Tania Diniz Machado

Early life stress is associated with anxiety, increased stress responsivity and preference for “comfort foods” in adult female rats

Abstract Chronic stress increases anxiety and encourages intake of palatable foods as “comfort foods”. This effect seems to be mediated by altered function of the hypothalamic–pituitary–adrenal axis. In the current study, litters of Wistar rats were subjected to limited access to nesting material (Early-Life Stress group – ELS) or standard care (Control group) from postnatal day 2 to 9. In adult life, anxiety was assessed using the novelty-suppressed feeding test (NSFT), and acute stress responsivity by measurement of plasma corticosterone and ACTH levels. Preference for palatable foods was monitored by a computerized system (BioDAQ, Research Diets®) in rats receiving only regular chow or given the choice of regular and palatable diet for 30 days. ELS-augmented adulthood anxiety in the NSFT (increased latency to eat in a new environment; decreased chow intake upon return to the home cage) and increased corticosterone (but not ACTH) secretion in response to stress. Despite being lighter and consuming less rat chow, ELS animals ate more palatable foods during chronic exposure compared with controls. During preference testing, controls receiving long-term access to palatable diet exhibited reduced preference for the diet relative to controls exposed to regular chow only, whereas ELS rats demonstrated no such reduction in preference after prolonged palatable diet exposure. The increased preference for palatable foods showed by ELS animals may result from a habit of using this type of food to ameliorate anxiety.

Impulsivity-based thrifty eating phenotype and the protective role of n-3 PUFAs intake in adolescents.

The goal of the present study was to investigate whether intrauterine growth restriction (IUGR) affects brain responses to palatable foods and whether docosahexaenoic acid (DHA, an omega-3 fatty acid that is a primary structural component of the human brain) serum levels moderate the association between IUGR and brain and behavioral responses to palatable foods. Brain responses to palatable foods were investigated using a functional magnetic resonance imaging task in which participants were shown palatable foods, neutral foods and non-food items. Serum DHA was quantified in blood samples, and birth weight ratio (BWR) was used as a proxy for IUGR. The Dutch Eating Behavior Questionnaire (DEBQ) was used to evaluate eating behaviors. In the contrast palatable food > neutral items, we found an activation in the right superior frontal gyrus with BWR as the most important predictor; the lower the BWR (indicative of IUGR), the greater the activation of this region involved in impulse control/decision making facing the viewing of palatable food pictures versus neutral items. At the behavioral level, a general linear model predicting external eating using the DEBQ showed a significant interaction between DHA and IUGR status; in IUGR individuals, the higher the serum DHA, the lower is external eating. In conclusion, we suggest that IUGR moderates brain responses when facing stimuli related to palatable foods, activating an area related to impulse control. Moreover, higher intake of n-3 PUFAs can protect IUGR individuals from developing inappropriate eating behaviors, the putative mechanism of protection would involve decreasing intake in response to external food cues in adolescents/young adults.

Early life trauma is associated with decreased peripheral levels of thyroid-hormone T3 in adolescents

An adverse early life environment can induce changes on behavioral and metabolic responses later in life. Recent studies in rats showed that the quality of maternal care as measured by high levels of pup licking and grooming (LG) was associated with changes in the relationship between the precursor thyroid‐hormone T4 and the more active T3. Here we investigated if early exposure to childhood abuse is associated with thyroid‐hormone levels in human adolescents. Given the empirical evidence from animal models showing that good maternal care was associated with increased conversion of T4 to T3, we hypothesized that early adversity would be associated with a decreased peripheral conversion of T4 to T3. A sample of 80 adolescents (10–18 years) participated in this study. We used the Childhood Trauma Questionnaire to investigate early life stress. We calculate the body mass index (BMI) assessing weight and height and sexual maturation stage was determined by self‐assessment. Blood samples were collected to measure T3 and T4 levels. ANCOVA were used to evaluate the influence of the Physical Abuse domain of the Childhood Trauma Questionnaire as the early life stress variable in T3 and T4 separately, adjusted for potential confounders such as pubertal status, gender, socioeconomic status and BMI. Early life trauma was associated with reduced T3 levels in adolescents, when adjusted for potential confounders (p = 0.013), but not with peripheral T4 levels (p = 0.625). We extended findings from animal models showing that adverse early experience persistently impacts on the individuals responses to stress, which is marked by an abnormal metabolism of thyroid hormones. Further studies are needed to further investigate the nature of such associations.

