Reproductive, endocrine and metabolic feto-maternal features and placental gene expression in a swine breed with obesity/leptin resistance

Maternal dietary antioxidant supplementation regulates weaned piglets' adipose tissue transcriptome and morphology

Antioxidant supplementation in critical periods may be useful for improvement of piglet early viability and development. We have evaluated the effects of maternal perinatal diet inclusion of a high vitamin E level (VE, 100 mg all-rac-α-tocopheryl acetate /kg), hydroxytyrosol (HT, 1.5 mg/kg), or their combination (VEHT), in comparison to a control diet (C, 30 mg all-rac-α-tocopheryl acetate /kg), on the offspring homeostasis and metabolism, analysing the weaned piglets' adipose tissue transcriptome and adipocyte morphology. Diets were provided to pregnant Iberian sows (n = 48, 12 per treatment) from gestation day 85 to weaning (28 days postpartum) and 48 piglets (n = 12 per treatment) were sampled 5 days postweaning for dorsal subcutaneous adipose tissue analyses. RNA obtained from 6 animals for each diet was used for paired-end RNA sequencing. Results show that supplementation of sows' diet with either vitamin E or hydroxytyrosol had substantial effects on weaned piglet adipose transcriptome, with 664 and 587 genes being differentially expressed, in comparison to C, respectively (q-value<0.10, Fold Change>1.5). Genes upregulated in C were mainly involved in inflammatory and immune response, as well as oxidative stress, and relevant canonical pathways and upstream regulators involved in these processes were predicted as activated, such as TNF, IFNB or NFKB. Vitamin E, when supplemented alone at high dose, activated lipid biosynthesis functions, pathways and regulators, this finding being accompanied by increased adipocyte size. Results suggest an improved metabolic and antioxidant status of adipose tissue in animals born from sows supplemented with individual antioxidants, while the combined supplementation barely affected gene expression, with VEHT showing a prooxidant/proinflamatory functional profile similar to C animals. Different hypothesis are proposed to explain this unexpected result. Findings allow a deeper understanding of the processes taking place in adipose tissue of genetically fat animals and the role of antioxidants in the regulation of fat cells function.

The importance of optimal body condition to maximise reproductive health and perinatal outcomes in pigs

Overnutrition or undernutrition during all or part of the reproductive cycle predisposes sows to metabolic consequences and poor reproductive health which contributes to a decrease in sow longevity and an increase in perinatal mortality. This represents not only an economic problem for the pig industry but also results in poor animal welfare. To maximise profitability and increase sustainability in pig production, it is pivotal to provide researchers and practitioners with synthesised information about the repercussions of maternal obesity or malnutrition on reproductive health and perinatal outcomes, and to pinpoint currently available nutritional managements to keep sows' body condition in an optimal range. Thus, the present review summarises recent work on the consequences of maternal malnutrition and highlights new findings.

Reduction of leptin levels during acute exercise is dependent on fasting but not on caloric restriction during chronic exercise: A systematic review and meta-analysis

BACKGROUND

The importance of leptin in controlling body mass has recently gained more attention. Its levels are directly associated with the amount of fat mass, but not necessarily dependent on it. Exercise has great potential in reducing leptin levels, however the response of exercise to this cytokine is still not well understood.

OBJECTIVE

The objective of the review was to analyze the effects of physical exercise on plasma leptin concentration, either acutely (post-exercise/training session) and/or after a training period (short- or long-term), as well as to investigate the existence of possible moderating variables.

METHODS

The studies included in this systematic review were published between 2005 and May 2023. Only peer-reviewed studies, available in English, performed with humans that evaluated the effects of any form of exercise on leptin levels were included. The search was conducted on May 03, 2023, in Embase (Elsevier), MEDLINE via PubMed®, and Web of Science (Core collection). The risk of bias in the included trials was assessed by the Physiotherapy Evidence Database tool, considering 11 questions regarding the methodology of each study with 10 questions being scored. The data (n, mean, and standard deviation) were extracted from included studies to perform random effects meta-analyses using standardized mean difference between the pre- and post-intervention effects.

