Effects of prenatal stress on corticosteroid receptors and monoamine concentrations in limbic areas of suckling piglets (Sus scrofa) at different ages

Risk Factors for Chronic Stress in Sows Housed in Groups, and Associated Risks of Prenatal Stress in Their Offspring

Chronic stress has a detrimental effect on sow welfare and productivity, as well as on the welfare and resilience of their piglets, mediated prenatally. Despite this, the specific risk factors for chronic stress in pregnant sows are understudied. Group-housed pregnant sows continuously face numerous challenges associated with aspects of the physical (group type and size, flooring, feeding system) and social (stocking density, mixing strategy) environment. There are many well-known potent stressors for pigs that likely contribute to chronic, physiological stress, including overcrowding, hot temperatures, feed restriction, inability to forage, uncomfortable floors, and poor handling. Some of these stressors also contribute to the development of production diseases such as lameness, which in turn are also likely causes of chronic stress because of the associated pain and difficulty accessing resources. The aim of this review is to discuss potential risk factors for chronic stress in pregnant sows such as space allowance, group size and type (stable/dynamic), feeding level, lameness, pen design, feed system, enrichment and rooting material, floor type, the quality of stockmanship, environmental conditions, and individual sow factors. The mechanisms of action of both chronic and prenatal stress, as well as the effects of the latter on offspring are also discussed. Gaps in existing research and recommendations for future work are outlined.

Characterizing the postnatal hypothalamic-pituitary-adrenal axis response of in utero heat stressed pigs at 10 and 15 weeks of age

In utero heat stress alters postnatal physiological and behavioral stress responses in pigs. However, the mechanisms underlying these alterations have not been determined. The study objective was to characterize the postnatal hypothalamic–pituitary–adrenal axis response of in utero heat-stressed pigs. Pigs were subjected to a dexamethasone suppression test followed by a corticotrophin releasing hormone challenge at 10 and 15 weeks of age. Following the challenge, hypothalamic, pituitary, and adrenal tissues were collected from all pigs for mRNA abundance analyses. At 10 weeks of age, in utero heat-stressed pigs had a reduced (P < 0.05) cortisol response to the corticotrophin releasing hormone challenge versus controls. Additionally, the cortisol response tended to be greater overall (P < 0.10) in 15 versus 10-week-old pigs in response to the dexamethasone suppression test. The cortisol response tended to be reduced overall (P < 0.10) in 15 versus 10-week-old pigs in response to the corticotrophin releasing hormone challenge. Hypothalamic corticotropin releasing hormone mRNA abundance tended to be greater (P < 0.10) in in utero heat-stressed versus control pigs at 15-weeks of age. In summary, in utero heat stress altered some aspects of the hypothalamic–pituitary–adrenal axis related to corticotropin releasing hormone signaling, and age influenced this response.

An approach to assess stress in response to drive hunts using cortisol levels of wild boar (Sus scrofa)

Hunting can easily be linked to stress in wildlife. Drive hunts performed two to three times in one area during the respective hunting period, are thought to decrease the pressure hunting places on wildlife. Nevertheless, the expression of cortisol—one of the main mammalian stress hormones—is considered to have negative impacts on animals’ well-being if expressed excessively, which may occur during some (especially repeated) hunting events. We explored the effect of drive hunts on cortisol levels in wild boar in Lower Saxony, Germany, compared these cortisol levels to reference values given by a similar study, and investigated the effect of age, sex, and pregnancy. Blood collected from wild boar shot on drive hunts was analysed using a radioimmunoassay. As expected, we observed elevated cortisol levels in all samples, however, we still found significant differences between age groups and sexes, as well as an influence of pregnancy on cortisol levels. The effect of drive hunts on cortisol levels appears to be weaker than predicted, while the effects of other variables, such as sex, are distinct. Only half of the evaluated samples showed explicitly increased cortisol levels and no significant differences were found between sampling months and locations. Group living animals and pregnant females showed significantly higher cortisol levels. The impact of hunting is measurable but is masked by natural effects such as pregnancy. Thus, we need more information on stress levels in game species.

Chronic Piromelatine Treatment Alleviates Anxiety, Depressive Responses and Abnormal Hypothalamic-Pituitary-Adrenal Axis Activity in Prenatally Stressed Male and Female Rats

The prenatal stress (PNS) model in rodents can induce different abnormal responses that replicate the pathophysiology of depression. We applied this model to evaluate the efficacy of piromelatine (Pir), a novel melatonin analog developed for the treatment of insomnia, in male and female offspring. Adult PNS rats from both sexes showed comparable disturbance associated with high levels of anxiety and depressive responses. Both males and females with PNS demonstrated impaired feedback inhibition of the hypothalamic-pituitary-adrenal (HPA) axis compared to the intact offspring and increased glucocorticoid receptors in the hippocampus. However, opposite to female offspring, the male PNS rats showed an increased expression of mineralocorticoid receptors in the hippocampus. Piromelatine (20 mg/kg, i.p., for 21 days injected from postnatal day 60) attenuated the high anxiety level tested in the open field, elevated plus-maze and light-dark test, and depressive-like behavior in the sucrose preference and the forced swimming tests in a sex-specific manner. The drug reversed to control level stress-induced increase of plasma corticosterone 120 min later in both sexes. Piromelatine also corrected to control level the PNS-induced alterations of corticosteroid receptors only in male offspring. Our findings suggest that the piromelatine treatment exerts beneficial effects on impaired behavioral responses and dysregulated HPA axis in both sexes, while it corrects the PNS-induced changes in the hippocampal corticosteroid receptors only in male offspring.

In utero heat stress alters postnatal phenotypes in swine

The prenatal environment influences offspring health and development, and this is readily apparent when considering the well-described effects of maternal nutrition and stress on the postnatal metabolism, neural function, and stress response of progeny. Moreover, in laboratory species, sheep, and humans, the effects of in utero heat stress on offspring development have been described in detail for >50 years. Despite our extensive knowledge of the postnatal phenotypes elicited by in utero stressors, the carryover effects of in utero heat stress in pigs have only recently begun to be elucidated. The effects of climate change on increasing global temperatures, combined with greater metabolic heat production in modern swine, has increased heat stress susceptibility in pigs. Greater heat stress susceptibility can negatively affect swine welfare and performance and may impact future generations of pigs through in utero heat stress. Pigs exposed to in utero heat stress develop a variety of postnatal phenotypes that prevent profitable production, and compromise health, and welfare in commercial production systems. Specifically, in utero heat stress alters the postnatal stress response, core body temperature, response to an immune challenge, and is teratogenic. In addition, in utero heat stress changes postnatal body composition through reduced lean and increased adipose tissue accretion rates, respectively. Furthermore, in utero heat stress reduces piglet birth weight, body weight gain, and reproductive efficiency. Although the economic impact of in utero heat stress in pigs has yet to be determined, it likely rivals the postnatal consequences of heat stress and is a threat to the global sustainability of swine production.

