Neuronal Regulation of State- Dependent Foraging in Caenorhabditis elegans

Abstract

Organisms exhibit flexible behaviors in response to the same stimulus, depending on their internal physiological states. For example, when animals are satiated and encounter non- preferred food sources, they typically exhibit reduced engagement, often redirecting their search toward more desirable options. However, after prolonged fasting, even less preferred food becomes valuable. Despite decades of research on feeding behaviors, the neural mechanisms that allow animals to adapt their responses based on their nutritional status remain elusive. Serotonin (5-HT), commonly referred to as the "happiness hormone," increases in response to food stimuli and modulates feeding behavior across species, suggesting a conserved role. In contrast, catecholamines, which are central to the stress response, regulate appetite by suppressing food intake in many animals. Using the nematode Caenorhabditis elegans—an organism with a simple, well-characterized nervous system—we investigate how the serotonergic and catecholaminergic systems interact to modulate food- related behaviors. Our findings provide key insights into how C. elegans integrates internal states to adjust its foraging strategies. Given the conservation of neuronal components across species, our results could offer a valuable framework for understanding the molecular mechanisms underlying state-dependent feeding behaviors in other organisms