Role of the G protein-coupled receptors GPR84 and GPR119 in the central regulation of food intake in rainbow trout

Abstract

We evaluated the role of GPR84 and GPR119 in food intake regulation in fish using rainbow trout (Oncorhynchus mykiss) as a model. In a first experiment, we assessed the effects on food intake of intracerebroventricular treatment with agonists of these receptors. In a second experiment, we assessed in hypothalamus and hindbrain the impact of the same treatments on mRNA abundance of neuropeptides involved in the metabolic control of food intake (npy, agrp1, pomca1, and cartpt) as well as in changes in parameters related to signalling pathways and transcription factors involved in the integrative response leading to neuropeptide production. Treatment with both agonists elicited an anorectic response in rainbow trout attributable to changes observed in the mRNA abundance of the four neuropeptides. Changes in neuropeptides relate to changes observed in mRNA abundance and phosphorylation status of the transcription factor Foxo1. These changes occurred in parallel with changes in phosphorylation status of Ampkα and Akt, mRNA abundance of mTOR as well as in signalling pathways related to PLCβ and IP3. These results allow us to suggest that 1) at least part of the capacity of fish brain to sense MCFA like octanoate depends on the function of GPR84, and 2) the capacity of fish brain to sense NAE or triglyceride-derived molecules through binding of these ligands to GPR119.