Effects of prenatal stress on development in mice: maturation and learning

Sex-dependence and comorbidities of the early-life adversity induced mental and metabolic disease risks: Where are we at?

Early-life adversity (ELA) is a major risk factor for developing later-life mental and metabolic disorders. However, if and to what extent ELA contributes to the comorbidity and sex-dependent prevalence/presentation of these disorders remains unclear. We here comprehensively review and integrate human and rodent ELA (pre- and postnatal) studies examining mental or metabolic health in both sexes and discuss the role of the placenta and maternal milk, key in transferring maternal effects to the offspring. We conclude that ELA impacts mental and metabolic health with sex-specific presentations that depend on timing of exposure, and that human and rodent studies largely converge in their findings. ELA is more often reported to impact cognitive and externalizing domains in males, internalizing behaviors in both sexes and concerning the metabolic dimension, adiposity in females and insulin sensitivity in males. Thus, ELA seems to be involved in the origin of the comorbidity and sex-specific prevalence/presentation of some of the most common disorders in our society. Therefore, ELA-induced disease states deserve specific preventive and intervention strategies.

The Behavior and Postnatal Development in Infant and Juvenile Rats After Ultrasound-Induced Chronic Prenatal Stress

Fetal development is susceptible to environmental factors. One such factor is exposure to stress during pregnancy. The present study aimed to investigate the effects of chronic prenatal stress (PS) on the development and behavior of rat offspring during infancy and juvenile ages. Existing approaches to modeling prenatal stress on animals do not correlate with the main type of stress in pregnant women, namely psychological stress. We used a new stress paradigm in the experiment, namely, stress induced by exposure to variable frequency ultrasound (US), which acted on pregnant Wistar rats on gestational days 1–21. This type of stress in rodents can be comparable to psychological stress in humans. We assessed physical development, reflex maturation, motor ability development, anxious behavior, response to social novelty, and social play behavior in male and female offspring. Additionally, we investigated maternal behavior and the effect of neonatal handling (NH) on behavior. Prenatal stress did not affect postnatal developmental characteristics in rat pups, but prenatally stressed rats had higher body weight in early and adult age than controls. Prenatal exposure to a stressor increased anxiety in the open-field test (OF), changed social preferences in the social novelty test (SN), and impaired social play behavior in males. Neonatal handling reduced anxiety and restored social behavior, but evoked hyperactive behavior in rat pups. Maternal behavior did not change. Our study demonstrated for the first time that exposure to variable frequency ultrasound during pregnancy influences offspring development and impairs behavior, correlating with the effects of other types of stress during pregnancy in rodents. This supports the idea of using this exposure to model prenatal stress.

Gender-specific effect of pregnancy-related anxiety on preschooler's emotional and behavioral development: A population-based cohort study

BACKGROUND

Pregnancy-related anxiety plays a major role in shaping offspring's neural development. However, its gender-specific effect on children's emotional and behavioral development is controversial and the knowledge of critical period is limited. This study aims to examine gender-specific effect of pregnancy-related anxiety on preschooler's emotional and behavioral development.

METHODS

This study was based on the China-Anhui Birth Cohort Study (C-ABCS). A total of 3443 mother-child pairs were included in final data analysis. Pregnancy-related anxiety was assessed by Pregnancy-Related Anxiety Questionnaire respectively in the 1^st and 3^rd trimester of pregnancy. Strengths and Difficulties Questionnaires (SDQ) were completed by parents to assess preschool emotional and behavioral development in boys and girls. Logistic regression models were used to examine the association between pregnancy-related anxiety and preschoolers' emotional and behavioral problems.

RESULTS

The overall prevalence of pregnancy-related anxiety was 31.6%. Compared with those whose mothers without pregnancy-related anxiety in either 1^st or 3^rd trimester, preschool boys born of mothers with pregnancy-related anxiety in the 1^st trimester and in the 3^rd trimester had an increased risk of conduct problems. Pregnancy-related anxiety in the 1^st, 3^rd trimester and in both trimesters all related with preschool boys' hyperactivity and total difficult problems. Pregnancy-related anxiety in the 1^st trimester and in both 1^st and 3^rd trimester increased the risk of preschool girls' emotional problems and total difficult problems.

CONCLUSION

Pregnancy-related anxiety may relate with preschool boys' externalizing problems in early and late of pregnancy and increase the risk of internalizing problems in girls in early pregnancy.

LIMITATIONS

There was no data on pregnancy-related anxiety in the second trimester.

Prenatal depression, fetal neurobehavior, and infant temperament: Novel insights on early neurodevelopment from a socioeconomically disadvantaged Indian cohort

This article extends the research focusing on the early origins of psychopathology into the prenatal period, by exploring the association between maternal prenatal depression and offspring (fetal and infant) neurobehavior. The sample is recruited from a rural population in South India where women in the third trimester of pregnancy were assessed for depression and the heart rate responses of their fetuses to extrinsically applied vibroacoustic stimuli were studied. At 2 months postbirth, infant temperament and cortisol responsivity to immunization were assessed. The association between maternal prenatal depression and fetal responsivity to vibroacoustic stimulation, and infant responsivity to immunization, was U shaped with higher levels of responsivity noted in the offspring of mothers with very high and very low depression scores, and lower levels noted in the offspring of mothers with moderate depression scores. Maternal prenatal depression was not associated with infant temperament. The findings highlight the importance of environmental influences in the developmental origins of neurobehavior, suggesting that such differences, not evident at baseline, may emerge upon exposure to stressors. The study also emphasizes the need for further investigation in low- and middle-income contexts by providing preliminary evidence of the differing patterns of association observed between high- and low-income populations.