Evaluating the Effects of In Utero Heat Stress on Piglet Physiology and Behavior Following Weaning and Transport

The study objective was to determine whether in utero heat stress (IUHS) affects piglet physiology and behavior following common production practices. A total of 12 gilts were confirmed pregnant and allocated to either heat stress (HS; n = 6) or thermoneutral (TN; n = 6) conditions on day 30⁻60 of gestation. At weaning (22.5 ± 2.3 days of age), 1 boar and 1 barrow of median weight were selected from each litter and transported for approximately 7 h. Piglets were then blocked into pens (n = 2/pen) by in utero treatment (IUHS (n = 12) or in utero thermoneutral (IUTN, n = 12)) and sexual status (boar (n = 6/in utero treatment) or barrow (n = 6/in utero treatment)). Plasma cortisol, non-esterified fatty acids (NEFA), insulin and glucose were evaluated 1 day prior to transport (pre-transport) and immediately after transport (post-transport). Behavioral data were collected on day 1⁻7 for 60 min at four different time points each day. In utero heat stressed piglets exhibited reduced cortisol concentrations compared to IUTN piglets immediately post-transport (p = 0.04). Glucose concentrations were not affected by in utero treatment. Insulin concentrations were reduced in IUTN piglets post-transport compared to pre-transport (p = 0.002), but no differences were detected for IUHS pigs. Non-esterified fatty acids tended to be reduced overall for IUHS vs. IUTN pigs (p = 0.08). Overall, IUHS piglets performed more drinking behaviors (p = 0.02) and tended to perform more aggressive behaviors (p = 0.07) than IUTN piglets in the 7 days post-transport. In summary, there was some evidence for altered physiological and behavioral responses among IUHS piglets compared to IUTN piglets following weaning and transport.

PHYSIOLOGY SYMPOSIUM: Postnatal consequences of in utero heat stress in pigs

Postnatal heat stress negatively impacts pig productivity and well-being as animals attempt to manage the resultant strain response. This is especially true when postnatal heat stress is combined with production stressors (e.g., mixing, weaning, transport, handling, and isolation) that have the potential to increase disease occurrence, morbidity and mortality. While pigs can utilize adaptive physiological mechanisms to compensate, these are often unfavorable to efficient livestock production. Specifically, postnatal heat stress decreases weight gain, reduces growth and production efficiency, alters carcass composition, and increases morbidity and mortality. Consequently, decreased animal performance constrains profitability and affects economic sustainability. In addition to the negative effects of postnatal heat stress, prenatal heat stress has long-term consequences that may compromise future piglet well-being and performance. Pigs gestated under heat stress conditions have an increased postnatal stress response and an increase in maintenance energy requirements. Furthermore, prenatal heat stress decreases swine birth weight, and increases teratogenicity, core body temperature set-point, and alters postnatal body composition (more adipose tissue and less skeletal muscle). Taken together, the effects of heat stress during pre- and postnatal pig development negatively influences productivity and well-being, a scenario that threatens the sustainability of global swine production.

Like mother, like daughter: heritability of female Richardson's ground squirrel Urocitellus richardsonii cortisol stress responses

Activation of the hypothalamic-pituitary-adrenal (HPA) axis liberates glucocorticoids, which provides an acute indication of an individual's response to stressors. The heritability of the stress response in wild mammals, however, remains poorly documented. We quantified the cortisol stress response of female Richardson's ground squirrels (RGSs) to handling and physical restraint, testing for: (1) the effects of individual age, time of day, and sample latency; (2) repeatability within individuals; (3) narrow-sense heritability; and (4) differences among individuals owing to potential genetic and/or environmental effects. We detected a positive linear relationship between baseline plasma cortisol (BL-cortisol) concentration and stress-induced plasma cortisol (SI-cortisol) concentration that defined each individual's cortisol stress response. BL-cortisol, SI-cortisol, and stress response did not differ according to the time the sample was taken, or by subject age. Cortisol stress response was highly repeatable within individuals, had a mother-offspring heritability of h 2 = 0.40 ± 0.24 (mean ± SE), full-sibling heritability ofh FS 2   =   0.37   ±   0.71 , and half-sibling heritability ofh HS 2 =   0.75   ±   1.41 . Stress responses of sibling groups, immediate-family groups, and squirrels within a given area did not differ, whereas those of individuals from more distantly related matrilines did. Our results highlight the natural variability in HPA axis reactivity among individuals by quantifying both BL- and SI-cortisol levels, demonstrate partial heritability of the stress response that is not attributable to environmental variation, and suggest that at least part of an individual's stress response can be accounted for by differences in matrilineal history.

Effect of prenatal exposure to maternal cortisol and psychological distress on infant development in Bengaluru, southern India: a prospective cohort study

BACKGROUND

The mental health status of a pregnant woman and its consequent impact on foetal well being is not given much importance compared to the risk imposed by obstetric complications and medical conditions. Maternal psychological distress is a major public health problem and needs timely detection and intervention to prevent any adverse pregnancy outcome. There is ample evidence from literature that justifies the association of prenatal maternal mental stress and elevated cortisol with delayed infant motor and cognitive development; evidence from India being rather limited. The study aim is to prospectively assess the association of maternal psychological distress and cortisol level with motor and cognitive development of the infant.

METHODS

A sample of 2612 eligible pregnant women who have been registered for antenatal care at selected public sector hospitals in Bengaluru will be recruited after obtaining written informed consent. They will be assessed for the presence of maternal psychological distress in the form of depression and anxiety using appropriate scales and saliva samples will be collected for cortisol estimation during early, mid and late pregnancy. Follow up visits after delivery will be done on day 10, 3 months, 8 months and 12 months. The Bayley Scales of Infant and Toddler Development [BSID] (Third edition) will be used to measure both motor and mental milestones in terms of Psychomotor Development Index (PDI) and Mental Development Index (MDI). Logistic regression model will be used to determine the association between the exposure variables and outcomes which will be reported as Odd's Ratio (OR) and 95% confidence intervals (CI).

DISCUSSION

Our study findings could add to the growing evidence that maternal psychological distress during pregnancy adversely influences growth and development in the offspring and subsequent development of the child. While maternal anxiety and depression can be measured by using self reporting instruments, estimation of maternal endogenous cortisol levels could serve as a biomarker of prenatal psychological stress. Findings from this study could be used to focus upon the burden of mental health problems during pregnancy and to consider steps to scale up prenatal mental health services in health care settings.

