Formula feeding alters hepatic gene expression signature, iron and cholesterol homeostasis in the neonatal pig

Breastfeeding is associated with enhanced intestinal gluconeogenesis in infants

BACKGROUND

Breastfeeding (BF) confers metabolic benefits to infants, including reducing risks of metabolic syndrome such as obesity and diabetes later in life. However, the underlying mechanism is not yet fully understood. Hence, we aim to investigate the impacts of BF on the metabolic organs of infants.

METHODS

Previous literatures directly studying the influences of BF on offspring's metabolic organs in both animal models and humans were comprehensively reviewed. A microarray dataset of intestinal gene expression comparing infants fed on breastmilk versus formula milk was analyzed.

RESULTS

Reanalysis of microarray data showed that BF is associated with enhanced intestinal gluconeogenesis in infants. This resembles observations in other mammalian species showing that BF was also linked to increased gluconeogenesis.

CONCLUSIONS

BF is associated with enhanced intestinal gluconeogenesis in infants, which may underpin its metabolic advantages through finetuning metabolic homeostasis. This observation seems to be conserved across species, hinting its biological significance.

Low colostrum intake results in potential accumulation of peroxisome lipid substrates in vaginal tissue of 3-week-old gilts

Low colostrum intake relates to poorer health and infertility in swine. We previously connected vaginal lipid profiles at weaning to fertility of sows. We hypothesized vaginal lipidome varied with colostrum intake. Our objective was to determine whether indicators of colostrum intake, immunocrit (IM) and weight gain 24 h postnatal (PN), related to vaginal lipids at d21 PN. Gilts (n=60) were weighed and blood sampled to measure IM. On d21 PN vaginal swabs were taken and lipids measured using multiple reaction monitoring. Abundance of multiple lipids differed (P<0.05) between gilts categorized as high versus low IM and high versus low 24 h gain. The abundance of multiple lipids correlated with IM and 24 h gain. Phosphatidylcholine PC(36:3), PC(36:2), and arachidonic acid (C20:4) positively (P<0.05) correlated with IM. The ether lipid PCo(38:6) and multiple cholesteryl esters negatively (P<0.05) correlated with IM. ROC analysis indicated arachidonic acid and docosanoic acid (C22:0) may serve as excellent biomarkers that distinguish between high and low IM. Similar to gilts found to be infertile, lipid profiles of low colostrum intake animals had greater abundance of very long chain fatty acids, lipids with high levels of unsaturation, and cholesteryl esters, which are metabolized in peroxisomes indicating their potential dysfunction.

Evaluation of the Safety of a Plant-Based Infant Formula Containing Almonds and Buckwheat in a Neonatal Piglet Model

A randomized neonatal piglet trial was conducted to evaluate the safety and the effects of a plant-based formula containing almonds and buckwheat as the main ingredients on growth and plasma parameters. From postnatal day (PND) 2 to 21, the piglets were fed a dairy-based milk formula (Similac Advance) or a plant-based formula (Else Nutrition) and all piglets were euthanized at day 21. No diarrhea was observed after PND 8 and all the piglets completed the trial. Body growth, kcal intake, the complete plasma count parameters and hematological parameters were within the reference range in both groups. Organ growth and development was similar between the two groups. Plasma glucose was higher in the dairy-based-fed piglets relative to the plant-based at 2 weeks of age. Liver function biomarkers levels were greater in the plasma of the plant-based compared to the dairy-based fed group. In addition, calcium levels were higher in the plant-based fed piglets at 1 week of age. Thus, the plant-based formula tested in this study was well tolerated by the piglets and supported similar growth compared to dairy-based milk formula. Therefore, the results support the safety of the tested plant-based infant formula during the neonatal period in comparison to the dairy-based formula fed group.