RESULTS

Twenty-five studies (acute effect: 262 subjects; short- and long-term effect: 377 subjects) were included in this systematic review and meta-analysis. Short- and long-term physical exercise and caloric restriction plus exercise reduce plasma leptin levels, presenting statistically significant differences (p<0.001); as well as acute effect (p = 0.035), however the latter result was influenced by the pre-exercise meal as shown in the subgroup analysis. In this meta-analysis the effect of moderating factors on leptin reduction, not addressed by past reviews, is verified, such as the relationship with caloric restriction, exercise intensity and pre-exercise meal on acute responses.

CONCLUSION

Both acute and chronic exercise reduce leptin levels, yet the acute effect is dependent on the pre-exercise meal. In addition to having a long-term reduction in leptin levels, the minimum amount of weekly exercise to have a significant reduction in plasma leptin is 180 minutes of moderate-intensity exercise and 120 minutes of high-intensity exercise.

Obesity and Metabolic Traits after High-Fat Diet in Iberian Pigs with Low Birth Weight of Placental Origin

Intrauterine growth restriction (IUGR) and later obesity and metabolic disorders have classically been associated with maternal malnutrition, but most cases of IUGR are related to placental insufficiency. The current study, using a swine model for IUGR and obesity, aimed to determine the interaction of birth weight (categorized as low birth weight [LBW] or normal birth-weight [NBW]) and postnatal diet (categorized as maintenance diet [MD] or fattening diet [FD]) on body weight, adiposity and metabolic traits. FD induced higher body weight and adiposity (both p < 0.0001), with higher fructosamine levels (p < 0.005) and a trend toward higher HOMA-β index (p = 0.05). NBW pigs remained heavier than LBW pigs during the early juvenile period (p < 0.005), but there were no differences at later stages. There were no differences in metabolic traits during juvenile development, but there were differences in adulthood, when LBW pigs showed higher glucose and lower insulin levels than NBW pigs (both p < 0.05). These results suggest that (a) FD allows LBW offspring to achieve similar obesity in adulthood as NBW offspring, and (b) glucose metabolism is more compromised in obese LBW than obese NBW pigs. The comparison of our data with previous studies highlights significant differences between offspring with LBW induced by maternal malnutrition or placental insufficiency, which should be considered when studying the condition.

Differential Effects of Litter Size and Within-Litter Birthweight on Postnatal Traits of Fatty Pigs

Simple Summary

The current work evaluated the relative effects of the number of piglets in the litter of origin (high vs. low litter size) and the birthweight (low (LBW) vs. normal (NBW) in large litters) on postnatal performance and quality of carcasses and meat in purebred Iberian pigs. The results indicated that NBW piglets born in large litters had disparities in developmental patterns in weight and size, back-fat deposition, and fatty acid composition of viscerae compared to NBW piglets from small litters, which again were different from those found in LBW piglets when compared to their NBW counterparts. However, both growth patterns were altered and might indicate previous phases of metabolic disorders.

Abstract

Fatty pigs are characterized by a thrifty genotype, adapted to harsh environments based on changes in metabolism and energy saving. Thus, we hypothesized that feto-maternal energy partitioning in large litters might have postnatal effects that might be independent of intrauterine growth restriction (IUGR) processes. Hence, the current work reported the influence of two effects on postnatal performance and carcass and meat quality of purebred Iberian pigs: (a) the effects of the number of piglets in the litter (high vs. low litter size), and (b) the effects of birthweight (low (LBW) vs. normal (NBW)) in large litters. The results confirmed that NBW piglets born in large litters had differences in developmental patterns of weight, back-fat deposition, and fatty acid (FA) composition when compared to NBW piglets from small litters. These results were different from those found in LBW piglets when compared to their NBW counterparts, which showed an initial asymmetrical growth and altered muscle FA composition at slaughtering. The assessment of FA composition indicated better metabolic status in NBW piglets from large litters than in LBW piglets. These data support the concept that the prenatal environment, even when the individual may cope with it, inescapably affects postnatal life.

