accurate detection. Nuclear magnetic resonance (NMR) spectroscopy is a key platform defining metabolic signatures in intact serum/plasma. In the present study, we used NMR-based analysis of macromolecules free-serum to accurately characterize the altered metabolic pathways of GDM and assessing their similarities to DM2. Our findings could contribute to the understanding of the pathophysiology of GDM and help in the identification of metabolomic markers of the disease.

METHODS

Sixty-two women with GDM matched with seventy-seven women without GDM (control group). ¹H NMR serum spectra were acquired on an 11.7 T Bruker Avance DRX NMR spectrometer.

RESULTS

We identified 55 metabolites in both groups, 25 of which were significantly altered in the GDM group. GDM group showed elevated levels of ketone bodies, 2-hydroxybutyrate and of some metabolic intermediates of branched-chain amino acids (BCAAs) and significantly lower levels of metabolites of one-carbon metabolism, energy production, purine metabolism, certain amino acids, 3-methyl-2-oxovalerate, ornithine, 2-aminobutyrate, taurine and trimethylamine N-oxide.

CONCLUSION

Metabolic pathways affected in GDM were beta-oxidation, ketone bodies metabolism, one-carbon metabolism, arginine and ornithine metabolism likewise in DM2, whereas BCAAs catabolism and aromatic amino acids metabolism were affected, but otherwise than in DM2.

Carnitine Intake and Serum Levels Associate Positively with Postnatal Growth and Brain Size at Term in Very Preterm Infants

Carnitine has an essential role in energy metabolism with possible neuroprotective effects. Very preterm (VPT, <32 gestation weeks) infants may be predisposed to carnitine deficiency during hospitalization. We studied the associations of carnitine intake and serum carnitine levels with growth and brain size at term equivalent age (TEA) in VPT infants. This prospective cohort study included 35 VTP infants admitted to Kuopio University Hospital, Finland. Daily nutrient intakes were registered at postnatal weeks (W) 1 and 5, and serum carnitine levels were determined at W1, W5, and TEA. The primary outcomes were weight, length, and head circumference Z-score change from birth to TEA, as well as brain size at TEA in magnetic resonance imaging. Carnitine intake at W1 and W5, obtained from enteral milk, correlated positively with serum carnitine levels. Both carnitine intake and serum levels at W1, W5, and TEA showed a positive correlation with weight, length, and head circumference Z-score change and with brain size at TEA. In linear models, independent positive associations of carnitine intake and serum carnitine levels with length and head circumference Z-score change and brain size at TEA were seen. In VPT infants, sufficient carnitine intake during hospitalization is necessary since it is associated with better postnatal growth and larger brain size at term age.

Maternal Serum and Placental Metabolomes in Association with Prenatal Phthalate Exposure and Neurodevelopmental Outcomes in the MARBLES Cohort

Prenatal exposure to phthalates, a family of endocrine-disrupting plasticizers, is associated with disruption of maternal metabolism and impaired neurodevelopment. We investigated associations between prenatal phthalate exposure and alterations of both the maternal third trimester serum metabolome and the placental metabolome at birth, and associations of these with child neurodevelopmental outcomes using data and samples from the Markers of Autism Risk in Babies Learning Early Signs (MARBLES) cohort. The third trimester serum (n = 106) and placental (n = 132) metabolomes were investigated using 1H nuclear magnetic resonance spectroscopy. Children were assessed clinically for autism spectrum disorder (ASD) and cognitive development. Although none of the urinary phthalate metabolite concentrations were associated with maternal serum metabolites after adjustment for covariates, mixture analysis using quantile g-computation revealed alterations in placental metabolites with increasing concentrations of phthalate metabolites that included reduced concentrations of 2-hydoxybutyrate, carnitine, O-acetylcarnitine, glucitol, and N-acetylneuraminate. Child neurodevelopmental outcome was not associated with the third trimester serum metabolome, but it was correlated with the placental metabolome in male children only. Maternal phthalate exposure during pregnancy is associated with differences in the placental metabolome at delivery, and the placental metabolome is associated with neurodevelopmental outcomes in males in a cohort with high familial ASD risk.

Maternal L-carnitine supplementation promotes brown adipose tissue thermogenesis of newborn goats after cold exposure

Brown adipose tissue (BAT) is an important component of energy expenditure and necessary to maintain body temperature for newborn mammals. In the previous study, we found that L-carnitine was enriched in BAT and promoted BAT adipogenesis and thermogenesis in goat brown adipocytes. However, whether dietary L-carnitine regulates BAT heat production and energy expenditure in lambs remains unclear. In this study, maternal L-carnitine supplementation elevated the rectal temperature, as well as the expression of UCP1 and mitochondrial DNA content to promote BAT thermogenesis in newborn goats. Moreover, maternal L-carnitine supplementation increased the levels of triglycerides (TG), non-esterified fatty acids (NEFA), and lactate in plasma, as well as the content of lipid droplet and glycogen in BAT of newborn goats. Lipidomic analysis showed that maternal L-carnitine supplementation remodeled the lipid composition of BAT in newborn goats. L-carnitine significantly increased the levels of TG and diglyceride (DG) and decreased the levels of glycerophospholipids and sphingolipids in BAT. Further studies showed that L-carnitine promoted TG and glycogen deposition in brown adipocytes through AMPKα. Our results indicate that maternal L-carnitine supplementation promotes BAT development and thermogenesis in newborn goats and provides new evidence for newborn goats to maintain body temperature in response to cold exposure.

