Distinct physiological, plasma amino acid, and liver transcriptome responses to purified dietary beef, chicken, fish, and pork proteins in young rats

Scope: We report on the impact of purified dietary meat proteins from four species on plasma insulin, lipid and amino acid (AA) concentrations, and hepatic transcriptome (RNA-sequencing). Methods and results: Young rats received semi-synthetic diets for 1 wk that differed only regarding protein source; casein (reference) was replaced by beef, chicken, fish, or pork proteins. Compared to casein, all proteins, except pork, increased total plasma AA concentrations. Pork protein reduced adipose tissue mass and liver triacylglycerol, which was accompanied by increased plasma triacylglycerol concentrations. Plasma cholesterol was reduced by fish protein. The number of differentially expressed genes ranged between 609 (pork) and 1258 (chicken); on average one-third of the changes were specific for each meat protein. Pathway responses were most similar for beef and chicken, followed by pork and fish. Although the extent varied, all meat proteins induced mRNA translation, antigen processing/presentation, intracellular vesicular trafficking, and oxidoreductive-transformation pathways, and suppressed signal-transduction (Notch, TGFB/SMAD, insulin) and mitochondrial biogenesis pathways. Lipid-and AA-metabolic pathways were repressed, except by pork. AA-transport pathways were induced by beef and fish only, and complement/coagulation-pathways were suppressed by chicken and beef. Fish suppressed nuclear-transport and cofactor metabolism. Conclusion: To conclude, short-term feeding of different meat proteins resulted in distinct physiological and transcriptome changes in young rats.