Soy Formula Is Not Estrogenic and Does Not Result in Reproductive Toxicity in Male Piglets: Results from a Controlled Feeding Study

Soy infant formula which is fed to over half a million infants per year contains isoflavones such as genistein, which have been shown to be estrogenic at high concentrations. The developing testis is sensitive to estrogens, raising concern that the use of soy formulas may result in male reproductive toxicity. In the current study, male White-Dutch Landrace piglets received either sow milk (Sow), or were provided milk formula (Milk), soy formula (Soy), milk formula supplemented with 17-beta-estradiol (2 mg/kg/d) (M + E2) or supplemented with genistein (84 mg/L of diet; (M + G) from postnatal day 2 until day 21. E2 treatment reduced testis weight (p < 0.05) as percentage of body weight, significantly suppressed serum androgen concentrations, increased tubule area, Germ cell and Sertoli cell numbers (p < 0.05) relative to those of Sow or Milk groups. Soy formula had no such effects relative to Sow or Milk groups. mRNAseq revealed 103 differentially expressed genes in the M + E2 group compared to the Milk group related to endocrine/metabolic disorders. However, little overlap was observed between the other treatment groups. These data suggest soy formula is not estrogenic in the male neonatal piglet and that soy formula does not significantly alter male reproductive development.

MicroRNA profiles were altered in neonatal piglet mammary glands following postnatal infant formula feeding

Postnatal dietary modulation of microRNAs (miRNAs) and effects on miRNA-mRNA interactions in tissues remain unknown. This study aimed to investigate whether dietary factors (formula vs. breastfeeding) affect mammary miRNA expression and to determine if these changes are concurrent with developmental alterations of the mammary gland in neonatal piglets. Female Yorkshire/Duroc piglets were fed sow's milk or cow's milk- or soy-based infant formula (from postnatal day 2 to day 21; n=6/group). Differentially expressed miRNAs were determined using mammary miRNA profiling, followed by miRNA and mRNA expressions characterized by quantitative reverse-transcription polymerase chain reaction. Milk and soy formulas reduced expressions of miR-1, -128, -133a, -193b, -206 and -27a; miRNA down-regulation altered mRNA expressions of genes (e.g., Ccnd1, Tgfb3, Igf1r and Tbx3) that were consistent with enhanced cell proliferation and suppressed apoptotic processes in the developing mammary gland. Interestingly, down-regulation of miR-1, -128 and -27a also correlated with increased mRNA genes such as Hmgcs and Hmgcr encoding cholesterol synthesis in the mammary glands in response to lower circulating cholesterol levels. Infant formula feeding affected mammary miRNA profiles in neonatal piglets, concurrent with increased expression of cell proliferation and cholesterol synthesis genes, suggesting early nutritional modulation of miRNAs may contribute to regulation of proliferative status and cholesterol homeostasis of developing mammary glands during infancy.

Porcine cytochrome P450 3A: current status on expression and regulation

The cytochrome P450s (CYPs) constitute a family of enzymes maintaining vital functions in the body and are mostly recognized for their significant role in detoxification. Of the CYP subfamilies, CYP3A, is one of the most active in the clearance of drugs and other xenobiotics. During the last decades, much focus has been on exploring different models for human CYP3A regulation, expression and activity. In that respect, the growing knowledge of the porcine CYP3As is of great interest. Although many aspects of porcine CYP3A regulation and activity are still unknown, the current literature provides a basic understanding of the porcine CYP3As that can be used e.g., when translating results from studies done in the porcine model into human settings. In this review, the current knowledge about porcine CYP3A expression, regulation, activity and metabolic significance are highlighted. Future research needs are also identified.

