Consequences of repeated early isolation in domestic piglets (Sus scrofa) on their behavioural, neuroendocrine, and immunological responses

Neonatal exposure to fenoterol and betamethasone: effects on the behavioral development in the rat

We investigated longitudinally the behavioral development in the rat following exposure to beta-agonists and glucocorticoids (GC). Neonatal rats received either 1 mg/kg fenoterol (FEN), 0.3 mg/kg betamethasone (BET), or saline (SAL). Weanling and young adult rats were tested in the open field, the elevated-plus maze, and the water maze. FEN-treated as well as BET-treated animals displayed increased anxiety-like behavior. Furthermore, BET-treated adult animals showed a reduced locomotor activity. An enhanced 24-h memory in the water maze in both treatment groups may be facilitated by emotional arousal due to the increased anxiety levels. The possible neurobiological underpinnings are discussed in detail.

Perceived social isolation and cognition

Social species, from Drosophila melanogaster to Homo sapiens, fare poorly when isolated. Homo sapiens, an irrepressibly meaning-making species, are, in normal circumstances, dramatically affected by perceived social isolation. Research indicates that perceived social isolation (i.e. loneliness) is a risk factor for, and may contribute to, poorer overall cognitive performance, faster cognitive decline, poorer executive functioning, increased negativity and depressive cognition, heightened sensitivity to social threats, a confirmatory bias in social cognition that is self-protective and paradoxically self-defeating, heightened anthropomorphism and contagion that threatens social cohesion. These differences in attention and cognition impact on emotions, decisions, behaviors and interpersonal interactions that can contribute to the association between loneliness and cognitive decline and between loneliness and morbidity more generally.

Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs

In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77-79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n=8) and d42 pigs (n=8), using (3)H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of (3)H-8-OH-DPAT (5-HT(1A) receptor agonist) or of (3)H-ketanserin (5-HT(2A) receptor antagonist) to any brain region studied. In d12 pigs, 5-HT(1A) receptor mRNA expression per unit area was 29%, 63%, 52% and 64% lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31%, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT(2A) receptor mRNA was expressed at a 25% and 28% higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT(1A) receptor mRNA data were 70-79% correlated with binding data but no correlation was found for 5-HT(2A) data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.

Repeated social defeat in female pigs does not induce neuroendocrine symptoms of depression, but behavioral adaptation

The aim of this study was to develop an animal model of major depression. Since two thirds of depressive patients are women, it is important to develop specific female animal models of depression. We therefore determined the consequences of chronic social defeat in individually housed prepubertal female pigs confronted with a dominant, older pig. Repeated defeat increased the salivary cortisol level, measured immediately after the confrontations, but this effect diminished after repeated confrontations. Neither organ weights nor the number of glucocorticoid (GR) and mineralocorticoid (MR) receptors in the ventral hippocampus were affected by repeated defeat. Serotonin turnover in the dorsal hippocampus was also unaffected. Behavioral analysis revealed that across confrontations, the pigs reduced the time spent actively attacking the dominant pigs, whereas the time increased in which the pigs passively underwent aggression and/or actively avoided aggression. Therefore, we conclude that the repeated social defeat paradigm does not induce long-lasting depression-like neuroendocrine effects as a consequence of behavioral adaptations (changes in the fighting strategy) in the young female pigs.

Exploration of the hypothalamic–pituitary–adrenal function as a tool to evaluate animal welfare