Piglet birthweight and sex affect growth performance and fatty acid composition in fatty pigs

This study aimed to determine the effects of piglet birthweight (BIW) and sex, and within-litter BIW variation, on postnatal growth traits and meat quality in fatty breeds of pig. In total, 406 crossbred piglets (half male, half female) born to Iberian sows were studied during their postnatal development until slaughter. After birth, piglets were classified into four BIW categories: very low, low, medium and high. There was a negative effect of low BIW on growth patterns and fatty acid (FA) composition, but effects of litter size and within-litter BIW variation were not found. The very low BIW piglets underwent a period of significant catch-up growth (P &lt; 0.005) relative to high BIW piglets during the early postnatal phase, but also showed a higher feed conversion rate and lower average daily weight gain (P &lt; 0.05 for both measures) throughout the study period. BIW affected development during the entire productive life, and the sex effect increased with age. As a result, the period to reach market weight was longer in very low BIW piglets, by 43 days for females and 15 days for males, compared with their high BIW counterparts. BIW and sex also influenced amount of intramuscular fat, n-3 FA content and monounsaturated FA composition. The study indicates that BIW, modulated by sex, is a critical point for productive traits in fatty pigs. These results provide a basis for future strategies to enhance productive efficiency and meat quality of traditional swine breeds.

Effects of maternal western-style diet on amniotic fluid volume and amnion VEGF profiles in a nonhuman primate model

During pregnancy, high fat diet (HFD) induces maternal obesity, insulin resistance, and placental inflammatory responses that compromise placental and fetal development. Whether maternal HFD would adversely affect amniotic fluid volume (AFV) has not been explored. Vascular endothelial growth factor (VEGF) is expressed in the amnion and has been proposed as a regulator of AFV. Our aim was to investigate the effects of HFD on AFV and the associated changes in VEGF and soluble VEGF receptor 1 (sFlt-1) expression profiles in three amnion regions of a nonhuman primate model. Further, we examined the relationships between VEGF expression and HFD-induced changes in maternal metabolic status. Japanese macaques were maintained on control or HFD and amniotic fluid index (AFI) was measured as an ultrasonic estimate of AFV. Amniotic fluid VEGF concentrations were determined by ELISA and amnion VEGF and sFlt-1 mRNA levels by real-time RT-qPCR. HFD increased maternal plasma triglyceride while glucose levels were unchanged. Maternal weight gain was found in diet-sensitive animals whereas amniotic fluid VEGF concentration was reduced in diet-resistant animals. HFD did not alter AFI and there was no correlation between AFI and maternal weight or amniotic fluid VEGF concentrations. VEGF mRNA levels were lowest in secondary placental amnion while sFlt-1 mRNA were lowest in the primary placental amnion. HFD did not affect amnion VEGF or sFlt-1 mRNA expression. These findings suggest that although maternal HFD increased maternal weight in diet-sensitive and reduced amniotic fluid VEGF concentrations in diet-resistant phenotype, AFV as indicated by the AFI, was not significantly affected.

Maternal undernutrition and offspring sex determine birth-weight, postnatal development and meat characteristics in traditional swine breeds

Background

The aim of this study was to determine how maternal undernutrition during pregnancy and offspring birth-weight can affect the postnatal development of offspring under farm conditions, which may lead to consequences in its meat and carcass quality. The current study involved a total of 80 litters from Iberian sows fed a diet fulfilling daily requirements (n = 47; control) or providing 70% daily requirements (n = 33; underfed) from d 38 to d 90 of gestation when fetal tissue development begins. After birth, piglets born live were classified as low birth-weight (LBW; < 1 kg) and normal birth-weight (NBW; ≥1 kg). During the growing phase, 240 control and 230 underfed pigs (50% males and females) distributed by BW category and sex were studied until the slaughter.

