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Effects of junk-food on food-motivated behavior and nucleus accumbens glutamate plasticity; insights into the mechanism of calcium-permeable AMPA receptor recruitment
In rats, consuming obesogenic diets boosts calcium-permeable AMPA receptor (CP-AMPAR) activity in the nucleus accumbens (NAc) core, increasing food-motivated behavior. Notably, these diet-induced changes in NAc transmission are more pronounced and long-lasting in obesity-prone (OP) male rats, while they are not observed in obesity-resistant (OR) rats. However, the impact of dietary changes on food motivation and the mechanisms behind this NAc plasticity in OP rats remain unclear. Fetterly, Catalfio, and Ferrario (2024) studied food-driven behavior in male selectively bred OP and OR rats by providing them with unrestricted access to either chow (CH), junk food (JF), or a sequence of 10 days on junk food followed by a return to a chow diet (JF-Dep). As anticipated, OP rats showed higher food motivation than OR rats. On the other hand, only the JF-Dep condition increased food-seeking behavior in the OP rat groups, while ongoing access to JF reduced food-seeking actions in both OPs and ORs. The authors also used optogenetic, chemogenetic, and pharmacological techniques to examine the activation of NAc CP-AMPARs in response to dietary changes, along with ex vivo treatment of brain slices, demonstrating that reducing excitatory transmission in the NAc was enough to activate CP-AMPARs in synapses of OP rats, but not in ORs. In OPs, increases in CP-AMPARs due to JF exposure were observed when monitoring medial prefrontal cortex (mPFC) inputs. However, a similar observation was not seen from the basolateral amygdala (BLA) to the NAc. These findings indicate that diet influences behavioral and neural plasticity differently in populations susceptible to obesity. The authors also identified the conditions necessary for the acute recruitment of NAc CP-AMPARs, suggesting that synaptic scaling mechanisms play a role in this process. This research deepens our understanding of how diet influences obesity susceptibility and impacts food-driven behavior, highlighting the recruitment of NAc CP-AMPARs. [NPID: Obesity, AMPAR, synaptic scaling, high-fat diet, striatum, motivation]
Year: 2024