Decreased comfort food intake and allostatic load in adolescents carrying the A3669G variant of the glucocorticoid receptor gene

BACKGROUND The A3669G single nucleotide polymorphism (SNP) of the glucocorticoid receptor (GR) gene NR3C1 is associated with altered tissue sensitivity to glucocorticoids (GCs). GCs modulate the food reward circuitry and are implicated in increased intake of palatable foods, which can lead to the metabolic syndrome and obesity. We hypothesized that presence of the G variant of the A3669G SNP would affect preferences for palatable foods and alter metabolic, behavioural, and neural outcomes. METHODS One hundred thirty-one adolescents were genotyped for the A3669G polymorphism, underwent anthropometric assessment and nutritional evaluations, and completed behavioural measures. A subsample of 74 subjects was followed for 5 years and performed a brain functional magnetic resonance imaging (fMRI) paradigm to verify brain activity in response to food cues. RESULTS Sugar and total energy consumption were lower in A3669G G allele variant carriers. On follow-up, this group also had reduced serum insulin concentrations, increased insulin sensitivity, and lower anxiety scores. Because of our unbalanced sample sizes (31/37 participants non-G allele carriers/total), our imaging data analysis failed to find whole brain-corrected significant results in between-group t-tests. CONCLUSION These results highlight that a genetic variation in the GR gene is associated, at the cellular level, with significant reduction in GC sensitivity, which, at cognitive and behavioural levels, translates to altered food intake and emotional stress response. This genetic variant might play a major role in decreasing risk for metabolic and psychiatric diseases.

Interaction between perceived maternal care, anxiety symptoms, and the neurobehavioral response to palatable foods in adolescents.

Abstract Studies in rodents have shown that early life trauma leads to anxiety, increased stress responses to threatening situations, and modifies food intake in a new environment. However, these associations are still to be tested in humans. This study aimed to verify complex interactions among anxiety diagnosis, maternal care, and baseline cortisol on food intake in a new environment in humans. A community sample of 32 adolescents and young adults was evaluated for: psychiatric diagnosis using standardized interviews, maternal care using the Parental Bonding Inventory (PBI), caloric consumption in a new environment (meal choice at a snack bar), and salivary cortisol. They also performed a brain fMRI task including the visualization of palatable foods vs. neutral items. The study found a three-way interaction between anxiety diagnosis, maternal care, and baseline cortisol levels on the total calories consumed (snacks) in a new environment. This interaction means that for those with high maternal care, there were no significant associations between cortisol levels and food intake in a new environment. However, for those with low maternal care and who have an anxiety disorder (affected), cortisol was associated with higher food intake; whereas for those with low maternal care and who did not have an anxiety disorder (resilient), cortisol was negatively associated with lower food intake. In addition, higher anxiety symptoms were associated with decreased activation in the superior and middle frontal gyrus when visualizing palatable vs. neutral items in those reporting high maternal care. These results in humans mimic experimental research findings and demonstrate that a combination of anxiety diagnosis and maternal care moderate the relationship between the HPA axis functioning, anxiety, and feeding behavior in adolescents and young adults.

Alterations in the hypothalamic–pituitary–thyroid axis in animals submitted to early-life trauma

Introduction: Changes in maternal care can affect offspring’s thyroid hormone T3 levels. Pups from highly caring mothers have higher levels of thyroid hormone T3. In humans, physical abuse in childhood is related to lower levels of T3 in adolescence. This study aimed at verifying if early-life trauma in rodents is correlated with T3 levels in adulthood. Methods: From the second day of life, litters of Wistar rats were subjected to reduced nesting material (Early–Life Stress-ELS) or standard care (Controls). In adult life, the animals were chronically exposed to standard diet or standard diet + palatable diet and plasma T3 levels were measured before and after the exposition to diet. Results: Thyroid hormone T3 levels in adult life correlated negatively with the licking and grooming (LG) scores in the ELS group. This correlation disappeared when the animals had the opportunity to choose between two diets chronically. Conclusion: The adverse environment affected maternal behavior and caused marks on the metabolism of the intervention group (T3), which were reverted by chronic palatable food consumption. Keywords: Trauma; T3; stress