Late-gestation Stress Research Articles

Impacts of Maternal Noise Exposure on Risk of Stillbirth and Oxidative Stress-Induced Neurobehavioral Changes in Offspring

Life does not start at birth but at conception. Embryonic development is a particularly difficult period in which genetic and environmental factors can interact to contribute to risk. In utero and early neonatal exposure to maternal stress are linked with psychiatric disorders, and the underlying mechanisms are currently being elucidated. This study examined novel relationships between maternal noise exposure causing oxidative-stress-induced neurobehavioral changes in cognition and autism spectrum disorder (ASD) in offspring. Pregnant Wistar albino rats were exposed to noise (100 dBA/4 h). There were three groups of pregnant rats exposed to noise during gestation, as well as a control group: early gestational stress (EGS), which occurs between the 1st and 10th days of pregnancy; late gestational stress (LGS), which occurs between the 11th day and the delivery day; and full-term gestational stress (FGS), which occurs during the entire pregnancy period. Maternal stress effects on the offspring were analyzed. This study observed that noise exposure becomes a psychosocial stressor in the prenatal period of motherhood. In the EGS and LGS groups, female rats showed continuous midterm abortion and stillbirth during noise exposure. The noise-exposed group exhibited significant changes in cognition, obsessive–compulsive behavior, fear, and anxiety. Corticosterone and oxidative stress markers increased, and the antioxidant level was significantly decreased in the noise-exposed group. Therefore, maternal noise exposure causes recurrent abortions and stillbirths, increases oxidative stress, and impairs the offspring’s neurodevelopment.

Adverse Maternal Environments Perturb Hepatic DNA Methylome and Transcriptome Prior to the Adult-Onset Non-Alcoholic Fatty Liver Disease in Mouse Offspring

Exposure to adverse early-life environments (AME) increases the incidence of developing adult-onset non-alcoholic fatty liver disease (NAFLD). DNA methylation has been postulated to link AME and late-onset diseases. This study aimed to investigate whether and to what extent the hepatic DNA methylome was perturbed prior to the development of NAFLD in offspring exposed to AME in mice. AME constituted maternal Western diet and late-gestational stress. Male offspring livers at birth (d0) and weaning (d21) were used for evaluating the DNA methylome and transcriptome using the reduced representation of bisulfite sequencing and RNA-seq, respectively. We found AME caused 5879 differentially methylated regions (DMRs) and zero differentially expressed genes (DEGs) at d0 and 2970 and 123, respectively, at d21. The majority of the DMRs were distal to gene transcription start sites and did not correlate with DEGs. The DEGs at d21 were significantly enriched in GO biological processes characteristic of liver metabolic functions. In conclusion, AME drove changes in the hepatic DNA methylome, which preceded perturbations in the hepatic metabolic transcriptome, which preceded the onset of NAFLD. We speculate that subtle impacts on dynamic enhancers lead to long-range regulatory changes that manifest over time as gene network alternations and increase the incidence of NAFLD later in life.

Uterine contractile activity and fetal outcome in rats treated with vitamin C during late gestational variable stress exposure.

Stress responses vary throughout pregnancy and impact of late gestational variable stress (LGVS) with vitamin C supplementation on uterine contractility is barely explored. This study investigates fetal weight outcome and in-vitro uterine contractile responses to pharmacological agents during LGVS exposure. Twenty four nulliparous pregnant rats were divided into four groups of six. During gestation days 10-19, groups 1 & 2 received normal saline and vitamin C (10mg/kg) respectively. Groups 3 and 4 were exposed to stress (sleep deprivation, predator exposure, immobility, rapid cage changes, noise, and foreign object) with group 4 concurrently supplemented with vitamin C (10mg/kg). Serum cortisol, oxidative bio-markers, fetal weights and in-vitro contractile responses of excised uterine tissue to acetylcholine (Ach), oxytocin, calcium chloride (CaCl2), potassium chloride (KCl), diclofenac, and magnesium ions were determined. Malondialdehyde activity and cortisol were significantly increased in variable stress only exposed group when compared with control and vitamin C supplemented groups. Fetal body weights, superoxide dismutase and catalase activity were significantly reduced in variable stress only exposed group. Significantly impaired contractile responses to Ach, CaCl2 & KCl in variable stress only exposed group were modulated in vitamin C supplemented groups. Impaired contractile response to oxytocin was however not reversed. Relaxation responses to diclofenac and magnesium ions were statistically unaltered across groups. Impaired fetal weights and uterine contractile activity to Ach, CaCl2 and KCl during LGVS was modulated by vitamin C supplementation. Impaired oxytocin contractile activity was however unreversed.

