Effects of perinatal diet and prenatal stress on the behavioural profile of aged male and female rats

Prenatal Cafeteria Diet Primes Anxiety-like Behavior Associated to Defects in Volume and Diffusion in the Fimbria-fornix of Mice Offspring

Prenatal exposure to high-energy diets primes brain alterations that increase the risk of developing behavioral and cognitive failures. Alterations in the structure and connectivity of brain involved in learning and memory performance are found in adult obese murine models and in humans. However, the role of prenatal exposure to high-energy diets in the modulation of the brain's structure and function during cognitive decline remains unknown. We used female C57BL6 mice (n = 10) exposed to a high-energy diets (Cafeteria diet (CAF)) or Chow diet for 9 weeks (before, during and after pregnancy) to characterize their effect on brain structural organization and learning and memory performance in the offspring at two-month-old (n = 17). Memory and learning performance were evaluated using the Y-maze test including forced and spontaneous alternation, novel object recognition (NORT), open field and Barnes maze tests. We found no alterations in the short- or long-time spatial memory performance in male offspring prenatally exposed to CAF diet when compared to the control, but they increased time spent in the edges resembling anxiety-like behavior. By using deformation-based morphometry and diffusion tensor imaging analysis we found that male offspring exposed to CAF diet showed increased volume in primary somatosensory cortex and a reduced volume of fimbria-fornix, which correlate with alterations in its white matter integrity. Biological modeling revealed that prenatal exposure to CAF diet predicts low volume in the fimbria-fornix, which was associated with anxiety in the offspring. The findings suggest that prenatal exposure to high-energy diets prime brain structural alterations related to anxiety in the offspring.

Sexual dimorphism in spatial learning and brain metabolism after exposure to a western diet and early life stress in rats

Prolonged daily intake of Western-type diet rich in saturated fats and sugars, and exposure to early life stress have been independently linked to impaired neurodevelopment and behaviour in animal models. However, sex-specific effects of both environmental factors combined on spatial learning and memory, behavioural flexibility, and brain oxidative capacity have still not been addressed. The current study aimed to evaluate the impact of maternal and postnatal exposure to a high-fat and high-sugar diet (HFS), and exposure to early life stress by maternal separation in adult male and female Wistar rats. For this purpose, spatial learning and memory and behavioural flexibility were evaluated in the Morris water maze, and regional brain oxidative capacity and oxidative stress levels were measured in the hippocampus and medial prefrontal cortex. Spatial memory, regional brain oxidative metabolism, and levels of oxidative stress differed between females and males, suggesting sexual dimorphism in the effects of a HFS diet and early life stress. Males fed the HFS diet performed better than all other experimental groups independently of early life stress exposure. However, behavioural flexibility evaluated in the spatial reversal leaning task was impaired in males fed the HFS diet. In addition, exposure to maternal separation or the HFS diet increased the metabolic capacity of the prefrontal cortex and dorsal hippocampus in males and females. Levels of oxidative stress measured in the latter brain regions were also increased in groups fed the HFS diet, but maternal separation seemed to dampen regional brain oxidative stress levels. Therefore, these results suggest a compensatory effect resulting from the interaction between prolonged exposure to a HFS diet and early life stress.

Behavioral effects of environmental enrichment on male and female wistar rats with early life stress experiences