Measuring HPA axis activity is the standard approach to the study of stress and welfare in farm animals. Although the reference technique is the use of blood plasma to measure glucocorticoid hormones (cortisol or corticosterone), several alternative methods such as the measurement of corticosteroids in saliva, urine or faeces have been developed to overcome the stress induced by blood sampling itself. In chronic stress situations, as is frequently the case in studies about farm animal welfare, hormonal secretions are usually unchanged but dynamic testing allows the demonstration of functional changes at several levels of the system, including the sensitization of the adrenal cortex to ACTH and the resistance of the axis to feedback inhibition by corticosteroids (dexamethasone suppression test). Beyond these procedural aspects, the main pitfall in the use of HPA axis activity is in the interpretation of experimental data. The large variability of the system has to be taken into consideration, since corticosteroid hormone secretion is usually pulsatile, follows diurnal and seasonal rhythms, is influenced by feed intake and environmental factors such as temperature and humidity, age and physiological state, just to cite the main sources of variation. The corresponding changes reflect the important role of glucocorticoid hormones in a number of basic physiological processes such as energy metabolism and central nervous system functioning. Furthermore, large differences have been found across species, breeds and individuals, which reflect the contribution of genetic factors and environmental influences, especially during development, in HPA axis functioning. Usually, these results will be integrated with data from behavioral observation, production and pathology records in a comprehensive approach of farm animal welfare.

Neuroendocrine-immune correlates of circadian physiology: studies in experimental models of arthritis, ethanol feeding, aging, social isolation, and calorie restriction

Virtually all neuroendocrine and immunological variables investigated in animals and humans display biological periodicity. Circadian rhythmicity is revealed for every hormone in circulation as well as for circulating immune cells, lymphocyte metabolism and transformability, cytokines, receptors, and adhesion molecules. Clock genes, notably the three Period (Per1/Per2/Per3) genes and two Cryptochrome (Cry1/Cry2) genes, are present in immune and endocrine cells and are expressed in a circadian manner in human cells. This review discusses the circadian disruption of hormone release and immune-related mechanisms in several animal models in which circulating cytokines are modified including rat adjuvant arthritis, social isolation in rats and rabbits and alcoholism, the aging process and calorie restriction in rats. In every case the experimental manipulation used perturbed the temporal organization by affecting the shape and amplitude of a rhythm or by modifying the intrinsic oscillatory mechanism itself.

Human-directed aggression in miniature pet pigs

OBJECTIVES

To determine whether associations exist between human-directed aggression and sex, neutering status, age of weaning, the presence of other pet pigs, or the presence of environmental enrichment objects in miniature pet pigs.

DESIGN

Internet survey.

STUDY POPULATION

Responses from 222 owners of miniature pet pigs.

PROCEDURES

Pet pig owners were requested to complete a 48-item multiple-choice and short-answer Internet survey for each pig that they presently owned.

RESULTS

Among 222 surveys that met enrollment criteria, human-directed aggression that occurred on at least 1 occasion was reported in 64% (n = 142) and aggression that occurred once or more per month was reported in 31% (69). No significant differences were found in the prevalence of human-directed aggression among castrated males, sexually intact females, and spayed females. Ages of weaning and neutering and the presence of objects intended to serve as environmental enrichment were not associated with frequency of aggression. A significant inverse association was detected between presence of other pigs in the same household and human-directed aggression, such that 21% (20/95) of pigs that lived with at least 1 conspecific were aggressive on a frequent basis, compared with 39% (49/126) of pigs that lived with no conspecific. A similar inverse association was evident regarding aggression that occurred on at least 1 occasion.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that human-directed aggression is a common problem in miniature pet pigs. The presence of a conspecific can be expected to reduce the likelihood of human-directed aggression.

Making sense of apparently conflicting data: Stress and immunity in swine and cattle1

Stress is generally considered to suppress the immune system and may lead to an increase in the occurrence of disease in the presence of a pathogen. The immune system is ordinarily brought back to a baseline response level after immune challenge through homeostatic processes, in part regulated by the hypothalamic-pituitary-axis. Often, findings reported from various studies investigating the effects of stress on the immune system are conflicting and difficult to reconcile into a cohesive and comprehensible set of universally applicable theories. These discrepancies may be partly explained by the types and durations of the stressors, the aspect(s) of immune system measured, genetics, and social status. A particular stressor may enhance cell-mediated immune responses while suppressing humoral responses or vice versa, thus disrupting the balance between these components of the immune system. How farm animals perceive their environment depends not only on traditional environmental stressors (e.g., heat, cold, humidity, pollutants), but also on aspects of their social environment. Dominant animals may have enhanced immune activation, whereas subordinates have suppression of the same immune component in response to the same stressor. This could explain why individual animals within a group respond differently to stressors and disease challenges. A better understanding of the consequences and complex interactions between social and environmental stressors for innate and adaptive immune traits must be developed so we can more fully understand the effects of stress on immunity in livestock. Once these complex relationships are better understood, more effective interventions can be designed to improve animal health and well-being.

