Early postnatal environmental enrichment restores neurochemical and functional plasticities of the cerebral cortex and improves learning performance in hidden-prenatally-malnourished young-adult rats

Nurturing development: how a mother's nutrition shapes offspring's brain through the gut

Pregnancy is a transformative period marked by profound physical and emotional changes, with far-reaching consequences for both mother and child. Emerging research has illustrated the pivotal role of a mother's diet during pregnancy in influencing the prenatal gut microbiome and subsequently shaping the neurodevelopment of her offspring. The intricate interplay between maternal gut health, nutrition, and neurodevelopmental outcomes has emerged as a captivating field of investigation within developmental science. Acting as a dynamic bridge between mother and fetus, the maternal gut microbiome, directly and indirectly, impacts the offspring's neurodevelopment through diverse pathways. This comprehensive review delves into a spectrum of studies, clarifying putative mechanisms through which maternal nutrition, by modulating the gut microbiota, orchestrates the early stages of brain development. Drawing insights from animal models and human cohorts, this work underscores the profound implications of maternal gut health for neurodevelopmental trajectories and offers a glimpse into the formulation of targeted interventions able to optimize the health of both mother and offspring. The prospect of tailored dietary recommendations for expectant mothers emerges as a promising and accessible intervention to foster the growth of beneficial gut bacteria, potentially leading to enhanced cognitive outcomes and reduced risks of neurodevelopmental disorders.

Environmental enrichment changes the effects of prenatal and postnatal undernutrition on memory, anxiety traits, Bdnf and TrkB expression in the hippocampus of male adult rats

Environmental factors such as undernutrition and environmental enrichment can promote changes in the molecular and behavioural mechanisms related to cognition. Herein, we investigated the effect of enriched environment stimulation in rats that were malnourished in the pre- and postnatal periods on changes in the gene expression of brain-derived neurotrophic factor and its receptor in the hippocampus, as well as on anxiety traits and memory. Early undernutrition promoted weight reduction, increased the risk analysis, reduced permanence in the open arm of the elevated plus-maze and induced a reduction in the gene expression of brain-derived neurotrophic factor and tropomyosin receptor kinase B. However, exposure to an enriched environment from 30 to 90 days' old maintained the malnourished phenotype, leading to weight reduction in the control group. In addition, the enriched environment did not alter the risk assessment in the undernourished group, but it did increase the frequency of labyrinth entries. Sixty-day exposure to the enriched environment resulted in a reversal in the gene expression of brain-derived neurotrophic factor and tropomyosin receptor kinase B in the hippocampus of malnourished rats and favoured of long-term memory in the object recognition test in the open-field. These results suggest that an enriched environment may have a protective effect in adult life by inducing changes in long-term memory and anxiety traits in animals that were undernourished in early life. Furthermore, reversing these effects of undernutrition involves mechanisms linked to the molecular signalling of brain-derived neurotrophic factor and tropomyosin receptor kinase B in the hippocampus.

Beneficial effects of enriched environment on behavior, cognitive functions, and hippocampal brain-derived neurotrophic factor level following postnatal serotonin depletion in male rats

The neurotransmitter serotonin (5-HT) is one of the most important modulators of neural circuitry and has a critical role in neural development and functions. Previous studies indicated that changes in serotonergic system signaling in early life critically impact mental health, behavior, the morphology of hippocampal neurons, and cognitive functions across the lifespan. The enriched environment (EE) has indicated beneficial effects on behavior and cognitive functions in the developmental period of life, but its impacts on cognitive impairments and behavioral changes following postnatal serotonin depletion are unknown. Therefore, the present study aimed to evaluate the influences of the EE housing (postnatal days [PNDs] 21-60) following postnatal serotonin depletion (by para-chlorophenylalanine [PCPA], 100 mg/kg, s.c, in PNDs 10-20) on anxiety-related behaviors, cognitive functions, and brain-derived neurotrophic factor (BDNF) mRNA expression in the hippocampus of male rats. Memory and behavioral parameters were examined in early adulthood and after that, the hippocampi of rats were removed to determine the BDNF mRNA expression by PCR (PNDs 60-70). The findings of the present work indicated that adolescent EE exposure alleviated memory impairment, decreased BDNF levels, and anxiety disorders induced by experimental depletion of serotonin. Overall, these results indicate that serotonergic system dysregulation during the developmental periods can be alleviated by adolescent EE exposure.