A Natural Mutation in Helix 5 of the Ligand Binding Domain of Glucocorticoid Receptor Enhances Receptor-Ligand Interaction

The glucocorticoid receptor (GR) is a central player in the neuroendocrine stress response; it mediates feedback regulation of the hypothalamus-pituitary-adrenal (HPA) axis and physiological actions of glucocorticoids in the periphery. Despite intensive investigations of GR in the context of receptor-ligand interaction, only recently the first naturally occurring gain-of-function substitution, Ala610Val, of the ligand binding domain was identified in mammals. We showed that this mutation underlies a major quantitative trait locus for HPA axis activity in pigs, reducing cortisol production by about 40-50 percent. To unravel the molecular mechanisms behind this gain of function, receptor-ligand interactions were evaluated in silico, in vitro and in vivo. In accordance with previously observed phenotypic effects, the mutant Val610 GR showed significantly increased activation in response to glucocorticoid and non-glucocorticoid steroids, and, as revealed by GR-binding studies in vitro and in pituitary glands, enhanced ligand binding. Concordantly, the protein structure prediction depicted reduced binding distances between the receptor and ligand, and altered interactions in the ligand binding pocket. Consequently, the Ala610Val substitution opens up new structural information for the design of potent GR ligands and to examine effects of the enhanced GR responsiveness to glucocorticoids on the entire organism.

Epigenetics and developmental programming of welfare and production traits in farm animals

The concept that postnatal health and development can be influenced by events that occur in utero originated from epidemiological studies in humans supported by numerous mechanistic (including epigenetic) studies in a variety of model species. Referred to as the 'developmental origins of health and disease' or 'DOHaD' hypothesis, the primary focus of large-animal studies until quite recently had been biomedical. Attention has since turned towards traits of commercial importance in farm animals. Herein we review the evidence that prenatal risk factors, including suboptimal parental nutrition, gestational stress, exposure to environmental chemicals and advanced breeding technologies, can determine traits such as postnatal growth, feed efficiency, milk yield, carcass composition, animal welfare and reproductive potential. We consider the role of epigenetic and cytoplasmic mechanisms of inheritance, and discuss implications for livestock production and future research endeavours. We conclude that although the concept is proven for several traits, issues relating to effect size, and hence commercial importance, remain. Studies have also invariably been conducted under controlled experimental conditions, frequently assessing single risk factors, thereby limiting their translational value for livestock production. We propose concerted international research efforts that consider multiple, concurrent stressors to better represent effects of contemporary animal production systems.

Social support modulates splenocyte glucocorticoid sensitivity in piglets exposed to social deprivation stress

There is growing evidence that positive social interactions can attenuate the effects of stressful life experiences. However, little is known about the benefits of social partners on stress responses in farm animals. Therefore, in this study we examined the effects of social support on the endocrine and immune stress responses to a single 4h social deprivation in domestic piglets at 7, 21 or 35days of age. The piglets were socially deprived of their mother and littermates. They were left alone (DA) or in the presence of a familiar (DF) or unfamiliar (DU) age-matched piglet. Non-socially deprived piglets served as a control. DA piglets displayed elevated plasma cortisol levels, higher lipopolysaccharide (LPS)-stimulated proliferation of splenocytes and increased TNF-α and IL-6 production in splenocyte cultures than the control piglets. There were no significant buffering effects of social partners on stress-induced plasma cortisol levels and splenocyte proliferation in response to LPS. However, the presence of an age-matched conspecific diminished the IL-6 production by splenocytes in younger, socially deprived piglets, and it reduced the TNF-α release in the older piglets. Compared to the controls, LPS-stimulated splenocytes from DA piglets were more resistant to the inhibitory effects of cortisol, which was demonstrated by a higher proliferative response and increased production of pro-inflammatory cytokines. The dose-dependent cortisol resistance was attenuated by the presence of a familiar or an unfamiliar conspecific at each of the three age categories. Indeed, in the present study, the familiarity level of the social partners did not seem to play a role in the alleviation of social stress-induced inflammatory activity and splenocyte cortisol resistance. In addition, the buffering effect of social support provided by an age-matched conspecific was more pronounced in older piglets. Conclusively, these findings suggest that social support is an important factor for enhancing piglets' abilities to cope with stressful challenges, and it may be a key approach needed to improve the health and welfare of farm animals.

Size at birth, morning cortisol and cardiometabolic risk markers in healthy Indian children

OBJECTIVE

Prenatal programming of the hypothalamic-pituitary-adrenal (HPA) axis may link reduced foetal growth with higher adult chronic disease risk. South Asians have a high prevalence of low birth weight and a thin-fat phenotype, which is associated with subsequent type 2 diabetes and the metabolic syndrome. Altered HPA activity could be one of the pathological processes underlying this link.

METHODS

Plasma morning cortisol and corticosteroid-binding globulin (CBG) concentrations were determined in 528 children aged 9·5 years from a prospective birth cohort in India. They had detailed anthropometry at birth, and current measurements of anthropometry, plasma glucose, insulin and lipid concentrations and blood pressure. Insulin resistance (Homeostasis Model Assessment) and insulin secretion (the 30-min insulin increment) were also assessed.

RESULTS

None of the birth measurements were associated with cortisol concentrations, but both birth weight (P = 0·03) and length (P = 0·004) were inversely associated with CBG concentrations. Cortisol concentrations were inversely associated with current body mass index (P = 0·02), and positively associated with glucose (fasting: P < 0·001; 30-min: P = 0·002) concentrations, and systolic blood pressure (P = 0·005), but not insulin resistance or the insulin increment.

CONCLUSION

Higher morning cortisol is associated with higher cardiometabolic risk markers in Indian children. Although cortisol concentrations did not appear to be related to birth size, small size at birth was associated with higher CBG levels, and may be one of the processes by which foetal undernutrition affects adult health. The findings suggest a need for dynamic testing of HPA axis activity (such as measuring stress responses).