Pathological anxiety in animals

Selective breeding programmes in domestic and laboratory animals generally focus on physiological and/or anatomical characteristics. However, selection may have an (unintended) impact on other characteristics and may lead to dysfunctional behaviour that can affect biological functioning and, as a consequence, compromise welfare and quality of life. In this review it is proposed that various behavioural dysfunctions in animals are due to pathological anxiety. Although several approaches have been undertaken to specify the diagnostic criteria of pathological anxiety as a behavioural disorder in animals, the causal aetiology largely remains unknown. This is mainly due to the fact that integrated concepts, combining the behavioural syndrome and (neuro-) physiological processes, are widely lacking. Moreover, even the term anxiety itself represents a poorly defined concept or category. A definition is suggested and the potential causes of pathological anxiety are explored with a plea for developing adequate diagnostic tools and therapies to fight pathological anxiety in animals based on insight from scientific research.

Social rank of pregnant sows affects their body weight gain and behavior and performance of the offspring1,2

Previous studies on group housing of pregnant sows have mainly focused on reproduction, but we hypothesized that the social rank of pregnant sows housed in groups could also affect birth weight, growth, and behavior of their offspring. Therefore, in the present study, pregnant gilts and sows were housed in 15 different groups (n = 7 to 14 animals per group) from 4 d after AI until 1 wk before the expected farrowing date. All groups were fed by an electronically controlled sow feeding system that registered, on a 24-h basis, the time of first visit, number of feeding and non-feeding visits, and number of times succeeding another sow within 2 s. Only in the first 6 groups (n = 57 animals), agonistic interactions were observed continuously. The percentage of agonistic interactions won was highly correlated (r(s) = 0.90, P < 0.001) with the percentage of displacement success (DS) at the feeding station, which was calculated as: [the number of times succeeding another sow within 2 s/(the number of times succeeded by another sow within 2 s + the number of times succeeding another sow within 2 s)] x 100. This allowed us to classify all sows (n = 166) according to their DS: high-social ranking (HSR) sows had a DS >50% (n = 62) and low-social ranking (LSR) sows a DS <50% (n = 104). Body weights before AI did not differ between HSR and LSR sows, but HSR sows gained more BW during gestation, and lost more BW and back-fat during lactation (P < 0.001). Maternal salivary cortisol concentrations at 2, 7, and 13 wk after AI did not differ between HSR and LSR sows, nor did gestation length, litter size, or percentage of live born piglets. During a novel object (NO) test at 3 wk of age, HSR offspring moved and vocalized more than LSR offspring (P < 0.05). In addition, the latency time to touch the NO was shorter in HSR offspring (P < 0.05), and HSR males spent more time near the NO than LSR males (P < 0.01). At weaning, HSR offspring weighed more than LSR offspring (P < 0.05), and at slaughter HSR offspring had more lean meat than LSR offspring (P < 0.05). Results indicate that the social rank of the sow during gestation affects her own BW gain and loss as well as the growth and behavior of her offspring. Pig breeders that apply group housing for pregnant sows should pay attention to reducing competition around the feeding area, which may reduce aggression among the sows and minimize differences between HSR and LSR sows.