Results

At birth and weaning, there were significant differences in all morphological measures and weight between NBW and LBW piglets as expected (P < 0.0005), but few effects of the gestational feed restriction. During the growing phase, NBW pigs continued with higher weight than LBW pigs on all the days of evaluation (P < 0.05), even though control-LBW-females and LBW-males showed a catch-up growth. However, underfed pigs showed slower growth and higher feed conversion ratio than control pigs (P < 0.0001) at 215 days old. Moreover, the average daily weight gain (ADWG) for the overall period was greater for NBW, male and control pigs than for their LBW, female and underfed pigs (P < 0.0001, P< 0.0005 and P< 0.05, respectively) and NBW pigs were slaughtered at a younger age than LBW pigs (P < 0.0001). After slaughtering, control pigs also had higher carcass yield and backfat depth than underfed pigs (P < 0.0005) and the maternal nutritional effect caused main changes in the polar lipid fraction of liver and loin. The fatty acid composition of loin in control pigs had higher C18:1n-9 and n-3 FA concentrations, as well as lower ∑n-6/∑n-3 ratio, than in underfed pigs (P < 0.005).

Conclusions

In brief, results showed that the effects of maternal nutritional restriction appeared and increased with offspring age, causing worse developmental patterns for underfed pigs than for control pigs.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0240-6) contains supplementary material, which is available to authorized users.

Ontogeny of Sex-Related Differences in Foetal Developmental Features, Lipid Availability and Fatty Acid Composition

Sex-related differences in lipid availability and fatty acid composition during swine foetal development were investigated. Plasma cholesterol and triglyceride concentrations in the mother were strongly related to the adequacy or inadequacy of foetal development and concomitant activation of protective growth in some organs (brain, heart, liver and spleen). Cholesterol and triglyceride availability was similar in male and female offspring, but female foetuses showed evidence of higher placental transfer of essential fatty acids and synthesis of non-essential fatty acids in muscle and liver. These sex-related differences affected primarily the neutral lipid fraction (triglycerides), which may lead to sex-related postnatal differences in energy partitioning. These results illustrate the strong influence of the maternal lipid profile on foetal development and homeorhesis, and they confirm and extend previous reports that female offspring show better adaptive responses to maternal malnutrition than male offspring. These findings may help guide dietary interventions to ensure adequate fatty acid availability for postnatal development.

Breeding animals for quality products: not only genetics

The effect of the Developmental Origins of Health and Disease on the spread of non-communicable diseases is recognised by world agencies such as the United Nations and the World Health Organization. Early environmental effects on offspring phenotype also apply to domestic animals and their production traits. Herein, we show that maternal nutrition not only throughout pregnancy, but also in the periconception period can affect offspring phenotype through modifications of gametes, embryos and placental function. Because epigenetic mechanisms are key processes in mediating these effects, we propose that the study of epigenetic marks in gametes may provide additional information for domestic animal selection.

Leptin and leptin-receptor polymorphisms in fertile and infertile men

The association of leptin (LEP) -2548G/A and/or leptin receptor (LEPR) Gln223Arg polymorphisms with male infertility and plasma FSH, LH, and testosterone (T) levels was examined. The genotypes and allele frequency distributions of LEP -2548G/A and LEPR Gln223Arg polymorphisms were investigated in 150 fertile and 150 infertile men by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Also, plasma levels of FSH, LH, and T were measured using commercial ELISA kits. Frequencies of AA, AG and GG genotypes of LEP-2548G/A polymorphism were statistically different in fertile and infertile men (p=0.012). The AG genotype showed a protective effect which could decrease risk of male infertility about 3 fold (p = 0.004). We did not observe any differences in frequencies of LEPR Gln223Arg alleles and genotypes between groups (p > 0.05). Sperm counts from infertile men with the AG and GG genotypes of the LEP polymorphism were significantly higher than AA genotype (p<0.05). Moreover, infertile men who carried the RR genotype of LEPR showed a statistically higher percentage of sperm with progressive motility than individuals with other genotypes (p = 0.004). There was no correlation between different combinations of LEP and LEPR genotypes and LH, FSH, and T levels (p > 0.05). Our study suggests that the LEP -2548G/A polymorphism may play a role in male fertility and the AG genotype may have a protective effect through increasing sperm counts. The distribution of genotypes of LEP -2548G/A polymorphism are different in fertile and infertile males and may be a useful tool in evaluation of male infertility.

