Periprandial response of central cannabinoid system to different feeding conditions in rainbow trout Oncorhynchus mykiss

Background: The mechanisms that regulate food intake are very complex since they comprise several neuroendocrine and metabolic signals responding to energetic or reward requirements. Previous studies in mammals indicate that cannabinoid system is implicated in homeostatic and hedonic regulation of food intake. In fish, several studies describe the components of this system, but only a little information is available regarding their role in food intake and energy balance regulation.

Objectives: The objective of this study was to evaluate the main components of cannabinoid system related to feeding conditions in fish.

Methods: Samples of blood and different brain areas (telencephalon and hypothalamus) were taken from rainbow trout under different nutritional status (fasted, fed and refed) at different periprandial times (-30, 0, +30 and +180 min).

Results: Changes in AEA and 2-AG levels were observed in plasma related to the nutritional status and the sampling times assessed. At central levels, changes in endocannabinoids levels were observed in hypothalamus and in mRNA abundance of cnr1 and tprv1 in telencephalon and faah, gpr55 and fos in both brain areas.

Discussion: The results obtained suggest a role of endocannabinoid system in the regulation of food intake in fish at central level but further studies are required to fully elucidate the mechanisms involved.