The use of pigs in neuroscience: Modeling brain disorders

The use of pigs in neuroscience research has increased in the past decade, which has seen broader recognition of the potential of pigs as an animal for experimental modeling of human brain disorders. The volume of available background data concerning pig brain anatomy and neurochemistry has increased considerably in recent years. The pig brain, which is gyrencephalic, resembles the human brain more in anatomy, growth and development than do the brains of commonly used small laboratory animals. The size of the pig brain permits the identification of cortical and subcortical structures by imaging techniques. Furthermore, the pig is an increasingly popular laboratory animal for transgenic manipulations of neural genes. The present paper focuses on evaluating the potential for modeling symptoms, phenomena or constructs of human brain diseases in pigs, the neuropsychiatric disorders in particular. Important practical and ethical aspects of the use of pigs as an experimental animal as pertaining to relevant in vivo experimental brain techniques are reviewed. Finally, current knowledge of aspects of behavioral processes including learning and memory are reviewed so as to complete the summary of the status of pigs as a species suitable for experimental models of diverse human brain disorders.

Early social isolation alters behavioral and physiological responses to an endotoxin challenge in piglets

Psychosocial stress in the form of maternal deprivation and social isolation during early postnatal life induces persistent alterations in behavioral and physiological mechanisms of adaptation. One consequence may be an increased susceptibility to diseases in later life. Therefore, the aim of the present study was to investigate in domestic piglets the effects of a repeated social isolation (2 h daily from day 3 to day 11 of age) on behavioral, endocrine and immune responses to an endotoxin challenge with lipopolysaccharide (LPS) 1 day or 45 days after the isolation period. Peripheral LPS administration caused serious sickness behavior (somnolence, shivering, vomiting) and provoked profound increases in circulating tumor necrosis factor-alpha (TNF-alpha), ACTH and cortisol concentrations. The prior social isolation treatment enhanced signs of sickness and impaired suckling behavior. Early isolated piglets responded to LPS by an increase of shivering on day 12 and by increased vomiting on day 56 compared to controls. Further, there were considerable delays and reductions of time isolated piglets spent suckling on day 12. The repeated isolation stressor diminished TNF-alpha increases after LPS, whereas stress hormone levels were not significantly affected by isolation treatment. Finally, stronger relationships between signs of sickness and physiological measures were revealed in early isolated piglets. The duration of somnolence in isolated piglets was related to changes of cortisol and TNF-alpha concentrations, and the highest impact on duration of shivering was found for changes in cortisol and corticosteroid binding globulin levels. The present results suggest a sustained adaptive sensitization of coping with infection by social stress experience during early development in piglets.

Effects of added fermentable carbohydrates in the diet on intestinal proinflammatory cytokine-specific mRNA content in weaning piglets

There is increasing evidence showing that dietary supplementation with prebiotics can be effective in the treatment of intestinal inflammation. Because weaning time is characterized by rapid intestinal inflammation, this study investigated the effect of a diet supplemented with a combination of 4 fermentable carbohydrates (lactulose, inulin, sugarbeet pulp, and wheat starch) on the mRNA content of proinflammatory cytokines in newly weaned piglets. Cytokines (IL-1beta, IL-6, IL-8, IL-12p40, IL-18, and tumor necrosis factor-alpha) were analyzed using a semiquantitative reverse-transcription PCR technique on d 1, 4, and 10 in the ileum and colon of piglets fed either a test diet (CHO) or a control diet. In addition to the diet, the effect of enforced fasting on cytokine mRNA content was also evaluated. No effect of fasting was observed on the pro-inflammatory cytokine mRNA content. Our results showed that the CHO diet induced an up-regulation of IL-6 mRNA content in the colon of piglets 4 d postweaning. This up-regulation was specific for the animals fed the CHO diet and was not observed in animals fed the control diet. An increase in IL-1beta mRNA content was also observed on d 4 postweaning in all of the piglets. Correlations between proinflammatory cytokines and the end-products of fermentation indicated that the regulation of cytokines may be linked with some of the fermentation end-products such as branched-chain fatty acids, which are in turn end-products of protein fermentation.

Acquisition of a conditioned avoidance reflex and morphometric characteristics of the sensorimotor cortex in rats subjected to social deprivation in early ontogenesis

Male Wistar rats were subjected to social deprivation from day 22 to day 70 of postnatal development to form a group of isolants. Measures of learning of a passive avoidance and the results of training to active avoidance of painful electrical stimulation in these rats were significantly lower at age 110-120 days than in control rats. The characteristics of movement activity in isolants during training and testing, as well as in the open field test, probably resulted from their high levels of anxiety. Morphometric measurements of the numbers of neurons, satellite glial cells, and free glial cells in the sensorimotor area of the neocortex showed that isolants had a significantly lower density of neural elements per unit area, which resulted from a decrease in the afferent flow due to social isolation.