ABBREVIATIONS

LEP: leptin; LEPR: leptin receptor; T: testosterone; FSH: follicle-stimulating hormone; LH: luteinizing hormone.

Developmental Origins of Health and Disease in swine: implications for animal production and biomedical research

The concept of Developmental Origins of Health and Disease (DOHaD) addresses, from a large set of epidemiological evidences in human beings and translational studies in animal models, both the importance of genetic predisposition and the determinant role of maternal nutrition during pregnancy on adult morphomics and homeostasis. Compelling evidences suggest that both overnutrition and undernutrition may modify the intrauterine environment of the conceptus and may alter the expression of its genome and therefore its phenotype during prenatal and postnatal life. In fact, the DOHaD concept is an extreme shift in the vision of the factors conditioning adult phenotype and supposes a drastic change from a gene-centric perspective, only modified by lifestyle and nutritional strategies during juvenile development and adulthood, to a more holistic approach in which environmental, parental, and prenatal conditions are strongly determining postnatal development and homeostasis. The implications of DOHaD are profound in all the mammalian species and the present review summarizes current knowledge on causes and consequences of DOHaD in pigs, both for meat production and as a well-recognized model for biomedicine research.

Developmental origins of metabolic disorders: The need for biomarker candidates and therapeutic targets from adequate preclinical models

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The research on obesity and associated disorders should rely on contrasted biomarkers.

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The discovery of biomarkers is flawed by inherent variability of human data.

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Hence, preclinical studies in animal models are essential.

The investigation on obesity and associated disorders have changed from an scenario in which genome drove the phenotype to a dynamic setup in which prenatal and early-postnatal conditions are determinant. However, research in human beings is difficult due to confounding factors (lifestyle and socioeconomic heterogeneity) plus ethical issues. Hence, there is currently an intensive effort for developing adequate preclinical models, aiming for an adequate combination of basic studies in rodent models and specific preclinical studies in large animals. The results of these research strategies may increase the identification and development of contrasted biomarkers and therapeutic targets.

Comparative Analysis of Muscle Transcriptome between Pig Genotypes Identifies Genes and Regulatory Mechanisms Associated to Growth, Fatness and Metabolism

Iberian ham production includes both purebred (IB) and Duroc-crossbred (IBxDU) Iberian pigs, which show important differences in meat quality and production traits, such as muscle growth and fatness. This experiment was conducted to investigate gene expression differences, transcriptional regulation and genetic polymorphisms that could be associated with the observed phenotypic differences between IB and IBxDU pigs. Nine IB and 10 IBxDU pigs were slaughtered at birth. Morphometric measures and blood samples were obtained and samples from Biceps femoris muscle were employed for compositional and transcriptome analysis by RNA-Seq technology. Phenotypic differences were evident at this early age, including greater body size and weight in IBxDU and greater Biceps femoris intramuscular fat and plasma cholesterol content in IB newborns. We detected 149 differentially expressed genes between IB and IBxDU neonates (p < 0.01 and Fold-Change > 1. 5). Several were related to adipose and muscle tissues development (DLK1, FGF21 or UBC). The functional interpretation of the transcriptomic differences revealed enrichment of functions and pathways related to lipid metabolism in IB and to cellular and muscle growth in IBxDU pigs. Protein catabolism, cholesterol biosynthesis and immune system were functions enriched in both genotypes. We identified transcription factors potentially affecting the observed gene expression differences. Some of them have known functions on adipogenesis (CEBPA, EGRs), lipid metabolism (PPARGC1B) and myogenesis (FOXOs, MEF2D, MYOD1), which suggest a key role in the meat quality differences existing between IB and IBxDU hams. We also identified several polymorphisms showing differential segregation between IB and IBxDU pigs. Among them, non-synonymous variants were detected in several transcription factors as PPARGC1B and TRIM63 genes, which could be associated to altered gene function. Taken together, these results provide information about candidate genes, metabolic pathways and genetic polymorphisms potentially involved in phenotypic differences between IB and IBxDU pigs associated to meat quality and production traits.