Influence of dietary L-carnitine and lysine-methionine levels on reproductive performance and blood metabolic constituents of breeder ducks

The present study aimed to evaluate the influence of dietary supplementation of different levels of L‐carnitine and/or lysine–methionine (Lys‐Met) on reproductive performance of breeder ducks. Three L‐carnitine (0, 75 and 150 mg/kg) and three lysine–methionine (100%, 110% and 120% above the NRC (Nutrient requirements of poultry, 1994, National Academy Press) recommendations) levels were fed to 180 breeder ducks (144 females and 36 males) in a completely randomized design for 49 days. Laying performance and reproductive traits were evaluated; additionally, uric acid, total protein total, triglycerides, total cholesterol, low‐density lipoprotein, high‐density lipoprotein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were assessed. The Lys‐Met above 100% NRC (Nutrient requirements of poultry, 1994, National Academy Press) recommendations with or without L‐carnitine improved feed utilization (p < .05). Furthermore, Lys‐Met above 100% recommendations without L‐carnitine improved egg fertility and hatchability. Fertility and hatchability improved in breeders fed on L‐carnitine with 120% Lys‐Met (p < .05). Serum glucose increased and total cholesterol reduced on 100% Ly‐Met without L‐carnitine or 110% Ly‐Met with 150 mg L‐carnitine (p < .05). Glucose was reduced, while total cholesterol increased on 75 mg L‐carnitine and 100% Lys‐Met (p < .05). Increasing Lys‐Met without L‐carnitine reduced serum protein (p < .05). Albumin and ALT increased on 75 mg L‐carnitine–100% Lys‐Met and reduced on 150 mg L‐carnitine–120% Lys‐Met (p < .05). There were no interaction effects on globulin, uric acid and AST (p > .05). Thus, based on findings, breeder ducks responded to dietary Lys‐Met more efficiently than L‐carnitine; however, more research is needed to evaluate also economic aspects related to L‐carnitine dietary supplementation.

Longitudinal Plasma Metabolomics Profile in Pregnancy-A Study in an Ethnically Diverse U.S. Pregnancy Cohort

Amino acids, fatty acids, and acylcarnitine metabolites play a pivotal role in maternal and fetal health, but profiles of these metabolites over pregnancy are not completely established. We described longitudinal trajectories of targeted amino acids, fatty acids, and acylcarnitines in pregnancy. We quantified 102 metabolites and combinations (37 fatty acids, 37 amino acids, and 28 acylcarnitines) in plasma samples from pregnant women in the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies—Singletons cohort (n = 214 women at 10–14 and 15–26 weeks, 107 at 26–31 weeks, and 103 at 33–39 weeks). We used linear mixed models to estimate metabolite trajectories and examined variation by body mass index (BMI), race/ethnicity, and fetal sex. After excluding largely undetected metabolites, we analyzed 77 metabolites and combinations. Levels of 13 of 15 acylcarnitines, 7 of 25 amino acids, and 18 of 37 fatty acids significantly declined over gestation, while 8 of 25 amino acids and 10 of 37 fatty acids significantly increased. Several trajectories appeared to differ by BMI, race/ethnicity, and fetal sex although no tests for interactions remained significant after multiple testing correction. Future studies merit longitudinal measurements to capture metabolite changes in pregnancy, and larger samples to examine modifying effects of maternal and fetal characteristics.

Potential Role of L-Carnitine in Autism Spectrum Disorder

L-carnitine plays an important role in the functioning of the central nervous system, and especially in the mitochondrial metabolism of fatty acids. Altered carnitine metabolism, abnormal fatty acid metabolism in patients with autism spectrum disorder (ASD) has been documented. ASD is a complex heterogeneous neurodevelopmental condition that is usually diagnosed in early childhood. Patients with ASD require careful classification as this heterogeneous clinical category may include patients with an intellectual disability or high functioning, epilepsy, language impairments, or associated Mendelian genetic conditions. L-carnitine participates in the long-chain oxidation of fatty acids in the brain, stimulates acetylcholine synthesis (donor of the acyl groups), stimulates expression of growth-associated protein-43, prevents cell apoptosis and neuron damage and stimulates neurotransmission. Determination of L-carnitine in serum/plasma and analysis of acylcarnitines in a dried blood spot may be useful in ASD diagnosis and treatment. Changes in the acylcarnitine profiles may indicate potential mitochondrial dysfunctions and abnormal fatty acid metabolism in ASD children. L-carnitine deficiency or deregulation of L-carnitine metabolism in ASD is accompanied by disturbances of other metabolic pathways, e.g., Krebs cycle, the activity of respiratory chain complexes, indicative of mitochondrial dysfunction. Supplementation of L-carnitine may be beneficial to alleviate behavioral and cognitive symptoms in ASD patients.

Sex-specific responses in placental fatty acid oxidation, esterification and transfer capacity to maternal obesity

Fatty acid metabolism and oxidation capacity in the placenta, which likely affects the rate and composition of lipid delivered to the fetus remains poorly understood. Long chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), are critical for fetal growth and brain development. We determined the impact of maternal obesity on placental fatty acid oxidation, esterification and transport capacity by measuring PhosphatidylCholine (PC) and LysoPhosphatidylCholine (LPC) containing DHA by mass spectrometry in mother-placenta-baby triads as well as placental free carnitine and acylcarnitine metabolites in women with normal and obese pre-pregnancy BMI. Placental protein expression of enzymes involved in beta-oxidation and esterification pathways, MFSD2a (lysophosphatidylcholine transporter) and OCTN2 (carnitine transporter) expression in syncytiotrophoblast microvillous (MVM) and basal (BM) membranes were determined by Western Blot. Maternal obesity was associated with decreased umbilical cord plasma DHA in LPC and PC fractions in male, but not female, fetuses. Basal membrane MFSD2a protein expression was increased in placenta of males of obese mothers. In female placentas, despite an increased MVM OCTN2 expression, maternal obesity was associated with a reduced MUFA-carnitine levels and increased esterification enzymes. We speculate that lower DHA-PL in fetal circulation of male offspring of obese mothers, despite a significant increase in transporter expression for LPC-DHA, may lead to low DHA needed for brain development contributing to neurological consequences that are more prevalent in male children. Female placentas likely have reduced beta-oxidation capacity and appear to store FA through greater placental esterification, suggesting impaired placenta function and lipid transfer in female placentas of obese mothers.

Effect of antioxidants on preimplantation embryo development in vitro: a review

In vitro culture of the embryo is a useful method to treat infertility that shows embryo potential for selecting the best one to transfer and successfully implantation. However, embryo development in vitro is affected by oxidative stresses such as reactive oxygen species that may damage embryo development. Antioxidants are molecules found in fruits, vegetables, and fish that play an important role in reducing oxidative processes. In the natural environment, there is a physiological antioxidant system that protects embryos against oxidative damage. This antioxidant system does not exist in vitro. Antioxidants act as free radical scavengers and protect cells or repair damage done by free radicals. Various studies have shown that adding antioxidants into embryo culture medium improves embryo development in vitro. This review article emphasizes different aspects of various antioxidants, including types, functions and mechanisms, on the growth improvement of different species of embryos in vitro.

