Pituitary Genomic Expression Profiles of Steers Are Altered by Grazing of High vs. Low Endophyte-Infected Tall Fescue Forages

Authors

Qing Li, University of KentuckyFollow
Raquel Hegge, University of KentuckyFollow
Phillip J. Bridges, University of KentuckyFollow
James C. Matthews, University of KentuckyFollow

Abstract

Consumption of ergot alkaloid-containing tall fescue grass impairs several metabolic, vascular, growth, and reproductive processes in cattle, collectively producing a clinical condition known as “fescue toxicosis.” Despite the apparent association between pituitary function and these physiological parameters, including depressed serum prolactin; no reports describe the effect of fescue toxicosis on pituitary genomic expression profiles. To identify candidate regulatory mechanisms, we compared the global and selected targeted mRNA expression patterns of pituitaries collected from beef steers that had been randomly assigned to undergo summer-long grazing (89 to 105 d) of a high-toxic endophyte-infected tall fescue pasture (HE; 0.746 μg/g ergot alkaloids; 5.7 ha; n = 10; BW = 267 ± 14.5 kg) or a low-toxic endophyte tall fescue–mixed pasture (LE; 0.023 μg/g ergot alkaloids; 5.7 ha; n = 9; BW = 266 ± 10.9 kg). As previously reported, in the HE steers, serum prolactin and body weights decreased and a potential for hepatic gluconeogenesis from amino acid-derived carbons increased. In this manuscript, we report that the pituitaries of HE steers had 542 differentially expressed genes (P < 0.001, false discovery rate ≤ 4.8%), and the pattern of altered gene expression was dependent (P < 0.001) on treatment. Integrated Pathway Analysis revealed that canonical pathways central to prolactin production, secretion, or signaling were affected, in addition to those related to corticotropin-releasing hormone signaling, melanocyte development, and pigmentation signaling. Targeted RT-PCR analysis corroborated these findings, including decreased (P < 0.05) expression of DRD2, PRL, POU1F1, GAL, and VIP and that of POMC and PCSK1, respectively. Canonical pathway analysis identified HE-dependent alteration in signaling of additional pituitary-derived hormones, including growth hormone and GnRH. We conclude that consumption of endophyte-infected tall fescue alters the pituitary transcriptome profiles of steers in a manner consistent with their negatively affected physiological parameters.

Document Type

Article

Publication Date

9-13-2017

Notes/Citation Information

Published in PLOS ONE, v. 12, 9, e0184612, p. 1-17.

© 2017 Li et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Digital Object Identifier (DOI)

https://doi.org/10.1371/journal.pone.0184612

Funding Information

This work is supported by a United States Department of Agriculture-Agricultural Research Service Cooperative Agreement (JCM) and by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Hatch project No. KY007095 (JCM, PB).

Related Content

This is publication No. 17-07-076 of the Kentucky Agricultural Experiment Station and is published with approval of the Director.

All relevant data are within the paper and its Supporting Information files, except for the .cel files which are available from GEO (http://www.ncbi.nlm.nih.gov/geo/) as accession no. GSE62570.

Repository Citation

Li, Qing; Hegge, Raquel; Bridges, Phillip J.; and Matthews, James C., "Pituitary Genomic Expression Profiles of Steers Are Altered by Grazing of High vs. Low Endophyte-Infected Tall Fescue Forages" (2017). Animal and Food Sciences Faculty Publications. 14.
https://uknowledge.uky.edu/animalsci_facpub/14