Periconceptional undernutrition in sheep leads to decreased locomotor activity in a natural environment

Stress response to social isolation followed by exposure to a novel object in aged ewes born to undernourished mothers

Fetal programming by subnutrition affects offspring's behaviour, metabolism, and sensitivity to stressors in sheep. The objective was to determine the stress response of ewes born to mothers nutritionally restricted during gestation to social isolation followed by exposure to a novel object. Twenty-six-year-old Corriedale ewes born to mothers who grazed high or low pasture allowances (HPA and LPA groups) from 23 days before conception until 122 days of gestation were used. Ewes were individually isolated in a novel place for 10 min, and 5 min after its beginning, an orange ball was dropped into the test pen. The ewes' behaviours were recorded during the test. Blood proteins, glucose and cortisol concentrations, heart and respiratory rates and rectal and surface temperatures were determined. The number of times looking at the ball tended to be greater in HPA ewes than LPA (6.7 ± 1.0 vs 4.7 ± 0.8, P = 0.08). The LPA ewes had greater serum albumin concentration than HPA ewes (3.2 ± 0.1 g/dL vs 3.0 ± 0.1 g/dL, P = 0.02), regardless of the applied stressors. Overall, the nutritional treatments applied to ewes during their intrauterine development did not modify the stress responses to social isolation followed by exposure to a novel object.

Birth weight, growth indices, and seminal parameters in male offspring are resilient features to maternal pre-conceptional dietary manipulation in sheep

Gestational diet manipulation can lead to inadequate fetal nutrient supply resulting in low birth weight, limited postnatal growth, and consequently, reduced reproductive performance in the progeny. However, effects of short-term maternal pre-conceptional dietary manipulation on postnatal growth and reproductive parameters of male offspring in large animals remains unexplored. To determine these consequences, female crossbred (Polypay x Dorset) sheep were allocated to three groups (n = 33/group) of dietary manipulation for 21 days prior to mating under the following conditions: (1) control at 100 % of maintenance energy requirements (40 Kcal of metabolizable energy/kg body weight [BW]), (2) undernutrition (UN) at 50 % of Control intake, and (3) overnutrition (ON) at 200 % of maintenance energy. Singleton ram lambs (UN:9; C:12; ON:6) were monitored from birth until 8 months of age, including birth weight, weekly weights, weight gain, body mass index (BMI), and circulating testosterone. After weaning, monthly scrotal circumference and subcutaneous fat depth were measured. Semen morphology and motility were evaluated at 7 and 8 months of age. Birth weight, weight gain, and BMI at birth and weaning were not significantly different among nutritional treatments. None of the pre-conceptional diets affected body weight change from weaning until 36 weeks of age, BMI, fat depth, or scrotal circumference across the experiment. A sustained rise in plasma testosterone concentrations was detected when ram lambs were, on average, 82 days old and 37 kg. Both testosterone concentrations and scrotal circumference were positively correlated to body weight regardless of treatment group. In addition, seminal parameters did not differ among treatments, but a transient increase in plasma testosterone at 18 weeks of age was observed in ON ram lambs compared to control rams. In conclusion, birth weight, growth indices, and seminal parameters in singleton rams are resilient features in the progeny upon maternal pre-conceptional dietary manipulation in sheep.

Thermoregulatory, metabolic and stress responses to spring shearing of aged ewes born to undernourished mothers

Maternal undernutrition during gestation affects the behaviour, metabolism, and sensitivity to stressors of the offspring. Shearing is a stressor that triggers physiological and behavioural changes and augments the thermoregulatory demands in sheep. The aim of this study was to compare the thermoregulatory, metabolic, and behavioural responses to spring shearing of aged ewes born to mothers who grazed different pasture allowances during gestation. Nineteen non-gestating six-year-old Corriedale ewes born to mothers who grazed two pasture allowances from 23 days before conception until 122 days of gestation were used. The pasture allowance offered to the mothers was high [HPA group; n = 11; 10-12 kg of dry matter (DM)/100 kg of body weight (BW)/day] or low [LPA group: n = 8; 5-8 kg of DM/100 kg of BW/day]. The adult offspring of both experimental groups were sheared during spring (Day 0), and remained outdoors, grazing natural grassland, and the behaviour, the surface temperature and the rectal temperature were recorded. Blood concentrations of albumin, total protein, glucose, and insulin were also determined. Data were compared with a mixed model. The LPA ewes had lower ear and nose maximum and minimum surface temperatures before shearing (P < 0.05). On Day 15, the average surface temperature of the vulva was lower in LPA than in HPA ewes (P < 0.05). After shearing, rumination frequency was greater in HPA than in LPA ewes (P = 0.01), and LPA ewes were observed more time standing up than HPA ewes (P < 0.0001). Insulin concentration tended to be greater in LPA than HPA ewes (P = 0.06). Maternal undernutrition during gestation modified the thermoregulatory responses and the acute behavioural changes after shearing in aged female offspring, whilst the metabolism was affected to a lesser degree. The long-term effects noticed in this study highlight the importance of providing proper nutrition to pregnant ewes.