Early Postnatal Metabolic Profile in Neonates With Different Birth Weight Status: A Pilot Study

Introduction: Restricted or enhanced intrauterine growth is associated with elevated risks of early and late metabolic problems in humans. Metabolomics based on amino acid and carnitine/acylcarnitine profile may have a role in fetal and early postnatal energy metabolism. In this study, the relationship between intrauterine growth status and early metabolomics profile was evaluated. Materials and Methods: A single-center retrospective cohort study was conducted. Three hundred and sixty-one newborn infants were enrolled into the study, and they were grouped according to their birth weight percentile as small for gestational age (SGA, n = 69), appropriate for gestational age (AGA, n = 168), and large for gestational age (LGA, n = 124) infants. In all infants, amino acid and carnitine/acylcarnitine profiles with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were recorded and compared between groups. Results: LGA infants had higher levels of glutamic acid and lower levels of ornithine, alanine, and glycine (p < 0.05) when compared with AGA infants. SGA infants had higher levels of alanine and glycine levels when compared with AGA and LGA infants. Total carnitine, C0, C2, C4, C5, C10:1, C18:1, C18:2, C14-OH, and C18:2-OH levels were significantly higher and C3 and C6-DC levels were lower in SGA infants (p < 0.05). LGA infants had higher C3 and C5:1 levels and lower C18:2 and C16:1-OH levels (p < 0.05). There were positive correlations between free carnitine and phenylalanine, arginine, methionine, alanine, and glycine levels (p < 0.05). Also, a positive correlation between ponderal index and C3, C5-DC, C14, and C14:1 and a negative correlation between ponderal index and ornithine, alanine, glycine, C16:1-OH, and C18:2 were shown. Conclusion: We demonstrated differences in metabolomics possibly reflecting the energy metabolism in newborn infants with intrauterine growth problems in the early postnatal period. These differences might be the footprints of metabolic disturbances in future adulthood.

Response of duck breeders to dietary L-Carnitine supplementation during summer season

A total number of 300 (225 ducks and 75 drakes) Sudani ducks, 28-wk-old were divided into five groups to investigate the effects of dietary L-carnitine (LC) supplementation on productive, hatching and physiological performance as well as nutrients digestibility coefficients. The results indicated that the productive performance and Semen quality parameters (ejaculate volume, sperms concentration and advanced motility) were significantly improved by LC supplementation (150-450 mg /kg diet) as compared to the control. Hatchability of fertile eggs (%) was significantly improved, while total embryonic mortality was significantly decreased by supplementing 300 and 450 mg LC/kg diet. Supplementing different dietary LC levels resulted in significantly high values of hemoglobin, red and white blood cells count and lymphocyte (L) cells percentage, while it decreased heterophils (H) cells and H/L ratio. Serum albumin, total cholesterol and AST enzyme values were significantly low in ducks fed diets supplemented with LC. Serum triglycerides were significantly the lowest by feeding 300 and 450 mg LC/kg diet. Nutrients digestibility coefficients were significantly improved in drakes fed diet supplemented with 450 mg LC/kg diet. Conclusively, dietary LC supplementation at 300 or 450 mg/kg for duck breeders in summer could improve productive, hatching and physiological performance and nutrients digestibility coefficients.

Serum metabolomics analysis of patients with polycystic ovary syndrome by mass spectrometry

Polycystic ovary syndrome (PCOS) is a set of symptoms caused by elevated androgens (male hormones) in females. PCOS is the most common endocrine disorder among women between 18 and 44 years. Currently, the pathogenesis of PCOS remains unclear. Liquid chromatography-mass spectrometry (LC/MS)-based metabolomics is becoming more and more useful for medical research, especially in revealing the mechanism of the disease. The aim of this study was to investigate the difference of serum metabolic profiles in patients with PCOS and healthy control to better understand the mechanism of this disease. Ten patients with PCOS and 10 healthy people were recruited for this study. The serum samples were collected for LC/MS analysis. Multivariate statistical analysis was performed to discover and identify the potential biomarkers. Six biomarkers were found and identified. The biomarkers belonged to different metabolic pathway including lipid metabolism, carnitine metabolism, androgen metabolism, and bile acid metabolism. Those biomarkers also played different roles in disease progression. Metabolomics is a powerful tool used in research of the mechanism involved in this disease to provide useful information for better understanding of PCOS.

Maternal L-carnitine supplementation ameliorates renal underdevelopment and epigenetic changes in male mice offspring due to maternal smoking

OBJECTIVES

Epidemiological and animal studies showed that L-carnitine (LC) supplementation can ameliorate oxidative stress-induced tissues damage. We have previously shown that maternal cigarette smoke exposure (SE) can increase renal oxidative stress in newborn offspring with postnatal kidney underdevelopment and renal dysfunction in adulthood, which were normalised by LC administration in the SE dams during pregnancy. Exposure to an adverse intrauterine environment may lead to alteration in the epigenome, a mechanism by which adverse prenatal conditions increase the susceptibility to chronic disease later in life. The current study aimed to determine whether maternal SE induces epigenetic changes in the offspring's kidney are associated with renal underdevelopment, and the protective effect of maternal LC supplementation.

METHOD

Female Balb/c mice (7 weeks) were exposed to cigarette smoke (SE) or air (Sham) for 6 weeks prior to mating, during gestation and lactation. A subgroup of the SE dams received LC via drinking water (SE + LC, 1.5 mmol/L) throughout gestation and lactation. Male offspring were studied at postnatal day (P)1, P20, and 13 weeks.

RESULTS

Maternal SE altered the expression of renal development markers glial cell line-derived neurotrophic factor and fibroblast growth factor 2, which were associated with increased renal global DNA methylation and DNA methyltransferase 1 mRNA expression at birth. These disorders were reversed by maternal LC administration.

CONCLUSION

The effect of maternal SE on renal underdevelopment involves global epigenetic alterations from birth, which can be prevented by maternal LC supplementation.