Heat and social rank impact behavior and physiology of PRRS-virus-infected pigs

Changes in thermal environment can invoke a stress response in pigs, which in turn can potentially impact their immune system and disease susceptibility. We investigated effects of heat stress and social rank on behavior, immune responsiveness, and performance of pigs challenged with porcine reproductive and respiratory syndrome (PRRS) virus. Sixty-four 7-week-old PRRS-naïve pigs were assigned to each of four experimental treatments consisting of a 2 x 2 factorial design: PRRS (PRRS- or PRRS+) and environmental temperature (24 degrees C or 32 degrees C). Blood samples were taken prior to and at days 7 and 14 post-inoculation, and alveolar macrophages were collected via bronchoalveolar lavage at day 14. Total white blood cell counts, natural killer cytotoxicity, macrophage numbers, macrophage subpopulations, and performance measures were all significantly affected by social rank, heat stress, and/or infection status of the pig. Heat stress and PRRS status also significantly influenced the amount of time pigs spent lying with or without contacting another animal. Cortisol and various immune measures were also affected by PRRS status. These results show not only that intranasal inoculation with PRRS virus affects physiological, behavioral, and performance measures in growing pigs, but that social rank influences pigs' immune responsiveness to PRRS as well. Moreover, heat stress does not have additive negative impact on physiological or performance traits in pigs challenged with PRRS virus.

Influence of teeth resection on the skin temperature and acute phase response in newborn piglets

Two experiments were carried out to determine the effect of different teeth resection methods on skin temperature, concentrations of the acute phase proteins C-reactive protein (CRP) and serum amyloid A (SAA), and cortisol in piglets. In Experiment 1, piglets from 60 litters were assigned to three treatments where the ‘needle’ teeth were clipped (CLIP), ground (GRIND) or left intact (INT) within 12 h of birth; skin temperature was measured immediately afterwards. Fourteen pigs were selected in each treatment for blood sampling at 1 day and 29 days-of-age for the determination of concentrations of CRP, SAA and cortisol. In Experiment 2, a 2 × 2 factorial design was used to determine the effect of teeth clipping and time spent out of the farrowing crate post-clipping on skin temperature. Piglets from 60 litters had their teeth clipped (CLIP) or left intact (INT) and were returned to the farrowing crate immediately or after 1 min. Skin temperature was measured after piglets were returned to the farrowing crate and after 10 min. In Experiment 1, CLIP and GRIND piglets had significantly lower skin temperatures than INT piglets; skin temperature was also significantly reduced in CLIP piglets in Experiment 2. Skin temperature did not differ between time-out groups. Plasma levels of CRP and SAA did not differ between treatments on day 1; however, concentrations of both proteins were significantly higher on day 29. CLIP pigs had significantly higher concentrations of CRP in comparison with GRIND pigs on day 29. Stress caused by teeth resection provoked a transient reduction in skin temperature. Furthermore, both resection methods caused infection and/or inflammation, but to a similar degree as that caused by leaving the teeth intact. These results indicate that the welfare of piglets is better in the short term if their teeth are left intact; however, if teeth resection is necessary grinding can be recommended in preference to clipping.

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.

Effects of stress on exacerbation of diabetes mellitus, serum glucose and cortisol levels and body weight in rats

OBJECTIVE

The effects of stress on the serum glucose, serum cortisol levels and body weight were investigated to clarify the possible link between the stress and diabetes.

METHODS

The experiments were performed on nondiabetic and streptozotocin diabetic rats divided to control, sham and stressed groups. Water immersion was used as stressor. After the experiment, blood samples were collected. The serum glucose level (SGL) was measured by the glucose oxidase method and serum cortisol level (SCL) was determined by radioimmunoassay.