35 Effect of Late Gestational Heat Stress on Placental Characteristics in Dairy Cattle

Abstract To determine the effects of late gestation heat stress on placental development, dairy cows were exposed to heat stress (HT, shade) or cooled (CL, shade, fans and soakers) during the final 46 d pre-calving on the University of Florida dairy facility (temperature-humidity index; THI >68). We hypothesize heat stress (or lack of heat abatement) will reduce placental efficiency and in turn increase placental weight, surface area, and volume. At expulsion all placentae were collected and total placental weight was determined as well as individual cotyledonary weights, surface areas, and volume. In addition, the total number of total cotyledons was recorded and cotyledonary color and placental growth abnormalities (i.e. teratomas) were recorded and photographed. All data were analyzed using PROC MIXED in SAS. In addition, associations between parameters were determined by calculating Pearson Correlation Coefficients using SAS. Placentae from HT cows had a higher total placental weight, higher non-vascular membrane weight, higher total cotyledonary weight, higher total cotyledonary volume, and a higher incidence of teratomas than those from CL cows (P < 0.05). HT cows also had placentae with a significantly greater average cotyledonary weight and volume (P < 0.05). HT cows tended to have a greater incidence of color abnormalities in the placenta (P < 0.075). In addition, HT cows had significantly lighter calves at birth (P < 0.05). These data demonstrate that heat stress (or lack of heat abatement) impacts placental growth during the final stages of gestation, resulting in heavier placentae, an increase in cotyledonary weight and volume, but not an increase in the total number of cotyledons or total cotyledonary surface area. These placental alterations ultimately resulted in lighter calves at birth.

Long-Term Effects of Late Gestation in Utero Hypoxic Stress on Neurodegeneration: Sex and Age Differences

Abstract Introduction: In utero insults have been proposed to lead to the onset of neurodegenerative diseases later in life, such as Parkinson’s disease (PD). In utero hypoxia is associated with a multitude of conditions, such as maternal sleep apnea, preeclampsia, gestational diabetes, and maternal hypertension. Exposure to in utero hypoxia may impact male progeny more than female progeny, which may underlie the male biased sex differences in PD. It is currently unknown whether late gestational hypoxic stress has a long-term effect on brain regions associated with PD, such as the nigrostriatal pathway. We hypothesized that exposure to late gestational hypoxia will result in nigrostriatal impairment in adult male progeny compared to adult female progeny. Methods: Timed pregnant female Long-Evans rats were exposed to five days (gestational days: 15-20) of chronic intermittent hypoxia (CIH) or room air (normoxia - 21% O2) for 8 hours during their sleep phase. Each CIH cycle was 6 min of 3 min hypoxia (10% O2) and 3 min normoxia (21% O2) for a total of 10 CIH cycles/hour. Gestational age at delivery was recorded and neonate’s body weights were measured within 12-16 hours from birth. At weaning (postnatal day, PND 28), progeny was pair-housed with a conspecific of the same sex and similar weight. To examine PD, we focused on PD associated characteristics of oxidative stress in the nigrostriatal pathway and behavioral impairments of motor (open field activity and ultrasonic vocalizations) and cognitive (spatial memory) function during puberty (PND 40-45) and young adulthood (PND 60-65). Results: Gestational CIH had no effect on the duration of gestation, litter size, and neonatal weight at birth. Gestational CIH did not impact circulating oxidative stress, regardless of sex or age of progeny. Offspring gross motor function (open field activity) and cognitive (Morris Water maze) function were unaffected by gestational CIH. In contrast, gestational CIH impaired ultrasonic vocalizations in adult male progeny. Gestational CIH increased the latency to vocalize and decreased the loudness of the vocalizations in adult male progeny. Conclusion: Exposure to CIH during gestation resulted in nigrostriatal impairment in adult male progeny, as evidenced by impaired ultrasonic vocalizations that require a functional nigrostriatal pathway. In utero hypoxia during late gestation may increase the risk for PD in males.

Neuroprotective Role of N-acetylcysteine against Learning Deficits and Altered Brain Neurotransmitters in Rat Pups Subjected to Prenatal Stress.

