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Doctoral thesis, 2017

Insulin and the early bovine embryo

Laskowski, Denise

Abstract

Metabolic imbalance is a problem in the dairy industry because the metabolic demands of increased milk production can lead to decreased fertility, and more knowledge about improving the management and physical conditions of the cow (the links between fertility, nutrition, milking, and dry period) is needed. Insulin is an important hormone regulating the energy balance in the body, and insulin concentrations change in situations of energy deficiency or excess, both of which are known to decrease fertility in cows as well as in humans. Hyperinsulinemia is associated with decreased fertility by impairing the developmental potential of embryos, but the underlying reasons for this remain unclear. Our aim was to investigate insulin-induced changes on development, morphology and molecular signature in bovine blastocysts on Day 8 (BC8). An in vitro model was used and morphology and gene expression were analysed by combining confocal microscopy and microarray-based transcriptome studies. Blastocysts were produced in vitro according to standard methods using oocytes that were supplemented with three different insulin levels (INS10 =10 µg/ml; INS0.1= 0.1 µg/ml; INS0=control) during maturation. The transcriptome profile of BC8 was obtained and embryo quality grades, developmental stages and morphologies were further assessed in terms of Factin, DNA, and active mitochondria. Significant differences were observed in developmental rates and morphology after insulin exposure. The observed changes were reflected by increased expression of genes involved in cell division and structure, mitochondrial activation, lipid metabolism, and oxidative stress. Combining all of the results, it was shown that elevated insulin impairs the developmental potential of the embryo. This work contributes to new knowledge about the molecular background of embryos developing under metabolic stress conditions such as hyperinsulinemia. Moreover, the studies are of comparative value for humans where impaired fertility is often related to metabolic disorders.

Keywords

reproduction, metabolic imbalance, embryo metabolism, oocyte maturation, insulin

Published in

Acta Universitatis Agriculturae Sueciae
2017, number: 2017:65
ISBN: 978-91-7760-020-6, eISBN: 978-91-7760-021-3
Publisher: Department of Clinical Sciences, Swedish University of Agricultural Sciences.

Authors' information

Swedish University of Agricultural Sciences, Department of Clinical Sciences

UKÄ Subject classification

Clinical Science

URI (permanent link to this page)

https://res.slu.se/id/publ/104121