PeptidesDec 19, 2016

Duplicate brain and gut peptides in Nile tilapia and their roles in controlling food intake

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Mar 28, 2026

Abstract

NPYa is identified as the primary neuropeptide Y involved in feeding regulation in Nile tilapia.

Nile tilapia possess two duplicates of neuropeptide Y (NPY) and peptide YY (PYY).
NPYa is predominantly expressed in the central nervous system, with significantly higher mRNA levels compared to NPYb.
Feeding leads to a decrease in NPYa expression, while fasting increases its levels; NPYb expression does not show this pattern.
Both NPYa and NPYb can stimulate food intake when injected into the brain, but NPYa is the main neuropeptide for this function.
PYYb is highly expressed in the gut and decreases food intake, while PYYa has moderate CNS expression and does not significantly affect food intake.

Simplified

In vertebrates, the neuropeptide Y (NPY) family peptides have been recognized as key players in food intake regulation. NPY centrally promotes feeding, while peptide YY (PYY) and pancreatic polypeptide (PP) mediate satiety. The teleost tetraploidization is well-known to generate duplicates of both NPY and PYY; however, the functional diversification between the duplicate genes, especially in the regulation of food intake, remains unknown. In this study, we identified the two duplicates of NPY and PYY in Nile tilapia (Oreochromis niloticus). Both NPYa and NPYb were primarily expressed in the central nervous system (CNS), but the mRNA levels of NPYb were markedly lower than those of NPYa. Hypothalamic mRNA expression of NPYa, but not NPYb, decreased after feeding and increased after 7-days of fasting. However, both NPYa and NPYb caused a significant increase in food intake after an intracranial injection of 50ng/g body weight dose. PYYb, one of the duplicates of PYY, had an extremely high expression in the foregut and midgut, whereas another form of duplicate PYYa showed only moderate expression in the CNS. Both hypothalamic PYYa and foregut PYYb mRNA expression increased after feeding and decreased after 7-days of fasting. Furthermore, the intracranial injection of PYYb decreased food intake, but PYYa had no significant effect. Our results suggested that although the mature peptides of NPYa and NPYb can both stimulate food intake, NPYa is the main endogenous functional NPY for feeding regulation. A functional division has been identified in the duplicates of PYY, which deems PYYb as a gut-derived anorexigenic peptide and PYYa as a CNS-specific PYY in Nile tilapia.

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Duplicate brain and gut peptides in Nile tilapia and their roles in controlling food intake

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