Effects of colostrum instead of formula feeding for the first 2 days postnatum on whole-body energy metabolism and its endocrine control in neonatal calves

Colostrum provides high amounts of nutritive and non-nutritive substrates, which are essential for calf nutrition and passive immunization. Colostral growth factors and hormones have beneficial effects on postnatal maturation and may affect substrate utilization and energy expenditure in neonatal calves. We tested the hypothesis that energy metabolism and its endocrine regulation differ during the first 10 d of life in calves fed either colostrum or a milk-based formula with a similar nutrient composition to colostrum, but largely depleted of bioactive substances, for the first 2 d postnatum. Male Holstein calves (n = 18) were fed either pooled colostrum (COL; n = 9) or a milk-based formula (FOR; n = 9) for the first 2 d of life. From d 3 on, all calves received same milk replacer. On d 2 and 7 of life, calves were placed in a respiration chamber for indirect calorimetric measurements to calculate heat production, fat (FOX) and carbohydrate oxidation (COX), as well as respiratory quotient. Blood was sampled on d 1 before first colostrum intake and on d 2, 3, 7, 8, 9, and 10 before morning feeding, to measure plasma concentrations of immunoglobulins, metabolites, and hormones. Additional postprandial blood samples were taken on d 1 and 9 at 30, 60, 120, 240, and 420 min after milk feeding. Liver samples were collected on d 10 of life to determine gene expression related to energy metabolism. Formula-fed calves showed lower plasma concentrations of total protein, immunoglobulins, haptoglobin, leptin, adiponectin, and insulin-like growth factor (IGF) binding protein (IGFBP)-4 during the whole study but temporarily higher plasma concentrations of urea, insulin, glucagon, triglyceride, and cholesterol on the first day after feeding, compared with concentrations in COL. The temporary increase in glucagon, triglyceride, and cholesterol on d 1 reversed on d 2 or 3, showing higher concentrations in COL than in FOR calves. In FOR, IGF-I, IGFBP-2, and IGFBP-3 were lower on d 3 than in COL. Interestingly, FOR calves had higher heat production during respiratory measurements on d 2 and higher body temperature on d 2, 3, and 5 than those of COL. The hepatic mRNA abundance of cytosolic phosphoenolpyruvate carboxykinase was higher in FOR than in COL. Our results indicate that first milk feeding after birth influenced whole-body energy expenditure but not FOX and COX in neonatal calves, and the absorption of colostral leptin and adiponectin might affect insulin sensitivity on d 1 of life.

Hepcidin Status at 2 Months in Infants Fed Breast Milk Compared with Formula

INTRODUCTION

The basis for the superior absorption of iron from breast milk compared with infant formulas is unclear. The hormone hepcidin downregulates dietary iron absorption. Hepcidin production increases with increased body iron status (reflected in serum ferritin levels). We hypothesized that serum hepcidin levels are suppressed relative to iron status in infants fed breast milk compared with formula.

METHODS

Subjects were healthy infants presenting for routine 2-month clinic visit and strictly fed either breast milk or standard infant formula. Urinary hepcidin and ferritin levels (reflective of serum levels) were analyzed and compared across the breast milk- and formula-fed groups. The relationship between urinary hepcidin and ferritin levels within each group was analyzed by linear regression.

RESULTS

Twenty-four subjects were enrolled in each group. The median urinary hepcidin level in the group fed breast milk was lower than in formula (130 vs. 359 ng hepcidin/mg creatinine, p < 0.05). However, the median ferritin levels were similar (2.1 vs. 1.9 ng/mL). Within each group, urinary hepcidin correlated with urinary ferritin (r = 0.5, p < 0.05 for each group); however, the slope of the regression line was lower in the group fed breast milk compared with formula (p < 0.005).

CONCLUSION

Despite similar urinary ferritin levels, urinary hepcidin levels are lower at 2 months in infants fed breast milk compared with infants fed formula. Hepcidin levels correlate with iron status in each group; however, this relationship is relatively dampened in infants fed breast milk. We speculate that relatively lower infant hepcidin contributes to the superior efficiency of iron absorption from breast milk.

Infant Formula Feeding Increases Hepatic Cholesterol 7α Hydroxylase (CYP7A1) Expression and Fecal Bile Acid Loss in Neonatal Piglets

Background

During the postnatal feeding period, formula-fed infants have higher cholesterol synthesis rates and lower circulating cholesterol concentrations than their breastfed counterparts. Although this disparity has been attributed to the uniformly low dietary cholesterol content of typical infant formulas, little is known of the underlying mechanisms associated with this altered cholesterol metabolism phenotype.

