Maternal High-fat Diet Programs Offspring Emotional Behavior in Adulthood

Relationship of maternal high-fat diet during pregnancy and lactation to offspring health

A balanced maternal diet is essential for proper fetal development, and the consumption of a nutritionally inadequate diet during intrauterine development and early childhood is associated with a significantly increased risk of metabolic and brain disorders in offspring. The current literature indicates that maternal exposure to a high-fat diet exerts an irreversible influence on the general health of the offspring. This review of preclinical research examines the relationship between a maternal high-fat diet during pregnancy or lactation and metabolic changes, molecular alterations in the brain, and behavioral disorders in offspring. Animal models indicate that offspring exposed to a maternal high-fat diet during pregnancy and lactation manifest increased depressive-like and aggressive behaviors, reduced cognitive development, and symptoms of metabolic syndrome. Recently, epigenetic and molecular studies have shown that maternal nutrition during pregnancy and the suckling period modifies the development of neurotransmitter circuits and many other factors important to central nervous system development. This finding confirms the importance of a balanced maternal diet for the health of offspring.

Maternal stressors and the developmental origins of neuropsychiatric risk

The maternal environment during pregnancy is critical for fetal development and perinatal perturbations can prime offspring disease risk. Here, we briefly review evidence linking two well-characterized maternal stressors - psychosocial stress and infection - to increased neuropsychiatric risk in offspring. In the current climate of increasing obesity and globalization of the Western-style diet, maternal overnutrition emerges as a pressing public health concern. We focus our attention on recent epidemiological and animal model evidence showing that, like psychosocial stress and infection, maternal overnutrition can also increase offspring neuropsychiatric risk. Using lessons learned from the psychosocial stress and infection literature, we discuss how altered maternal and placental physiology in the setting of overnutrition may contribute to abnormal fetal development and resulting neuropsychiatric outcomes. A better understanding of converging pathophysiological pathways shared between stressors may enable development of interventions against neuropsychiatric illnesses that may be beneficial across stressors.

Significant Effects of Maternal Diet During Pregnancy on the Murine Fetal Brain Transcriptome and Offspring Behavior

BACKGROUND

Maternal over- and undernutrition in pregnancy plays a critical role in fetal brain development and function. The effects of different maternal diet compositions on intrauterine programing of the fetal brain is a lesser-explored area. The goal of this study was to investigate the impact of two chowmaternal diets on fetal brain gene expression signatures, fetal/neonatal growth, and neonatal and adult behavior in a mouse model.

METHODS

Throughout pregnancy and lactation, female C57Bl/6J mice were fed one of two standard, commercially available chow diets (pellet versus powder). The powdered chow diet was relatively deficient in micronutrients and enriched for carbohydrates and n-3 long-chain polyunsaturated fatty acids compared to the pelleted chow. RNA was extracted from embryonic day 15.5 forebrains and hybridized to whole genome expression microarrays (N = 5/maternal diet group). Functional analyses of significantly differentially expressed fetal brain genes were performed using Ingenuity Pathways Analysis and Gene Set Enrichment Analysis. Neonatal behavior was assessed using a validated scale (N = 62 pellet-exposed and 31 powder-exposed). Hippocampal learning, locomotor behavior, and motor coordination were assessed in a subset of adults using fear conditioning, open field testing, and Rotarod tests (N = 16 pellet-exposed, 14 powder-exposed).

RESULTS

Comparing powdered to pelleted chow diets, neither maternal weight trajectory in pregnancy nor embryo size differed. Maternal powdered chow diet was associated with 1647 differentially expressed fetal brain genes. Functional analyses identified significant upregulation of canonical pathways and upstream regulators involved in cell cycle regulation, synaptic plasticity, and sensory nervous system development in the fetal brain, and significant downregulation of pathways related to cell and embryo death. Pathways related to DNA damage response, brain immune response, amino acid and fatty acid transport, and dopaminergic signaling were significantly dysregulated. Powdered chow-exposed neonates were significantly longer but not heavier than pelleted chow-exposed counterparts. On neonatal behavioral testing, powdered chow-exposed neonates achieved coordination- and strength-related milestones significantly earlier, but sensory maturation reflexes significantly later. On adult behavioral testing, powdered chow-exposed offspring exhibited hyperactivity and hippocampal learning deficits.