Prenatal noise and restraint stress interact to alter exploratory behavior and balance in juvenile rats, and mixed stress reverses these effects

We aimed to investigate in adolescent rats the individual and combined effects of prenatal noise and restraint stress on balance control, exploration, locomotion and anxiety behavior. Three groups of pregnant rats were exposed to daily repeated stress from day 11 to day 19 of pregnancy: 3 min noise (Noise Stress, NS); 10 min restraint (restraint stress, RS); or 3 min noise followed by 10 min restraint (mixed stress, MS). On postnatal days (PND) 44, 45 and 46, four groups of male rats (Control, NS, RS:, MS; 16 rats each), were tested as follows: (1) beam walking (BW), (2) open field (OF) and (3) elevated plus maze (EPM). Our results show that the NS group had significantly impaired balance control, locomotion and both horizontal and vertical exploration (p < .01 for all measures). The RS group showed only a decrease in vertical exploration (p < .05). In contrast, locomotion and balance were not affected in the MS group (OF: crossed squares: p = .34, missteps: p = .18). However, MS rats exhibited significantly higher anxiety levels (less time in EPM open arms: p < .05), and took more time to complete BW: p < .05). Hence, combined prenatal stressors exert non-additive effects on locomotion, exploration and balance control, but induce greater anxiety through additive effects. Terminal plasma ACTH concentration was increased by prenatal stress, especially noise, which group had the largest adrenal glands. Overall, contrary to expectation, combined prenatal stressors can interact to increase anxiety level, but diminish alteration of exploration, locomotion and impaired balance control, which were strongly induced by noise stress. Lay summary: Experience of stress in pregnancy can have negative effects on the offspring that are long-lasting. Here, we used laboratory rats to see whether repeated episodes of exposure to loud noise or preventing free movement, alone or together, during pregnancy had different effects on behaviors of the adolescent offspring. Using standard tests, we found the prenatal stresses caused the offspring to be anxious, and not to balance when moving around as well as normal offspring; the degree of impairment depended on the type of stress - loud noise exposure had the greatest effects, but if the stresses were combined the effects were not worse. The results point to the need to aim to avoid stress in pregnant women.

The Synergistic Roles of the Chronic Prenatal and Offspring Stress Exposures in Impairing Offspring Learning and Memory

In Alzheimer's disease (AD), extensive experimental studies have demonstrated a negative impact of chronic stress during various stages of life (including prenatal phase) on some aspects of AD pathology. Nevertheless, presently, few studies have been involved in the learning and memory impairments, as well as neuropathology elicited by the chronic prenatal stress (CPS) and the chronic offspring stress (COS) exposures simultaneously, particularly for the adult male APPswe/PS1dE9 murine offspring. Therefore, the aim of the present study was to investigate the influence of CPS on learning and memory impairments induced by COS in 6-month-old male APPswe/PS1dE9 offspring mice and the related mechanism. Our study firstly demonstrates that 14-day exposure to CPS could exacerbate the learning and memory impairments, as well as neuropathological damages in the CA3 regions of the hippocampus and cortex neurons, which is induced by the 28-day exposure to COS in 6-month-old male APPswe/PS1dE9 offspring mice. In addition, CPS could potentiate the production of AβPP, Aβ42, and corticosterone in 6-month-old male APPswe/PS1dE9 offspring that also suffer COS. In conclusion, our novel findings strongly implicate the synergistic roles of the CPS and COS exposures in impairing offspring learning and memory. Moreover, CPS potentiating the production of Aβ42 might be mediated by glucocorticoids through increasing the expression of APP and BACE1 gene.

Investigation of the effect of the efficiency of noise at different intensities on the DNA of the newborns

Hearing loss can occur in newborns exposed to high-level noise; noise exposure can cause more physiological stress and can lead to DNA damage. This study was designed to determine DNA damage in newborn rats exposed to sound at different concentrations. For this purpose, 28 newborn (3-6 days old) rats were divided into four groups of 7 rats in each group (Control and Groups of 40 decibel (dB), 70 dB, and 110 dB]. In the experimental groups, 40 dB, 70 dB, and 110 dB (7.5-15 kHz) of sound was applied to the experimental groups for 30 min a day for 7 days. DNA damage levels in the serums obtained from this study were determined by the enzyme-linked immunosorbent assay (ELISA) method. According to this, it was determined that DNA damage in the group exposed to 110 dB showed a statistically significant increase (P < 0.05) compared to the compared to the control, 40 dB, and 70 dB groups. Related to the subject, it was concluded that DNA damage may occur in newborns exposed to 110 dB or higher sound in neonatal units, wards, and home environments with newborn babies. Mothers should be warned about this situation and noise should be kept under 110 dB volume in the environments with the newborns.

Does prenatal restraint stress change the craniofacial growth pattern of rat offspring?

A major and frequently encountered condition underlying the long-term programming effects of the intrauterine environment is exposure to stress. Gestational stress is an environmental factor that induces physical and behavioral alterations in offspring. Seventy female virgin Wistar rats were mated with one male rat for a maximum of four times, after which 52 pregnant rats were divided into two groups. In the experimental group the rats were exposed to restraint stress during pregnancy, whereas the control group did not receive the stress protocol. One male litter was randomly chosen from the offspring of each rat with 8-13 pups. A total of 40 male rat offspring were available for analysis. Thirty-one linear and angular measurements were analyzed in both study groups to investigate whether prenatal restraint stress changes the craniofacial growth pattern of rat offspring. In the prenatally stressed group, anterior cranial base length and viscerocranium measures were significantly increased compared with the control group, whereas cranial width, mandibular dimensions, and posterior cranial height and length remained unchanged. Furthermore, the prenatally stressed group showed backward rotation of the midface and decreased flattening of the cranial vault. It was concluded that prenatal chronic stress can induce alterations in the craniofacial growth pattern by promoting endochondral growth in the cranial base and nasal septum.

Differences in Maternal Behavior and Development of Their Pups Depend on the Time of Methamphetamine Exposure During Gestation Period

The present study examined the hypothesis that the extension of noxious effect of methamphetamine (MA) on maternal behavior and postnatal development on the pups may differ in dependence with time of application. Female rats were injected with MA (5 mg/kg) or saline during first (embryonic day (ED) 1-11) or second (ED 12-22) half of gestation. Our results demonstrated that MA exposure on ED 12-22 led to decreased birth weight and weight gained during lactation period relative to rats treated on ED 1-11. Both sexes treated prenatally with MA on ED 1-11 opened eyes earlier compared to animals treated on ED 12-22. As a matter of sensorimotor development application of MA on ED 1-11 impaired the righting reflex, while MA exposure on ED 12-22 impaired the performance of beam balance test in male rats. There were no differences in maternal behavior. Therefore, it seems that MA exposure in the first half of the gestation impaired the early sensorimotor development that is under control of the brain stem, while the MA exposure in the second half of gestation affected the beam balance performance that is dependent on the function of the cerebellum.