Objective

We aimed to determine the molecular etiology of diet-associated changes in early-life cholesterol metabolism with the use of a postnatal piglet feeding model.

Methods

Two-day-old male and female White-Dutch Landrace piglets were fed either sow milk (Sow group) or dairy-based (Milk group; Similac Advance powder) or soy-based (Soy group; Emfamil Prosobee Lipil powder) infant formulas until day 21. In addition to measuring serum cholesterol concentrations, hepatic and intestinal genes involved in enterohepatic circulation of cholesterol and bile acids were analyzed by real-time reverse-transcriptase polymerase chain reaction and Western blot. Bile acid concentrations were measured by liquid chromatography-mass spectrometry in serum, liver, and feces.

Results

Compared with the Sow group, hepatic cholesterol 7α hydroxylase (CYP7A1) protein expression was 3-fold higher in the Milk group (P < 0.05) and expression was 10-fold higher in the Soy group compared with the Milk group (P < 0.05). Likewise, fecal bile acid concentrations were 3-fold higher in the Soy group compared with the Milk group (P < 0.05). Intestinal mRNA expression of fibroblast factor 19 (Fgf19) was reduced in the Milk and Soy groups, corresponding to 54% and 67% decreases compared with the Sow group. In the Soy group, small heterodimer protein (SHP) protein expression was 30% lower compared with the Sow group (P < 0.05).

Conclusions

These results indicate that formula feeding leads to increased CYP7A1 protein expression and fecal bile acid loss in neonatal piglets, and this outcome is linked to reduced efficacy in inhibiting CYP7A1 expression through FGF19 and SHP transcriptional repression mechanisms.

Effects of infant formula composition on long-term metabolic health

Early nutrition may have long-lasting metabolic impacts in adulthood. Even though breast milk is the gold standard, most infants are at least partly formula-fed. Despite obvious improvements, infant formulas remain perfectible to reduce the gap between breastfed and formula-fed infants. Improvements such as reducing the protein content, modulating the lipid matrix and adding prebiotics, probiotics and synbiotics, are discussed regarding metabolic health. Numerous questions remain to be answered on how impacting the infant formula composition may modulate the host metabolism and exert long-term benefits. Interactions between early nutrition (composition of human milk and infant formula) and the gut microbiota profile, as well as mechanisms connecting gut microbiota to metabolic health, are highlighted. Gut microbiota stands as a key actor in the nutritional programming but additional well-designed longitudinal human studies are needed.

Adverse Effects of Nutraceuticals and Dietary Supplements

Over 70% of Americans take some form of dietary supplement every day, and the supplement industry is currently big business, with a gross of over $28 billion. However, unlike either foods or drugs, supplements do not need to be registered or approved by the US Food and Drug Administration (FDA) prior to production or sales. Under the Dietary Supplement Health and Education Act of 1994, the FDA is restricted to adverse report monitoring postmarketing. Despite widespread consumption, there is limited evidence of health benefits related to nutraceutical or supplement use in well-nourished adults. In contrast, a small number of these products have the potential to produce significant toxicity. In addition, patients often do not disclose supplement use to their physicians. Therefore, the risk of adverse drug-supplement interactions is significant. An overview of the major supplement and nutraceutical classes is presented here, together with known toxic effects and the potential for drug interactions.

Selenium, copper and iron in veterinary medicine-From clinical implications to scientific models

Diseases related to copper, selenium or iron overload or deficiency are common and well-described in large animal veterinary medicine. Some of them certainly have the potential to serve as useful animal models for ongoing research in the field of trace elements. Obvious advantages of large animal models compared to laboratory animal models like rats and mice are the option of long-term, consecutive examinations of progressive deficient or toxic stages and the opportunity to collect various, high volume samples for repeated measurements. Nevertheless, close cooperation between scientific disciplines is necessary as scientists using high sophisticated analytical methods and equipment are not regularly in touch with scientists working with large animal diseases. This review will give an introduction into some typical animal diseases related to trace elements and will present approaches where the animal diseases were used already as a model for interdisciplinary research.