Prenatal adversaries like stress are known to harm the progeny and oxidative stress, which is known to be one of the causative factors. N-acetyl cysteine (NAC), which is a potent antioxidant, has been shown to play a neuroprotective role in humans and experimental animals. This study examines the benefits of NAC on the prenatal stress-induced learning and memory deficits and alteration in brain neurotransmitter in rat pups. Pregnant dams were restrained (45 min; 3 times/day) during the early or late gestational period. Other groups received early or late gestational restrain stress combined with NAC treatment throughout the gestational period. At postnatal day (PND) 28, offspring were tested in a shuttle box for assessing learning and memory, which was followed by a brain neurotransmitter (dopamine, norepinephrine, and serotonin) estimation on PND 36. Late gestational stress resulted in learning deficits, the inability to retain the memory, and reduced brain dopamine content while not affecting norepinephrine and serotonin. NAC treatment in prenatally stressed rats reversed learning and memory deficits as well as brain dopamine content in offspring. These findings suggest that NAC protect the progeny from an undesirable cognitive sequel associated with prenatal stress.

Combined effect of gestational stress and postpartum stress on maternal care in rats

Variations in maternal care in the rat influence the development of individual differences in behavioral and endocrine responses to stress. This study aimed to examine the interaction between intragastric intubation during late gestation and postpartum stress, induced by pup separation, on maternal behavior and on dams' emotional state and HPA axis function. Rats received intragastric intubation of water on days 12–20 of gestation or remained untreated in their home cage (naïve dams). Pup separation was used as a model of postpartum stress. The procedure consisted of a daily separation of the dam from its litter for 3h from PND 3 until PND 15. Pup separation was carried out in both naïve and intubated dams. The behavioral results indicate that the association of these two stressors significantly decreased arched-back nursing (ABN) and licking and grooming (LG), behaviors considered important parameters to discriminate the high quality of maternal care. Moreover, dams that received both stressors displayed less nest building and blanket nursing behaviors; no effect on the frequency of passive and total nursing was recorded. The analysis of single effects on ABN and LG, revealed that dams that underwent gestational stress induced by intragastric intubation displayed less LG, but ABN was overall unchanged. On the contrary, pup separation stress significantly increased ABN and LG upon reunion of naïve dams with their pups. Treatments per se or the association of both induced modest changes in plasma levels of allopregnanolone and corticosterone that likely did not influence maternal care. These data show that the association of a mild stress during gestation with an unfavorable experience after parturition had a significant impact on maternal care. This effect seems independent from HPA axis activation or from changes in emotional state; further studies would be necessary to ascertain the neural changes that could contribute to altered maternal behavior in stressed mothers. Moreover, these results suggest that the use of intragastric intubation during gestation would interfere with measures of drug-induced changes in maternal behavior and likely their consequences on the offspring.

Status of the brain antioxidant system at different growing periods after prenatal stress and N -acetyl cysteine administration.

<i>Prenatal stress-induced neurobehavioral deficits observed in offspring are multifactorial, including oxidative stress in the developing brain. The time by which the developing brain acquires self-defense against oxidative stress is not clear. Hence in the present study we aimed to evaluate the brain antioxidant status during different developing periods. Further the study also evaluates the role of the glutathione precursor, N-acetyl cysteine (NAC) on the brain antioxidant status. Pregnant rats were subjected to restraint stress during an early or late gestational period. Another set of rats received NAC during the entire gestational period along with early or late gestational stress. The study parameters included several antioxidant studies directly from rat brain homogenate on postnatal day 24 or 48. Early or late gestational stress has caused severe oxidative stress in the developing brain on postnatal day 24 in all the parameters studied. However, brain reduced glutathione (GSH), superoxide dismutase (SOD) and total antioxidant activity (TAO) were not affected by either early or late gestational stress on postnatal day 48, but the brain malondialdehyde (MDA) level remained high and brain glutathione reductase (GSS-Rd) level remained low on postnatal day 48. Prenatal NAC treatment has reversed the oxidative damage in all the parameters on postnatal day 24 and also the brain MDA level and GSS-Rd level on postnatal day 48. This study confirms that the growing brain acquires antioxidant capacity over time but during early postnatal development it is vulnerable to oxidative stress and related neurological consequences. N-acetyl cysteine treatment during the prenatal period as an antioxidant supplement exerted a beneficiary effect in this study. Hence glutathione supplement in the nutritional source would be an idealistic approach to prenatal stress-induced neurological comorbidities in children.</i>.