Maternal depression and foetal responses to novel stimuli: insights from a socio-economically disadvantaged Indian cohort

Maternal stress during pregnancy has pervasive effects on stress responsivity in children. This study is the first to test the hypothesis that maternal prenatal depression, as observed in South India, may be associated with how foetuses respond to a potentially stressful stimulus. We employed measures of foetal heart rate at baseline, during exposure to a vibroacoustic stimulus, and post-stimulation, to study patterns of response and recovery in 133 third trimester foetuses of depressed and non-depressed mothers. We show that the association between maternal depression and foetal stress responsivity is U-shaped with foetuses of mothers with high and low depression scores demonstrating elevated responses, and poorer recovery, than foetuses of mothers with moderate levels. The right amount of intra-uterine stimulation is important in conditioning foetuses towards optimal regulation of their stress response. Our results imply that, in certain environmental contexts, exposure to moderate amounts of intra-uterine stress may facilitate this process.

Impairment of rat tooth eruption in pups born to mothers exposed to chronic stress during pregnancy

OBJECTIVE

Tooth eruption is a multifactorial process in which bone tissue plays a prevailing role. In this study we evaluated the bone overlying the developing tooth germ and the degree of tooth eruption of the first mandibular molar in pups born to mothers subjected to constant light during pregnancy.

DESIGN

Pregnant rats were divided into two groups: mothers chronically exposed to a 12:12 light/light cycle (LL) from day 10 to 20 of pregnancy and controls (C) maintained on a 12:12 h light/dark cycle. Pups from each group were euthanized at the age 3 or 15 days. Buccolingually oriented sections of mandibles were stained with haematoxylin-eosin or for histochemical detection of tartrate resistant acid phosphatase (TRAP). The histomorphometric parameters evaluated were bone volume, number of osteoclasts, TRAP+ bone surface, number of TRAP+ and TRAP- osteoclasts per mm(2) and degree of tooth eruption (mm).

RESULTS

It was found an increase in bone volume (LL: 58.14±4.24 vs. C: 32.31±2.16; p<0.01) and a decrease in the number of osteoclasts (LL: 3.5±0.65 vs. C: 8.03±1.31; p<0.01) and TRAP+ cells (LL: 0.84±0.53 vs. C: 8.59±1.26; p<0.01) in 3-day-old pups born to LL-exposed mothers. These observations are consistent with the decrease in the degree of tooth eruption observed in 15-day-old experimental pups (LL: -0.605±0.05 vs. C: -0.342±0.02; p<0.0001).

CONCLUSION

Our results suggest that chronic constant light applied as a pre-natal stressor impairs the resorptive capacity of osteoclasts involved in the formation of the eruption pathway and consequently the degree of tooth eruption.

Developmental programming: cumulative effects of increased pre-hatching corticosterone levels and post-hatching unpredictable food availability on physiology and behaviour in adulthood

Prolonged exposure to stress during development can have long-term detrimental effects on health and wellbeing. However, the environmental matching hypothesis proposes that developmental stress programs physiology and behaviour in an adaptive way that can enhance fitness if early environments match those experienced later in life. Most research has focused on the harmful effects that stress during a single period in early life may exert in adulthood. In this study, we tested the potential additive and beneficial effects that stress experienced during both pre- and post-hatching development may have on adult physiology and behaviour. Japanese quail experienced different stress-related treatments across two developmental life stages: pre-hatching corticosterone (CORT) injection, post-hatching unpredictable food availability, both pre- and post-hatching treatments, or control. In adulthood, we determined quails' acute stress response, neophobia and novel environment exploration. The pre-hatching CORT treatment resulted in attenuated physiological responses to an acute stressor, increased activity levels and exploration in a novel environment. Post-hatching unpredictable food availability decreased adults' latency to feed. Furthermore, there were cumulative effects of these treatments across the two developmental stages: quail subjected to both pre- and post-hatching treatments were the most explorative and risk-taking of all treatment groups. Such responses to novel environments could enhance survival in unpredictable environments in later life. Our data also suggest that these behavioural responses may have been mediated by long-term physiological programming of the adrenocortical stress response, creating phenotypes that could exhibit fitness-enhancing behaviours in a changing environment.

Prenatal stress alters the behavior and dendritic morphology of the medial orbitofrontal cortex in mouse offspring during lactation

Several preclinical and clinical studies have shown that prenatal stress alters neuronal dendritic development in the prefrontal cortex, together with behavioral disturbances (anxiety). Nevertheless, neither whether these alterations are present during the lactation period, nor whether such findings may reflect the onset of anxiety disorders observed in childhood and adulthood has been studied. The central aim of the present study was to determine the effects of prenatal stress on the neuronal development and behavior of mice offspring during lactation (postnatal days 14 and 21). We studied 24 CF-1 male mice, grouped as follows: (i) control P14 (n=6), (ii) stressed P14 (n=6), (iii) control P21 (n=6) and (iv) stressed P21 (n=6). On the corresponding days, animals were evaluated with the open field test and sacrificed. Their brains were then stained in Golgi-Cox solution for 30 days. The morphological analysis dealt with the study of 96 pyramidal neurons. The results showed, first, that prenatal stress resulted in a significant (i) decrease in the apical dendritic length of pyramidal neurons in the orbitofrontal cortex at postnatal day 14, (ii) increase in the apical dendritic length of pyramidal neurons in the orbitofrontal cortex at postnatal day 21, and (iii) reduction in exploratory behavior at postnatal day 14 and 21.