Effect of maternal periconceptional undernutrition in sheep on cortisol regulation in offspring from mid-late gestation, through to adulthood

INTRODUCTION

Maternal periconceptional undernutrition (PCUN) alters fetal hypothalamic-pituitary-adrenal axis (HPAA) function and placental glucocorticoid metabolism in sheep. The effects of PCUN on HPAA function in adult life are not known. We investigated the effects of PCUN on fetal adrenal development across gestation and on cortisol regulation in adult offspring.

METHODS

Ewes were undernourished from 61 days before to 30 days after conception ('PCUN') or fed ad libitum ('N'). mRNA expression in the fetal adrenal gland of ACTH receptor (ACTHR), steroidogenic acute regulatory protein (STAR), cytochrome P450 17A1 (CYP17A1), 11beta-hydroxysteroid-dehydrogenase type 2 (11βHSD2), insulin-like growth factor-2 (IGF2), and in the fetal hippocampus of 11βHSD1, 11βHSD2, mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) was determined at 50 (adrenal only), 85, 120 and 131 days of gestation (term=148 days). In adult offspring (≥ 3 years, N; 10 female, 5 male, PCUN; 10 female, 10 male) a combined arginine vasopressin (AVP, 0.1 μg/kg) and corticotropin-releasing hormone (CRH, 0.5 μg/kg) challenge and a metyrapone (40 mg/kg) challenge were undertaken. mRNA expression of ACTHR, STAR and CYP17A1 were determined in adult adrenals.

RESULTS

Fetal adrenal STAR, CYP17A1 and IGF2 mRNA expression were not different between groups in early gestation but were higher in PCUN than N at 131 days' gestation (all p<0.01). PCUN reduced fetal hippocampal MR and GR mRNA expression by 50% at 85 day, but not in later gestation. Adult offspring plasma cortisol responses to AVP+CRH or metyrapone were not different between groups. Plasma ACTH response to AVP+CRH was lower in PCUN males but ACTH response to metyrapone was not different between groups. Adult adrenal ACTHR, STAR, and CYP17A1 mRNA expression were not affected by PCUN.

CONCLUSIONS

We conclude that the effects of PCUN on fetal HPAA function that became apparent in late gestation, are not reflected in adrenal cortisol secretion in mid-adulthood.

Maternal Diabetes and Postnatal High-Fat Diet on Pregnant Offspring

Maternal diabetes-induced fetal programming predisposes offspring to type 2 diabetes, cardiovascular disease, and obesity in adulthood. However, lifelong health and disease trajectories depend on several factors and nutrition is one of the main ones. We intend to understand the role of maternal diabetes-induced fetal programming and its association with a high-fat diet during lifelong in the female F1 generation focusing on reproductive outcomes and the possible changes in physiological systems during pregnancy as well as the repercussions on the F2 generation at birth. For this, we composed four groups: F1 female pups from control (OC) or from diabetic dams (OD) and fed with standard (SD) or high-fat diet from weaning to full-term pregnancy. During pregnancy, glucose intolerance and insulin sensitivity were evaluated. In a full-term pregnancy, the maternal blood and liver were collected to evaluate redox status markers. The maternal blood, placental tissue, and fetal blood (pool) were collected to evaluate adiponectin and leptin levels. Maternal reproductive parameters were evaluated as well. Maternal diabetes and high-fat diet consumption, in isolation, were both responsible for increased infertility rates and fasting glucose levels in the F1 generation and fetal growth restriction in the F2 generation. The association of both conditions showed, in addition to those, increased lipoperoxidation in maternal erythrocytes, regardless of the increased endogenous antioxidant enzyme activities, glucose intolerance, decreased number of implantation sites and live fetuses, decreased litter, fetal and placental weight, increased preimplantation losses, and increased fetal leptin serum levels. Thus, our findings show that fetal programming caused by maternal diabetes or lifelong high-fat diet consumption leads to similar repercussions in pregnant rats. In addition, the association of both conditions was responsible for glucose intolerance and oxidative stress in the first generation and increased fetal leptin levels in the second generation. Thus, our findings show both the F1 and F2 generations harmed health after maternal hyperglycemic intrauterine environment and exposure to a high-fat diet from weaning until the end of pregnancy.