Fetal Sex Modulates Developmental Response to Maternal Malnutrition

The incidence of obesity and metabolic diseases is dramatically high in rapidly developing countries. Causes have been related to intrinsic ethnic features with development of a thrifty genotype for adapting to food scarcity, prenatal programming by undernutrition, and postnatal exposure to obesogenic lifestyle. Observational studies in humans and experimental studies in animal models evidence that the adaptive responses of the offspring may be modulated by their sex. In the contemporary context of world globalization, the new question arising is the existence and extent of sex-related differences in developmental and metabolic traits in case of mixed-race. Hence, in the current study, using a swine model, we compared male and female fetuses that were crossbred from mothers with thrifty genotype and fathers without thrifty genotype. Female conceptuses evidence stronger protective strategies for their adequate growth and postnatal survival. In brief, both male and female fetuses developed a brain-sparing effect but female fetuses were still able to maintain the development of other viscerae than the brain (mainly liver, intestine and kidneys) at the expense of carcass development. Furthermore, these morphometric differences were reinforced by differences in nutrient availability (glucose and cholesterol) favoring female fetuses with severe developmental predicament. These findings set the basis for further studies aiming to increase the knowledge on the interaction between genetic and environmental factors in the determination of adult phenotype

Early Life Nutrition and Energy Balance Disorders in Offspring in Later Life

The global pandemic of obesity and type 2 diabetes is often causally linked to changes in diet and lifestyle; namely increased intake of calorically dense foods and concomitant reductions in physical activity. Epidemiological studies in humans and controlled animal intervention studies have now shown that nutritional programming in early periods of life is a phenomenon that affects metabolic and physiological functions throughout life. This link is conceptualised as the developmental programming hypothesis whereby environmental influences during critical periods of developmental plasticity can elicit lifelong effects on the health and well-being of the offspring. The mechanisms by which early environmental insults can have long-term effects on offspring remain poorly defined. However there is evidence from intervention studies which indicate altered wiring of the hypothalamic circuits that regulate energy balance and epigenetic effects including altered DNA methylation of key adipokines including leptin. Studies that elucidate the mechanisms behind these associations will have a positive impact on the health of future populations and adopting a life course perspective will allow identification of phenotype and markers of risk earlier, with the possibility of nutritional and other lifestyle interventions that have obvious implications for prevention of non-communicable diseases.

Advances in understanding the interrelations between leptin resistance and obesity

Obesity, which has developed into a global epidemic, is a risk factor in most chronic diseases and some forms of malignancy. The discovery of leptin in 1994 has opened a new field in obesity research. Currently, we know that leptin is the primary signal from energy stores and exerts negative feedback effects on energy intake. However, most individuals with diet-induced obesity (DIO) develop leptin resistance, which is characterized by elevated circulating leptin levels and decreased leptin sensitivity. To date, though various mechanisms have been proposed to explain leptin resistance, the exact mechanisms of leptin resistance in obesity are poorly understood. Consequently, it's an important issue worth discussing regarding what the exact interrelations between leptin resistance and obesity are. Here, we review the latest advancements in the molecular mechanisms of leptin resistance and the exact interrelations between leptin resistance, obesity, and obesity-related diseases, in order to supply new ideas for the study of obesity.

Relationship between pregnancy rate and serum progesterone concentration in cases of porcine embryo transfer

The level of P4 at the time of embryo transfer (ET) is important. P4 concentrations and numbers of corpora lutea for 126 recipients were evaluated. Nuclear transfer embryos were transferred into 126 surrogates. 11 maintained their pregnancy until full-term delivery, 17 miscarried, and implantation failed in 98 animals. P4 levels in the full-term group were significantly different from those of the pigs that aborted or in which implantation failed (p < 0.05). However, the numbers of corpora lutea were not significantly different. These findings indicate that the concentration of progesterone can be an important factor for successful ET in pigs.