Effects of chronic maternal stress on hypothalamo-pituitary-adrenal (HPA) function and behavior: no reversal by environmental enrichment

Maternal stress during pregnancy is linked to increased risk for impaired behavioral and emotional development and affective disorders in children. In animal models, acute periods of prenatal or postnatal stress have profound effects on HPA function and behavior in adult offspring. However, few animal studies have determined the impact of chronic exposure to stress throughout the perinatal period. The objective of this study was to determine the effects of chronic maternal stress (CMS) during the 2nd half of pregnancy and nursing on HPA function, locomotor behavior and prepulse inhibition in adult guinea pig offspring, as well as to determine whether environmental enrichment (EE) could reverse the effects of CMS. Guinea pigs were exposed to a random combination of variable stressors every other day over the 2nd half of gestation and from postnatal day (pnd) 1 until weaning (pnd25). Following weaning, offspring were housed in either standard conditions or EE. In both adult male and female offspring, there was no effect of CMS on basal or activated HPA function. CMS significantly increased locomotor activity in an open-field in male offspring, though no effect was observed in females. In female offspring, CMS disrupted PPI; however there was no effect on male PPI. EE had a number of effects on HPA function and behavior but in most cases these were independent of the influence of CMS. EE significantly elevated basal cortisol levels in male offspring at pnd70, whereas in female offspring, EE interacted with CMS to elevate basal cortisol levels from pnd35 to pnd70. In female offspring, EE decreased locomotor activity. In males, EE enhanced PPI; however in female offspring EE disrupted PPI. In conclusion, while CMS had minimal effects on HPA function, there were significant long-term sex-specific effects on behavior. EE did not reverse the effects observed as a result of CMS, but rather modified HPA function and behavior independently of CMS. Further, there was significant interaction of CMS with EE that resulted in elevation of basal HPA function in female offspring. These data, combined with previous studies from our laboratory, suggest that acute phases of maternal stress in late pregnancy may have greater long-term effects on HPA function and related behaviors than prolonged chronic maternal stress.

Maternal stress during pregnancy causes sex-specific alterations in offspring memory performance, social interactions, indices of anxiety, and body mass

Prenatal stress (PS) impairs memory function; however, it is not clear whether PS-induced memory deficits are specific to spatial memory, or whether memory is more generally compromised by PS. Here we sought to distinguish between these possibilities by assessing spatial, recognition and contextual memory functions in PS and nonstressed (NS) rodents. We also measured anxiety-related and social behaviors to determine whether our unpredictable PS paradigm generates a behavioral phenotype comparable to previous studies. Female Sprague-Dawley rats were exposed to daily random stress during the last gestational week and behavior tested in adulthood. In males but not females, PS decreased memory for novel objects and novel spatial locations, and facilitated memory for novel object/context pairings. In the elevated zero maze, PS increased anxiety-related behavior only in females. Social behaviors also varied with sex and PS condition. Females showed more anogenital sniffing regardless of stress condition. In contrast, prenatal stress eliminated a male-biased sex difference in nonspecific bodily sniffing by decreasing sniffing in males, and increasing sniffing in females. Finally, PS males but not females gained significantly more weight across adulthood than did NS controls. In summary, these data indicate that PS differentially impacts males and females resulting in sex-specific adult behavioral and bodily phenotypes.

Prenatal antecedents of newborn neurological maturation

Fetal neurobehavioral development was modeled longitudinally using data collected at weekly intervals from 24 to 38 weeks gestation in a sample of 112 healthy pregnancies. Predictive associations between 3 measures of fetal neurobehavioral functioning and their developmental trajectories to neurological maturation in the first weeks after birth were examined. Prenatal measures included fetal heart rate (FHR) variability, fetal movement, and coupling between fetal motor activity and heart rate patterning; neonatal outcomes include a standard neurologic examination (n = 97) and brainstem auditory evoked potential (BAEP; n = 47). Optimality in newborn motor activity and reflexes was predicted by fetal motor activity, FHR variability, and somatic-cardiac coupling predicted BAEP parameters. Maternal pregnancy-specific psychological stress was associated with accelerated neurologic maturation.

Interaction between environmental and genetic factors modulates schizophrenic endophenotypes in the Snap-25 mouse mutant blind-drunk

To understand the pathophysiology of neuropsychiatric disorders such as schizophrenia requires consideration of multiple genetic and non-genetic factors. However, very little is known about the consequences of combining models of synaptic dysfunction with controlled environmental manipulations. Therefore, to generate new insights into gene–environment interactions and complex behaviour, we examined the influence of variable prenatal stress (PNS) on two mouse lines with mutations in synaptosomal-associated protein of 25 kDa (Snap-25): the blind-drunk (Bdr) point mutant and heterozygous Snap-25 knockout mice. Neonatal development was analysed in addition to an assessment of adult behavioural phenotypes relevant to the psychotic, cognitive and negative aspects of schizophrenia. These data show that PNS influenced specific anxiety-related behaviour in all animals. In addition, sensorimotor gating deficits previously noted in Bdr mutants were markedly enhanced by PNS; significantly, these effects could be reversed with the application of anti-psychotic drugs. Moreover, social interaction abnormalities were observed only in Bdr animals from stressed dams but not in wild-type littermates or mutants from non-stressed mothers. These results show for the first time that combining a synaptic mouse point mutant with a controlled prenatal stressor paradigm produces both modified and previously unseen phenotypes, generating new insights into the interactions between genetics and the environment relevant to the study of psychiatric disease.

The endocannabinoid system during development: emphasis on perinatal events and delayed effects

The endocannabinoid system (ECS) including its receptors, endogenous ligands ("endocannabinoids"), synthesizing and degradating enzymes, and transporter molecules has been detected from the earliest embryonal stages and throughout pre- and postnatal development; endocannabinoids, notably 2-arachidonoylglycerol, are also present in maternal milk. During three developmental stages, (1) early embryonal, (2) prenatal brain development, and (3) postnatal suckling, the ECS plays an essential role for development and survival. During early gestation, successful embryonal passage through the oviduct and implantation into the uterus require critical enzymatic control of the endocannabinoids. During fetal life, endocannabinoids and the cannabinoid CB(1) receptor are important for brain development, regulating neural progenitor differentiation and guiding axonal migration and synaptogenesis. Postnatally, CB(1) receptor activation by 2-arachidonoylglycerol appears to play a critical role in the initiation of milk suckling in mouse pups, possibly by enabling innervation and/or activation of the tongue muscles. Perinatal manipulation of the ECS, by administering cannabinoids or by maternal marijuana consumption, alters neurotransmitter and behavioral functions in the offspring. Interestingly, the sequelae of prenatal cannabinoids are similar to many effects of prenatal stress, which may suggest that prenatal stress impacts on the ECS and that vice versa prenatal cannabinoid exposure may interfere with the ability of the fetus to cope with the stress. Future studies should further clarify the mechanisms involved in the developmental roles of the ECS and understand better the adverse effects of prenatal exposure, to design strategies for the treatment of conditions including infertility, addiction, and failure-to-thrive.

