Hepatic transcriptomic adaptation from prepartum to postpartum in dairy cows

Area of Science:

• Animal Science
• Metabolic Biochemistry
• Genomics

Background:

• The transition from pregnancy to lactation presents significant metabolic challenges for high-producing dairy cows.
• The liver is central to adaptation during this peripartum period, with previous studies indicating increased hepatic glucose synthesis, cholesterol metabolism, lipogenesis, and inflammatory responses.
• Limitations in prior research included small sample sizes and the use of microarray technology.

Purpose of the Study:

• To comprehensively investigate the hepatic transcriptomic changes in dairy cows during the challenging transition to lactation.
• To overcome limitations of previous studies by employing RNA sequencing on a larger cohort.
• To identify key metabolic pathways and signaling networks involved in liver adaptation post-calving.

Main Methods:

• RNA sequencing analysis of liver biopsies from 20 Holstein cows.
• Samples were collected before calving (Pre-P) and after calving (Post-P).
• Differential gene expression analysis and bioinformatic analyses, including co-expression network analysis, were performed.

Main Results:

• Identified 1,475 upregulated and 1,199 downregulated differentially expressed genes (DEGs) between Pre-P and Post-P (FDR adjusted P-value < 0.01).
• Revealed activation of lipid, glucose, and amino acid metabolism, with increased mitochondrial activity and roles for peroxisome proliferator-activated receptor (PPAR) and adipocytokine signaling pathways.
• Observed induction of gluconeogenesis and fatty acid oxidation, increased amino acid utilization for glucose production, enhanced cell proliferation, and inhibited xenobiotic metabolism, alongside decreased glucose transporter expression.

Conclusions:

• The liver undergoes significant metabolic adaptation to support early lactation in dairy cows, with a crucial role for lipid and glucose metabolism.
• Peroxisome proliferator-activated receptor (PPAR) and adipocytokine signaling pathways are pivotal in coordinating these adaptive processes.
• Gene expression patterns suggest a coordinated response involving protein synthesis, energy and lipid metabolism, and cell proliferation, alongside a liver response to inflammatory-like conditions.