Insights into sexual dimorphisms: Analysis of lipid metabolites, biochemical markers, and sex steroid profiling in serum of captive Chinese Sturgeon (Acipenser sinesis) at early stage of gonadal development

Abstract

The Chinese sturgeon (Acipenser sinensis) is a critically endangered species, yet there is a limited knowledge regarding the sexual dimorphism in their reproductive biology, hindering long-term conservation efforts through artificial propagation. This study determined and compared the serum steroid hormones, lipid metabolites, biochemical parameters, and fatty acid profiles between male and female Chinese sturgeon (11 years old). Results revealed that male sturgeons exhibited significantly higher levels of serum testosterone, dihydrotestosterone, and 7α, 25-dihydroxycholesterol compared to females (P < 0.05), while no significant differences in levels of serum pregnenolone and 17β-estradiol levels were found. Lipidomic analysis identified 65 out of 1469 lipids, showing significant gender differences. Males exhibited higher levels of serum polar lipids (phospholipids, sphingolipids and ceramides), cholesteryl esters (CE), and prostaglandin E2 (PGE2) compared to the females, and those differential lipids in the metabolism category were predominantly enriched in key metabolic pathways including bile secretion, steroid biosynthesis, and ovarian steroidogenesis. Gas chromatography (GC) analysis showed that males exhibited higher levels of C18:1n9c and total monounsaturated fatty acids (MUFA), but lower levels of C18:3n3 and several n-6 polyunsaturated fatty acids (PUFA) in the serum compared to the female counterparts (P < 0.05), and n-3 LC-PUFAs tended to accumulate in the serum of male sturgeons. SOD activity and GLU levels were higher in males, while LDL levels were lower compared to females (P < 0.05). These findings highlight significant sexual dimorphisms in the lipid metabolites, serum steroid hormone profiling, and physiological traits of Chinese sturgeon. The information provided valuable insights into the reproductive physiology of the species and offer important foundation for advancing the understanding of reproductive physiology and developing gender-specific conservation strategies.