Profiling of urinary bile acids in piglets by a combination of enzymatic deconjugation and targeted LC-MRM-MS

We present a method using a combination of enzymatic deconjugation and targeted LC-multiple reaction monitoring (MRM)-MS analysis for analyzing all common bile acids (BAs) in piglet urine, and in particular, for detecting conjugated BAs either in the absence of their standards, or when present in low concentrations. Initially, before enzymatic deconjugation, 19 unconjugated BAs (FBAs) were detected where the total concentration of the detected FBAs was 9.90 μmol/l. Sixty-seven conjugated BAs were identified by LC-MRM-MS analysis before and after enzymatic deconjugation. Four enzymatic assays were used to deconjugate the BA conjugates. FBAs in urine after cholylglycine hydrolase/sulfatase treatment were 33.40 μmol/l, indicating the urinary BAs were comprised of 29.75% FBAs and 70.25% conjugated BAs in single and multiple conjugated forms. For the conjugates in single form, released FBAs from cholylglycine hydrolase deconjugation indicated that the conjugates with amino acids were 14.54% of urinary BAs, 16.27% glycosidic conjugates were found by β-glucuronidase treatment, and sulfatase with glucuronidase inhibitor treatment liberated FBAs that constituted 16.67% of urinary BAs. Notably, chenodeoxycholic acid (CDCA) was initially detected only in trace amounts in urine, but was found at significant levels after the enzymatic assays above. These results support that CDCA is a precursor of γ-muricholic acid in BA biosynthesis in piglets.

Effects of soy containing diet and isoflavones on cytochrome P450 enzyme expression and activity

Cytochromes P450 (CYPs) play an important role in metabolism and clearance of most clinically utilized drugs and other xenobiotics. They are important in metabolism of endogenous compounds including fatty acids, sterols, steroids and lipid-soluble vitamins. Dietary factors such as phytochemicals are capable of affecting CYP expression and activity, which may be important in diet-drug interactions and in the development of fatty liver disease, cardiovascular disease and cancer. One important diet-CYP interaction is with diets containing plant proteins, particularly soy protein. Soy diets are traditionally consumed in Asian countries and are linked to lower incidence of several cancers and of cardiovascular disease in Asian populations. Soy is also an important protein source in vegetarian and vegan diets and the sole protein source in soy infant formulas. Recent studies suggest that consumption of soy can inhibit induction of CY1 enzymes by polycyclic aromatic hydrocarbons (PAHs) which may contribute to cancer prevention. In addition, there are data to suggest that soy components promiscuously activate several nuclear receptors including PXR, PPAR and LXR resulting in increased expression of CYP3As, CYP4As and CYPs involved in metabolism of cholesterol to bile acids. Such soy-CYP interactions may alter drug pharmacokinetics and therapeutic efficacy and are associated with improved lipid homeostasis and reduced risk of cardiovascular disease. The current review summarizes results from in vitro; in vivo and clinical studies of soy-CYP interactions and examines the evidence linking the effects of soy diets on CYP expression to isoflavone phytoestrogens, particularly, genistein and daidzein that are associated with soy protein.

Formula diet alters small intestine morphology, microbial abundance and reduces VE-cadherin and IL-10 expression in neonatal porcine model

BACKGROUND

Breastfeeding is associated with a variety of positive health outcomes in children and is recommended exclusively for the first 6 months of life; however, 50-70 % of infants in the US are formula-fed. To test the hypothesis that immune system development and function in neonates and infants are significantly influenced by diet, 2-day old piglets were fed soy or milk formula (n = 6/group/gender) until day 21 and compared to a sow-fed group (n = 6/gender).

METHODS

Histomorphometric analyses of ileum, jejunum and Peyer's patches were carried out, to determine the inflammation status, mRNA and protein expression of pro-inflammatory, anti-inflammatory and growth-related chemokines and cytokines.

