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Modulation des taux plasmatiques d’insuline par l’apport de propylène glycol dans l’alimentation : effet sur la quantité, la qualité des ovocytes et des embryons produits in vitro chez des génisses laitières

Abstract : The ovum pick-up and in vitro embryo production method in heifers can accelerate the speed of genetic progress through the female line. However, to be effective it requires high numbers of usable oocytes to be collected and high numbers of transferable embryos and high embryo survival after cryopreservation to ensure the maintenance of pregnancy after transfer. The variability in the quality of oocytes and embryo development rates in vitro may be influenced by the dietary intake of donor cattle before oocyte recovery and may be related to the concentrations of metabolites and hormones involved in regulating energy metabolism: in particular, increased levels of insulin and IGF1 were associated with high energy intake in dairy heifers. Moreover, in heifers, it was shown that diets that increase insulin concentrations negatively influence the quality of oocytes. However an increase in insulin concentrations over a short lapse of time has a positive effect on the growth of small follicles prior to superovulatory treatment. These findings support the idea that it may be possible to modulate insulin concentrations transiently to improve reproductive success. The addition of propylene glycol (PG) to the diet increases the concentrations of insulin and IGF1 in plasma in cows during the post-partum period. Anti-müllerian hormone (AMH) is an endocrine marker of the size of the pool of ovarian gonadotrophin-responsive follicles in the cow, and plasma AMH concentrations measured before stimulation of follicular growth with FSH hormone treatment can help predict the response of individuals. In this thesis, we investigated the effect of shortterm PG administration to modulate the levels of insulin, follicular growth, the superovulatory response and in vitro embryo production after OPU in heifers with different pre-experimental circulating AMH profiles (high, H vs. low, L). Firstly, the relationship between the dose of propylene glycol in dairy heifers and the insulin response was established. Secondly, the number and morphological quality of oocytes and embryos produced with and without a supplement of propylene glycol in feed-restricted heifers were determined. Thirdly, the gene expression patterns of the IGF system in oocytes and cumulus cells and the expression profile of selected candidate genes that are important for in vitro embryo development were evaluated. Plasma concentrations of some hormones and metabolites and their relationship with PG were also studied.Our data show that administration of PG increased plasma insulin, IGF1 and glucose concentrations and decreased plasma β-hydroxybutyrate (BHB) and urea concentrations in feed-restricted heifers. PG as an oral drench also increased IGF1 concentrations in follicular fluid. In addition, PG increased the number of small (2–3mm) follicles on Day 2 during the first follicle wave in both AMH groups (H and L) compared with the control treatment (water drench). PG only continued to have a positive effect on the number of medium (4–8mm) follicles on Day 5 after stimulation of follicular growth in the AMH H group. Additionally, there was a significant increase in Day 7 Grade 1 blastocysts (expressed as a percentage of fertilized oocytes) after PG compared with control treatment in both AMH groups of heifers. PG increased the number of expanded blastocysts at Day 7 compared with control but only in AMH H and not AMH L heifers. Additionally, PG modified the gene expression pattern of the IGF system in cumulus cells and produced changes in gene expression in blastocysts. Consequently, our data showed that PG administration is effective in improving in vitro embryo production probably due to the existence of epigenetic regulation induced by PG during follicular growth in the IGF1 system. This regulation system may modulate the follicular environment and level of gene expression up to the blastocyst stage more markedly in heifers with high compared to low AMH levels.
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Submitted on : Friday, November 27, 2020 - 10:59:25 AM
Last modification on : Friday, August 5, 2022 - 2:38:11 PM
Long-term archiving on: : Sunday, February 28, 2021 - 6:59:06 PM


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  • HAL Id : tel-03027529, version 2
  • PRODINRA : 273693



Giselle del Carmen Gamarra Lazo. Modulation des taux plasmatiques d’insuline par l’apport de propylène glycol dans l’alimentation : effet sur la quantité, la qualité des ovocytes et des embryons produits in vitro chez des génisses laitières. Sciences agricoles. AgroParisTech, 2014. Français. ⟨NNT : 2014AGPT0083⟩. ⟨tel-03027529v2⟩



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