Effects of low and high protein:carbohydrate ratios in the diet of pregnant gilts on maternal cortisol concentrations and the adrenocortical and sympathoadrenal reactivity in their offspring

Inadequate maternal nutrition during gestation may cause an adverse environment for the fetus leading to alterations of the hypothalamic-pituitary-adrenal (HPA) and sympatho-adrenomedullary (SAM) systems later in life. In the present study, we investigated the effects of diets with low and high protein:carbohydrate ratios on cortisol concentrations of pregnant gilts as well as the long-term effects on the function of the HPA and SAM axes in their offspring. Throughout gestation, 33 German Landrace gilts were fed high (HP, 30%), low (LP, 6.5%), or adequate (AP, 12.1%) protein diets, which were made isocaloric by adjusting the carbohydrate content. The salivary cortisol concentrations of the sows were measured in the course of the gestation period. The offspring were cross-fostered, and the plasma cortisol and catecholamine concentrations of the offspring were determined on postnatal d (PND) 1 and 27 and under specific challenging conditions: after weaning (PND 29) and after ACTH and insulin challenges (PND 68 and 70, respectively). Glucocorticoid receptor (GR) binding and neurotransmitter concentrations were measured in stress-related brain regions, and histological analyses of the adrenal were performed. Maternal salivary cortisol concentrations increased throughout gestation (P < 0.001) and the LP gilts had greater salivary cortisol compared with the AP and HP gilts (P < 0.05). No differences between diets were found for cortisol, corticosteroid-binding globulin, and catecholamine concentrations in plasma and for GR binding in hippocampus and hypothalamus in piglets at PND 1 and 27. However, the cortisol response to weaning was increased in LP piglets (P < 0.05), and in HP offspring the basal plasma noradrenaline concentrations were increased (P < 0.05). The cortisol response to the ACTH and the insulin challenge did not differ between diets. On PND 81, an increased adrenal medulla area was observed in LP offspring compared with the AP offspring (P < 0.05). Our results show that maternal diets with aberrant protein:carbohydrate ratios during gestation have moderate long-term effects on the function of the HPA and SAM system in the offspring, which indicates that pigs show a considerable plasticity to cope with maternal malnutrition.

Effects of inadequate maternal dietary protein:carbohydrate ratios during pregnancy on offspring immunity in pigs

BACKGROUND

Inadequate nutrition in utero may retard foetal growth and alter physiological development of offspring. This study investigated the effects of low and high protein diets fed to primiparous German Landrace sows throughout pregnancy on the immune function of their offspring at different ages. Sows were fed diets with adequate (AP, 12.1%; n = 13), low (LP, 6.5%; n = 15), or high (HP, 30%; n = 14) protein content, made isoenergetic by varying carbohydrate levels. Cortisol, total protein and immunoglobulin (IgG, IgM, IgA) concentrations were measured in the blood of sows over the course of pregnancy. Cortisol, total protein, immunoglobulins, lymphocyte proliferation, immune cell counts, and cytokines were assessed in the blood of offspring at baseline and under challenging conditions (weaning; lipopolysaccharide (LPS) administration).

RESULTS

In sows, the LP diet increased cortisol (P < 0.05) and decreased protein levels (P < 0.01) at the end of pregnancy. Immunoglobulin concentrations were decreased in LP (IgA) and HP piglets (IgG, IgM and IgA) on the first day of life (P < 0.05), whereas the number of lymphocytes and mitogen-induced lymphocyte proliferation of the piglets were unaffected by the maternal diet. Mortality during the suckling period was higher in LP piglets compared with AP and HP offspring (P < 0.01). Furthermore, LP piglets showed an elevated cortisol response to weaning, and in HP piglets, the CD4+ cell percentage and the CD4+/CD8+ ratio increased after weaning (P < 0.05). The lipopolysaccharide-induced rise of IL-6 was higher in LP (P = 0.09) and HP (P < 0.01) compared with AP piglets, and LP piglets displayed higher IL-10 levels than AP piglets (P < 0.05).

CONCLUSIONS

Our results indicate that both low and high protein:carbohydrate ratios in the diet of pregnant sows can induce short-term as well as long-lasting effects on immune competence in piglets that may have serious consequences for host defence against bacterial pathogens.

Biotic and abiotic factors influencing distribution and abundance of Culicoides obsoletus group (Diptera: Ceratopogonidae) in central Italy

In the framework of a bluetongue surveillance program including clinical, serological, and entomological activities, Culicoides biting midges were light trapped weekly in two regions of central Italy, Lazio and Tuscany. In the period January 2002 through December 2005, 3,944 collections were carried out in 189 trap sites distributed in all the provinces of the two regions. Abundance data of C. obsoletus group were analyzed in relation to trap site altitude, distance from the sea, land use, and number of farmed animals. Species seasonality and overall temporal trend were also described. C. obsoletus was distributed over the whole study area, almost in all trapping sites and with high abundances. The species group was dominant among all captured Culicoides, with higher abundances recorded inland and in areas where land cover was partially or completely natural-wooded. Adults on the wing were caught all year round, with peaks in May-June and middle October. The observed trend through years recorded a peak during autumn 2002, in concomitance with a local epidemic of bluetongue.

Maternal social stress during late pregnancy affects hypothalamic-pituitary-adrenal function and brain neurotransmitter systems in pig offspring

Maternal stress in pregnant sows may induce long-lasting alterations in the behavior, physiology, and immunity of their offspring. The aim of the present study was to investigate the consequences of repeated social stress during late gestation on determinants of the hypothalamic-pituitary-adrenal axis and on hippocampal neurotransmitter profiles in pig offspring. All pregnant gilts were housed in pairs. Each Stress gilt was mixed with an unfamiliar gilt twice a week between days 77 and 105 of gestation (n=18). Control gilts were housed in stable pairs over the same period (n=18). Plasma cortisol and corticosteroid binding globulin (CBG) were measured in 1 male and 1 female per litter in a basal situation on postnatal days (PND) 4, 26, and 60 and in a stressful situation at PND 28 (2 d after weaning) and 62 (2 d after relocation to a new building). Prenatal stress had no effect on plasma cortisol, but it decreased CBG at PND 26. Brain and adrenals were collected from 1 female per litter after weaning or relocation at PND 28 and PND 62. Adrenals were additionally collected at PND 4. Glucocorticoid receptor binding in the hippocampus and hypothalamus was not affected by prenatal treatment. However, prenatal stress increased the expression of 11beta-hydroxysteroid dehydrogenase type 1 mRNA in the hippocampus after weaning (P<0.05) and after relocation (P=0.08). In addition, prenatally stressed piglets showed an increased 5-hydroxyindole-3-acetic acid to 5-hydroxytryptamine ratio in the hippocampus after weaning and increased hippocampal c-fos mRNA expression and noradrenaline concentration after relocation (P<0.05). Prenatal stress also increased the relative adrenal weight at PND 4 and the cell density in the cortex and the medulla at PND 28, whereas no difference was found for activities of catecholamine-synthesising enzymes in the medulla. Overall, our data indicate that repeated social stress during pregnancy has long-lasting consequences on hypothalamic-pituitary-adrenal axis and hippocampal neurotransmitter activity in the offspring of pigs.