RESULTS

In formula-fed animals, increases in ileum and jejunum villus height and crypt depth were observed in comparison to sow-fed animals (jejunum, p < 0.01 villus height, p < 0.04 crypt depth; ileum p < 0.001 villus height, p < 0.002 crypt depth). In formula-fed the lymphoid follicle size (p < 0.01) and germinal centers (p < 0.01) with in the Peyer's patch were significantly decreased in comparison to sow-fed, indicating less immune education. In ileum, formula diet induced significant up-regulation of AMCFII, IL-8, IL-15, VEGFA, LIF, FASL, CXCL11, CCL4, CCL25 and down-regulation of IL-6, IL-9, IL-10, IL-27, IFNA4, CSF3, LOC100152038, and LOC100736831 at the transcript level. We have confirmed some of the mRNA data by measuring protein, and significant down-regulation of anti-inflammatory molecule IL-10 in comparison to sow-fed piglets was observed. To further determine the membrane protein expression in the ileum, VE-cadherin, occludin, and claudin-3, Western blot analyses were conducted. Sow fed piglets showed significantly more VE-Cadherin, which associated with levels of calcium, and putrescine measured. It is possible that differences in GI tract and immune development are related to shifts in the microbiome; notably, there were 5-fold higher amounts of Lactobacillaceae spp and 3 fold higher Clostridia spp in the sow fed group in comparison to milk formula-fed piglets, whereas in milk formula-fed pigs Enterobacteriaceae spp was 5-fold higher.

CONCLUSION

In conclusion, formula diet alters GI morphology, microbial abundance, intestinal barrier protein VE-cadherin and anti-inflammatory molecule IL-10 expression. Further characterization of formula effects could lead to modification of infant formula to improve immune function, reduce inflammation and prevent conditions such as allergies and infections.

Uterine responses to feeding soy protein isolate and treatment with 17β-estradiol differ in ovariectomized female rats

There are concerns regarding reproductive toxicity from consumption of soy foods, including an increased risk of endometriosis and endometrial cancer, as a result of phytoestrogen consumption. In this study, female rats were fed AIN-93G diets made with casein (CAS) or soy protein isolate (SPI) from postnatal day (PND) 30, ovariectomized on PND 50 and infused with 5 μg/kg/d 17β-estradiol (E2) or vehicle. E2 increased uterine wet weight (P<0.05). RNAseq analysis revealed that E2 significantly altered expression of 1991 uterine genes (P<0.05). SPI feeding had no effect on uterine weight and altered expression of far fewer genes than E2 at 152 genes (P<0.05). Overlap between E2 and SPI genes was limited to 67 genes. Functional annotation analysis indicated significant differences in uterine biological processes affected by E2 and SPI and little evidence for recruitment of estrogen receptor (ER)α to the promoters of ER-responsive genes after SPI feeding. The major E2 up-regulated uterine pathways were carcinogenesis and extracellular matrix organization, whereas SPI feeding up-regulated uterine peroxisome proliferator activated receptor (PPAR) signaling and fatty acid metabolism. The combination of E2 and SPI resulted in significant regulation of 504 fewer genes relative to E2 alone. The ability of E2 to induce uterine proliferation in response to the carcinogen dimethybenz(a)anthracene (DMBA) as measured by expression of PCNA and Ki67 mRNA was suppressed by feeding SPI (P<0.05). These data suggest that SPI is a selective estrogen receptor modulator (SERM) interacting with a small sub-set of E2-regulated genes and is anti-estrogenic in the presence of endogenous estrogens.