Chemistry of Human Breast Milk-A Comprehensive Review of the Composition and Role of Milk Metabolites in Child Development

Early nutrition has an enormous influence on a child's physiological function, immune system maturation, and cognitive development. Human breast milk (HBM) is recognized as the gold standard for human infant nutrition. According to a WHO report, breastfeeding is considered as an unequaled way of providing ideal food to the infant, which is required for his healthy growth and development. HBM contains various macronutrients (carbohydrates, proteins, lipids, and vitamins) as well as numerous bioactive compounds and interactive elements (growth factors, hormones, cytokines, chemokines, and antimicrobial compounds. The aim of this review is to summarize and discuss the current knowledge about metabolites, which are the least understood components of HBM, and their potential role in infant development. We focus on small metabolites (<1500 Da) and characterize the chemical structure and biological function of polar metabolites such as human milk oligosaccharides, nonprotein molecules containing nitrogen (creatine, amino acids, nucleotides, polyamines), and nonpolar lipids. We believe that this manuscript will provide a comprehensive insight into a HBM metabolite composition, chemical structure, and their role in a child's early life nutrition.

PEMT rs12325817 and PCYT1A rs7639752 polymorphisms are associated with betaine but not choline concentrations in pregnant women

Maternal metabolism during gestation may depend on nutrient intake but also on polymorphism of genes encoding enzymes involved in metabolism of different nutrients. Data on choline or carnitine metabolism in pregnant women are scarce. We hypothesized that (1) choline intake in Polish pregnant women is inadequate and (2) choline and carnitine metabolism would differ by genotype and nutritional status of pregnant women. One hundred three healthy Polish women aged 18 to 44 years in the third trimester of pregnancy were enrolled in the study. The average choline, folate, and carnitine intakes were 365 ± 14 mg/d, 1089 ± 859 μg, and 132 ± 8 mg/d, respectively. Most women did not achieve an adequate intake of choline. Average choline, betaine, trimethylamine oxide, l-carnitine, and acetylcarnitine concentrations were 10.64 ± 3.30 μmol/L, 14.43 ± 4.01 μmol/L, 2.01 ± 1.24 μmol/L, 12.73 ± 5.41 μmol/L, and 6.79 ± 3.82 μmol/L, respectively. Approximately 15% lower betaine concentrations were observed in the GG homozygotes of PEMT rs12325817 and in the GG homozygotes of PCYT1A rs7639752 than in the respective minor allele carriers. Birth weight was higher in the G allele homozygotes of the CHDH rs2289205 than in the minor allele carriers: GG: 3398 ± 64 g; GA+AA: 3193 ± 76 g. Our study shows that choline intake in Polish pregnant women is inadequate and that polymorphisms of PEMT rs12325817 and PCYT1A rs7639752 are associated with betaine but not choline concentrations.

Two Uneventful Pregnancies in a Woman with Glutaric Aciduria Type 1

Glutaric aciduria type 1 (GA1) is an autosomal recessive rare disorder caused by mutations in the GCDH gene resulting in deficiency of glutaryl-CoA dehydrogenase, leading to accumulation of the amino acids lysine, hydroxylysine and tryptophan and other metabolites. The phenotypic spectrum of disease is broad. Stress caused by infection and fever and possibly pregnancy may lead to worsening of the signs and symptoms, often with uncertain recovery.We describe a case of a female patient with GA1 who had two clinically uneventful pregnancies.At the age of 11 she was diagnosed with GA1 by family screening. The cultured skin fibroblast showed reduced glutaryl-CoA dehydrogenase activity (0.16 mg protein per min).The initial diagnostic urine glutaric acid level for this patient was 1,784 μmol/mmol creatinine. Mutation analysis showed compound heterozygosity for the p.(Gly185Arg), c.553G>A in exon 7 and p.(Arg402Trp), c.1204C.T in exon 11 mutations of the GCDH.Her pregnancy at the age of 23 was complicated by pre-eclampsia and required treatment with beta-blockers. Four years later the second pregnancy was uncomplicated. The management plan during the caesarean section included intravenous dextrose and lipid infusions. The patient rapidly recovered from both surgeries.Both babies have had normal development to date. On newborn screening, plasma acylcarnitine showed a transient increase in glutarylcarnitine, and the urine organic acid analysis showed a trace of 3-hydroxyglutarylcarnitine, likely to be of maternal transfer.The multidisciplinary team, consisting of metabolic, dietetic and obstetric care providers, have responsibility to ensure the risk of acute decompensation in pregnant GA1 women is minimal.

Metabolomics biomarker analysis of threatened abortion in polycystic ovary syndrome: a clinical discovery study

In this study, using an advanced metabolomics platform based on UPLC-QTOF-MS, we found that pregnancy significantly altered the profile of metabolites in the plasma of women with PCOS.

Longitudinal Metabolomic Profiling of Amino Acids and Lipids across Healthy Pregnancy

Pregnancy is characterized by a complexity of metabolic processes that may impact fetal development and ultimately, infant health outcomes. However, our understanding of whole body maternal and fetal metabolism during this critical life stage remains incomplete. The objective of this study is to utilize metabolomics to profile longitudinal patterns of fasting maternal metabolites among a cohort of non-diabetic, healthy pregnant women in order to advance our understanding of changes in protein and lipid concentrations across gestation, the biochemical pathways by which they are metabolized and to describe variation in maternal metabolites between ethnic groups. Among 160 pregnant women, amino acids, tricarboxylic acid (TCA) cycle intermediates, keto-bodies and non-esterified fatty acids were detected by liquid chromatography coupled with mass spectrometry, while polar lipids were detected through flow-injected mass spectrometry. The maternal plasma concentration of several essential and non-essential amino acids, long-chain polyunsaturated fatty acids, free carnitine, acetylcarnitine, phosphatidylcholines and sphingomyelins significantly decreased across pregnancy. Concentrations of several TCA intermediates increase as pregnancy progresses, as well as the keto-body β-hydroxybutyrate. Ratios of specific acylcarnitines used as indicators of metabolic pathways suggest a decreased beta-oxidation rate and increased carnitine palmitoyltransferase-1 enzyme activity with advancing gestation. Decreasing amino acid concentrations likely reflects placental uptake and tissue biosynthesis. The absence of any increase in plasma non-esterified fatty acids is unexpected in the catabolic phase of later pregnancy and may reflect enhanced placental fatty acid uptake and utilization for fetal tissue growth. While it appears that energy production through the TCA cycle increases as pregnancy progresses, decreasing patterns of free carnitine and acetylcarnitine as well as increased carnitine palmitoyltransferase-1 rate and β-hydroxybutyrate levels suggest a concomitant upregulation of ketogenesis to ensure sufficient energy supply in the fasting state. Several differences in metabolomic profiles between Hispanic and non-Hispanic women demonstrate phenotypic variations in prenatal metabolism which should be considered in future studies.