Primary tooth size asymmetry in twins and singletons.

To explore asymmetry values of antimeric deciduous tooth crown dimensions in three types of twins: monozygotic (MZ), dizygotic same-sex (DZ) and opposite-sex (OS) vs. single-born controls. Mesiodistal and labio-lingual crown dimensions of second deciduous molars and mesiodistal canine and first molar crown dimensions of 2159 children at 6-12 years of age were evaluated, originating from the US cross-sectional Collaborative Perinatal Study from the 1970s, including altogether MZ (n = 28), DZ same-sex (n = 33) and OS (n = 39) pairs. Single born (n = 1959) were used as controls. Dental casts were measured for comparison of variance relationships calculated from antimeric teeth, exhibiting fluctuating (FA), and directional (DA) asymmetry using anova. Significant differences appeared in MZ and OS girls in DA of deciduous canines, which gain size in the first and second trimester, and deciduous second molars, which finally stop crown growth during the early post-natal period. Significantly, increased FA values appeared for lower deciduous canines and second molars, indicating greatest environmental stress in OS girls, MZ girls and DZ boys. Twin girls had more fluctuating and directional crown asymmetry than twin boys, but in some dimensions, the twins were more symmetric than controls. Transmembrane hormonal influence between opposite-sex twins, and late gestational stress factors, caused by placental malfunction and/or monochorionicity, may be involved in asymmetric growth of antimers, during critical periods of crown size gain.

Prenatal stress-induced alterations in major physiological systems correlate with gut microbiota composition in adulthood

Early-life adverse experiences, including prenatal stress (PNS), are associated with a higher prevalence of neurodevelopmental, cardiovascular and metabolic disorders in affected offspring. Here, in a rat model of chronic PNS, we investigate the impact of late gestational stress on physiological outcomes in adulthood. Sprague-Dawley pregnant dams were subjected to repeated restraint stress from embryonic day 14 to day 20, and their male offspring were assessed at 4 months of age. PNS induced an exaggeration of the hypothalamic-pituitary-adrenal (HPA) axis response to stress, as well as an elevation of blood pressure and impairment of cognitive function. Altered respiratory control was also observed, as demonstrated by increased variability in basal respiratory frequency and abnormal frequency responses to both hypoxic and hypercapnic challenges. PNS also affected gastrointestinal neurodevelopment and function, as measured by a decrease in the innervation density of distal colon and an increase in the colonic secretory response to catecholaminergic stimulation. Finally, PNS induced long lasting alterations in the intestinal microbiota composition. 16S rRNA gene 454 pyrosequencing revealed a strong trend towards decreased numbers of bacteria in the Lactobacillus genus, accompanied by elevated abundance of the Oscillibacter, Anaerotruncus and Peptococcus genera in PNS animals. Strikingly, relative abundance of distinct bacteria genera significantly correlated with certain respiratory parameters and the responsiveness of the HPA axis to stress. Together, these findings provide novel evidence that PNS induces long-term maladaptive alterations in the gastrointestinal and respiratory systems, accompanied by hyper-responsiveness to stress and alterations in the gut microbiota.

Resveratrol for prenatal-stress-induced oxidative damage in growing brain and its consequences on survival of neurons

Prenatal-stress-induced neuronal damage in offspring is multifactorial, including oxidative damage in the developing brain. Resveratrol is known to exert its neuroprotective potentials by upregulating several antioxidant systems. Hence, the study was undertaken to evaluate the neuroprotective effect of resveratrol against prenatal-stress-induced hippocampal damage and oxidative damage in neonate rat brains. Pregnant rats were subjected to restraint stress during early or late gestational period. Another set of rats received resveratrol during the entire gestational period along with early or late gestational stress. The study parameters included several antioxidant studies directly from rat brain homogenate on the 40th postnatal day and hippocampal neuronal assay on the 21st postnatal day. Early as well as late gestational stress resulted in a significant increase in lipid peroxidation and advanced oxidation protein products and decrease in total antioxidant activity and nitric oxide levels in rat brain homogenate. The neurons of the dentate gyrus were severely affected in early and late gestational stress, and only the neurons of the CA3 region were adversely affected in late gestational stress. Administration of resveratrol reversed the prenatal-stress-induced oxidative damage and neurons of dentate gyrus but not the CA3 hippocampal neurons. These results show the neuroprotective abilities of resveratrol against prenatal-stress-induced oxidative damage in neonatal rat brain.