Intake of high saturated-fat diets disturbs steroidogenesis, lipid metabolism and development of obese-swine conceptuses from early-pregnancy stages

The current study indicates that life-long intake, from early-life, of an obesogenic diet with high saturated-fat (HSF) content induces dyslipidemia (high plasma concentrations of triglycerides in concurrence with low concentrations of HDL-cholesterol) in obese swine with leptin resistance (Iberian sows). In case of pregnancy, ovarian features (ovulatory efficiency and luteal steroidogenesis) of sows fed with HSF are not affected but embryo features are affected at so early stages like 28 days of pregnancy (first quarter), although embryo viability was still not affected. In this way, offspring from HSF sows showed a higher incidence of alterations in their developmental trajectory, mainly due to a higher incidence of growth retardation, in their steroidogenic activity and in their availability of triglycerides and cholesterol. In conclusion, the results obtained in the present study illustrate the deleterious effects of maternal dyslipidemia, induced by the intake of HSF diets, on the oestradiol secretion of the conceptuses at early-pregnancy stages and, thus, on their developmental and metabolic features. This article is part of a Special Issue entitled 'Pregnancy and steroids'.

Sex and breed-dependent organ development and metabolic responses in foetuses from lean and obese/leptin resistant swine

The present study aimed to determine the effects of breed and sex on growth patterns and metabolic features of advanced-pregnancy foetuses exposed to the same environmental conditions. Thus, at Day 62 of pregnancy, swine foetuses from an obese breed with leptin resistance (Iberian breed) were compared to lean crossbred foetuses (25% Large White ×25% Landrace ×50% Pietrain). There were differential developmental patterns in foetuses with leptin resistance, mainly a higher relative weight of the brain resembling “brain-sparing effect”. Prioritization of brain growth may be protective for the adequate growth and postnatal survival of the Iberian individuals, an ancient breed reared in extensive semi-feral conditions for centuries. There were also clear sex-related differences in foetal development and metabolism in the Iberian breed. Female Iberian foetuses were similar in size and weight to male littermates but had a significantly higher relative liver to body weight ratio resembling “liver-sparing effect” and a trend for a higher relative intestine to body ratio. Moreover, the availability of triglycerides, cholesterol and IL-6 in female Iberian foetuses was similar to that of lean crossbred foetuses. Overall, these features may favour a better postnatal survival and development of females, the sex more critical for the species survival. These findings set the basis for future translational studies aimed at increasing the knowledge on the interaction between genetic and environmental factors in the early programming of the adult phenotype.

Gender-specific early postnatal catch-up growth after intrauterine growth retardation by food restriction in swine with obesity/leptin resistance

The effects of undernutrition during pregnancy on prenatal and postnatal development of the offspring were evaluated in sows with obesity/leptin resistance. Females were fed, from day 35 of pregnancy onwards, a diet fulfilling either 100% (group control,n=10) or 50% of the nutritional requirements (group underfed,n=10). In the control group, maternal body weight increased during pregnancy (P<0.05) while it decreased or remained steady in the underfed group. At days 75 and 100 of gestation, plasma triglycerides were lower but urea levels were higher in restricted than in control sows (P<0.05 for both). Assessment of the offspring indicated that the trunk diameter was always smaller in the restricted group (P<0.01 at day 50,P<0.005 at days 75 and 100 andP<0.0001 at birth) while head measurements were similar through pregnancy, although smaller in the restricted than in the control group at birth (P<0.05). Newborns from restricted sows were also lighter than offspring from control females (P<0.01) and had higher incidence of growth retardation (P<0.01). Afterwards, during lactation, early postnatal growth in restricted piglets was modulated by gender. At weaning, males from restricted sows were still lighter than their control counterparts (P<0.05), while females from control and underfed sows were similar. Thus, the current study indicates a gender-related differential effect in the growth patterns of the piglets, with females from restricted sows evidencing catch-up growth to neutralise prenatal retardation and reaching similar development than control counterparts.