Physical and mental health outcomes of prenatal maternal stress in human and animal studies: a review of recent evidence

Prenatal maternal stress (PNMS) has been linked with adverse health outcomes in the offspring through experimental studies using animal models and epidemiological studies of human populations. The purpose of this review article is to establish a parallel between animal and human studies, while focusing on methodological issues and gaps in knowledge. The review examines the quality of recent evidence for prevailing PNMS theoretical models, namely the biopsychosocial model for adverse pregnancy outcomes and the fetal programming model for chronic diseases. The investigators used PubMed (2000-06) to identify recently published original articles in the English language literature. A total of 103 (60 human and 43 animal) studies were examined. Most human studies originated from developed countries, thus limiting generalisability to developing nations. Most animal studies were conducted on non-primates, rendering extrapolation of findings to pregnant women less straightforward. PNMS definition and measurement were heterogeneous across studies examining similar research questions, thus precluding the conduct of meta-analyses. In human studies, physical health outcomes were often restricted to birth complications while mental health outcomes included postnatal developmental disorders and psychiatric conditions in children, adolescents and adults. Diverse health outcomes were considered in animal studies, some being useful models for depression, schizophrenia or attention deficit hyperactivity disorder in human populations. The overall evidence is consistent with independent effects of PNMS on perinatal and postnatal outcomes. Intervention studies and large population-based cohort studies combining repeated multi-dimensional and standardised PNMS measurements with biomarkers of stress are needed to further understand PNMS aetiology and pathophysiology in human populations.

Maternal and genetic effects on the acoustic startle reflex and its sensitization in C3H/HeN, DBA/2JHd and NMRI mice following blastocyst transfer

In the present study, reciprocal embryo transfers were conducted to examine genetic and maternal effects on the baseline and fear-sensitized acoustic startle response (ASR) in the two inbred strains C3H/HeN and DBA/2JHd and the outbred strain NMRI. The largest differences in the ASR were found in untreated strains (effect size 0.6). The transfer procedure per se had a significant effect on the behavior of NMRI mice resulting in a reduction in the baseline, and an increase in the fear-sensitized ASR. In contrast, there were no significant effects of the transfer procedure in the two inbred strains. Autosomal genetic effects had a stronger impact on the amplitude of the ASR (effect sizes 0.5) than sex (effect sizes 0.06) as revealed by reciprocal embryo transfer. Nevertheless, the genetic effects on the fear-sensitized ASR were somewhat more variable and strain-dependent (effect sizes 0.1-0.2). Global maternal effects were detected after embryo transfer into NMRI mothers resulting in a larger reduction of the ASR in the offspring of DBA and NMRI donors than C3H donors (effect sizes 0.1-0.2). An additional fostering procedure was introduced to dissect uterine and postnatal maternal effects in NMRI offspring. Uterine factors changed the baseline ASR of the offspring in direction of the recipient mother strain. Surprisingly, postnatal maternal effects on the ASR were contrary to the behavior of the rearing mother. In conclusion, both genetic and prenatal/postnatal maternal factors persistently influenced the ASR of the offspring, whereas the fear-sensitized ASR was mainly influenced by genetic factors. Our study shows that uterine and postnatal maternal influences deserve more attention when determining the phenotype of genetically engineered mice at least in the first generation following embryo transfer.

CNS effects of developmental Pb exposure are enhanced by combined maternal and offspring stress

Lead (Pb) exposure and elevated stress are co-occurring risk factors. Both impact brain mesolimbic dopamine/glutamate systems involved in cognitive functions. We previously found that maternal stress can potentiate Pb-related adverse effects in offspring at blood Pb levels averaging approximately 40 microg/dl. The current study of combined Pb exposure and stress sought to extend those results to lower levels of Pb exposure, and to examine relationships among consequences in offspring for fixed interval (FI) schedule-controlled behavior, neurochemistry and corticosterone levels. Dams were exposed to maternal Pb beginning 2 months prior to breeding (0, 50 or 150 ppm in drinking water), maternal restraint stress on gestational days 16 and 17 (MS), or the combination. In addition, a subset of offspring from each resultant treatment group was also exposed intermittently to variable stressors as adults (MS+OS). Marked "Pb-stress"-related increases in response rates on a fixed interval schedule, a behavioral performance with demonstrated sensitivity to Pb, occurred preferentially in female offspring even at mean blood Pb levels of 11 microg/dl when 50 ppm Pb was combined with maternal and offspring stress. Greater sensitivity of females to frontal cortex catecholamine changes may contribute to the elevated FI response rates as mesocorticolimbic systems are critical to the mediation of this behavior. Basal and final corticosterone levels of offspring used to evaluate FI performance differed significantly from those of non-behaviorally tested (NFI) littermates, demonstrating that purported mechanisms of Pb, stress or Pb/stress effects determined in non-behaviorally trained animals cannot necessarily be generalized to animals with behavioral histories. Finally, the persistent and permanent consequences of Pb, stress and Pb+stress in offspring of both genders suggest that Pb screening programs should include pregnant women at risk for elevated Pb exposure, and that stress should be considered as an additional risk factor. Pb+stress effects observed in the absence of either risk factor alone (i.e., potentiated effects) raise questions about the capacity of current hazard identification approaches to adequately identify human health risks posed by neurotoxicants.