RESULTS

Stress caused a significant increase in glucose level in both nondiabetic and diabetic rats. In diabetes rats, a significant increase in SCL was observed. Stress did not cause, however, significant increases in SCL. A significant weight loss took place in rats exposed to stress and that was much greater in diabetic animals.

CONCLUSION

The stress with mainly psychic component exacerbated the diabetes in streptozotocin treated rats and the glucose levels increased significantly also in nondiabetic controls, but no glucose was detected in their urine.

Investigation of changes in global gene expression in the frontal cortex of early-weaned and socially isolated piglets using microarray and quantitative real-time RT-PCR

We hypothesize that early-weaned piglets experience aberrant expression of stress-responsive genes in the frontal cortex, a key brain area involved in cognitive function and behavior organization. To test this hypothesis, female early-weaned piglets (EW; n = 6) were weaned 10 days after birth, while non-weaned piglets (NW; n = 6) were left with their dams. Half of EW (n = 3) and NW (n = 3) animals were socially isolated (SI) for 15 min at 12 days of age, when all animals (n = 12) were euthanized and tissue collected. The effects of EW and SI were examined by gene expression profiling using cDNA microarray hybridizations, generated from a porcine brain cDNA library. A total of 103 genes were differentially expressed (P < 0.05, fold change >1.25) among four direct comparisons. Forty-two genes had known functions, from which 24 showed relevant brain-related functions. Quantitative real-time polymerase chain reaction (Q-RT-PCR) was used to confirm regulation of expression of a subset of 6 genes with important brain functions, selected from the microarray outcomes. In non-weaned animals, a significant suppression of mRNA abundance for carboxypeptidase E, 14-3-3 protein and phosphoprotein enriched in astrocytes 15 kDa was observed in response to SI. Also, in early-weaned animals, diazepam binding inhibitor and actin-related protein 2/3 complex mRNA levels were suppressed in response to SI. Results suggest that social isolation of non- and early-weaned piglets may impact expression of genes involved in regulation of neuronal function, development, and protection in the frontal cortex of young pigs.

Effects of early weaning and social isolation on the expression of glucocorticoid and mineralocorticoid receptor and 11beta-hydroxysteroid dehydrogenase 1 and 2 mRNAs in the frontal cortex and hippocampus of piglets

Pigs weaned at young ages show more abnormal and aggressive behaviors and cognitive deficits compared to later weaned pigs. We investigated the effects of age, weaning and/or social isolation on the expression of genes regulating glucocorticoid response [glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11beta-hydroxysteroid dehydrogenases 1 and 2 (11beta-HSD1 and 11beta-HSD2)] in the frontal cortex and hippocampus. Early- (EW; n = 6) and conventionally-weaned (CW; n = 6) piglets were weaned at 10 and 21 days after birth, respectively. Non-weaned (NW) piglets of both ages (NW; n = 6/group) remained with their dams. Immediately before euthanasia, half of CW, EW and NW animals were socially isolated for 15 min at 12 (EW, NW) and 23 (CW, NW) days of age. Differences in amounts of 11beta-HSD1, 11beta-HSD2, GR and MR mRNA were determined by quantitative real-time RT-PCR and data subjected to multivariate linear mixed model analysis. When compared with NW piglets at 12 days of age, the hippocampi of EW piglets showed decreased gene expression (P < 0.01). Social isolation decreased gene expression (P < 0.05) in the frontal cortex of all piglets. Twelve-day-old piglets showed higher MR mRNA in the frontal cortex (P < 0.01) and lower 11beta-HSD2 and GR mRNA (P < 0.05) in the hippocampus compared to 23-day-old animals. Results indicate that EW affected the hippocampus of piglets at 12 days of age, while social isolation affected frontal cortex regardless of age. These results may be correlated with behavioral and cognitive changes reported in EW piglets.