In vivo longitudinal proton magnetic resonance spectroscopy on neonatal hypoxic-ischemic rat brain injury: Neuroprotective effects of acetyl-L-carnitine

PURPOSE

This study evaluated the longitudinal metabolic alterations after neonatal hypoxia-ischemia (HI) in rats and tested the neuroprotective effect of acetyl-L-carnitine (ALCAR) using in vivo proton short-TE Point-RESolved Spectroscopy method.

METHODS

Rice-Vannucci model was used on 7-day-old Sprague-Dawley rats. Data were acquired from contralateral and ipsilateral cortex and hippocampus, respectively at 4 time points (24-h, 72-h, 7-days, 28-days) post-HI. The effect of subcutaneous administration of ALCAR (100 mg/kg) immediately after HI, at 4-h, 24-h, and 48-h post-HI was determined.

RESULTS

Significant reductions in glutathione (P < 0.005), myo-inositol (P < 0.002), taurine (P < 0.001), and total creatine (P < 0.005) were observed at 24-h postinjury compared with the control group in the ipsilateral hippocampus of the HI rat pups. ALCAR-treated-HI rats had lower levels of lactate and maintained total creatine at 24-h and had smaller lesion size compared with the HI only rats.

CONCLUSION

Severe oxidative, osmotic stress, impaired phosphorylation, and a preference for anaerobic glycolysis were found in the ipsilateral hippocampus in the HI pups at 24-h postinjury. ALCAR appeared to have a neuroprotective effect if administered early after HI by serving as an energy substrate and promote oxidative cerebral energy producing and minimize anaerobic glycolysis.

Analysis and interpretation of acylcarnitine profiles in dried blood spot and plasma of preterm and full-term newborns

BACKGROUND

Acylcarnitines are biomarkers of fatty acid metabolism, and examining their patterns in preterm newborn may reveal metabolic changes associated with particular conditions related to prematurity. Isomeric acylcarnitines in dried blood spots (DBS) and plasma have never been assessed in preterm infants.

METHODS

We studied 157 newborn divided into four groups by weeks of gestational age (GA), as follows: 22-27 wk in group 1; 28-31 wk in group 2; 32-36 wk in group 3; and 37-42 wk in group 4. Samples were collected on the third day of life. Acylcarnitines were separated and quantified using ultra-performance liquid chromatography tandem mass spectrometry.

RESULTS

Acylcarnitine concentrations correlated significantly with GA and birth weight in both DBS and plasma samples. Concentrations were lower in preterm newborn, except for acylcarnitines derived from branched-chain amino acids, which were higher and correlated with enteral feeding. On day 3 of life, no correlations emerged with gender, respiratory distress syndrome, bronchopulmonary dysplasia, surfactant administration, or mechanical ventilation.

CONCLUSION

We established GA-based reference ranges for isomeric acylcarnitine concentrations in preterm newborn, which could be used to assess nutritional status and the putative neuroprotective role of acylcarnitines.

Newborn hypocarnitinemia due to long-term transplacental pivalic acid passage

Infants often develop hypocarnitinemia and resultant hypoglycemia during long-term treatment with antibiotics that contain pivalic acid, but it is unknown whether maternal treatment with such agents during pregnancy induces hypocarnitinemia in fetuses or neonates. A woman at week 28 of pregnancy was prescribed cefcapene pivoxil for 84 consecutive days for treatment and prophylaxis of pyelonephritis. Using tandem mass spectrometry, both the mother and newborn were found to have hypocarnitinemia soon after delivery. It was concluded that the baby suffered from secondary hypocarnitinemia due to long-term prenatal treatment with antibiotics containing pivalic acid. Long-term treatment with antibiotics containing pivalic acid in pregnant women can induce hypocarnitinemia in both the mother and neonate; reported herein is the first case observed in humans.

Biology of diabetic neuropathy

More than half of all patients with diabetes develop neuropathic disorders affecting the distal sensory and/or motor nerves, or autonomic or cranial nerve functions. Glycemic control can decrease the incidence of neuropathy but is not adequate alone to prevent or treat the disease. This chapter introduces diabetic neuropathy with a morphological description of the disease then describes our current understanding of metabolic and molecular mechanisms that contribute to neurovascular dysfunctions. Key mechanisms include glucose and lipid imbalances and insulin resistance that are interconnected via oxidative stress, inflammation, and altered gene expression. These complex interactions should be considered for the development of new treatment strategies against the onset or progression of neuropathy. Advances in understanding the combined metabolic stressors and the novel study of epigenetics suggest new therapeutic targets to combat this morbid and intractable disease affecting millions of patients with type 1 or type 2 diabetes.

Systematic Evaluation of Key L-Carnitine Homeostasis Mechanisms during Postnatal Development in Rat

Background

The conditionally essential nutrient, L-carnitine, plays a critical role in a number of physiological processes vital to normal neonatal growth and development. We conducted a systematic evaluation of the developmental changes in key L-carnitine homeostasis mechanisms in the postnatal rat to better understand the interrelationship between these pathways and their correlation to ontogenic changes in L-carnitine levels during postnatal development.

Methods

mRNA expression of heart, kidney and intestinal L-carnitine transporters, liver γ-butyrobetaine hydroxylase (Bbh) and trimethyllysine hydroxylase (Tmlh), and heart carnitine palmitoyltransferase (Cpt) were measured using quantitative RT-PCR. L-Carnitine levels were determined by HPLC-UV. Cpt and Bbh activity were measured by a spectrophotometric method and HPLC, respectively.

Results

Serum and heart L-carnitine levels increased with postnatal development. Increases in serum L-carnitine correlated significantly with postnatal increases in renal organic cation/carnitine transporter 2 (Octn2) expression, and was further matched by postnatal increases in intestinal Octn1 expression and hepatic γ-Bbh activity. Postnatal increases in heart L-carnitine levels were significantly correlated to postnatal increases in heart Octn2 expression. Although cardiac high energy phosphate substrate levels remained constant through postnatal development, creatine showed developmental increases with advancing neonatal age. mRNA levels of Cpt1b and Cpt2 significantly increased at postnatal day 20, which was not accompanied by a similar increase in activity.