Undernutrition during development modulates endoplasmic reticulum stress genes in the hippocampus of juvenile rats: Involvement of oxidative stress

To evaluate whether exercise training mitigates the deleterious effects of undernutrition during the developmental period in juvenile Wistar rats. Pregnant Wistar rats were fed with a diet containing 17 % or 8 % casein during pregnancy and lactation. At 30 days of life, male offspring were divided into 4 groups: Low-Protein non-trained (LS), Low-Protein Trained (LT), Normoprotein non-trained (NS), and Normoprotein Trained (NT). Trained rats performed aerobic exercise training (AET) for 4 weeks, 5 days a week, 1 h a day. 24 h from the last day of training, the animals were sacrificed. The tissues were removed to analyze indicators of mitochondrial metabolism, oxidative stress, and gene expression of GRP78, PERK, ATF6 ER stress markers, and BDNF. The results showed that undernutrition during development promotes deleterious effects on mitochondrial oxidative metabolism and induces reticulum stress in the hippocampus of juvenile rats. On the other hand, AET improves mitochondrial function and increases enzymatic and non-enzymatic antioxidant capacity, as well as declines ER stress. AET at moderate intensity for 4 weeks in male juvenile Wistar rats acts as a lifestyle intervention opposing the negative effects induced by a protein-restricted maternal diet.

Duodenal infusion of soy protein hydrolysate activates cAMP signaling and hypothalamic neurotransmitter synthesis in pigs

An increased soy protein hydrolysate (SPH) level promoted hypothalamic acetylcholine, dopamine, and brain-derived neurotrophic factor (BDNF) synthesis.

Malnutrition and the microbiome as modifiers of early neurodevelopment

Malnutrition refers to a dearth, excess, or altered differential ratios of calories, macronutrients, or micronutrients. Malnutrition, particularly during early life, is a pressing global health and socioeconomic burden that is increasingly associated with neurodevelopmental impairments. Understanding how perinatal malnutrition influences brain development is crucial to uncovering fundamental mechanisms for establishing behavioral neurocircuits, with the potential to inform public policy and clinical interventions for neurodevelopmental conditions. Recent studies reveal that the gut microbiome can mediate dietary effects on host physiology and that the microbiome modulates the development and function of the nervous system. This review discusses evidence that perinatal malnutrition alters brain development and examines the maternal and neonatal microbiome as a potential contributing factor.

Environmental Complexity and Research Outcomes

Environmental complexity is an experimental paradigm as well as a potential part of animals' everyday housing experiences. In experimental uses, researchers add complexity to stimulate brain development, delay degenerative brain changes, elicit more naturalistic behaviors, and test learning and memory. Complexity can exacerbate or mitigate behavioral problems, give animals a sense of control, and allow for expression of highly driven, species-typical behaviors that can improve animal welfare. Complex environments should be designed thoughtfully with the animal's natural behaviors in mind, reported faithfully in the literature, and evaluated carefully for unexpected effects.

Sex-dependent effects of postweaning exposure to an enriched environment on novel objective recognition memory and anxiety-like behaviors: The role of hippocampal BDNF level

Exposure to enriched environment (EE) has been indicated to enhance cognitive functions, hippocampal neural plasticity, neurogenesis, long-term potentiation, and levels of the brain-derived neurotrophic factor (BDNF) in laboratory animals. Also, studies on the sex-dependent effects of exposure to EE during adolescence on adult cognitive functions are less. This is important because the beneficial effects of EE may be predominant in the adolescence stage. Therefore, the present study was designed to compare the effects of EE during adolescence (PND21-PND60) on novel objective recognition memory (NORM), anxiety-like behaviors, and hippocampal BDNF mRNA level in the adult male and female rats. Assessment of NORM and anxiety-like behaviors has been done by novel objective recognition task, open field (OF), and elevated plus maze (EPM), respectively. The expression of BDNF mRNA level was also evaluated by quantitative RT-PCR. Our findings demonstrated that housing in the EE during adolescence improves NORM in adult male rats. Also, exposure to EE during adolescence had a different effect on anxiety-like behaviors in both sexes. Additionally, our results indicated an augmented BDNF level in the hippocampus of male and female rats. In conclusion, adolescent exposure to EE has sex-dependent effects on cognitive functions and anxiety-like behaviors and increases BDNF mRNA expression in the hippocampus of both male and female rats; thus, BDNF is an important factor that can mediate the beneficial effects of EE and running exercise on cognitive functions and psychiatric traits.