Exposure to adverse childhood experiences or early life stress experiences (ELSs) increase the risk of non-adaptive behaviors and psychopathology in adulthood. Environmental enrichment (EE) has been proposed to minimize these effects. The vast number of methodological variations in animal studies underscores the lack of systematicity in the studies and the need for a detailed understanding of how enrichment interacts with other variables. Here we evaluate the effects of environmental enrichment in male and female Wistar rats exposed to adverse early life experiences (prenatal, postnatal, and combined) on emotional (elevated plus maze), social (social interaction chamber), memory (Morris water maze) and flexibility tasks. Our results—collected from PND 51 to 64—confirmed: 1) the positive effect of environmental enrichment (PND 28–49) on anxiety-like behaviors in animals submitted to ELSs. These effects depended on type of experience and type of enrichment: foraging enrichment reduced anxiety-like behaviors in animals with prenatal and postnatal stress but increased them in animals without ELSs. This effect was sex-dependent: females showed lower anxiety compared to males. Our data also indicated that females exposed to prenatal and postnatal stress had lower anxious responses than males in the same conditions; 2) no differences were found for social interactions; 3) concerning memory, there was a significant interaction between the three factors: A significant interaction for males with prenatal stress was observed for foraging enrichment, while physical enrichment was positive for males with postnatal stress; d) regarding cognitive flexibility, a positive effect of EE was found in animals exposed to adverse ELSs: animals with combined stress and exposed to physical enrichment showed a higher index of cognitive flexibility than those not exposed to enrichment. Yet, within animals with no EE, those exposed to combined stress showed lower flexibility than those exposed to both prenatal stress and no stress. On the other hand, animals with prenatal stress and exposed to foraging-type enrichment showed lower cognitive flexibility than those with no EE. The prenatal stress-inducing conditions used here 5) did not induced fetal or maternal problems and 6) did not induced changes in the volume of the dentate gyrus of the hippocampus.

Object recognition tasks in rats: Does sex matter?

Novelty recognition tasks based on object exploration are frequently used for the evaluation of cognitive abilities and investigation of neurobiological and molecular aspects of memory in rodents. This is an interesting approach because variations of the object recognition tasks focus on different aspects of the memory events such as novelty, location, context, and combinations of these elements. Nevertheless, as in most animal neuroscience research, female subjects are underrepresented in object recognition studies. When studies include females, the particularities of this sex are not always considered. For example, appropriate controls for manipulations conducted exclusively in females (such as estrous cycle verification) are not included. In addition, interpretation of data is often based on standardizations conducted with male subjects. Despite that, females are frequently reported as deficient and unable to adequately perform some memory tests. Thus, our study aims to review studies that describe similarities and differences between male and female performances in the different variations of object recognition tasks. In summary, although females are commonly described with deficits and the articles emphasize sex differences, most published data reveal similar performances when sexes are compared.

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.

Effects of ambient air pollution, fresh fruit and vegetable intakes as well as maternal psychosocial stress on the outcome of newborn otoacoustic emission hearing screening

BACKGROUND

Newborn hearing screening results indicated that more than 40% of the detected infants had no recognized risk factors. To determine whether maternal exposure to ambient air pollutants and experience of stressful life event, as well as lack of fresh fruit and vegetable during pregnancy are associated with the abnormal hearing development among newborns.

METHODS

A total of 1193 newborns and their mothers were recruited in this study. Personal information and covariates were collected by face to face interview. Medical examination results of newborns and their mothers were extracted from medical record. We estimated personal air pollutant exposure level through inverse distance weighted method based on data from air quality monitoring stations and assessed the auditory development of newborns via distortion product otoacoustic emission (DPOAE). Unconditional logistic regression model was used to estimate the relationship between DPOAE screening result and the potential influential factors as well as the combined effect.

RESULTS

The results indicated that PM₁₀ exposure during the second trimester and stressful life event during the third trimester could increase the risk of not passing DPOAE test among newborns. However, frequent intakes of fruit and vegetable significantly reduced the risk. There was a synergetic interaction between PM₁₀ exposure and stressful life event on neonatal hearing development.

CONCLUSIONS

To alleviate abnormal auditory development among fetus, pregnant woman should decrease the exposures to ambient air pollutant and negative life event and at the same time, intake sufficient fresh fruit and vegetable.

Western Diet Consumption During Development: Setting the Stage for Neurocognitive Dysfunction

The dietary pattern in industrialized countries has changed substantially over the past century due to technological advances in agriculture, food processing, storage, marketing, and distribution practices. The availability of highly palatable, calorically dense foods that are shelf-stable has facilitated a food environment where overconsumption of foods that have a high percentage of calories derived from fat (particularly saturated fat) and sugar is extremely common in modern Westernized societies. In addition to being a predictor of obesity and metabolic dysfunction, consumption of a Western diet (WD) is related to poorer cognitive performance across the lifespan. In particular, WD consumption during critical early life stages of development has negative consequences on various cognitive abilities later in adulthood. This review highlights rodent model research identifying dietary, metabolic, and neurobiological mechanisms linking consumption of a WD during early life periods of development (gestation, lactation, juvenile and adolescence) with behavioral impairments in multiple cognitive domains, including anxiety-like behavior, learning and memory function, reward-motivated behavior, and social behavior. The literature supports a model in which early life WD consumption leads to long-lasting neurocognitive impairments that are largely dissociable from WD effects on obesity and metabolic dysfunction.

