Association of glucose-6-phosphate dehydrogenase activity with oocyte cytoplasmic lipid content, developmental competence, and expression of candidate genes in a sheep model

To evaluate associations of glucose-6-phosphate dehydrogenase (G6PDH) activity in sheep oocytes with cytoplasmic lipid content, maturational competence, developmental competence to the blastocyst stage, and gene expression of certain molecular markers.Purpose To evaluate associations of glucose-6-phosphate dehydrogenase (G6PDH)activity in sheep oocytes with cytoplasmic lipid content, maturational competence,developmental competence to the blastocyst stage, and gene expression of certainmolecular markers.Methods Before brilliant cresyl blue (BCB) staining test, oocytes were classified ashigh, middle, and low cytoplasmic lipid content (HCLC, MCLC, and LCLC) and after thetest as having low or high G6PDH-activity (BCB+ and BCB-, respectively). Aftermaturation in vitro, a group of oocytes were subjected to IVF followed by in vitroembryo culture and another group was used for evaluation of expression of candidategenes.Results The cleavage and blastosyst rates were lowest (P &lt; 0.05) in LCLC group,intermediate (P &lt; 0.05) in MCLC group and highest (P &lt; 0.05) in HCLC group. More(P &lt; 0.05) oocytes in HCLC group were BCB+, and higher (P &lt; 0.05) maturation,cleavage, and blastocyst rates were seen for BCB+ oocytes than the BCB- oocytes.Our gene expression data indicated that mRNA transcript abundance of ITGB2, pZP3,BMP15, and GDF9 genes were similar between BCB oocytes groups. However, theexpression of ATP1A1 was higher (P &lt; 0.05) for BCB+ oocytes compared to BCBoocytes.In addition, BAX transcript abundance was similar (P &gt; 0.05) among BCB+,BCB-, and control groups, before and after maturation in vitro.Conclusion Activity of G6PDH in sheep oocytes is highly associated with lipid content,and compared with the morphological parameters, might be a more precise andobjective predictor for subsequent developmental competence in vitro.</p