Trace element status and zinc homeostasis differ in breast and formula-fed piglets

Differences in trace element composition and bioavailability between breast milk and infant formulas may affect metal homeostasis in neonates. However, there is a paucity of controlled studies in this area. Here, piglets were fed soy infant formula (soy), cow's milk formula (milk), or were allowed to suckle from the sow from PND2 to PND21. Serum iron concentrations were higher in formula-fed compared to breastfed piglets (P < 0.05). Serum zinc values were higher in milk compared to breastfed or soy groups (P < 0.05). Zinc transporter Zip4 mRNA was elevated in small intestine of the soy compared to breastfed group (P < 0.05). Transporter Znt1 mRNA was greater in small intestine of both formula-fed groups and in liver of the milk compared to the breastfed group (P < 0.05). Metallothionein Mt1 mRNA expression was higher in small intestine and liver of milk compared to breastfed and soy groups (P < 0.05). In liver, metallothionein protein levels and protein bound zinc were also highly elevated in the milk compared to other groups (P < 0.05). mRNA encoding the hepatic zinc-regulated gene Gclc was higher in the milk than soy group (P < 0.05). ChIP assay revealed increased binding of the zinc-regulated transcription factor MTF1 to the promoters of hepatic Mt3 and Gclc genes in the milk compared to the soy group. These data provide evidence that trace element status differs in breastfed, milk-fed, and soy-fed piglets and that despite similar levels of dietary supplementation, allows strong causal inference that significant differences in serum zinc after cow's milk formula compared to soy formula consumption result in compensatory changes in expression of zinc transporters, binding proteins, and zinc-regulated genes.

Matrix effects break the LC behavior rule for analytes in LC-MS/MS analysis of biological samples

High-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) are generally accepted as the preferred techniques for detecting and quantitating analytes of interest in biological matrices on the basis of the rule that one chemical compound yields one LC-peak with reliable retention time (Rt.). However, in the current study, we have found that under the same LC-MS conditions, the Rt. and shape of LC-peaks of bile acids in urine samples from animals fed dissimilar diets differed significantly among each other. To verify this matrix effect, 17 authentic bile acid standards were dissolved in pure methanol or in methanol containing extracts of urine from pigs consuming either breast milk or infant formula and analyzed by LC-MS/MS. The matrix components in urine from piglets fed formula significantly reduced the LC-peak Rt. and areas of bile acids. This is the first characterization of this matrix effect on Rt. in the literature. Moreover, the matrix effect resulted in an unexpected LC behavior: one single compound yielded two LC-peaks, which broke the rule of one LC-peak for one compound. The three bile acid standards which exhibited this unconventional LC behavior were chenodeoxycholic acid, deoxycholic acid, and glycocholic acid. One possible explanation for this effect is that some matrix components may have loosely bonded to analytes, which changed the time analytes were retained on a chromatography column and interfered with the ionization of analytes in the MS ion source to alter the peak area. This study indicates that a comprehensive understanding of matrix effects is needed towards improving the use of HPLC and LC-MS/MS techniques for qualitative and quantitative analyses of analytes in pharmacokinetics, proteomics/metabolomics, drug development, and sports drug testing, especially when LC-MS/MS data are analyzed by automation software where identification of an analyte is based on its exact molecular weight and Rt.

Dietary energy source largely affects tissue fatty acid composition but has minor influence on gene transcription in Iberian pigs

A trial was performed to compare the effects of different dietary sources of MUFA on the fatty acid (FA) composition, lipid metabolism, and gene transcription in different tissues of Iberian pigs. Twenty-seven Iberian male pigs of 28 kg live weight (LW) were divided in 2 groups and fed with 1 of 2 isocaloric diets: a standard diet with carbohydrates as energy source (CH) and a diet enriched with high-oleic sunflower oil (HO). Ham adipose tissue was sampled by biopsy at 44 and 70 kg LW. At 110 kg LW pigs were slaughtered and backfat, loin, and liver tissues were sampled. Animals of the HO group showed higher MUFA content and lower SFA in all the analyzed tissues (P < 0.001). These main effects were established early during the treatment and increased only slightly along time. Small diet effects were also detected on PUFA, which showed differences according to sampling time, tissue, and lipid fraction. Effects of diet on gene expression were explored with a combined approach analyzing adipose tissue transcriptome and quantifying the expression of a panel of key genes implicated in lipogenesis and lipid metabolism processes in backfat, muscle, and liver. Backfat transcriptome showed small effects of diet on gene expression, in number and magnitude. According to the posterior probabilities (PP) of the probe-specific expression differences between dietary groups (PP < 0.01), 37 genes were considered differentially expressed (DE). Gene ontology allowed relating them with several biological functions including lipid metabolic processes. Quantitative PCR confirmed several DE genes in adipose tissue (RXRG, LEP, and ME1; P < 0.0001, P < 0.05, and P < 0.0001, respectively), but no DE gene was found in loin or liver tissues. Joint results agree with a metabolic adjustment of adipose tissue FA levels by the subtle effect of the diet on the regulation of several lipid metabolism pathways, mainly FA oxidation and prostanoid synthesis, with LEP, RXRG, and PTGS2 genes playing mayor roles.

