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Weaning induced expression changes of genes associated with lactation and oestrogen signalling in the hypothalamus of postpartum cows

Ainu Husna M.S. Suhaimi ^1,2,3,5,*, Traute Flatscher-Bader ^1,2, Sigrid A. Lehnert ^1,3, Antonio Reverter^1,3, Eva Chan ^1,3, Nancy J. Phillips ^1,4, Michael McGowan ^1,4 and Michael J. D?Occhio ^1,2

¹CRC for Beef Genetic Technologies, CJ Hawkins Homestead, University of New England, Armidale, New South Wales, Australia 2351,
²The University of Queensland, School of Animal Studies, Gatton Campus, Gatton, Queensland, Australia 4343,
³CSIRO Livestock Industries, Queensland Bioscience Precinct, St Lucia, Brisbane, Queensland, Australia 4067,
⁴The University of Queensland, School of Veterinary Science, St Lucia, Brisbane, Queensland, Australia 4072, ⁵Malaysian Agricultural Research and Development Institute, P.O. Box 12301, General Post Office, 50740 Kuala Lumpur Malaysia.

Malaysian J. Anim. Sci. 2018 21(2): 7-26

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Weaning influences the hypothalamic control of reproduction. To understand how weaning affects hypothalamic gene expression patterns in beef cows, RNA samples from the anterior and ventral posterior hypothalamic regions of suckled and weaned primiparous cows were  hybridized to Agilent bovine microarray to reveal possible interactions.  In total, 199 differentially expressed genes were observed between suckled and weaned cows. Among these genes, gene ontology-molecular function terms hormone activity and signal transducer activity  and KEGG pathway neuroactive?ligand receptor interaction were significantly over-represented as a response to weaning. Ten genes associated with physiological processes characteristic of lactation, namely osmolarity and stress, energy balance and suckling were revealed differentially expressed. These genes included angiotensin receptor 1 (AGTR1), arginine vasopressin (AVP), calcitonin-related polypeptide beta (CALCB), corticotrophin releasing hormone binding protein (CRHBP), neuropeptide Y (NPY), growth hormone (GH), growth hormone releasing hormone (GHRH), agouti related protein homolog (AGRP), oxytocin receptor (OXTR), prolactin (PRL). In addition, 37 genes encoded transcription factors, hormones and proteins that were either modulated by oestrogen or involved in oestrogen signaling in various tissues. ESR1 and 9 of these genes had the same regional expression where eight of these genes coded for either a hormone or receptor. The significant differential expression of AGRP, NPY, ESR1 and PRL that was observed with microarray showed the same trend when verified by qRT-PCR.  In summary, the altered expression of genes associated with lactation and oestrogen signaling in the hypothalamus upon weaning could be important in the control of postpartum reproduction.