Using rainbow trout fed with low fat (LF) or high-fat (HF) diets we aimed to determine if the response of food intake, mRNA abundance of hypothalamic neuropeptides involved in the metabolic regulation of food intake, and fatty acid (FA) sensing systems in hypothalamus and liver is similar to that previously observed when levels of specific FA were raised by injection. Moreover, we also aimed to determine if the phosphorylation state of intracellular energy sensor 5′-AMP-activated protein kinase (AMPK), and proteins involved in cellular signalling such as protein kinase B (Akt) and target of rapamycin (mTOR) display changes that could be related to FA-sensing and the control of food intake. The increased levels of FA in hypothalamus and liver of rainbow trout fed the HF diet only partially activated FA-sensing systems and did not elicit changes in food intake suggesting that FA-sensing response in fish to increased levels of FA is more dependent on the presence of specific FA such as oleate or octanoate rather than to the global increase in FA. We also obtained, for the first time in fish, evidence for the presence and function of energy sensors like AMPK and proteins involved in cellular signaling like mTOR and Akt in hypothalamus. These proteins in hypothalamus and liver were generally activated in fish fed the HF vs LF diet suggesting the activation of the cellular signaling pathways in response to the increased availability of FA.
- © 2015. Published by The Company of Biologists Ltd