The expression and correlations of repressors, intermediaries, and end-products of the IGF1 and insulin signaling pathways within the hepatic and reproductive tissues of holstein cattle h [electronic resource]

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Selection for high milk production has created a physiologically different dairy cow with lower fertility. The growth hormone (GH)/insulin-like growth factor 1 (IGF1)/insulin endocrine system underpins the physiology for increased milk production and also plays a functional role in ovarian and uterine biology. This endocrine system, therefore, may link greater milk production to lower fertility in dairy cattle. The objectives of these studies were to investigate the expression of repressors, intermediaries, and end-products of the IGF1 and insulin signaling pathways (n = 32 genes) within the liver during the periparturient period and also within liver and uterus of postpartum cows. We used a quantitative real-time polymerase chain reaction (qRT-PCR) assay for this work. Bovine primers were developed to measure mRNA for 32 different genes within in the IGF1 and insulin signaling pathways. We concluded that changes in IGF1 expression in liver may be the principle driver to altered insulin/IGF1 signaling in periparturient cows. Liver and uterine tissue were different in terms of level of expression and gene expression across the tissues was not correlated. Within a single sample there was a high correlation between the expression of different genes. Correlated gene expression may imply a biological mechanism through which the cell coordinates the expression of multiple genes within the same endocrine signaling pathway.