Acute paternal alcohol use affects offspring development and adult behavior

Swiss Webster pups were fathered by sires given either an acute dose of alcohol (alcohol-sired) or saline (saline-sired) 12-24 h before mating. The same sires were used to father both groups of pups. Alcohol-sired pups were significantly lighter at birth and for the following three weeks than were saline-sired pups. Significantly more pups were fathered by saline-exposed sires, and dams carrying those pups had significantly longer gestations than those carrying pups of alcohol-using sires. More runts were born to the alcohol-sired group, and more pups in that group died over the next three weeks than in the saline-sired group. Significantly more pups in the saline-sired group achieved such developmental milestones as surface righting, clinging, the tail-pull reflex, rotation, linear movement and climbing an inclined surface earlier than did alcohol-sired pups. As adults, animals from the alcohol-sired group showed significantly less risk assessment behavior and longer latencies to such behaviors as stretched attention, flatback, freezing and defensive burying than did the saline-sired animals. Alcohol-sired animals contacted the stimulus object in the risk assessment test significantly sooner and more often than did the saline-sired group. In tests of aggression, alcohol-sired male offspring showed more frequent aggressive behaviors such as on-top, lateral attacks and jump-attacks, and significantly fewer defensive/fearful behaviors such as piloerection, tail rattling and jump-escape. This pattern of results suggests that exposure of the sire to one acute dose of alcohol before insemination caused some early developmental delays and that alcohol-sired animals are less fearful and more aggressive as adults than saline-sired animals.

Maternal psychological distress during pregnancy in relation to child development at age two

Concern exists that a constellation of negative maternal emotions during pregnancy generates persistent negative consequences for child development. Maternal reports of anxiety, pregnancy-specific and nonspecific stress, and depressive symptoms were collected during mid-pregnancy and at 6 weeks and 24 months after birth in a sample of healthy women with low risk pregnancies. Developmental assessment and cardiac vagal tone monitoring were administered to 94 children at age 2. Higher levels of prenatal anxiety, nonspecific stress, and depressive symptoms were associated with more advanced motor development in children after postnatal control for each psychological measure; anxiety and depression were also significantly and positively associated with mental development. Mild to moderate levels of psychological distress may enhance fetal maturation in healthy populations.

Is corticosterone-mediated phenotype development adaptive? Maternal corticosterone treatment enhances survival in male lizards

Hormones are an important interface between genome and environment, because of their ability to modify the phenotype. More particularly, glucocorticoids are known to affect both morphological, physiological and behavioral traits. Many studies suggest that prenatal stress (associated with an elevation of corticosterone) has deleterious effects on offspring, an altered physiology resulting in retardation of fetal growth and higher percentage of dead neonates. In this study, we investigate the consequences of an artificial increase of corticosterone in pregnant female Lacerta vivipara on two important fitness components: growth and survival. Do stressed females decrease or enhance offspring survival? In 2000 and 2001, we collected pregnant females from four populations of the Cevennes and kept them in the laboratory until parturition. We applied a corticosterone solution daily onto the backs of some females. A similar solution, but without corticosterone, was applied to the remaining females as a control. Immediately after birth, we measured juveniles' morphological characteristics and released them on the field. In September of the year of release and in May of the following year, we recaptured offspring to estimate growth and survival. The elevation of the corticosterone level in pregnant females L. vivipara had a profound impact on juvenile traits. The size, the body condition and the growth of juveniles were decreased by the corticosterone treatment. In contrast, in male juveniles, survival was higher for juveniles from corticosterone-treated females than from placebo females. Thus, corticosterone does not seem to have detrimental effects on offspring survival, suggesting that it may have an adaptive function.

Seizure-prone EL/Suz mice exhibit physical and motor delays and heightened locomotor activity in response to novelty during development

Seizure-prone EL/Suz mice have been studied as a model of multifactorial epilepsy for five decades. In prior behavioral studies, EL/Suz mice were shown to exhibit heightened locomotor activity, which implies a state of underlying hyperexcitability. The aim of the present study was to establish the premorbid behavioral development of basic motor skills and activity levels of EL/Suz mice, as compared with DDY mice, the control strain that is not seizure-prone. EL/Suz and DDY pups were monitored from Postnatal Day (PND) 3 to assess body weight, surface righting, negative geotaxis, forelimb grip strength, eye opening, habituation to a novel environment, and exploratory behavior in a two-compartment task. EL/Suz mice weighed less from PNDs 3 to 21 and exhibited delayed surface righting (PNDs 3, 5, 7) and negative geotaxis (PNDs 5, 7, 9) responses. EL/Suz and DDY mice differed in their habituation to a novel environment, with EL/Suz mice exhibiting higher activity, both within a single 10-minute session and across the 3 days of testing. EL/Suz and DDY mice also differed in the two-compartment task, with EL/Suz mice exhibiting increased locomotor activity and spending a greater amount of time in the light compartment. Thus, the present findings reveal that EL/Suz mice exhibit some developmental delays, altered habituation to a novel environment, and increased exploratory activity. Overall, the present results demonstrate that the behavioral and physiological phenotype of seizure-prone EL/Suz mice is deviant more than 2 months before the onset of seizure susceptibility.

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.

Effects of prenatal exposure to chronic mild stress and toluene in rats

The aim of the present study was to elucidate whether prenatal chronic stress, in combination with exposure to a developmental neurotoxicant, would increase effects in the offspring compared with the effects of either exposure alone. Development and neurobehavioral effects were investigated in female offspring of pregnant rats (Mol:WIST) exposed to chronic mild stress (CMS) during gestational days (GD) 9-20, or 1500 ppm toluene, 6 h/day during gestational days 7-20, or a combination of the two. Prenatal CMS was associated with decreased thymic weight and increased auditory startle response. The corticosterone response to restraint seemed modified by prenatal exposure to toluene. Lactational body weight was decreased in offsprings subjected to CMS, primarily due to effects in the combined exposure group. Cognitive function was investigated in the Morris water maze, and some indications of improved function due to CMS were observed. In the present experimental setting, there was no indication of the two exposures potentiating each other with respect to adverse effects on the nervous system. However, the effects of prenatal CMS indicate that stress during fetal life may interfere with the development of the thymus and increase the reactivity (startle reflex) of the offspring.

