Hepatic pyruvate carboxylase expression differed prior to hyperketonemia onset in transition dairy cows

PLoS One. 2020 Nov 9;15(11):e0241929. doi: 10.1371/journal.pone.0241929. eCollection 2020.

Abstract

Fatty acids (FA) provide an energy source to the liver during negative energy balance; however, when FA influx is excessive, FA can be stored as liver lipids or incompletely oxidized to β-hydroxybutyrate (BHB). The objectives of this study were to quantify plasma and liver FA profiles and hepatic gene expression in cows diagnosed with hyperketonemia (HYK; BHB ≥ 1.2 mM) or not (nonHYK; BHB < 1.2 mM) to determine a relationship between FA profile and expression of hepatic genes related to oxidation and gluconeogenesis. Production parameters, blood samples (-28, -3, 1, 3, 5, 7, 9, 11, and 14 d relative to parturition; n = 28 cows), and liver biopsies (1, 14, and 28 d postpartum; n = 22 cows) were collected from Holstein cows. Cows were retrospectively grouped as HYK or nonHYK based on BHB concentrations in postpartum blood samples. Average first positive test (BHB ≥ 1.2 mM) was 9 ± 5 d (± SD). Cows diagnosed with HYK had greater C18:1 and lower C18:2 plasma proportions. Liver FA proportions of C16:0 and C18:1 were related to proportions in plasma, but C18:0 and C18:2 were not. Some interactions between plasma FA and HYK on liver FA proportion suggests that there may be preferential use depending upon metabolic state. Cows diagnosed with HYK had decreased pyruvate carboxylase (PC) expression, but no difference at 1 d postpartum in either cytosolic or mitochondrial isoforms of phosphoenolpyruvate carboxykinase (PCK). The increased PC to PCK ratios in nonHYK cows suggests the potential for greater hepatic oxidative capacity, coinciding with decreased circulating BHB. Interestingly, FA, known regulators of PC expression, were not correlated with PC expression at 1 d postpartum. Taken together, these data demonstrate that HYK cows experience a decrease in the ratio of hepatic PC to PCK at 1 day postpartum prior to HYK diagnosis which, on average, manifested a week later. The differential regulation of PC involved in HYK diagnosis may not be completely due to shifts in FA profiles and warrants further investigation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Age of Onset
  • Animals
  • Cattle
  • Cattle Diseases / enzymology*
  • Cattle Diseases / metabolism
  • Fatty Acids / blood
  • Fatty Acids / metabolism
  • Female
  • Ketosis / enzymology
  • Ketosis / metabolism
  • Ketosis / veterinary*
  • Liver / metabolism
  • Pyruvate Carboxylase / metabolism*
  • Retrospective Studies

Substances

  • Fatty Acids
  • Pyruvate Carboxylase

Grants and funding

Funding for this research was provided by USDA Hatch grant number WIS01877 from the Wisconsin Agricultural Experiment Station (Madison, WI; HW received funding) and Fermented Nutrition Corporation (Luxemburg, WI; HW received funding). Graduate student fellowship support was provided by Purina Animal Nutrition, LLC (KW received funding). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. There was no additional external funding received for this study.