Cross-fostering selectively bred High Runner mice affects adult body mass but not voluntary exercise

While nursing, mammals progress through critical developmental periods for the cardiovascular, musculoskeletal, and central nervous systems. The suckling period in mammals is therefore especially vulnerable to environmental factors that may affect the "developmental programming" of many complex traits. As a result, various aspects of maternal behavior and physiology can influence offspring in ways that have lasting effects into adulthood. Several recent studies of animal models have shown that maternal effects can partially program adult activity behaviors, which has important implications for health and locomotor performance. Here, we used cross-fostering to test for possible maternal effects on adult wheel-running behavior (voluntary exercise), maximal aerobic capacity during forced exercise (VO₂max), body mass and composition, and organ masses. Subjects were from a line of mice that has been selectively bred for ∼90 generations for high voluntary wheel-running behavior (High Runner; HR) and a non-selected Control (C) line. Adult HR mice run ∼3-fold the daily distances of C mice and have evolved other differences associated with exercise capacity, including elevated VO₂max, reduced body mass and fat mass, and larger hearts. At birth, we fostered offspring to create 4 experimental groups: C pups to other C dams (in-foster), HR pups to other HR dams (in-foster), C pups to HR dams (cross-foster), HR pups to C dams (cross-foster). Thus, all pups were fostered to a different mother. Mice were weaned 3 weeks later, and adult testing began at ∼6 weeks of age. At weaning, pups raised by HR dams were smaller than those raised by C dams for both sexes and as expected, HR pups raised by HR dams weighed less than C pups raised by C dams. As adults, mice raised by HR dams continued to have reduced body masses. As expected, adult HR mice ran approximately 3-fold more than their C counterparts and females ran more than males. However, cross-fostering did not statistically affect any aspect of wheel-running behavior (distance, duration, speed). Similarly, with body mass as a covariate, HR mice had higher VO₂max than C mice, and males had higher VO₂max than females, but cross-fostering had no effect. With body mass as a covariate, cross-fostering had variable effects on adult organ masses in a sex-specific manner. Overall, our results indicate that development of the adult High Runner phenotype does not require rearing by an HR dam, suggesting that high adult activity in humans may be independent of high maternal activity.

Effects of early-life exposure to Western diet and voluntary exercise on adult activity levels, exercise physiology, and associated traits in selectively bred High Runner mice

Exercise behavior is under partial genetic control, but it is also affected by numerous environmental factors, potentially including early-life experiences whose effects persist into adulthood. We studied genetic and early-life environmental effects on wheel-running behavior in a mouse model that includes four replicate high runner (HR) lines selectively bred for increased voluntary wheel running as young adults and four non-selected control (C) lines. In a full factorial design, mice from each line were granted wheel access or not and administered either standard or Western diet (WD) from weaning (3 weeks old) to 6 weeks of age (sexual maturity). In addition to acute effects, after a washout period of 8 weeks (∼6 human years) in which all mice had standard diet and no wheel access, we found both beneficial and detrimental effects of these early-life exposures. During the first week of treatments, WD increased distance run by 29% in C mice and 48% in HR mice (significant Diet × Linetype interaction), but diet effects disappeared by the third week. Across the three weeks of juvenile treatment, WD significantly increased fat mass (with lean mass as a covariate). Tested as adults, early-life exercise increased wheel running of C mice but not HR mice in the first week. Early-life exercise also reduced adult anxiety-like behavior and increased adult fasted blood glucose levels, triceps surae mass, subdermal fat pad mass, and brain mass, but decreased heart ventricle mass. Using fat mass as a covariate, early-life exercise treatment increased adult leptin concentration. In contrast, early-life WD increased adult wheel running of HR mice but not C mice. Early-life WD also increased adult lean mass and adult preference for Western diet in all groups. Surprisingly, early-life treatment had no significant effect on adult body fat or maximal aerobic capacity (VO2max). No previous study has tested for combined or interactive effects of early-life WD and exercise. Our results demonstrate that both factors can have long-lasting effects on adult voluntary exercise and related phenotypes, and that these effects are modulated by genetic background. Overall, the long-lasting effects of early-life exercise were more pervasive than those of WD, suggesting critical opportunities for health intervention in childhood habits, as well as possible threats from modern challenges. These results may be relevant for understanding potential effects of activity reductions and dietary changes associated with the obesity epidemic and COVID-19 pandemic.