Alterations in 'inflammatory' pathways in the rat prefrontal cortex as early biological predictors of the long-term negative consequences of exposure to stress early in life

Early life stress, especially when experienced during the first period of life, affects the brain developmental trajectories leading to an enhanced vulnerability for stress-related psychiatric disorders later in life. Although both clinical and preclinical studies clearly support this association, the biological pathways deregulated by such exposure, and the effects in shaping the neurodevelopmental trajectories, have so far been poorly investigated. By using the prenatal stress (PNS) model, a well-established rat model of early life stress, we performed transcriptomic analyses in the prefrontal cortex of rats exposed or not to PNS and sacrificed at different postnatal days (PNDs 21, 40, 62). We first investigated the long-lasting mechanisms and pathways affected in the PFC. We have decided to focus on the prefrontal cortex because we have previously shown that this brain region is highly sensitive to PNS exposure. We found that adult animals exposed to PNS show alterations in 389 genes, mainly involved in stress and inflammatory signalling. We then wanted to establish whether PNS exposure could also affect the neurodevelopmental trajectories in order to identify the most critical temporal window. We found that PNS rats show the most significant changes during adolescence (between PND 40 versus PND 21), with alterations of several pathways related to stress, inflammation and metabolism, which were maintained until adulthood.

Prenatal Maternal Distress: A Risk Factor for Child Anxiety?

The deleterious association between various types of prenatal maternal psychological distress (PNMS, anxiety, depression, psychological distress, stress) and childhood anxiety symptomatology (internalizing behaviors, anxiety symptoms) has been established using both retrospective and prospective longitudinal studies across varied demographic cohorts and throughout development. Yet, the existing literature cannot claim maternal distress during pregnancy to be a specific risk factor for anxiety symptomatology, as studies utilizing such observational designs are unable to adequately account for confounding of potential genetic factors and the postnatal environment. In this review, we examine studies that attempt to minimize such confounding and thus disentangle the unique intrauterine exposure effect of varying types of PNMS on childhood anxiety symptomatology. Such methodologies include paternal versus maternal comparison studies, sibling comparisons, prenatal cross-fostering designs and timing of exposure studies (including disaster studies). Of the identified studies, findings indicate that prenatal maternal distress is likely to constitute a risk factor for anxiety symptomatology, although more studies are needed to replicate current findings in order to determine whether there are clear differences in effects across specific types of PNMS and for specific subpopulations. We review the methodological limitations and strengths of the literature prior to exploring avenues of future research and implications for theory and clinical practice.

Carbohydrates and cognitive function

PURPOSE OF REVIEW

Recent evidence documents the negative impact of obesity, diabetes mellitus, and other metabolic dysregulation on neurocognitive function. This review highlights a key dietary factor in these relationships: refined carbohydrates.

RECENT FINDINGS

Chronic consumption of refined carbohydrates has been linked to relative neurocognitive deficits across the lifespan. Hippocampal function is especially impacted, but prefrontal and mesolimbic reward pathways may also be altered. Early life exposure to refined carbohydrates, (i.e., prenatal, juvenile, and adolescence periods) may be particularly toxic to cognitive functioning. The impact of acute carbohydrate administration is mixed, with some findings showing benefits while others are neutral or negative. Potential mechanisms of the carbohydrate-cognition relationship include dysregulation in metabolic, inflammatory, and vascular factors, whereas moderators include age, genetic factors, physiological (e.g., glucoregulatory) function and the timing and type of carbohydrate exposure. Critically, the negative neurocognitive impacts of diets high in refined carbohydrates have been shown to be independent of total body weight.

SUMMARY

Neurocognitive deficits induced by a diet high in refined carbohydrates may manifest before overt obesity or metabolic disease onset, suggesting that researchers and providers may need to target subclinical metabolic, inflammatory, and vascular dysregulation factors in efforts to preserve cognitive function across the lifespan.