Conclusions

Several L-carnitine homeostasis pathways underwent significant ontogenesis during postnatal development in the rat. This information will facilitate future studies on factors affecting the developmental maturation of L-carnitine homeostasis mechanisms and how such factors might affect growth and development.

Timing and Duration of Drug Exposure Affects Outcomes of a Drug-Nutrient Interaction During Ontogeny

Significant drug-nutrient interactions are possible when drugs and nutrients share the same absorption and disposition mechanisms. During postnatal development, the outcomes of drug-nutrient interactions may change with postnatal age since these processes undergo ontogenesis through the postnatal period. Our study investigated the dependence of a significant drug-nutrient interaction (cefepime-carnitine) on the timing and duration of drug exposure relative to postnatal age. Rat pups were administered cefepime (5 mg/kg) twice daily subcutaneously according to different dosing schedules (postnatal day 1-4, 1-8, 8-11, 8-20, or 1-20). Cefepime significantly reduced serum and heart L-carnitine levels in postnatal day 1-4, 1-8 and 8-11 groups and caused severe degenerative changes in ventricular myocardium in these groups. Cefepime also altered the ontogeny of several key L-carnitine homeostasis pathways. The qualitative and quantitative changes in levels of hepatic γ-butyrobetaine hydroxylase mRNA and activity, hepatic trimethyllysine hydroxlase mRNA, intestinal organic cation/carnitine transporter (Octn) mRNA, and renal Octn2 mRNA depended on when during postnatal development the cefepime exposure occurred and duration of exposure. Despite lower levels of heart L-carnitine in earlier postnatal groups, levels of carnitine palmitoyltransferase mRNA and activity, heart Octn2 mRNA and ATP levels in all treatment groups remained unchanged with cefepime exposure. However, changes in other high energy phosphate substrates were noted and reductions in the phosphocreatine/ATP ratio were found in rat pups with normal serum L-carnitine levels. In summary, our data suggest a significant drug-nutrient transport interaction in developing neonates, the nature of which depends on the timing and duration of exposure relative to postnatal age.

Polymerization of cyclic esters initiated by carnitine and tin (II) octoate

Low-molecular weight poly(ε-caprolactone), polylactides and copolymers of ε−caprolactone and lactides were obtained by the polymerization of cyclic esters in the presence of a carnitine/SnOct₂ system. Their structures were proven by means of MALDI−TOF, IR and NMR studies. Effects of temperature, reaction time and carnitine dosage on the polymerization process were examined.

Maternal dietary L-carnitine supplementation influences fetal carnitine status and stimulates carnitine palmitoyltransferase and pyruvate dehydrogenase complex activities in swine

Effects of increasing maternal L-carnitine on carnitine status and energy metabolism in the fetus were evaluated by feeding pregnant swine a corn-soybean-based diet containing either 0 or 50 mg/kg added L-carnitine (n = 10/treatment) during the first 70 d of gestation. Carnitine, carnitine palmitoyltransferase (CPT), and pyruvate dehydrogenase complex (PDHC) activities were analyzed in tissues collected from fetuses on d 55 and 70. Maternal L-carnitine supplementation increased both fetal free and long-chain carnitine concentrations by 45% in liver and free carnitine by 31% in heart tissues but did not affect kidney tissue. Elevations in free and acylcarnitines increased with gestational age from 55 to 70 d in liver but not in heart and kidney. The increased carnitine concentrations resulted in a 45% increase in PDHC activity in heart and liver on d 70 of gestation but did not affect kidney and liver on d 55 of gestation. The increases in carnitine concentrations were accompanied by a 70% increase in hepatic CPT activity in 70-d-old fetuses, but activities in heart and kidney were unaffected. The Michaelis constant (K(m)) of CPT for carnitine in fetal tissues was not influenced by carnitine supplementation (P > 0.1). Notably, the concentrations of carnitine measured on d 70 were only 25-40% of the K(m) values in liver, 60-70% in heart, and 30-40% in kidney (P < 0.001). We conclude that carnitine ingestion during pregnancy increases fetal carnitine concentrations and stimulates heart PDHC and liver CPT activity without altering carnitine K(m).

Acute administration of cefepime lowers L-carnitine concentrations in early lactation stage rat milk

Our study investigated the potential for important in vivo drug-nutrient transport interactions at the lactating mammary gland using the L-carnitine transporter substrates, cefepime and L-carnitine, as proof-of-concept. On d 4 (n = 6/treatment) and d 10 (n = 6/treatment) of lactation, rats were administered cefepime (250 mg/h) or saline by continuous i.v. infusion (4 h). Serum and milk L-carnitine and cefepime concentrations were quantified by HPLC-UV. In whole mammary gland, organic cation/carnitine transporter (OCTN)1, OCTN2, OCTN3, amino acid transporter B(0,+) (ATB(0,+)), and L-carnitine transporter 2 expression were determined by quantitative RT-PCR and by western blot and immunohistochemistry when possible. Cefepime caused a 56% decrease in milk L-carnitine concentrations on lactation d 4 (P = 0.0048) but did not affect milk L-carnitine at lactation d 10 or serum L-carnitine concentrations at either time. The mean L-carnitine and cefepime milk:serum ratios (M/S) decreased from 9.1 +/- 0.4 to 4.9 +/- 0.6 (P < 0.0001) and 0.89 +/- 0.3 to 0.12 +/- 0.02 (P = 0.0473), respectively, between d 4 and d 10 of lactation. In both groups, OCTN2 (P < 0.0001), OCTN3 (P = 0.0039), and ATB(0,+) (P = 0.004) mRNA expression and OCTN2 protein (P < 0.0001) were higher in mammary glands at d 4 of lactation compared with d 10. Immunohistochemistry revealed OCTN1 and OCTN2 localization in the mammary alveolar epithelium and OCTN3 expression in the interstitial space and blood vessel endothelium. In conclusion, cefepime significantly decreased milk L-carnitine concentrations only at d 4 of lactation. Relative to d 10, enhanced expression of OCTN2 and ATB(0,+) in mammary glands at d 4 of lactation and higher M/S (L-carnitine and cefepime) suggests cefepime competes with L-carnitine for L-carnitine transporters expressed in the lactating mammary gland to adversely affect L-carnitine milk concentrations and these effects depend upon lactation stage.

