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.
Keywords: Comfort food; Feeding behaviour; Glucocorticoid receptor gene polymorphism; Insulin; Reward circuitry.
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