Leucine sensing in rainbow trout hypothalamus is direct but separate from mTOR signalling in the regulation of food intake

In prior studies, we evidenced the presence in fish hypothalamus of different systems sensing changes leucine levels to relate them food intake control. To assess whether or not those effects are due a direct action leucine, evaluated present vitro study if rainbow trout (Oncorhynchus mykiss) respond way comparable that observed vivo. Thus, incubated with increased concentrations (1, 5 and 25 mM). Then, parameters related mechanisms amino acid as well transcription factors, neuropeptides. Amino metabolism BCAA glutamine GCN2 kinase activated by vivo thus supporting on them. However, activation these did trigger mTOR signalling pathway including downstream protein targets mTOR, mRNA abundance neuropeptides involved regulation intake. Therefore, hypothalamic after administration is response but indirect. The absence connections between other brain areas and/or lack hormones, particularly insulin, could be responsible this differential response.