In this work, we assessed periprandial serotonin and 5-hydroxyindolacetic acid abundance in several brain areas of rainbow trout, in parallel with the evaluation of gene expression of tryptophan hydroxilase 1 and 2, neuropeptides involved in the central control of food intake, and the quantification of plasma glucose and cortisol. The results showed severe changes in serotonergic systems around mealtime, the most prominent being the increase in their activity just after food intake, suggesting that serotonin has a relevant role in relation to the daily timing of food intake, probably triggering satiety signals. In addition, a temporal adjustment of neuropeptide expression and plasma cortisol was found in relation to food intake, supporting its role in the regulation of feeding behaviour.

The data used in this work were obtained by HPLC coupled with coulochem detector, qPCR, ELISA and commercial spectrophotometric kits.