Outcome of three cases of untreated maternal glutaric aciduria type I

We report, for the first time, the outcome of three children born to two women with untreated glutaric aciduria type I (GA I). Isolated hypocarnitinemia in neonatal screening in one baby allowed the identification of the disease in his mother, who was undiagnosed so far and had had a previous daughter. The other baby was born to an already diagnosed mother who was not treated; newborn screening in the child reflected the metabolic state of the mother. Biochemical abnormalities returned to normal within one week. At the age of 4 months, neuroimaging showed Sylvian enlargement in both infants and bilateral temporal arachnoid cysts in one. Physical and neurological developments were normal for the three patients at ages 2 and 5 years. We conclude that long-term follow up will determine the true impact of GA I in such children.

Biochemical factors limiting myocardial energy in a chicken genotype selected for rapid growth

Broiler chickens (Gallus gallus) genetically selected for rapid growth are inherently predisposed to heart failure. In order to understand the biochemical mechanisms associated with the deterioration of heart function and development of congestive heart failure (CHF) in fast-growing chickens, this study examined several factors critical for myocardial energy metabolism. Measured variables included cardiac energy substrates [creatine phosphate (CrP), adenosine triphosphate (ATP), l-carnitine], activity of selected cytosolic enzymes [creatine kinase (CK; EC 2.7.3.2), lactate dehydrogenase (LDH; EC 1.1.1.27)] and mitochondrial enzymes [pyruvate dehydrogenase (PDH; EC 1.2.4.1), alpha-ketoglutarate dehydrogenase (alpha-KGDH; EC 1.2.4.2)]. The CK activities were higher in fast-growing and CHF broilers as compared to slow-growing broilers (p<0.05). Cardiac LDH and alpha-KGDH activities were not changed (p>0.05), whereas PDH activity was highest (p<0.05) in broilers with CHF. Deterioration of heart function is correlated with lowered cardiac ATP, CrP, and l-carnitine levels (all p<0.05). Depletion of high energy phosphate substrates, ATP and CrP, is evident in fast-growing chickens and those that developed CHF. Increased activity of CK suggests that cardiac energy management in fast-growing broilers and those with CHF largely depends on contribution of this pathway to regeneration of ATP from CrP. In this scenario, inadequate level of CrP is a direct cause of ATP insufficiency, whereas low cardiac l-carnitine, because of its role in fatty acid transport, is most likely an important factor contributing to shortage of key substrate required for synthesis of cardiac ATP. The insufficiencies in cardiac energy substrate synthesis provide metabolic basis of myocardial dysfunction in chickens predisposed to heart failure.

Serum carnitine, triglyceride and cholesterol profiles in Korean neonates

This study evaluated carnitine and lipid status of fifty Korean newborns. Each subject was assigned to two groups: one according to body weight at birth and the other according to gestational age. Serum total, HDL- and LDL-cholesterol were significantly lower and triacylglycerols were significantly higher, by 14 %, in the low birth weight infant (LBWI, 1310–2490 g) group compared with the normal birth weight infant (NBWI, 2570–4420 g) group. Neither birth weight nor gestational age affected serum total carnitine concentrations. However, serum ASAC (acid-soluble acylcarnitine) concentrations were 43 % higher (P < 0·001) in the LBWI group compared with the NBWI group, and approximately twice as high (P < 0·05) in the 28–32 gestational age group compared with the other gestational age groups. NEC (non-esterified acyl carnitine) fractions were significantly higher in the NBWI and 28–32 week groups (P < 0·001 andP < 0·05); consequently serum acyl/NEC carnitine ratios were four times higher in the LBWI group compared with the NBWI group and 2–3 times higher in the 25–32 week age group compared with the more advanced gestational age groups. Urinary carnitine excretion, including the NEC fraction and total carnitine, was significantly higher (P < 0·001) for LBWI than for NBWI. By gestational age, NEC excretion of the 28–32 week group was significantly (P < 0·05) higher than that of the other two groups, but total carnitine excretion was not different among the groups. This study demonstrated that Korean immature and preterm newborns have higher serum triacylglycerol concentrations but lower carnitine status than NBWI. Therefore, the lower carnitine status and moderately higher triacylglycerols may suggest that LBWI in Korea might be at risk for poor carnitine status and decreased capacity to utilise fatty acids for energy.

Carnitine prevents cyclic GMP-induced inhibition of peroxisomal enzyme activities

Peroxisomes, also termed as microbodies, are now known to carry out several specialized metabolic activities that are vital to cellular function. A defect in peroxisomal function leads to development of a fatal human disease, and a number of peroxisomal disorders are now linked to inherited peroxisomal enzyme abnormalities. Peroxisomal enzyme activities are also altered during pathophysiological conditions through various endogenously produced bio-molecules such as nitric oxide (NO). NO produced by cytokines or NO-donors is known to modulate peroxisomal functions, and these effects of NO are mediated through cGMP. We are reporting for the first time that L-carnitine (1-5 mm) prevents cGMP-mediated impairment of peroxisomal enzyme activities. Cyclic GMP (250-1000 muM) significantly inhibited (p < 0.01) the specific activities of catalase, acyl CoA oxidase and dihydroxyacetone-phosphate acyltransferase (DHAPATase) in human dermal fibroblasts, and treatment of cells with 1-5 mM of carnitine significantly (p < 0.001) reduced the inhibitory effects of cGMP on peroxisomal enzyme activities. These findings suggest that carnitine, previously thought to participate only in fatty acid oxidation, may in fact be regulating other cellular events including oxidative stress, and could possibly be used to correct cytokine-impaired peroxisomal functions.

Serum carnitine levels in newborns with perinatal asphyxia and relation to neurologic prognosis

Neonatal hypoxic encephalopathy is one of the major causes of permanent neurological sequel. This study was conducted to investigate serum total, free and acylcarnitine levels in asphyxiated newborns with or without encephalopathy. Serum total, free and acylcarnitine levels were investigated in 21 newborns with and seven asphyxiated newborns without signs of encephalopathy. The newborns with encephalopathy were further divided into grade 1, 2 and 3 encephalopathy groups. Serum total and acylcarnitine concentrations of the whole encephalopathy group were significantly lower than the non-encephalopathy group (p = 0.042 for both). Serum total and acylcarnitine concentrations of grade 3 encephalopathy group were significantly lower than the non-encephalopathy group (p = 0.014 and p = 0.040, respectively). No significant differences were noticed for free carnitine levels. Total carnitine levels were positively correlated with birth weight and 10th minute apgar score, whereas acylcarnitine levels were found to correlate with cord blood pH and free carnitine levels with birth weight. Cord blood pH, and total carnitine levels were found to be the most significant determinants of the neurological outcome at one year of age. It was emphasized that carnitine deficiency could occur in severely affected asphyxiated newborns and it is related to the outcome at one year of age.