CONCLUSION

In wild-type offspring, two diets that differed primarily with respect to micronutrient composition had significant effects on the fetal brain transcriptome, neonatal and adult behavior. These effects did not appear to be mediated by alterations in gross maternal nutritional status nor fetal/neonatal weight. Maternal dietary content is an important variable to consider for investigators evaluating fetal brain development and offspring behavior.

Maternal Consumption of a Diet Rich in Maillard Reaction Products Accelerates Neurodevelopment in F1 and Sex-Dependently Affects Behavioral Phenotype in F2 Rat Offspring

Thermal processing of foods at temperatures > 100 °C introduces considerable amounts of advanced glycation end-products (AGEs) into the diet. Maternal dietary exposure might affect the offspring early development and behavioral phenotype in later life. In a rat model, we examined the influence of maternal (F0) dietary challenge with AGEs-rich diet (AGE-RD) during puberty, pregnancy and lactation on early development, a manifestation of physiological reflexes, and behavioral phenotype of F1 and F2 offspring. Mean postnatal day of auditory conduit and eye opening, or incisor eruption was not affected by F0 diet significantly. F1 AGE-RD offspring outperformed their control counterparts in hind limb placing, in grasp tests and surface righting; grandsons of AGE-RD dams outperformed their control counterparts in hind limb placing and granddaughters in surface righting. In a Morris water maze, female AGE-RD F1 and F2 offspring presented better working memory compared with a control group of female offspring. Furthermore, male F2 AGE-RD offspring manifested anxiolysis-like behavior in a light dark test. Mean grooming time in response to sucrose splash did not differ between dietary groups. Our findings indicate that long-term maternal intake of AGE-RD intergenerationally and sex-specifically affects development and behavioral traits of offspring which have never come into direct contact with AGE-RD.

Maternal Flavonoids Intake Reverts Depression-Like Behaviour in Rat Female Offspring

Maternal hypercaloric exposure during pregnancy and lactation is a risk factor for developing diseases associated with inflammation such as obesity, diabetes and, neurological diseases in the offspring. Neuroinflammation might modulate neuronal activation and flavonoids are dietary compounds that have been proven to exert anti-inflammatory properties. Thus, the aim of the present study is to evaluate the effect of maternal supplementation with flavonoids (kaempferol-3-O-glucoside and narirutin) on the prevention of depression-like behaviour in the female offspring of dams fed with an obesogenic diet during the perinatal period. Maternal programming was induced by high fat (HFD), high sugar (HSD), or cafeteria diets exposure and depressive like-behaviour, referred to as swimming, climbing, and immobility events, was evaluated around postnatal day 56–60 before and after 30 mg/kg i.p. imipramine administration in the female offspring groups. Central inflammation was analyzed by measuring the TANK binding kinase 1 (TBK1) expression. We found that the offspring of mothers exposed to HSD programming failed to show the expected antidepressant effect of imipramine. Also, imipramine injection, to the offspring of mothers exposed to cafeteria diet, displayed a pro-depressive like-behaviour phenotype. However, dietary supplementation with flavonoids reverted the depression-like behaviour in the female offspring. Finally, we found that HSD programming increases the TBK1 inflammatory protein marker in the hippocampus. Our data suggest that maternal HSD programming disrupts the antidepressant effect of imipramine whereas cafeteria diet exposure leads to depressive-like behaviour in female offspring, which is reverted by maternal flavonoid supplementation.

Comparative analysis of the influence of a high-fat/high-carbohydrate diet on the level of anxiety and neuromotor and cognitive functions in Wistar and DAT-KO rats

