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

ABSTRACT

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.

KEYWORDS:

• Rainbow trout
• cannabinoid
• feeding condition
• food intake
• hypothalamus
• telencephalon
• periprandial time

Acknowledgements

Authors wish to thank staff members of CACTI (Centre of Scientific and Technical Support, Vigo University) for their help in cannabinoid analysis. M.C–S and J.L.S. conceived and designed the research; A.D-R, M.C., C.V., S.C. and M.C–S performed experiments; A.D-R and M.C. analyzed data; all authors interpreted results of the experiments; A.D-R, J.L.S. and M.C–S. prepared figures; all authors drafted, edited and revised manuscript, with M.C–S and J.L.S. having the main contribution and approving the final version of manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by research grants from Spanish Agencia Estatal de Investigación and European Fund of Regional Development (PID2019-103969RB-C31), and Xunta de Galicia (Consolidación e estructuración de unidades de investigación competitivas do SUG, ED431B 2019/37) to J.L.S. A.D-R. was recipient of a predoctoral fellowship from Xunta de Galicia (ED481A-2019/291). M.C. was recipient of a predoctoral fellowship (Program FPI) from Spanish Ministerio de Ciencia e Innovación (BES-2017-079708). S.C. was recipient of a predoctoral fellowship (Program FPU) from Spanish Ministerio de Educación, Cultura y Deporte (FPU16/00045). M.C-S. was recipient of a postdoctoral fellowship from Xunta de Galicia (ED481B2018/018).