Effects of maternal periconceptional undernutrition in sheep on offspring glucose-insulin axis function into adulthood

Maternal periconceptional undernutrition (PCUN) affected fetal pancreatic maturation in late gestation lambs and impaired glucose tolerance in 10-month-old sheep. To examine the importance of the timing of maternal undernutrition around conception, a further cohort was born to PCUN ewes [undernourished for 61 d before conception (PreC), 30 d after conception (PostC), or 61 d before until 30 d after conception (PrePostC)], or normally fed ewes (Control) (n = 15-20/group). We compared glucose tolerance, insulin secretion, and sensitivity at 36 months of age. We also examined protein expression of insulin signalling proteins in muscle from these animals and in muscle from a fetal cohort (132 d of gestation; n = 7-10/group). Adult PostC and PrePostC sheep had higher glucose area under the curve than Controls (P = 0.07 and P = 0.02, respectively), whereas PreC sheep were similar to Controls (P = 0.97). PostC and PrePostC had reduced first-phase insulin secretion compared with Control (P = 0.03 and P = 0.02, respectively). PreC was similar to Control (P = 0.12). Skeletal muscle SLC2A4 protein expression in PostC and PrePostC was increased 19%-58% in fetuses (P = 0.004), but decreased 39%-43% in adult sheep (P = 0.003) compared with Controls. Consistent with this, protein kinase C zeta (PKCζ) protein expression tended to be increased in fetal (P = 0.09) and reduced in adult (P = 0.07) offspring of all PCUN ewes compared with Controls. Maternal PCUN alters several aspects of offspring glucose homeostasis into adulthood. These findings suggest that maternal periconceptional nutrition has a lasting impact on metabolic homeostasis of the offspring.

Maternal exposure to Western diet affects adult body composition and voluntary wheel running in a genotype-specific manner in mice

Some human diseases, including obesity, Type II diabetes, and numerous cancers, are thought to be influenced by environments experienced in early life, including in utero. Maternal diet during the perinatal period may be especially important for adult offspring energy balance, potentially affecting both body composition and physical activity. This effect may be mediated by the genetic background of individuals, including, for example, potential "protective" mechanisms for individuals with inherently high levels of physical activity or high basal metabolic rates. To examine some of the genetic and environmental factors that influence adult activity levels, we used an ongoing selection experiment with 4 replicate lines of mice bred for high voluntary wheel running (HR) and 4 replicate, non-selected control lines (C). Dams (half HR and half C) were fed a "Western" diet (WD, high in fat and sucrose) or a standard diet (SD) from 2weeks prior to mating until their pups could feed on solid food (14days of age). We analyzed dam and litter characteristics from birth to weaning, and offspring mass and physical activity into adulthood. One male offspring from each litter received additional metabolic and behavioral tests. Maternal WD caused pups to eat solid food significantly earlier for C litters, but not for HR litters (interaction of maternal environment and genotype). With dam mass as a covariate, mean pup mass was increased by maternal WD but litter size was unaffected. HR dams had larger litters and tended to have smaller pups than C dams. Home-cage activity of juvenile focal males was increased by maternal WD. Juvenile lean mass, fat mass, and fat percent were also increased by maternal WD, but food consumption (with body mass as a covariate) was unaffected (measured only for focal males). Behavior in an elevated plus maze, often used to indicate anxiety, was unaffected by maternal WD. Maximal aerobic capacity (VO₂max) was also unaffected by maternal WD, but HR had higher VO₂max than C mice. Adult lean, fat, and total body masses were significantly increased by maternal WD, with greater increase for fat than for lean mass. Overall, no aspect of adult wheel running (total distance, duration, average running speed, maximum speed) or home-cage activity was statistically affected by maternal WD. However, analysis of the 8 individual lines revealed that maternal WD significantly increased wheel running in one of the 4 HR lines. On average, all groups lost fat mass after 6days of voluntary wheel running, but the absolute amount lost was greater for mice with maternal WD resulting in no effect of maternal WD on absolute or % body fat after wheel access. All groups gained lean and total body mass during wheel access, regardless of maternal WD or linetype. Measured after wheel access, circulating leptin, adiponectin, and corticosterone concentrations were unaffected by maternal WD and did not differ between HR and C mice. With body mass as a covariate, heart ventricle mass was increased by maternal WD in both HR and C mice, but fat pads, liver, spleen, and brain masses were unaffected. As found previously, HR mice had larger brains than C mice. Body mass of grand-offspring was unaffected by grand-maternal WD, but grand-offspring wheel running was significantly increased for one HR line and decreased for another HR line by grand-maternal WD. In summary, maternal Western diet had long-lasting and general effects on offspring adult morphology, but effects on adult behavior were limited and contingent on sex and genetic background.

