Fish rely on signals from the brain and other organs to balance food intake with their energy needs. One such signal, melanin-concentrating hormone (MCH), was first discovered in salmon and has since been studied across vertebrates. In mammals, MCH generally promotes eating, but studies in fish have produced mixed results: its associated gene appears to respond differently to feeding and fasting in different species. Siberian sturgeon are widely farmed for meat and caviar, yet little was known about their pmch genes, where those genes are active, or how they respond when food becomes available or scarce.
A study (DOI: 10.48130/jai-0026-0004) published in Journal of Applied Ichthyology on 30 July 2026 by Zhiqiong Li's & Ni Tang's team, Chengdu Agricultural College, reports two pmch forms whose expression patterns suggest possible roles in appetite regulation and liver energy metabolism.
The researchers first isolated and sequenced two pmch transcripts, named pmcha and pmchb, from Siberian sturgeon. Their sequences encode precursor proteins of 179 and 158 amino acids, respectively. Although the full proteins differ considerably from those of many other vertebrates, both contain the same mature MCH peptide sequence. The team then measured gene expression in brain regions and other tissues. pmcha was especially abundant in the liver, cerebellum and hypothalamus, while pmchb was abundant in the liver and cerebellum. This difference suggests that the two forms may be regulated differently across tissues. To examine responses around a meal, the researchers compared fed juveniles with unfed fish at matched times. One hour after feeding, expression of both genes was higher in the hypothalamus of fed fish. The increase in pmchb was still evident three hours after feeding, whereas the difference in pmcha was no longer observed. In the liver, both genes showed the opposite pattern at first: expression was lower in fed fish after one hour, then higher after three hours. The team also compared fish fed daily with fish fasted for one or ten days, and examined fish one hour after refeeding following the longer fast. After one day without food, hypothalamic expression of both genes was lower than in fed fish. After ten days, hypothalamic pmchb remained lower, while pmcha showed no significant difference. Refeeding increased expression of both genes in the hypothalamus. In the liver, one day of fasting produced no significant change, but ten days reduced expression of both genes. Together, these measurements show that the two genes respond to feeding status on different timescales in the brain and liver.
The results provide molecular evidence that MCH-related signaling may participate in feeding regulation in Siberian sturgeon. The rise in hypothalamic gene expression after a meal is consistent with an appetite-limiting role, while the liver findings suggest a connection to energy use during feeding and fasting. Gene expression alone cannot establish what the peptides do or whether changing them alters food intake. Further experiments measuring peptide activity, feeding behavior and growth will be needed before these findings can guide aquaculture practice.
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References
DOI
10.48130/jai-0026-0004
Original Source URL
https://doi.org/10.48130/jai-0026-0004
Funding information
This study was funded by the grants of the National Natural Science Foundation of China (3230210433), the Sichuan Science and Technology Program (24NSFSC0754), and the grants of the Research Fund Project of Chengdu Agricultural College (26BS02).
About Journal of Applied Ichthyology
Journal of Applied Ichthyology (e-ISSN 1439-0426; p-ISSN 0175-8659) is an open-access, peer-reviewed journal dedicated to publishing high-quality research on applied ichthyology, aquaculture, and marine fisheries, including management of fisheries resources, fisheries ecology, fish health and pathology.