Brain Region for Oral Sensation Controls Eating and Body Weight

The mesencephalic trigeminal nucleus (Mes5) is a brain region primarily known for processing oral sensory-motor information, which is crucial for functions like chewing and swallowing. However, its specific involvement in regulating energy balance, including food intake and body weight, has remained largely unexplored. This study aimed to investigate the role of Mes5 in energy balance and identify potential neural pathways involved in appetite control.

The study confirmed that the Mes5 indeed expresses the melanocortin-4 receptor (MC4R). Microinjection of melanotan-II (MTII) into the Mes5 significantly suppressed food intake by a considerable margin and led to a noticeable reduction in body weight in mice. Chemogenetic activation of NTS POMC-projecting neurons that project to the Mes5 also resulted in a robust suppression of food intake, demonstrating a direct neural circuit influence. While Mes5 MC4Rs were shown to be sufficient for these suppressive effects, they did not appear to be necessary for the baseline control of food intake or body weight. These findings highlight the Mes5 as a novel and functionally relevant target for the melanocortinergic control of food intake and body weight regulation.