Effects of maternal deprivation on the adrenocorticotrophic and gonadotrophic axes in the hypothalamo-pituitary unit of preweanling female sheep: the histomorphometric approach

This study was designed to investigate the histochemical effects of maternal deprivation on the adrenocorticotrophic and gonadotrophic axes in the hypothalamo-pituitary unit of preweanling lambs. Twelve-week-old female lambs were divided into either the control (lambs reared under undisturbed maternal conditions; n=3) or the maternally deprived group (lambs separated for three days from their dams; n=3). The corticotrophin-releasing hormone (CRH) and gonadotrophin-releasing hormone (GnRH) in the median eminence and the adenohypophyseal adrenocorticotrophin (ACTH), gonadotrophins (LH and FSH) and mRNAs for their beta-subunits were investigated using the immunohistochemistry or hybridohistochemistry. In maternally deprived lambs, the percentage of the area occupied by immunoreactive (ir)-CRH nerve terminals was lower (P<0.05) and the percentage of the adenohypophyseal area (PAA) occupied by ir-ACTH cells was higher (P<0.05) compared with the control lambs. In the hypothalamo-gonadotrophic axis of maternally deprived lambs the percentage of area occupied by ir-GnRH nerve terminals was higher (P<0.05) and the PAA occupied by ir-FSHbeta cells was lower (P<0.05) in comparison with controls. The PAA occupied by gonadotrophs detected using hybridohistochemistry was higher (P<0.05) for LHbeta-mRNA in contrast to a lower (P<0.05) percentage for FSHbeta-mRNA in maternally deprived lambs compared with those staying with dams. In conclusion, maternal deprivation affected the accumulation of CRH and ACTH. The different and more striking alterations in FSH synthesis and storage in comparison with those concerning LH were observed in maternally deprived lambs. Thus, rupture of the preweanling young-mother social contact can affect the gonadotroph population activity, especially that relating to FSH-producing cells in the infantile female sheep.

Intravenous catecholamine administration affects mouse intestinal lymphocyte number and apoptosis

The purposes of this study were to determine plasma and intestinal epinephrine (E) and norepinephrine (NE) concentrations in mice after exercise stress and, the effect of intravenous injection of E and NE (at concentrations during exercise) on viability of intestinal lymphocytes (IL). Exhaustive exercise significantly elevated plasma E and NE, and intestinal E, compared with sedentary animals. Twenty-four hours after intravenous NE administration, IL counts were higher (p<0.001) and % apoptotic IL were lower (p<0.001) than saline conditions. E resulted in fewer apoptotic IL at 24 h compared to saline controls. E and NE differentially influence IL numbers at 24 h after injection although both result in fewer % apoptotic IL relative to mice given saline only.

24-hour pattern of circulating prolactin and growth hormone levels and submaxillary lymph node immune responses in growing male rats subjected to social isolation

To assess the effect of social isolation of growing rats on 24-h rhythmicity of circulating prolactin and growth hormone (GH) levels and submaxillary lymph node immune responses, male Wistar rats were either individually caged or kept in groups (4-5 animals per cage) for 30 d starting on d 35 of life. Plasma prolactin and GH levels, and submaxillary lymph node lymphocyte subset populations, interferon (IFN)-gamma release and mitogenic responses to concanavalin A (Con A) and lipopolysaccharide (LPS) were determined at six time intervals during the 24 h span. Social isolation brought about changes in mean values and 24-h pattern of plasma prolactin and GH levels and lymph node immune responses. After isolation, prolactin and GH mean values decreased, and lymph node T, B, non T-non B, CD8+, and CD4+-CD8+ cells augmented, whereas lymph node CD4+/CD8+ ratio, IFN-gamma release and mitogenic responses decreased. Social isolation resulted in disruption of 24 h rhythmicity of every immune parameter tested. CD4+/CD8+ ratio, IFN-gamma release and Concanavalin A (Con A) and lipopolysaccharide (LPS) responses correlated significantly with plasma prolactin or GH levels while T/B ratio correlated with plasma prolactin levels only. B, non T-non B, and CD4+-CD8+ cells correlated negatively with plasma prolactin. Modifications in mean value and 24-h rhythmicity of plasma prolactin and GH levels are presumably involved in the effect of social isolation on immune responsiveness.