Plasma carnitine levels in preterm infants with respiratory distress syndrome

BACKGROUND

Antenatal carnitine administration has been shown to induce fetal lung maturity by increasing pulmonary surfactant in animal and human studies. In this study, the aim was to investigate the status of carnitine in maternal and neonatal plasma of preterm infants with respiratory distress syndrome (RDS) in the first hours of life.

METHODS

Maternal plasma carnitine levels were determined before delivery and neonatal plasma carnitine levels were determined within 2 h of birth in preterm infants (< 34 weeks gestational age) who developed RDS in the first 6 h of life and in the control group.

RESULTS

The mean neonatal plasma free carnitine level was significantly lower in preterm infants with RDS than in the control group (28.3 +/- 8.8 micromol/L and 36.9 +/- 18.4 micromol/L, respectively; P < 0.05) while the mean maternal plasma-free carnitine levels were similar in both groups.

CONCLUSIONS

Low neonatal plasma carnitine levels in preterm infants with RDS may be due to decreased maternal-fetal transfer of carnitine or to increased consumption of carnitine in fetal lung tissue for surfactant synthesis. This could be a contributing factor in the pathogenesis of respiratory distress syndrome in preterm infants.

EXPRESSION, LOCALIZATION, AND FUNCTION OF THE CARNITINE TRANSPORTER OCTN2 (SLC22A5) IN HUMAN PLACENTA

L-carnitine is assumed to play an important role in fetal development, and there is evidence that carnitine is transported across the placenta. The protein involved in this transfer, however, has not been identified on a molecular level. We therefore characterized localization and function of the carnitine transporter OCTN2 in human placenta. Significant expression of OCTN2 mRNA was detected in human placenta applying real-time polymerase chain reaction technology. Confocal immunofluorescence microscopy using an antibody directed against the carboxy terminus of OCTN2 protein revealed that it is predominantly expressed in the apical membrane of syncytiotrophoblasts. This was confirmed by the costaining of organic anion-transporting polypeptide B and MRP2, which are known to be expressed mainly in the basal and apical syncytiotrophoblasts membrane, respectively. To further support this finding, we performed transport studies using basal and apical placenta membrane vesicles. We could demonstrate that the carnitine uptake into the apical vesicles was about eight times higher compared with the basal ones. Moreover, this uptake was sodium- and pH-dependent with an apparent K(m) value of 21 muM and inhibited by verapamil, which is in line with published data for recombinant OCTN2. Finally, experiments using trophoblasts in cell culture revealed that expression of OCTN2 paralleled human choriogonadotropin production and thus is modulated by cellular differentiation. In summary, we show expression and function of OCTN2 in human placenta. Moreover, several lines of evidence indicate that OCTN2 is localized in the apical membrane of syncytiotrophoblasts, thereby suggesting a major role in the uptake of carnitine during fetal development.

Interaction between Anticonvulsants and Human Placental Carnitine Transporter

PURPOSE

To examine the inhibitory effect of anticonvulsants (AEDs) on carnitine transport by the human placental carnitine transporter.

METHODS

Uptake of radiolabeled carnitine by human placental brush-border membrane vesicles was measured in the absence and presence of tiagabine (TGB), vigabatrin (VGB), gabapentin (GBP), lamotrigine (LTG), topiramate (TPM), valproic acid (VPA), and phenytoin (PHT). The mechanism of the inhibitory action of TGB was determined.

RESULTS

Most of the AEDs inhibited placental carnitine transport. Kinetic analyses showed that TGB had the greatest inhibitory effect [50% inhibitory concentration (IC50, 190 microM)], and the order of inhibitory potency was TGB > PHT > GBP > VPA > VGB, TPM > LTG. Further studies showed that TGB competitively inhibited carnitine uptake by the human placental carnitine transporter, suggesting that it may be a substrate for this carrier.

CONCLUSIONS

Although the involvement of carnitine deficiency in fetal anticonvulsant syndrome requires further evaluation, potential interference with placental carnitine transport by several AEDs was demonstrated. Despite the higher inhibitory potency of TGB, given the therapeutic unbound concentrations, the results for VPA and PHT are probably more clinically significant.

Neonatal blood carnitine concentrations: normative data by electrospray tandem mass spectometry

Despite a number of published reports, there is limited information about carnitine metabolism in the newborn. To establish normative data, we analyzed whole-blood carnitine concentrations in 24,644 newborns at age 1.85 +/- 0.95 d and umbilical cord whole blood and plasma carnitine concentrations in 50 full-term newborns. Total carnitine (TC), free carnitine (FC), and acylcarnitine (AC) were measured by electrospray tandem mass spectrometry. AC/FC ratios were derived from these measurements. The entire cohort was stratified according to TC values into a middle TC group representing 90% of the population and lower and upper TC groups representing 5% of the population, respectively. Normative data were derived from the middle TC group of full-term infants (N = 19,595). TC was 72.42 +/- 20.75 microM, FC was 44.94 +/- 14.99 microM, AC was 27.48 +/- 8.05 microM, and AC/FC ratio was 0.64 +/- 0.19 (+/-SD). These values differed significantly from umbilical cord whole blood TC values of 31.27 +/- 10.54 microM determined in 50 samples. No meaningful correlation was found between TC and gestational age or birth weight in any group. In controlled analyses, prematurity was not associated with TC levels, whereas low birth weight (<2500 g) and male sex were significantly associated with higher TC levels. The association of low birth weight with higher TC values may be related to decreased tissue carnitine uptake. The sex effect may be related to hormonal influences on carnitine metabolism. Our study provides normative data of carnitine values measured by the highly precise method of electrospray tandem mass spectrometry in a large cohort of newborns and provides the basis for future studies of carnitine metabolism in health and disease states during the neonatal period.