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.

Early-Life Effects on Adult Physical Activity: Concepts, Relevance, and Experimental Approaches

Locomotion is a defining characteristic of animal life and plays a crucial role in most behaviors. Locomotion involves physical activity, which can have far-reaching effects on physiology and neurobiology, both acutely and chronically. In human populations and in laboratory rodents, higher levels of physical activity are generally associated with positive health outcomes, although excessive exercise can have adverse consequences. Whether and how such relationships occur in wild animals is unknown. Behavioral variation among individuals arises from genetic and environmental factors and their interactions as well as from developmental programming (persistent effects of early-life environment). Although tremendous progress has been made in identifying genetic and environmental influences on individual differences in behavior, early-life effects are not well understood. Early-life effects can in some cases persist across multiple generations following a single exposure and, in principle, may constrain or facilitate the rate of evolution at multiple levels of biological organization. Understanding the mechanisms of such transgenerational effects (e.g., exposure to stress hormones in utero, inherited epigenetic alterations) may prove crucial to explaining unexpected and/or sex-specific responses to selection as well as limits to adaptation. One area receiving increased attention is early-life effects on adult physical activity. Correlational data from epidemiological studies suggest that early-life nutritional stress can (adversely) affect adult human activity levels and associated physiological traits (e.g., body composition, metabolic health). The few existing studies of laboratory rodents demonstrate that both maternal and early-life exercise can affect adult levels of physical activity and related phenotypes. Going forward, rodents offer many opportunities for experimental studies of (multigenerational) early-life effects, including studies that use maternal exposures and cross-fostering designs.

Effects of a maternal high-fat diet on offspring behavioral and metabolic parameters in a rodent model

Maternal diet-induced obesity can cause detrimental developmental origins of health and disease in offspring. Perinatal exposure to a high-fat diet (HFD) can lead to later behavioral and metabolic disturbances, but it is not clear which behaviors and metabolic parameters are most vulnerable. To address this critical gap, biparental and monogamous oldfield mice (Peromyscus polionotus), which may better replicate most human societies, were used in the current study. About 2 weeks before breeding, adult females were placed on a control or HFD and maintained on the diets throughout gestation and lactation. F1 offspring were placed at weaning (30 days of age) on the control diet and spatial learning and memory, anxiety, exploratory, voluntary physical activity, and metabolic parameters were tested when they reached adulthood (90 days of age). Surprisingly, maternal HFD caused decreased latency in initial and reverse Barnes maze trials in male, but not female, offspring. Both male and female HFD-fed offspring showed increased anxiogenic behaviors, but decreased exploratory and voluntary physical activity. Moreover, HFD offspring demonstrated lower resting energy expenditure (EE) compared with controls. Accordingly, HFD offspring weighed more at adulthood than those from control fed dams, likely the result of reduced physical activity and EE. Current findings indicate a maternal HFD may increase obesity susceptibility in offspring due to prenatal programming resulting in reduced physical activity and EE later in life. Further work is needed to determine the underpinning neural and metabolic mechanisms by which a maternal HFD adversely affects neurobehavioral and metabolic pathways in offspring.