Resveratrol improves postnatal hippocampal neurogenesis and brain derived neurotrophic factor in prenatally stressed rats

Prenatal stress induced neuronal dysfunction is multifactorial, including suppressed neurogenesis in developing brain. Resveratrol is known to exert its neuroprotective potential by enhancing neurogenesis. But the efficacy of resveratrol against prenatal stress was not addressed in detail. Hence in the present study we evaluated the neuroprotective action of resveratrol on prenatal stress-induced impaired neurogenesis. Pregnant rats were subjected to restraint stress during early or late gestational period. Another sets of rats received resveratrol during entire gestational period along with early or late gestational stress. The study parameters included neuronal assay of doublecortin positive neurons (DCX +ve) and brain derived neurotrophic factor (BDNF) estimations in 40th postnatal day rat brain. Both early and late gestational stress resulted in significant decrease in generation of new born neurons and BDNF expression in hippocampus. The decrease in number of DCX +ve neurons and hippocampal BDNF expression was more profound in the offspring who received late gestational stress compared to early gestational stress. Resveratrol treatment has improved the expression of DCX +ve neurons and BDNF expression. These data suggest the neuroprotective efficacy of resveratrol against prenatal stress induced impaired neurogenesis.

Neuroprotective effect of resveratrol against prenatal stress induced cognitive impairment and possible involvement of Na+, K+-ATPase activity

Resveratrol, an active ingredient of red wine extracts, has been shown to exhibit neuroprotective effects in several experimental models. Hence in the present study, the protective effects of resveratrol on cognitive deficits induced by prenatal stress were evaluated in offspring, and the possible involvement of Na+, K+-ATPase in learning deficits were explored. Pregnant rats were subjected to restraint stress during early or late gestational period. Another set of rats received resveratrol during the entire gestational period along with early or late gestational stress. The study parameters included various behavioral tests like open field test and Morris water maze test. At the end of the behavioral tests (on 40th postnatal day), the offspring were sacrificed, and their brain homogenate was subjected to Na+, K+-ATPase estimation. Early and late gestational stress affected spatial learning and memory and prenatal resveratrol has reversed these cognitive deficits. The Na+, K+-ATPase activity in the offspring brain homogenate was reduced in the late gestational stress group; however prenatal resveratrol treatment has not affected this activity. These data suggest the neuroprotective efficacy of resveratrol against prenatal stress induced cognitive impairment. Though late gestational stress involves Na+, K+-ATPase activity in rat brain homogenate, this would not be the primary cause in prenatal stress-induced cognitive dysfunction.

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

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

Maternal Stress During Pregnancy Predisposes for Iron Deficiency in Infant Monkeys Impacting Innate Immunity

The influence of maternal stress during pregnancy on the postpartum iron status and immune maturation of infants was investigated in a nonhuman primate model. Forty infant rhesus monkeys were generated from two types of disturbed pregnancies, early or late gestation stress, and compared with 24 undisturbed controls. Prenatal stress increased the prevalence and magnitude of iron deficiency (ID) as the infants' growth-related demands for iron exceeded dietary intake from breast milk. At 4-6 mo of age, the emergence of ID significantly accentuated an effect of prenatal stress on natural killer cell activity, an important component of innate immunity. These findings indicate that maternal stress, especially early in pregnancy, should be added to the list of risk factors that warrant closer scrutiny of hematological profiles in fast-growing babies.

Clinical Problems Associated with Starvation in Western Beef Herds

The term "starvation", as I refer to it, may cover several situations:(I) Complete deprivation of food is probably rarely seen by the practitioner and is usually due to severe weather conditions-floods, blizzards, drought, etc. (2) Simple slow starvation (protein and energy deficiency) is seen far more often, particularly in cold climates during late winter and early spring months when animal's nutritional requirements are going up due to late gestation, lactation, and / or cold stress, often in the face of reduced feed . (3) Partial starvation, is the deficiencies of one or more essential nutrient. Other nutrients may be substandard, minimal or adequate. This condition is often confused by the presence of concurrent infectious disease problems. The last situation is one which western bovine practitioners see often but may not recognize.