# Liver metabolomic profiles of sea lamprey (Petromyzon marinus) are influenced by sex and maturation stages

## TL;DR

This study shows how liver metabolism in sea lampreys changes with sex and reproductive stages, supporting their unique reproductive strategies.

## Contribution

The study reveals sex-specific and maturation-stage-specific liver metabolomic profiles in sea lampreys linked to reproductive functions.

## Key findings

- Mature male sea lampreys show upregulated amino acid and fatty acid metabolisms.
- Amino acid regulation is slightly higher in sexually immature females compared to males.
- Metabolic changes in livers align with the species' reproductive strategies.

## Abstract

Sea lamprey (Petromyzon marinus) is a unique vertebrate model to examine how liver metabolomes support different reproductive functions. Juvenile sea lamprey prey on other fish species by attaching to their body and feeding on their blood and body fluids. Once reaching adulthood, they cease feeding, migrate to spawning streams and begin their final sexual maturation. During these processes, the male livers produce large quantities of bile acid pheromone precursors to be modified and released via gills, whereas the female livers synthesize vast amounts of vitellogenin (yolk lipophosphoprotein) to be transported to the ovary.

We aim to test the hypothesis that the liver metabolic pathways exhibit dramatic changes during sexual maturation of sea lampreys that support their reproductive strategies.

Liver tissues from prespermiating (PSM) and spermiating (SM) males, and preovulatory (POF) and ovulatory (OF) females were homogenized, extracted and analyzed using the Thermo Q-exactive Orbitrap UPLC/MS/MS. Progenesis QI, Compound Discoverer, and Metaboanalyst were used for alignment, peak picking, deconvolution, and annotation. Data were subjected to analyses such as PCA and PLS-DA, using the SIMCA® software. The glycogen and triglyceride content in liver were also examined to determine levels of stored energy.

Overall, we found upregulations of amino acid and fatty acid metabolisms in mature male sea lamprey compared to the immature ones. Although the metabolic differences were comparatively subdued in the sexually immature males and females, amino acid regulation was slightly higher in females.

We conclude that the metabolic dynamics in sea lamprey livers are consistent with their reproductive strategies.

The online version contains supplementary material available at 10.1007/s11306-025-02266-8.