We compared anxiety, neuromotor, and cognitive functions in mutant rats with different allelic variants of dopamine transporter DAT knockout receiving balanced or excess in fat and fructose diet. The experiments were performed in DAT-/- homozygotes, DAT+/- heterozygotes, and DAT+/+ wild type rats. The genotype of DAT-KO rats was confirmed by restriction analysis of DAT gene compared to behavioral responses in the open field test (OF). Animals in the first groups of each strain were fed a balanced AIN93M diet; and those in the second groups with a high-fat/high-fructose diet. Neuromotor function was studied as grip strength, and behavioral responses were assessed in the elevated plus maze and conditioned passive avoidance response tests. The mass of the internal organs and white and brown fat, as well as selected lipid and nitrogen metabolism parameters in blood plasma were determined at the end of the experiment. DAT-/- had the highest specific grip strength, and showed an increase in initial exploratory activity in comparison with DAT+/- and DAT +/+. The exploratory activity was significantly reduced in the second test compared to the first one in DAT-/- and DAT+/- of first but not second group. Anxiety decreased with age in the second groups of DAT+/- and DAT+/+ (but not in DAT-/-) and was higher in DAT+/+ than in DAT+/- and DAT-/-. Excess fat and fructose resulted in the deterioration of short-term memory in DAT+/+. Lipidomic indices of blood plasma were less responsive to diet in DAT-/- and DAT-/+ in comparison to DAT+/+. The increased AsAT/AlAT activity ratio in DAT-/- compared with those in DAT+/+ suggests the activation of catabolism activity in the mutants. The consumption of excess fat and fructose significantly modified the effects produced by DAT gene allelic variants presumably due to the influence on the processes of dopamine metabolism.

Placental Macrophages: A Window Into Fetal Microglial Function in Maternal Obesity

Fetal placental macrophages and microglia (resident brain macrophages) have a common origin in the fetal yolk sac. Yolk-sac-derived macrophages comprise the permanent pool of brain microglia throughout an individual's lifetime. Inappropriate fetal microglial priming may therefore have lifelong neurodevelopmental consequences, but direct evaluation of microglial function in a living fetus or neonate is impossible. We sought to test the hypothesis that maternal obesity would prime both placental macrophages and fetal brain microglia to overrespond to an immune challenge, thus providing a window into microglial function using placental cells. Obesity was induced in C57BL/6 J mice using a 60% high-fat diet. On embryonic day 17.5, fetal brain microglia and corresponding CD11b + placental cells were isolated from fresh tissue. Cells were treated with media or lipopolysaccharide (LPS). Tumor necrosis factor-alpha (TNF-α) production by stimulated and unstimulated cells was quantified via ELISA. We demonstrate for the first time that the proinflammatory cytokine production of CD11b + placental cells is strongly correlated with that of brain microglia (Spearman's ρ = 0.73, p = 0.002) in the setting of maternal obesity. Maternal obesity-exposed CD11b + cells had an exaggerated response to LPS compared to controls, with a 5.1-fold increase in TNF-α production in placentas (p = 0.003) and 3.8-fold increase in TNF-α production in brains (p = 0.002). In sex-stratified analyses, only male obesity-exposed brains and placentas had significant increase in TNF-α production in response to LPS. Taken together, these data suggest that maternal obesity primes both placental macrophages and fetal brain microglia to overproduce a proinflammatory cytokine in response to immune challenge. Male brain and placental immune response is more marked than female in this setting. Given that fetal microglial priming may impact neuroimmune function throughout the lifespan, these data could provide insight into the male predominance of certain neurodevelopmental morbidities linked to maternal obesity, including cognitive dysfunction, autism spectrum disorder, and ADHD. Placental CD11b+ macrophages may have the potential to serve as an accessible biomarker of aberrant fetal brain immune activation in maternal obesity. This finding may have broader implications for assaying the impact of other maternal exposures on fetal brain development.

Grandmaternal high-fat diet primed anxiety-like behaviour in the second-generation female offspring

The health consequences of maternal obesity during pregnancy are disturbing as they may contribute to mental disorders in subsequent generations. We examine the influence of suboptimal grandmaternal diet on potential metabolic and mental health outcome of grand-progenies with a high-fat diet (HFD) manipulation in adulthood in a rat HFD model. Grandmaternal exposure to HFD exacerbated granddaughter's anxiety-like phenotype. Grandmaternal exposure to HFD led to upregulated corticotropin-releasing hormone receptor 2 mRNA expression involved in the stress axis in the male F₂ offspring. Thus, we demonstrate that suboptimal grandmaternal diet prior to and during pregnancy and lactation may persist across subsequent generations. These findings have important implications for understanding both individual rates of metabolic and mental health problems and the clinical impact of current global trends towards comorbidity of obesity and depression and anxiety. In conclusion, the effect of grandmaternal HFD consumption during pregnancy on stress axis function and mental disorders may be transmitted to future generations.