Effects of maternal dexamethasone treatment in early pregnancy on pituitary-adrenal axis in fetal sheep

Fetal exposure to elevated levels of bioactive glucocorticoids early in gestation, as in suspected cases of congenital adrenal hyperplasia, may result in adverse neurological events. Fetal hypothalamic-pituitary-adrenal development and function may be involved. We investigated immediate and long-term effects of maternal dexamethasone (DEX) administration early in pregnancy on fetal growth and pituitary-adrenal activity in sheep. Pregnant ewes carrying singleton fetuses (total n = 119) were randomized to control (2 ml saline/ewe) or DEX-treated groups (im injections of 0.14 mg/kg ewe weight . 12 h) at 40-41 d gestation (dG). At 50, 100, 125, and 140 dG, fetal plasma and tissues were collected. DEX-exposed fetuses were lighter than controls at 100 dG (P < 0.05) but not at any other times. Fetal plasma ACTH levels and pituitary POMC and PC-1 mRNA levels were similar between groups. Fetal plasma cortisol levels were significantly reduced after DEX exposure in both male and female fetuses at 50 dG (P < 0.05), were similar at 100 and 125 dG, but were significantly higher than controls at 140 dG. At 140 dG, there was increased adrenal P450C(17) and 3beta-HSD mRNA in female fetuses and reduced expression of ACTH-R mRNA in males. Fetal hepatic CBG mRNA levels mimicked plasma cortisol patterns. DEX exposure reduced CBG only in males at 50 dG (P < 0.05). Placental mRNA levels of 11beta-HSD2 were increased after DEX in males (P < 0.05). Therefore, in sheep, early DEX may alter the developmental trajectory of the fetal hypothalamic-pituitary-adrenal axis, directly increasing fetal adrenal activation but not anterior pituitary function. In females, this effect may be attributed, in part, to increased fetal adrenal steroidogenic activity.

Comparative effects of a prenatal stress occurring during early or late gestation on pig immune response

The aim of this work was to investigate the immune effects of prenatal stress (PNS) in pigs, when maternal stressor is applied during early or late gestation. In two separate experiments, gilts were submitted to a social-stress routine between either days 24 and 48 (stress (S) group, n=8 vs. control (C) group, n=6) or days 79 and 103 of gestation (S group, n=10 vs. C group, n=7). During the first month of life of the piglets, their cortisol levels were assessed in basal state and after stressful events (castration, new environment, and weaning). Piglets were immunized against ovalbumin (OVA) at 7 (D7) and 19 (D19) days of age. Lymphocyte proliferation in response to OVA and mitogens was investigated in blood in both sexes from D5 to D29 as well as in the spleen, thymus and crural lymph nodes from females euthanized on D5 and D26. On D27, the cytokine response of male piglets to an injection of lipopolysaccharide was investigated. Special care was taken to minimize the stress at blood sampling and euthanasia. We found that early gestational stress only affected the relative weight of adrenals on D5 (S<C, P<0.05). On the contrary, late gestational stress increased the proliferation index of blood cells regardless of the age, in both sexes in response to PHA (P=0.06), and in females only in response to ConA (P<0.01) and PWM (P<0.05). Overall, the effects of PNS in pigs seem to depend on the stage of gestation, gender and the immune compartment.

Bone development of suckling piglets after prenatal, neonatal or perinatal treatment with dexamethasone

In mammals, the release from growth-inhibiting conditions results in catch-up growth. To investigate animal evidence for whether prenatal dexamethasone (DEX) treatment leads to the development of growth restriction especially reduced mineralization of skeleton, and release from it leads to the phenomenon of catch-up, piglets were prenatally exposed to DEX (3.0 mg/sow per day(-2)) during the last 24 days of prenatal life and tested further in two different ways: discontinued at birth and continued administration of DEX (0.5 mg/kg day(-2)) to piglets through 30 days of neonatal life. Using dual energy X-ray absorptiometry methods, bone mineral density (BMD) and bone mineral content (BMC) were measured. The three-point bending test was applied to determine the mechanical properties of the bones. Furthermore, geometric properties of the bones were assessed. Serum concentration of osteocalcin (OC) was determined. Histomorphological analysis of the ribs was also performed. The consequences of neonate DEX treatment and in utero DEX exposure were reflected in a dramatic decrease of BMD, BMC and blood serum OC concentration and geometric parameters of piglets' bones. Prenatal action of DEX during the last 24 days of pregnancy resulted in continued neonatal modification of bone tissues, thus diminishing bone quality, and negatively influenced structural development and mechanical properties, finally increasing the risk of fractures of ribs and limb bones. Prenatal DEX treatment limited to the last 24 days of foetal life did not reduce the term birth weight and the growth of suckling piglets followed up to 30 days of neonatal life, and catch-up in bone mineralization did not occur.

Modelling the distributions and spatial coincidence of bluetongue vectors Culicoides imicola and the Culicoides obsoletus group throughout the Iberian peninsula

Data obtained by a Spanish national surveillance programme in 2005 were used to develop climatic models for predictions of the distribution of the bluetongue virus (BTV) vectors Culicoides imicola Kieffer (Diptera: Ceratopogonidae) and the Culicoides obsoletus group Meigen throughout the Iberian peninsula. Models were generated using logistic regression to predict the probability of species occurrence at an 8-km spatial resolution. Predictor variables included the annual mean values and seasonalities of a remotely sensed normalized difference vegetation index (NDVI), a sun index, interpolated precipitation and temperature. Using an information-theoretic paradigm based on Akaike's criterion, a set of best models accounting for 95% of model selection certainty were selected and used to generate an average predictive model for each vector. The predictive performances (i.e. the discrimination capacity and calibration) of the average models were evaluated by both internal and external validation. External validation was achieved by comparing average model predictions with surveillance programme data obtained in 2004 and 2006. The discriminatory capacity of both models was found to be reasonably high. The estimated areas under the receiver operating characteristic (ROC) curve (AUC) were 0.78 and 0.70 for the C. imicola and C. obsoletus group models, respectively, in external validation, and 0.81 and 0.75, respectively, in internal validation. The predictions of both models were in close agreement with the observed distribution patterns of both vectors. Both models, however, showed a systematic bias in their predicted probability of occurrence: observed occurrence was systematically overestimated for C. imicola and underestimated for the C. obsoletus group. Average models were used to determine the areas of spatial coincidence of the two vectors. Although their spatial distributions were highly complementary, areas of spatial coincidence were identified, mainly in Portugal and in the southwest of peninsular Spain. In a hypothetical scenario in which both Culicoides members had similar vectorial capacity for a BTV strain, these areas should be considered of special epidemiological concern because any epizootic event could be intensified by consecutive vector activity developed for both species during the year; consequently, the probability of BTV spreading to remaining areas occupied by both vectors might also be higher.