Acceleration of visual system development by environmental enrichment

Thus far, the developmental plasticity of the visual system has been studied by altering or reducing visual experience. Here, we investigated whether a complex sensory-motor stimulation, provided by rearing animals in an enriched environment, affects visual system development. We found that raising mice in this condition causes an earlier eye opening, a precocious development of visual acuity, and an accelerated decline of white matter-induced long-term potentiation. These effects are accompanied by a precocious cAMP response element-mediated gene expression and a significant increase of BDNF protein and GAD65/67 expression in enriched pups. In addition, we showed that enriched pups experienced higher levels of licking behavior provided by adult females. Thus, rearing mice from birth in an enriched environment leads to a conspicuous acceleration of visual system development as ascertained at behavioral, electrophysiological, and molecular level.

Does prenatal stress affect the motoric development of rat pups?

Pregnant rats were exposed to an acute or a repeated stress (presence of a cat) either at the 10th or the 14th gestational day, and the development of their offspring was studied during the first 2 weeks of life. Motor development was measured by different tests: rooting reflex, vibrissae placing response, righting reflex, negative geotaxis. Other landmarks such as eye opening and spontaneous locomotor activity were also recorded. The results showed that, except for the rooting reflex which was most often enhanced (while not significantly) in prenatally stressed rats, the development of the vibrissae placing response, the righting reflex and the negative geotaxis behavior was delayed in the offspring of dams stressed at the 10th gestational day and not (or almost not) in the offspring of dams stressed at the 14th gestational day, the delay being more severe when the prenatal stress was repeated than when it was acutely administered. The spontaneous motor activity was also altered in repeatedly prenatally stressed rats, whatever the day of pregnancy when it was administered, while it was unaffected in acutely prenatally stressed animals. The delay in motor reflexes development was interpreted as alterations in maturation of nervous structures sustaining motor skills, while permanent decrease of spontaneous motor activity was explained by emotional and motivational alterations due to prenatal stress.

Brain injury and neurofunctional deficit in neonatal mice with hypoxic-ischemic encephalopathy

Birth asphyxia accounts for the majority of developmental motor and cognitive deficits. Studies were undertaken to develop a reproducible murine model of perinatal hypoxic-ischemic encephalopathy (HIE) which would permit both anatomic and neurofunctional quantification of injury. Short-term neurofunctional outcomes consisted of three developmental reflexes (righting, cliff aversion and geotaxis) assessed in 7-day-old mouse pups 24 h after unilateral carotid artery ligation followed by inhalation of 8% oxygen. Cerebral infarct volume was dependent on duration of hypoxia, being approximately 2.5-fold greater with longer (60 min) versus shorter (30 min) hypoxia exposure (P=0.001). All three sensorimotor neonatal reflexes assessed at 24 h after HIE injury correlated significantly with long-term neurofunction evaluated using a water-maze test of navigational learning and memory assessed 8 weeks later in the same animals. Cerebral atrophy, a delayed consequence of HIE in this model, also correlated strongly with water-maze performance (r=0.86, P=0.002). These data demonstrate for the first time that murine neonatal sensorimotor reflex performance can be rigorously quantified in the acute phase of perinatal HIE and has strong predictive value not only for anatomic extent of cerebral injury, but also for long-term neurofunctional outcome.

Effect of prenatal stress and gonadal hormone condition on depressive behaviors of female and male rats

Whether prenatal stress (PNS) and gonadal hormones may influence depressive behavior of rats in the forced swim test was investigated. In Experiment I, adult diestrous female rats had increased immobility, which is indicative of depression, but did not show any significant difference in the duration of struggling compared to intact adult males. In Experiment 2, the behavior of adult intact, castrated, or castrated dihydrotestosterone (DHT)- or estrogen (E2)-replaced offspring of dams that were restrained under lights for 45 min on gestational day 18 (PNS) or were not subjected to gestational stress (non-PNS, control condition) were compared. There were no effects of PNS, but DHT and E2 produced anti-depressant effects on behavior of male rats. Castration decreased struggling and increased immobility compared to intact rats. DHT or E2 replacement was able to partially reinstate struggling and immobility behavior but not to levels of intact males. In Experiment 3, behavior of PNS or control rats that were in proestrus or were ovariectomized and DHT, E2, or vehicle-replaced were compared. Ovariectomy decreased struggling and increased immobility compared to that of proestrous rats. E2 or DHT to control females increased anti-depressant struggling behavior compared to ovariectomized control or PNS rats administered vehicle, which demonstrated greater duration of struggling than did E2-primed, PNS rats. E2 or DHT administration decreased immobility of PNS and control females. These findings suggest that E2 and DHT have some anti-depressant effects but that modest PNS may alter E2's ability to alleviate some depressive behavior in female, but not male rats.

Early social stress in female guinea pigs induces a masculinization of adult behavior and corresponding changes in brain and neuroendocrine function

This study was undertaken to investigate, in guinea pigs, the effects of pre- and early postnatal social stress on the functioning of hormonal-, autonomic-, behavioral-, and limbic-brain systems. Dams had either lived in groups with a constant composition (i.e. stable social environment) or in groups with changing compositions, that means every 3 days two females were transferred from one group to another (i.e. unstable social environment). The subjects studied were female offspring of dams who had either lived in a stable social environment during pregnancy and lactation (i.e. control daughters, CF) or in an unstable social environment during this period of life (i.e. early stressed daughters, SF). After weaning, each five groups of CF and SF, consisting of two females each, were established. The spontaneous behavior of the females was recorded, blood samples were taken to determine cortisol, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate and estrogen levels, the adrenals were prepared to determine tyrosinehydroxylase (TH) activities and the brains to investigate the distribution of sex hormone receptors. SF showed not only a behavioral and endocrine masculinization, but also an upregulation of androgen receptor and estrogen receptor-alpha in the medial preoptic area and the nucleus arcuatus of the hypothalamus, the nucleus paraventricularis of the thalamus, and the CA1 region of the hippocampus. These findings corresponded with distinctly elevated serum-concentrations of testosterone and increased activities of the adrenal TH. In conclusion, early social stress caused by an unstable social environment induces in female guinea pigs a permanent behavioral masculinization that is accompanied by changes in the endocrine and autonomic system as well as by changes in the distribution of sex hormone receptors in the limbic system.

