Global view of neuropeptides and their receptors in the brain and pituitary of grass carp (Ctenopharyngodon idellus)

Neuropeptides, the largest amount of signaling molecules mainly secreted in the brain, play important roles in many physiological processes, including reproduction, growth, homeostasis and metabolism. Generally, neuropeptides exert physiological function via activating their specific G protein-coupled receptors (GPCRs). However, compared to mammals, the global information on neuropeptides and their GPCRs in teleost is still highly scarce. In this study, using grass carp as a model, a total of 91 preproneuropeptides of 23 families were identified from grass carp genome and transcriptome databases, as well as 112 GPCRs potentially binding with these neuropeptides. Then, using RNA-seq, the transcript levels of these preproneuropeptides and their GPCRs were examined among six different brain regions (hypothalamus, olfactory bulb, telencephalon, optic tectum, cerebellum, and medulla oblongata) and pituitary, respectively. Finally, basing on the tissue distribution of these preproneuropeptides and their receptors in different brain areas and pituitary, we further predict the potential function for each neuropeptide family in grass carp. This study will provide a significant contribution to further clarifying the functional role of each neuropeptide family in the neuroendocrine system of grass carp.