The Fetal Brain in Bovine Viral Diarrhea Virus-infected Calves: Lesions, Distribution, and Cellular Heterogeneity of Viral Antigen at 190 Days Gestation

Previous studies have shown that the brain is a target of persistent infection with bovine viral diarrhea virus (BVDV) and have demonstrated viral tropism for neurons as well as other endogenous cell types in diverse brain areas. Apart from foci of mild residual inflammation in some postnatal calves, consistent brain lesions, per se, have not been reported. No similar comprehensive studies of the brain have been reported in bovine fetuses. In the current study, 12 BVDV-seronegative heifers were inoculated intranasally with a 2-ml 4.4 log10 TCID50/ml dose of noncytopathic type 2 BVDV at 75 and 175 days of gestation to create persistently and transiently infected fetuses, respectively. In only persistently infected fetuses, encephaloclastic lesions resulting in pseudocysts were observed in the subependymal zone in the region of the median eminence and adjacent corona radiata as well as in the region of the external capsule associated with lenticulostriate arteries. Additionally, areas of rarefaction in white matter were observed at the tips of cerebrocortical gyri and in the external capsule. The distribution of viral antigen was examined by immunohistochemical labeling using the 15C5 anti-BVDV monoclonal antibody. Viral antigen was detected only in calves inoculated at 75 days of gestation, i.e., persistently infected. The pattern of BVDV immunolabeling revealed both similarities and differences compared with previous studies in postnatal calves, suggesting that viral infection in the brain is a dynamic and progressive rather than static process.

Molecular identification of Western European species of obsoletus complex (Diptera: Ceratopogonidae) by an internal transcribed spacer-1 rDNA multiplex polymerase chain reaction assay

In southern Europe, orbiviral diseases such as bluetongue (BT) have been assumed to have been largely transmitted by the classical Afro-Asian vector Culicoides imicola Kieffer (Diptera: Ceratopogonidae). Recent outbreaks have occurred in regions where C. imicola is normally absent, supporting the theory that other species belonging to the Obsoletus or Pulicaris complexes may play a role in BT virus transmission. Investigations of the ecology of the species within the former group are hampered by females of member species being extremely difficult to separate by classical morphology. To allow straightforward separation of these species in France, a multiplex polymerase chain reaction-based on internal transcribed spacer (ITS)-1 rDNA was developed to distinguish between Culicoides chiopterus Meigen, Culicoides dewulfi Goetghebuer, Culicoides montanus Shakirjanova, Culicoides obsoletus Meigen, and Culicoides scoticus Downes & Kettle. This tool will be useful in defining both the vector role and larval biotopes of these species in Europe.

Prenatal dexamethasone exposure induces changes in nonhuman primate offspring cardiometabolic and hypothalamic-pituitary-adrenal axis function

Prenatal stress or glucocorticoid administration has persisting "programming" effects on offspring in rodents and other model species. Multiple doses of glucocorticoids are in widespread use in obstetric practice. To examine the clinical relevance of glucocorticoid programming, we gave 50, 120, or 200 microg/kg/d of dexamethasone (dex50, dex120, or dex200) orally from mid-term to a singleton-bearing nonhuman primate, Chlorocebus aethiops (African vervet). Dexamethasone dose-dependently reduced maternal cortisol levels without effecting maternal blood pressure, glucose, electrolytes, or weight gain. Birth weight was unaffected by any dexamethasone dose, although postnatal growth was attenuated after dex120 and dex200. At 8 months of age, dex120 and dex200 offspring showed impaired glucose tolerance and hyperinsulinemia, with reduced (approximately 25%) pancreatic beta cell number at 12 months. Dex120 and dex200 offspring had increased systolic and diastolic blood pressures at 12 months. Mild stress produced an exaggerated cortisol response in dex200 offspring, implying hypothalamic-pituitary-adrenal axis programming. The data are compatible with the extrapolation of the glucocorticoid programming hypothesis to primates and indicate that repeated glucocorticoid therapy and perhaps chronic stress in humans may have long-term effects.

Distribution and abundance of Bluetongue vectors in Sardinia: comparison of field data with prediction maps

Following the spread of Bluetongue virus (BTV) in many Mediterranean countries during the last 5 years, presence of the main BTV vector, Culicoides imicola Kieffer (Diptera: Ceratopogonidae), was recorded in the region, including the island of Sardinia where the first BT epidemic originally started in the year 2000. Several models were also designed based on climate variables and satellite imaging in order to predict the presence and abundance of BTV vectors across Europe. A 3 years entomological survey (2001-2003) was conducted in the southern part of Sardinia confirming the widespread presence of C. imicola. However, substantial differences in terms of relative abundance were observed between field data and prediction maps based on satellite-derived climate variables. Distribution of other potential BT vectors, belonging to Culicoides obsoletus Meigen and Culicoides pulicaris Linnaeus groups was also not congruent with model-based predictions. These results stress the need of taking into account additional environmental factors (such as soil type, land usage, etc.) and local microclimatic conditions, especially related to breeding site requirements of Culicoides species, in order to predict the presence and abundance of BT vectors and to design reliable prediction maps on a local scale.

Spatial and temporal distribution of bluetongue and its Culicoides vectors in Bulgaria

Surveillance of Culicoides (Diptera: Ceratopogonidae) biting midges was carried out between 2001 and 2003, at 119 sites within a 50 x 50-km grid distributed across Bulgaria, using light trap collections around the time of peak adult midge abundance. Sentinel and ad hoc serum surveillance of hosts susceptible to bluetongue infection was carried out at around 300 sites between 1999 and 2003. Following the initial incursion of bluetongue virus 9 (BTV-9) into Bourgas province in 1999, affecting 85 villages along the southern border, a further 76 villages were affected along the western border in 2001, with outbreaks extending as far north as 43.6 degrees N. The BTV-9 strain in circulation was found to have a low pathogenicity for Bulgarian sheep populations, with less than 2% of susceptible individuals becoming sick and seroconversions detected up to 30 km from recorded outbreaks in the south. The major Old World vector Culicoides imicola Kieffer was not detected among over 70,000 Culicoides identified in summer collections, suggesting that BTV-9 transmission in Bulgaria was primarily carried out by indigenous European vectors. The most likely candidates, the Palaearctic species complexes - the Culicoides obsoletus Meigen and C. pulicaris L. complexes - were widespread and abundant across the whole country. The C. obsoletus complex represented 75% of all individuals trapped in summer and occurred in high catch sizes (up to 15,000 individuals per night) but was not found across all outbreak sites, indicating that both Palearctic complexes probably played a role in transmission. Within the C. pulicaris complex, only C. pulicaris s.s., C. punctatus Meigen and C. newsteadi Austen were sufficiently abundant and prevalent to have been widely involved in transmission, whilst within the C. obsoletus complex most trapped males were C. obsoletus s.s. Adult vectors were found to be largely absent from sites in west Bulgaria for a period of at least 3 months over winter, which, taken along with the spatiotemporal pattern of outbreaks in the region between years, indicates the virus may be overwintering here by an alternative mechanism - either by covert persistence in the vertebrate host or possibly by persistence in larval stages of the vector.