Prenatal stress affects the rate of sexual maturation and attractiveness in bank voles

Field studies reveal that bank vole females' mobility and aggression increase during pregnancy. Here we investigated the reaction of pregnant females to social stress evoked by short but frequent meetings with another female at the same stage of pregnancy. The stress neither evoked pregnancy termination nor affected pregnancy duration but had a long-term effect on the reproductive activity of the offspring. Prenatal stress reduced the rate of sexual maturation of voles as estimated at the age of 20 days. Uterine weights of prenatally stressed females and testes weights of prenatally stressed males were significantly lower than in offspring born to nonstressed mothers. Olfactory signals are known to be important in the sexual preferences of bank voles. Adult prenatally stressed females were more attractive to other adult females than were nonstressed animals. For bank vole males, however, prenatal stress decreased the attractiveness of females; adult males selected nonstressed females over stressed partners, by odor. This study shows that prenatal conditions evoked by short but frequent encounters with another pregnant female lead to delayed puberty in females and males, and decrease sexual attractiveness in adult offspring. These two negative effects may significantly limit the reproduction of prenatally stressed offspring.

Behavioural development in the neonatal lamb: effect of maternal and birth-related factors

The survival of the neonate relies on the integrated expression of appropriate behaviours from both the mother and young. In precocious species, like the sheep, the speed with which the lamb stands and seeks the udder is related to lamb survival. In this study the effects of birth difficulty, lamb birth weight, ewe loss or gain in backfat from conception to delivery, ewe parity, litter size, and lamb sex on neonatal lamb behavioural development were investigated in over 500 lambs of two breeds (Scottish Blackface and Suffolk). Lambs that required assistance to be delivered were significantly slower to perform all neonatal behaviours than unassisted lambs (P<0.001), and were less active over the first 3 days after delivery (P<0.05). There were no effects of lamb birthweight that were not accounted for by the increased likelihood of requiring assistance in heavier birth weight lambs. Ewes that mobilised less body fat during their pregnancy produced lambs that stood and sucked quickly (P<0.001), and were more active over the first 3 days of life. Lambs born to first parity ewes were slower to stand and suck than lambs born to experienced ewes (P<0.001). There was an improvement in time taken by lambs to stand, seek the udder and to suck with each increase in ewe parity. Litter size had an additional retarding influence on the behaviour of multiple-born lambs that could not be accounted for by birthweight. In the Suffolk breed male lambs were slower to stand and suck than female lambs, this effect was not seen in Blackface lambs. These data demonstrate that lambs that require assistance at birth, even if they survive the birth process, lambs born to ewes that lose a lot of condition over pregnancy or first parity ewes, triplet lambs and, at least in some breeds, male lambs are slower to progress through the sequence of neonatal behaviours. These lambs are, therefore, at greater risk of not surviving to weaning.

Maternal stress differently alters nociceptive behaviors in the formalin test in adult female and male rats

The long-term effects of restraint stress in Wistar rats during the last week of gestation were investigated on the acute and tonic phases of the specific biphasic nociceptive behavioral response in the formalin test in offspring, females and males, at 90 days. Prenatal stress produced significant changes in formalin-induced pain, which was more pronounced in females as compared to males. The distorted response in females was more at the supraspinal level with an increased intensity of the licking response in both phases as well as with an increased their duration. Results concerning changes of the interphase length indicate the impairments of inhibitory mechanisms in the central nervous system. Furthermore, profound difference in the effects of prenatal stress on the first phase but similarity in these effects on the second phase in females and males are indirect strong support of the view that the second phase in the formalin test can not be mediated by central sensitization alone but greatly depends on signals ongoing from nociceptive primary afferents. Finally, the results obtained in males are important argument in favor of assumption about different mechanisms of acute and tonic pain. Taken together, these studies show that prenatal stress alters nociceptive behaviors in the formalin test in rats at 90 days in a sex-specific manner.

Intrauterine position effects

A review of the literature suggests that individual variability in sex-related traits may be influenced by variations in hormonal exposure during fetal development. In litter-bearing mammals, fetuses develop in utero and may be subjected to differing hormonal environments based upon the sex of neighboring fetuses. Female fetuses developing between two males tend to show masculinized anatomical, physiological and behavioral traits as adults. Female fetuses developing without adjacent males, on the other hand, tend to show more feminized traits as adults. These traits include permanently altered hormone levels, reproductive organs, aggressive behaviors, secondary sex ratios and susceptibility to endocrine disruption. This intrauterine effect is due to the transfer of testosterone from male fetuses to adjacent fetuses. While these effects have been most clearly demonstrated in mice, other rodents and swine also show intrauterine position (IUP) effects. Some of these effects are similar to the influence of prenatal stress on adult phenotypes. A few reports on human twins suggest that variability in some masculine and feminine traits may be due to intrauterine hormonal signals. IUP effects may impact a number of scientific fields of research such as endocrine disruption, toxicology, population biology, animal production and health.

Effects of stress during pregnancy on maternal behavior in mice

The effects of stress experienced during pregnancy and raising stressed offspring on maternal behavior were investigated in Swiss-Webster mice. Dams were either stressed or not stressed during pregnancy, and raised either prenatally stressed or nonstressed cross-fostered pups. Maternal behaviors such as grooming, nursing, pup retrieval and maternal aggression were assessed during the first 4 days after birth. Nonstressed dams raising stressed pups and stressed dams raising nonstressed pups groomed and nursed their pups significantly less than did control dams (stressed dams raising stressed pups and nonstressed dams raising nonstressed pups). Nonstressed dams raising stressed pups were also the slowest to retrieve both the first and last pup in retrieval tests. Nonstressed dams raising nonstressed pups were significantly less aggressive than other dams. In contrast, stressed dams raising stressed pups exhibited high levels of nursing and grooming, retrieved their pups rapidly and were very aggressive towards an intruder. These results indicate that raising stressed pups, or experiencing stress during a pregnancy can have significant effects on maternal behaviors. Stressed dams raising stressed pups exhibit maternal care comparable to that of nonstressed dams raising nonstressed pups at least for nesting/nurturing behaviors, and show increased levels of aggression and pup retrieval.