Prenatal and postnatal energetic conditions and sex steroids levels across the first year of life

OBJECTIVES

Human biologists have documented variability in reproductive maturation, fertility, and cancer risk related to developmental conditions. Yet no previous studies have directly examined the impact of prenatal and postnatal energetic environments on sex steroids in infancy, a critical period for hypothalamic-pituitary-gonadal axis development. Thus, we examined the impact of maternal characteristics, birth size, and feeding practices on fecal sex steroid production in a longitudinal sample of 31 American infants followed from 2 weeks to 12 months of age.

METHODS

Maternal characteristics and birth size were collected at study enrollment, infant diet was assessed through weekly 24-h food diaries, and anthropometrics were measured weekly. Fecal estradiol and testosterone levels were assessed weekly using validated microassay RIA techniques. Mixed models were used to test for associations between maternal and birth characteristics, feeding practices, and sex steroids across the first year of life. Formal mediation analysis examined whether the relationship between infant feeding and hormone levels was mediated by infant size.

RESULTS

Maternal and birth characteristics had persistent effects on fecal sex steroid levels, with taller maternal height and larger birth size associated with lower estradiol levels in girls and higher testosterone levels in boys. Infant diet was also associated with sex steroid levels independently of infant size. Formula feeding was associated with higher estradiol levels in boys and girls and with higher testosterone in girls.

CONCLUSION

These results suggest that markers of early energy availability influence sex hormone levels with potential long-term consequences for reproductive development and function.

Female mice lacking p47phox have altered adipose tissue gene expression and are protected against high fat-induced obesity

The current study was designed to determine if the NADPH-oxidase NOX2 plays a role in development of obesity after high fat feeding. Wild-type (WT) mice and mice lacking the essential cytosolic NOX2 system component p47phox (P47KO mice) were fed AIN-93G diets or high-fat diets (HFD) containing 45% fat and 0.5% cholesterol for 13 wk from weaning. Fat mass was increased to a similar degree by HFD in males of both genotypes ( P < 0.05). However, female P47KO-HFD mice had no increase in adiposity or adipocyte size relative to female WT-HFD mice. Resistance to HFD-driven obesity in P47KO females was associated with increased expression of hepatic TFAM and UCP-2 mRNA, markers of mitochondrial number and uncoupling, and increased expression of hepatic mitochondrial respiratory complexes and whole body energy expenditure in response to HFD. Microarray analysis revealed significantly lower expression of mRNA encoding genes linked to energy metabolism, adipocyte differentiation (PPARγ), and fatty acid uptake (CD36, lipoprotein lipase), in fat pads from female P47KO-HFD mice compared with WT-HFD females. Moreover, differentiation of preadipocytes ex vivo was suppressed more by 17β-estradiol in cells from P47KO compared with cells from WT females in conjunction with overexpression of mRNA for Pref-1 ( P < 0.05). HFD mice of both sexes were resistant to the development of hyperglycemia and hepatic steatosis ( P < 0.05) and had reduced serum triglycerides, leptin, and adiponectin relative to WT-HFD mice ( P < 0.05). These data suggest that NOX2 is an important regulator of metabolic homeostasis and diet-induced obesity.