Placental restriction in multi-fetal pregnancies increases spontaneous ambulatory activity during daylight hours in young adult female sheep

Intrauterine growth restriction (IUGR) has adverse effects on metabolic health and early life, whereas physical activity is protective against later development of metabolic disease. Relationships between birth weight and physical activity in humans, and effects of IUGR on voluntary activity in rodents, are mixed and few studies have measured physical activity in a free-ranging environment. We hypothesized that induced restriction of placental growth and function (PR) in sheep would decrease spontaneous ambulatory activity (SAA) in free-ranging adolescent and young adult progeny from multi-fetal pregnancies. To test this hypothesis, we used Global Positioning System watches to continuously record SAA between 1800 and 1200 h the following day, twice during a 16-day recording period, in progeny of control (CON, n=5 males, 9 females) and PR pregnancies (n=9 males, 10 females) as adolescents (30 weeks) and as young adults (43 weeks). PR reduced size at birth overall, but not in survivors included in SAA studies. In adolescents, SAA did not differ between treatments and females were more active than males overall and during the day (each P<0.001). In adults, daytime SAA was greater in PR than CON females (P=0.020), with a similar trend in males (P=0.053) and was greater in females than males (P=0.016). Adult SAA was negatively correlated with birth weight in females only. Contrary to our hypothesis, restricted placental function and small size at birth did not reduce progeny SAA. The mechanisms for increased daytime SAA in adult female PR and low birth weight sheep require further investigation.

Prenatal Undernutrition and Physical Function and Frailty at the Age of 68 Years: The Dutch Famine Birth Cohort Study

BACKGROUND

There is evidence suggesting that the aging process has its origins in utero. We have previously shown that prenatal exposure to the Dutch famine is associated with chronic noncommunicable diseases and poorer cognitive function in men and women and increased mortality in women. We investigated whether prenatal undernutrition during early gestation is associated with decreased physical function in later life.

METHODS

Between November 2012 and September 2013, we have studied a random subsample of 150 members of the Dutch famine birth cohort at the age of 68 years, of which 49 were exposed to prenatal undernutrition. In this observational study, we measured indicators of physical function including grip strength and the short physical performance battery. We composed categories of frailty, according to the Fried frailty scale. We also assessed self-reported activity and self-perceived health.

RESULTS

Men, but not women, exposed to prenatal undernutrition had significantly lower grip strength (B = -4.2kg; 95% confidence interval: -8.2 to -0.3) and a lower physical performance score (B = -0.8 points; 95% confidence interval: -1.5 to 0.0) than unexposed men, independent of relevant confounders. There were no differences in frailty, self-reported activity, or self-perceived health between exposed and unexposed groups.

CONCLUSIONS

Our study results suggest that prenatal undernutrition is associated with decreased physical function in later life in men, but not in women. Our findings provide further evidence for the hypothesis that prenatal undernutrition may lead to an accelerated aging process in humans. We currently do not have sufficient power to detect effects on frailty.

Prenatal origins of postnatal variation in growth, development and productivity of ruminants

This review provides an update on recent research into the effects of maternal nutrition on fetal biology and the growth, development and productivity of progeny in postnatal life of ruminant livestock. Evidence is summarised for effects on postnatal growth and body composition, feed intake and efficiency, carcass characteristics and meat quality, wool production, reproduction and lactation performance. In general, these demonstrated effects are not large in relation to the effects of postnatal nutrition and other environmental influences. The mechanisms underpinning the above production outcomes are briefly discussed in terms of systemic endocrine and metabolic responses, and cellular and molecular effects in skeletal muscle, bone, adipose tissue, wool follicles and brain of fetal, neonatal and adult progeny. Treatments observed to elicit tissue responses include maternal under- and overnutrition at various stages of pregnancy and placental insufficiency caused by increased litter size, chronic maternal heat stress and premating carunclectomy in sheep. The as yet meagre evidence for epigenetic mediation of intergenerational effects in ruminants is considered, as is the likelihood that other, more conventional explanations may suffice in some cases. Finally, evidence is summarised for the proposition that the placenta is not merely a passive conduit for nutrient transfer from dam to fetus, but plays an active role in buffering the effects of variations in maternal nutrition on fetal growth and development, and thence, postnatal outcomes.

