Hypothalamic and mRNA Responses to Gastrointestinal Fullness and Fasting in Atlantic Salmon (, L.).

The orexigenic agouti-related protein (AgRP) and the anorexigenic pro-opiomelanocortin (POMC) are crucial players in the control of feed intake in vertebrates, yet their role in teleosts has not been fully established. Triplicate groups of Atlantic salmon () post smolts were subjected to (1) fasting for 3 days (fast) and (2) normal feeding (fed), resulting in a significant ( < 0.05) upregulation of hypothalamic transcripts levels in the fast group. Moreover, the mRNA abundance of was significantly ( < 0.05) correlated with the stomach dry weight content. Corresponding inverse patterns were observed for , albeit not statistically significant. No significant differences were found for the other paralogues, and and between fed and fast groups. The significant correlation between stomach fullness and mRNA expression suggests a possible link between the stomach filling/distension and satiety signals. Our study indicates that hypothalamic acts as an orexigenic signal in Atlantic salmon.