Cortisol administration to pregnant sows affects novelty-induced locomotion, aggressive behaviour, and blunts gender differences in their offspring

Several behavioural effects of prenatal stress are reported in literature, and these seem to depend, among other factors, on the gender studied and the period of gestation in which prenatal stress is applied. In the present study, oral administration of hydrocortisone-acetate (HCA) to 41 pregnant sows was used as a model for prenatal stress, since corticosteroids are considered a key mediator in the effects of prenatal stress. HCA was orally administered to pregnant sows during three periods of gestation: 21-50 (period 1, P1, n = 10), 51-80 (period 2, P2, n = 10) and 81-110 (period 3, P3, n = 10) days after insemination (term 115 days). Control sows (n = 11) received vehicle from 21 to 110 days after insemination. Between days 9 and 48 after birth, treatment effects on male and female piglet behaviour were determined in the home pen and in four different behavioural tests. During the backtest, no gender differences were observed in vocalisations in HCA-piglets, while control males vocalised more than control females. In the home pen at 14 days of age, HCA-piglets spent less time in social interactions than control piglets. During the novel environment test, P1- and P3-piglets walked more than control piglets, but this was not observed during the novel object test, four days later. At weaning, P2- and P3-piglets performed less individual play. Prior to mixing with an unfamiliar piglet (male piglets only), HCA-piglets had lower salivary cortisol concentrations than control piglets, but no difference was observed after mixing. P1-, P2-, and P3- piglets had fewer non-aggressive encounters, and P2-piglets continued fighting longer than control piglets. The present study demonstrates that elevated maternal cortisol concentrations during gestation affect piglet behaviour, and effects do differ between male and female piglets. In addition, effects depend on the period of cortisol administration.

Attention deficit disorders: are we barking up the wrong tree?

Attention deficit disorder (AAD) and attention deficit/hyperactivity disorder (ADHD) are very frequent and protean developmental disorders without a definite biologic marker. This review proposes a framework to understand the enlarged spectrum of its manifestations based on current knowledge of the mechanisms underlying arousal and attention variations during sleep/wake cycle. The neuro-modulation's pivotal role in this process as well as in the fine tuning of synaptic architecture during development must be taken into account when trying to understand the marked fuzziness of the symptoms and the very high prevalence of reported co-morbidities. The series of related interactions includes a cyclic deactivation of the dorso-lateral portion of the prefrontal cortex (DLPFC) during sleep, suspending executive functions, co-occurring with rhythmic periods of decreased noradrenergic tonus. A protracted unbalance in modulation, with catecholaminergic relative deficiency, could explain less-than-optimum waking DLPFC activation and the most important manifestations of ADD. Beside the well documented dopaminergic effects of stimulant medication used in ADD and ADHD, a more important role must be assigned to noradrenaline (NA). At this light hyperactivity and impulsivity are less important dimensions. Rather, an attention deficit spectrum disorder should probably be regarded as a complication of a core defect in prefrontal cortex dependent inhibitory control, underlying inattention.

Lower birth weight and attenuated adrenocortical response to ACTH in offspring from sows that orally received cortisol during gestation

Prenatal stress is known to affect several offspring characteristics, but its effects depend among other factors on the period of gestation in which it is applied. In the present study, oral administration of hydrocortisone-acetate (HCA) was used to elevate cortisol concentrations in pregnant sows to levels also observed after psychological stress. HCA was administered during three different periods of gestation (115 days in pigs): period 1: 21-50 (P1, n = 10), period 2: 51-80 (P2, n = 10) and period 3: 81-110 (P3, n = 10) days after insemination. Control sows (n = 11) received vehicle from 21-110 days after insemination. When P1-, P2- and P3-sows did not receive HCA, they also received vehicle. During gestation, weekly saliva samples were taken from the sows to determine salivary cortisol concentrations. Treatment effects on sow, litter and piglet characteristics were determined. In addition, two female piglets per litter were subjected to an ACTH-challenge test at 6 weeks of age to determine the adrenocortical response to ACTH. Pigs were slaughtered at 6 months of age and slaughter weight, back fat thickness and percentage of lean meat were analysed. During the period of treatment with HCA, salivary cortisol concentrations were increased in P1-, P2- and P3-sows compared to control sows (P < 0.01). The total number of piglets born per litter did not differ among treatment groups (P > 0.30), but pooled HCA-litters had a higher percentage of live born piglets (P < 0.05) and fewer mummies than control litters (P < 0.05). Gestation length did not differ among treatment groups (P = 0.21), but did affect treatment effects on birth weight. Overall, HCA-piglets weighed less at birth, and remained lighter until weaning (P < 0.05). The salivary cortisol concentrations after i.m. injection of ACTH (2.5 IU/kg) were lower in P1- and P3-piglets compared to control piglets. At slaughter, HCA-treatment indirectly decreased lean meat percentage and increased back fat thickness. In conclusion, elevated peripheral cortisol concentrations in pregnant sows affect both litter characteristics and piglet physiology, the latter depending on the period of gestation during which concentrations were elevated. Underlying mechanisms require further investigation.

Fetal programming of hypothalamo-pituitary-adrenal function: prenatal stress and glucocorticoids

Prenatal stress (PS) and maternal exposure to exogenous glucocorticoids can lead to permanent modification of hypothalamo-pituitary-adrenal (HPA) function and stress-related behaviour. Both of these manipulations lead to increased fetal exposure to glucocorticoids. Glucocorticoids are essential for many aspects of normal brain development, but exposure of the fetal brain to an excess of glucocorticoids can have life-long effects on neuroendocrine function. Both endogenous glucocorticoid and synthetic glucocorticoid exposure have a number of rapid effects in the fetal brain, including modification of neurotransmitter systems and transcriptional machinery. Such fetal exposure permanently alters HPA function in prepubertal, postpubertal and ageing offspring, in a sex-dependent manner. Prenatal stress and exogenous glucocorticoid manipulation also lead to the modification of behaviour, brain and organ morphology, as well as altered regulation of other endocrine systems. It is also becoming increasingly apparent that the timing of exposure to PS or synthetic glucocorticoids has tremendous effects on the nature of the phenotypic outcome. Permanent changes in endocrine function will ultimately impact on health in both human and animal populations.

