The essential role of mTOR in promoting feeding behavior through regulating NPY and AgRP expression in mandarin fish (Siniperca chuatsi) larvae

This is the authors' abstract. We don't add key points for this paper.

The success of initial feeding during the mouth-opening stage is crucial for the survival and growth of fish larvae. Carnivorous mandarin fish ( Siniperca chuatsi ) face unique challenges in capturing live prey during this period. The aim of this study was to explore the factors influencing initial feeding in mandarin fish larvae during the mouth-opening stage and validate their functional roles. Transcriptomic analysis of both first feeding and unfed larvae revealed significant changes in the expression of genes related to vision and taste, while fewer changes were observed in genes associated with olfaction. Further sensory inhibition experiments demonstrated that vision and taste are the primary sensory factors driving initial feeding, while olfaction plays a less significant role. Gene set enrichment analysis revealed that the mammalian target of rapamycin (mTOR) is a core regulatory factor in this process. In situ hybridization indicated significant changes in the expression and distribution of mTOR, agouti-related peptide (AgRP), and neuropeptide Y (NPY) before and after feeding. Rapamycin-mediated mTOR inhibition significantly reduced the expression of appetite stimulants (NPY, AgRP, GHRL, and orexin1) and decreased feeding rates. Moreover, we found that inhibiting mTOR signaling also lowered the expression of key digestive enzymes, including pepsin, lipase, and trypsin. In summary, our study identifies vision and taste as the primary sensory factors influencing initial feeding in mandarin fish and clarifies the critical role of the mTOR pathway in coordinating appetite regulation and digestive preparation. These mechanistic insights provide promising targets for improving feeding habit programs for this economically valuable species.