GPR84 and GPR119 in the central regulation of food intake in rainbow trout

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 signaling 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 signaling 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