Effect of periconceptional nutrition on the growth, behaviour and survival of the neonatal lamb

Periconceptional nutrition (PCN) can influence foetal hypothalamo-pituitary adrenal (HPA) axis function and alter cortisol secretion with possible consequences for maturation and growth of major organs, gestation length and behaviour. We examined effects of PCN on phenotype and survival of the neonatal lamb in 466 Merino ewes allocated to treatments providing 70%, 100% and 150% respectively, of maintenance requirements for 17 days prior and 6 days after insemination. Gestation length and birth weight for lambs in PCN treatment groups was similar (P > 0.05) but low PCN decreased the size of the neonate (crown-rump-length and metacarpal length P < 0.05). A subset of lambs euthanased at 5 days of age further showed that low PCN decreased the amount of peri-renal fat (P < 0.05) and increased liver mass (P < 0.05) while high PCN increased neck thymus and ovary mass (P < 0.05). Neonatal lambs from low PCN ewes returned faster to their mothers after release (P < 0.05) and contacted the udder in the shortest time (P < 0.05). Significant interactions between PCN treatment and sex (P < 0.05) and between PCN treatment and ewe age (P < 0.05) were also observed for time lambs took to follow the ewe. Survival of lambs was similar but potential differences may have been masked by favourable weather conditions. In conclusion, this study provides evidence of significant changes in lamb growth and development dependent on PCN and, for the first time, links these changes with significant changes in behaviour of the neonate. The impact of these effects on lamb survival and potential reproductive capacity of female offspring remains to be determined.

The effect of periconceptional undernutrition of sheep on the cognitive/emotional response and oocyte quality of offspring at 30 days of age

Maternal periconceptional undernutrition is associated with altered development and increased risks of adverse outcomes in the offspring. This circumstance is normal in flocks under extensive farming systems, which depend on natural forage resources. The aim of this study was to determine the effect of periconceptional undernutrition in sheep on behavioral and reproductive aspects of the offspring. Eighty ewes were synchronized in estrus and allocated to two groups (n=40) to be fed diets that provided 1.5 (C) or 0.5 (L) times the requirements for maintenance. Ewes were mated and 7 days later fed the control diet until lambing. One month after lambing, 32 lambs were exposed to tests to determine their cognitive and emotional responses. Six ewe lambs were euthanized and in vitro maturation and fertilization procedures were performed. L ewes presented a significant reduction in prolificacy and fecundity (P<0.05) in comparison with C ewes. Mean LW at lambing of L lambs was significantly higher than C lambs (C: 3.80 ± 0.11; L: 4.24 ± 0.15 kg, P<0.05). Lambs born from C ewes spent more time walking than L lambs (P<0.05) in the isolation test, revealing a decrease in the locomotor activity of lambs born from undernourished ewes around conception. Ewe lambs from the undernourished ewes presented a total population of oocytes 2.3 times higher than ovaries from control ewe lambs (60.0 ± 7.8 v. 140.0 ± 18.5 oocytes; P<0.05). In conclusion, periconceptional undernutrition is able to produce an increment in the body weight and the oocyte population, and an alteration of the locomotor activity of the offspring.

Maternal obesity and high-fat diet program offspring metabolic syndrome

OBJECTIVE

We determined the potential programming effects of maternal obesity and high-fat (HF) diet during pregnancy and/or lactation on offspring metabolic syndrome.

STUDY DESIGN

A rat model of maternal obesity was created using an HF diet prior to and throughout pregnancy and lactation. At birth, pups were cross-fostered, thereby generating 4 paradigms of maternal diets during pregnancy/lactation: (1) control (Con) diet during pregnancy and lactation (Con/Con), (2) HF during pregnancy and lactation (HF/HF), (3) HF during pregnancy alone (HF/Con), and (4) HF during lactation alone (Con/HF).

RESULTS

Maternal phenotype during pregnancy and the end of lactation evidenced markedly elevated body fat and plasma corticosterone levels in HF dams. In the offspring, the maternal HF diet during pregnancy alone programmed increased offspring adiposity, although with normal body weight, whereas the maternal HF diet during lactation increased both body weight and adiposity. Metabolic disturbances, particularly that of hyperglycemia, were apparent in all groups exposed to the maternal HF diet (during pregnancy and/or lactation), although differences were apparent in the manifestation of insulin resistant vs insulin-deficient phenotypes. Elevated systolic blood pressure was manifest in all groups, implying that exposure to an obese/HF environment is disadvantageous for offspring health, regardless of pregnancy or lactation periods. Nonetheless, the underlying mechanism may differ because offspring that experienced in utero HF exposure had increased corticosterone levels.

CONCLUSION

Maternal obesity/HF diet has a marked impact on offspring body composition and the risk of metabolic syndrome was dependent on the period of exposure during pregnancy and/or lactation.

Periconception weight loss: common sense for mothers, but what about for babies?

