Early Life Stress, Brain Development, and Obesity Risk: Is Oxytocin the Missing Link?

Early life stress and body-mass-index modulate brain connectivity in alcohol use disorder

Early life stress (ELS) significantly increases susceptibility to alcohol use disorder (AUD) by affecting the interplay between the executive and the salience networks (SNs). The link between AUD and higher body-mass index (BMI) is known, but we lack understanding of how BMI impacts the relationship between ELS and brain connectivity in individuals with AUD. To bridge this gap, we investigated the main and interaction effects of ELS and BMI on brain connectivity in individuals with AUD compared to non-AUD participants (n = 77 sex-matched individuals per group). All participants underwent resting-state functional magnetic resonance imaging, revealing intriguing positive functional connectivity between SN seeds and brain regions involved in somatosensory processing, motor coordination and executive control. Examining the relationship of brain connectivity with ELS and BMI, we observed positive associations with the correlations of SN seeds, right anterior insula (RAIns) and supramarginal gyrus (SMG) with clusters in motor [occipital cortex, supplementary motor cortex]; anterior cingulate cortex (ACC) with clusters in frontal, or executive, control regions (middle frontal gyrus; MFG, precentral gyrus) that reportedly are involved in processing of emotionally salient stimuli (all |β | > 0.001, |p | < 0.05). Interestingly, a negative association of the interaction effect of ELS events and BMI measures with the functional connectivity of SN seeds ACC with decision-making (MFG, precentral gyrus), RAIns and RSMG with visuo-motor control regions (occipital cortex and supplementary motor cortex) (all |β | = -0.001, |p | < 0.05). These findings emphasize the moderating effect of BMI on ELS-associated SN seed brain connectivity in AUD. Understanding the neural mechanisms linking BMI, ELS and AUD can guide targeted interventions for this population.

The Role of Oxytocin in Early-Life-Stress-Related Neuropsychiatric Disorders

Early-life stress during critical periods of brain development can have long-term effects on physical and mental health. Oxytocin is a critical social regulator and anti-inflammatory hormone that modulates stress-related functions and social behaviors and alleviates diseases. Oxytocin-related neural systems show high plasticity in early postpartum and adolescent periods. Early-life stress can influence the oxytocin system long term by altering the expression and signaling of oxytocin receptors. Deficits in social behavior, emotional control, and stress responses may result, thus increasing the risk of anxiety, depression, and other stress-related neuropsychiatric diseases. Oxytocin is regarded as an important target for the treatment of stress-related neuropsychiatric disorders. Here, we describe the history of oxytocin and its role in neural circuits and related behaviors. We then review abnormalities in the oxytocin system in early-life stress and the functions of oxytocin in treating stress-related neuropsychiatric disorders.

Oxytocin and eating disorders: Knowledge gaps and future directions

Eating disorders continue to be a major public health issue and important cause of morbidity and premature mortality, particularly for young people. Yet in a concerning dialectic, this occurs in the context of an epidemic of obesity which, with its medical complications, constitutes another vexing public health challenge. While it is not an eating disorder per se obesity is often comorbid with eating disorders. Effective treatment for both eating disorders and obesity has proven to be elusive and in the search for novel therapeutic interventions, the prosocial, anxiolytic, brain plasticity and metabolic effects of oxytocin (OT) have been examined from this perspective. The availability of intranasal oxytocin (IN-OT) has led to a number of interventional treatment studies in anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED), their atypical and subclinical forms and in medical and psychiatric conditions co-occurring or comorbid with these, obesity with BED would be included here. The aim of this mini review is to collate recent findings on OT as a novel therapeutic intervention in eating disorders and obesity and to identify and address some of the knowledge gaps in the use of IN-OT. The wider clinical perspective utilised here might better address some of the gaps and identify future directions of research. Clearly much remains to be done for OT to fulfil its therapeutic promise in eating disorders. OT might yet be of therapeutic promise and will be appreciated where treatment advances have been hard to come by and prevention challenging for these disorders.

Effects of chronic psychosocial stress on 'binge-like' sucrose intake in mice

Binge eating episodes are persistent and are essential features of numerous eating disorders (EDs). Susceptibility to EDs is largely presumed to be associated with early life stress. In fact, converging evidence from preclinical animal studies have implicated stress as a driver of binge eating. Still, literature examination indicates that vulnerability to EDs may depend on factors such as severity, time, and the type of stressor. Therefore, we aimed at exploring the link between chronic psychosocial stress and 'binge-like' sucrose intake in adolescent mice. To this aim, intruders' experimental mice were exposed to the chronic subordinate colony (CSC) housing, in the presence of a resident aggressive mouse for 2 weeks. At the end of the stress period, mice were tested for anxiety-like behavior then assessed for 'binge-like' intake of sucrose using a long-term drinking in the dark (DID) method that successfully replicates binge eating in humans. As expected, and compared to single housed colony controls (SHC), CSC exposure elicited an anxiogenic-like response in the open field (OF) and elevated-plus maze (EPM) tests and reduced weight gain. Most importantly, we report here for the first time, that mice exposed to chronic psychosocial stress displayed a 'binge-like' consumption of sucrose. However, neither quinine (bitter) nor saccharin (sweet) intakes were affected by CSC exposure. Finally, using Pearson's correlation, results showed a strong correlation between anxiety-like behavior parameters and sucrose intake. Overall these findings support the validity of our chronic psychosocial stress to model binge EDs and establish the long-term consequences of stress on 'binge-like' eating in male mice. These data suggest that chronic psychosocial stress is a risk factor for developing anxiety-associated EDs.