Adolescent food insecurity impairs gut signal sensitivity and cue-induced appetitive behaviours in female rats

Unpredictable and insufficient access to food, known as food insecurity, is associated with the development of obesity. However, causal mechanisms underlying this paradoxical relationship remain poorly understood. Using a rat model of food insecurity, this study investigated whether food insecurity causes dysregulated feeding behaviours, specifically impaired gut signal sensitivity and enhanced cue-driven appetitive responses. Adolescent female rats were assigned to receive either ad libitum chow access (Food secure), 90% caloric restriction (Food restricted) or unpredictable quantity and timing of food access (Food insecure), for 4 weeks. After which, rats were returned to an ad libitum chow diet for the remainder of the study. To examine gut signal sensitivity, we measured the effects of cholecystokinin (CCK) on 10% sucrose intake. To examine cue-driven feeding behaviours, we used Pavlovian appetitive conditioning and measured appetitive responses towards a food-predictive cue. Results showed that prior food insecure rats were less sensitive to the intake inhibitory effects of CCK and exhibited enhanced cue-induced appetitive behaviours, when compared to food secure and food restricted groups. Anxiety-like behaviours or learning and memory was not different between groups. At the end of the study, adolescent caloric restriction resulted in reduced fat mass, plasma leptin levels and body weight when compared to food secure, but not food insecure rats, suggesting that adolescent food insecurity somewhat overcame these metabolic effects. Taken together, our findings suggest that adolescent food insecurity impaired gut signal sensitivity and heightened food cue sensitivity, which may cause enduring metabolic and behavioural adaptations that promote overeating and weight gain.