Age, gender and litter-related variation in T-lymphocyte cytokine production in young pigs

The capacity of farm animals to produce cytokines could be an important determinant of robustness and health. From research in rodents and humans it appears that the production and the balance of T helper 1 (Th1) and T helper 2 (Th2)-type cytokines influences susceptibility to autoimmune and infectious diseases. It is known that pigs show a large variation in many immune response parameters. So far the extent of individual variation in the production of Th1- and Th2-type cytokines in commercial outbred pigs has not been reported. In the current experiment we determined mRNA expression, as well as protein production of cytokines in 32 pigs from eight litters. From each litter two male and two female pigs were tested at 2, 5 and 8 weeks of age. Two Th1-type cytokines, interleukin (IL)-2 and interferon (IFN)-gamma, and two Th2-type cytokines, IL-4 and IL-10, were measured after phytohaemagglutinin (PHA)-stimulation of blood mononuclear cells. Cytokine production and the Th1/Th2-ratio were highly variable. The variation in cytokine protein production was moderately consistent across ages, i.e. pigs that produced high levels of cytokine at 2 weeks of age tended to do so as well at 5 and 8 weeks of age. Cytokine production tended to increase with age, and gilts and boars differed in their IL-2/IL-4 ratio. Unexpectedly, age, gender and litter effects often differed for mRNA and protein production data. We hypothesize that cytokine production is a consistent trait in pigs, especially at the protein production level. Future investigations in more animals and across a wider age range are necessary.

Glucocorticoid programming of adult disease

Fetal exposure to elevated levels of glucocorticoids can occur naturally when maternal glucocorticoids are elevated in times of stress or when exogenous glucocorticoids are administered. Epidemiological studies and animal models have shown that, whereas short-term benefits may be associated with fetal glucocorticoid exposure, long-term deleterious effects may arise. This review compares the effects of exposure to natural versus synthetic glucocorticoids and considers the ways in which the timing of the exposure and the sex of the fetus may influence outcomes. Some of the long-term effects of glucocorticoid exposure may be explained by epigenetic mechanisms.

RETRACTED: Maternal adversity, glucocorticoids and programming of neuroendocrine function and behaviour

The fetus may be exposed to increased endogenous glucocorticoid or synthetic glucocorticoid in late gestation. Approximately 7% of pregnant women in Europe and North America are treated with synthetic glucocorticoid to promote lung maturation in fetuses at risk of preterm delivery. Very little is known about the mechanisms by which synthetic glucocorticoid or prenatal stress influence neurodevelopment in the human, or whether specific time windows of increased sensitivity exist. Glucocorticoids are essential for many aspects of normal brain development, but exposure of the fetal brain to excess glucocorticoid can have life-long effects on neuroendocrine function and behaviour. Both endogenous glucocorticoid and synthetic glucocorticoid exposure have a number of rapid effects in the fetal brain, including modification of neurotransmitter systems and transcriptional machinery. Such fetal exposure permanently alters hypothalamo-pituitary-adrenal (HPA) function in prepubertal, postpubertal and aging offspring, in a sex-dependent manner. Prenatal glucocorticoid manipulation also leads to modification of behaviour, brain and organ morphology, as well as altered regulation of other endocrine systems. Permanent changes in endocrine function will impact on health, since elevated cumulative exposure to endogenous glucocorticoid is linked to the premature onset of pathologies associated with aging.

Stress-related gene expression in brain and adrenal gland of porcine fetuses and neonates

This study was conducted to examine stress-induced effects on gene expression of specific markers for HPA axis and neuronal activity in fetuses and neonatal pigs. Brain, pituitary gland, and adrenal gland were obtained to determine the mRNA levels for corticotropin-releasing hormone (CRH), CRH receptor 1 (CRHR1), pro-opiomelanocortin (POMC), ACTH receptor (MC2R), c-jun and c-fos. The suitability of these molecular markers was determined in neonatal pigs which were maternally deprived for two hours. It was found that maternal deprivation caused significantly higher transcript levels of c-fos and CRH in brain accompanied by a down-regulation of CRHR1 mRNA and an up-regulation of c-jun in the pituitary gland. To determine the effect of elevated maternal cortisol levels on gene expression of these molecular markers in fetuses, pregnant sows were treated with 100 IU ACTH (Synacthen Depot) s.c. every two days between Day 49 and Day 75 of gestation (normal gestation length 114 days). Animals were killed 48 hours after the last ACTH administration and fetuses of each sow were isolated. The ACTH treatment of sows significantly increased mRNA expression of c-fos but not of CRH in the fetal brain, and significantly decreased MC2R mRNA expression in the adrenal gland. However, HPA axis seems not to be fully developed in Day 77-fetuses because fetal pituitary CRHR1 and POMC mRNA expression was low in most of the fetuses. Although the expression of endocrine regulatory factors was partially incomplete in fetuses at the beginning of the third-trimester, ACTH dependent activation of c-fos mRNA in brain indicates a stress-related increase of neuronal activity. Based on these results it is assumed that prenatal stress in pigs may also have effects on the activity of the HPA axis in the offspring.

Effects of adrenocorticotropin stimulation on cortisol dynamics of pregnant gilts and their fetuses: implications for prenatal stress studies

The effect of adrenocorticotropic hormone (ACTH) administration on plasma cortisol concentrations was determined in pregnant gilts and their fetuses. In a first experiment, 100 IU ACTH (Synacthen Depot) was administered intramuscularly to the gilts every second day from Days 49 to 75 of gestation. ACTH injections were carried out at 08:00 h and, thereafter, 10 blood samples were taken within the following 8h via jugular catheters. Blood samples were analysed for plasma cortisol concentrations, and results were compared with values from animals which were treated with physiological saline and untreated animals (blood sampling only). The values for plasma cortisol concentrations increased until 3h after ACTH applications to a mean maximum level of 276.5+/-17.2 nmol/l in the whole 4-week stimulation period. Plasma cortisol levels did not return to pre-treatment values within the 8 h post-injection. No differences in cortisol levels were found between the physiological saline and untreated control, and no habituation of the adrenocortical response to ACTH was found during the 4-week stimulation period. In a second experiment, 100 IU ACTH were administered to pregnant gilts at gestation Day 65. After 3 h, fetuses were recovered under general anaesthesia and blood samples were taken from the umbilical vein, artery, and, after decapitation, from periphery. Application of ACTH to the sows significantly increased their plasma cortisol concentrations (P<0.001), and also increased plasma cortisol concentrations in peripheral blood samples from the fetuses (P=0.09) and in the umbilical vein (P<0.001) and artery (P<0.01), respectively. Plasma ACTH concentrations did not differ in fetuses from ACTH-treated or control sows. The results show that in gilts the adrenocortical response to an exogenous application of Synacthen Depot is consistent over time during mid-gestation. Furthermore, cortisol but not ACTH levels were increased in fetuses from ACTH-treated sows, indicating that maternal cortisol can cross the placenta during mid-gestation. The stimulation of maternal cortisol release through exogenous ACTH with subsequent elevation of fetal cortisol levels is, therefore, a useful approach for studying effects of elevated maternal glucocorticoids in prenatal stress studies in pigs.