Obesity in the childbearing population is increasingly common. Obesity is associated with increased risk for a number of maternal and neonatal pregnancy complications. Some of these complications, such as gestational diabetes, are risk factors for long-term disease in both mother and baby. While clinical practice guidelines advocate for healthy weight prior to pregnancy, there is not a clear directive for achieving healthy weight before conception. There are known benefits to even moderate weight loss prior to pregnancy, but there are potential adverse effects of restricted nutrition during the periconceptional period. Epidemiological and animal studies point to differences in offspring conceived during a time of maternal nutritional restriction. These include changes in hypothalamic-pituitary-adrenal axis function, body composition, glucose metabolism, and cardiovascular function. The periconceptional period is therefore believed to play an important role in programming offspring physiological function and is sensitive to nutritional insult. This review summarizes the evidence to date for offspring programming as a result of maternal periconception weight loss. Further research is needed in humans to clearly identify benefits and potential risks of losing weight in the months before conceiving. This may then inform us of clinical practice guidelines for optimal approaches to achieving a healthy weight before pregnancy.

Moderate exercise during pregnancy in Wistar rats alters bone and body composition of the adult offspring in a sex-dependent manner

Exercise during pregnancy may have long-lasting effects on offspring health. Musculoskeletal growth and development, metabolism, and later-life disease risk can all be impacted by the maternal environment during pregnancy. The skeleton influences glucose handling through the actions of the bone-derived hormone osteocalcin. The purpose of this study was to test the effects of moderate maternal exercise during pregnancy on the bone and body composition of the offspring in adult life, and to investigate the role of osteocalcin in these effects. Groups of pregnant Wistar rats either performed bipedal standing exercise to obtain food/water throughout gestation but not lactation, or were fed conventionally. Litters were reduced to 8/dam and pups were raised to maturity under control conditions. Whole body dual-energy x-ray absorptiometry, and ex vivo peripheral quantitative computed tomography scans of the right tibia were performed. At study termination blood and tissue samples were collected. Serum concentrations of fully and undercarboxylated osteocalcin were measured, and the relative expression levels of osteocalcin, insulin receptor, Forkhead box transcription factor O1, and osteotesticular protein tyrosine phosphatase mRNA were quantified. Body mass did not differ between the offspring of exercised and control dams, but the male offspring of exercised dams had a greater % fat and lower % lean than controls (p=0.001 and p=0.0008, respectively). At the mid-tibial diaphysis, offspring of exercised dams had a lower volumetric bone mineral density than controls (p=0.01) and in the male offspring of exercised dams the bone: muscle relationship was fundamentally altered. Serum concentrations of undercarboxylated osteocalcin were significantly greater in the male offspring of exercised dams than in controls (p=0.02); however, the relative expression of the measured genes did not differ between groups. These results suggest that moderate exercise during pregnancy can result in lasting changes to the musculoskeletal system and adiposity in offspring, in a sex-specific manner.

Maternal undernutrition programs tissue-specific epigenetic changes in the glucocorticoid receptor in adult offspring

Epidemiological data indicate that an adverse maternal environment during pregnancy predisposes offspring to metabolic syndrome with increased obesity, and type 2 diabetes. The mechanisms are still unclear although epigenetic modifications are implicated and the hypothalamus is a likely target. We hypothesized that maternal undernutrition (UN) around conception in sheep would lead to epigenetic changes in hypothalamic neurons regulating energy balance in the offspring, up to 5 years after the maternal insult. We found striking evidence of decreased glucocorticoid receptor (GR) promoter methylation, decreased histone lysine 27 trimethylation, and increased histone H3 lysine 9 acetylation in hypothalami from male and female adult offspring of UN mothers. These findings are entirely compatible with the increased GR mRNA and protein observed in the hypothalami. The increased GR predicted the decreased hypothalamic proopiomelanocortin expression and increased obesity that we observed in the 5-year-old adult males. The epigenetic and expression changes in GR were specific to the hypothalamus. Hippocampal GR mRNA and protein were decreased in UN offspring, whereas pituitary GR was altered in a sex-specific manner. In peripheral polymorphonuclear leukocytes there were no changes in GR methylation or protein, indicating that this epigenetic analysis did not predict changes in the brain. Overall, these results suggest that moderate changes in maternal nutrition, around the time of conception, signal life-long and tissue-specific epigenetic alterations in a key gene regulating energy balance in the hypothalamus.