Inhibition of the Primary Bile Acid Synthesis Pathways in SD Rats at Different Altitudes

mRNA expression in the liver, ileum, duodenum, and colon was significantly decreased with increasing altitude. Meanwhile, the protein expression of both FGF15 and SHP showed a downward trend, with a significant decrease for FGF15 and a non-significant decrease for SHP. These findings suggest that primary bile acid synthesis in SD rats is dominated by the classical pathway. As altitude increases, bile acid synthesis in SD rats is significantly inhibited, indicating that high-altitude hypobaric hypoxia is the primary inhibitory factor. This study provides critical data for elucidating the adaptive mechanisms of bile acid metabolism in mammals exposed to high-altitude hypoxia, thereby establishing a theoretical foundation for investigating the regulation of host lipid metabolism influenced by such conditions.