Abstract
Oxidative stress, mitochondrial and endoplasmic reticulum (ER) stress have been recently postulated as main drivers of altered pathways in the oocyte linking maternal metabolic disorders to low fertility outcomes. Upregulated lipolysis, commonly associated with obesity and other metabolic disorders, increases the concentrations of lipotoxic fatty acids in the follicular fluid, which were shown to have a direct detrimental impact on oocyte quality and subsequent embryo development. Oocyte maturation involves complex nuclear, cytoplasmic, and molecular changes that determines its developmental competence. In human IVF clinics, oocytes are usually collected after hormonal stimulation and thus after exposure to metabolic stress during maturation in the follicle in affected mothers. It is not known if the deterioration in developmental competence of these metabolically-compromised oocytes can be rescued by alleviating mitochondrial and endoplasmic stress during or after fertilization, or should the stress be prevented during maturation. This project aims to test sensitive windows for preventative or reparative measures that may improve in vitro embryo production from metabolically-compromised oocytes, and examine the intrinsic quality of the embryos produced after treatment. A well-established bovine in vitro model will be used to generate metabolically-compromised oocytes by exposure to elevated pathophysiological levels of palmitic acid. MitoQ, a highly efficient mitochondria-targeted antioxidant, and Sirolimus, a specific ER-stress inhibitor, will be used to alleviate cellular stress either during fertilization or embryo culture, or during maturation. Embryo development will be recorded and blastocysts quality will be assessed by examining their metabolism, cell proliferation, cell lineage, DNA damage, markers for cellular stress and apoptosis. RNA-seq will be used to detect any persistent alterations in the transcriptomic profile. These studies will help defining windows of sensitivity and efficiency of targeting intracellular stress as a treatment option for infertile patients suffering from metabolic diseases.
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