Insulin influences developmental competence of bovine oocytes cultured in α-MEM plus follicle-simulating hormone

Abstract

The aim of this study was to evaluate the dose-response effect of insulin, plus follicle-simulating hormone (FSH) at a fixed concentration, in a serum-free defined culture medium (DCM) on the in vitro maturation of bovine cumulus-oocyte complexes (COCs). For oocyte nuclear maturation, the expression levels of GDF9, GLUT1, PRDX1 and HSP70.1 transcripts related to oocyte and embryo developmental competence were analysed. For in vitro maturation (IVM), cumulus-oocyte complexes from slaughterhouse ovaries were distributed into four groups based on insulin concentration added to serum-free DCM, which was composed of alpha minimum essential medium (α-MEM), as basal medium: (1) DCM control: 0 ng/ml; (2) DCM1: 1 ng/ml; (3) DCM10: 10 ng/ml; and (4) DCM100: 100 ng/ml. After IVM, the nuclear status of a sample of oocytes was analysed and the other oocytes were submitted for in vitro fertilization (IVF) and in vitro culture (IVC). Different concentrations of insulin did not affect significantly the nuclear maturation and cleavage rate (72 h post-insemination) across all groups. Blastocyst rate (192 h post-insemination) did not differ in DCM control (24.3%), DCM1 (27.0%) and DCM10 (26.3%) groups, but the DCM100 (36.1%) group showed a greater blastocyst rate (P 0.05) was observed at the different insulin concentrations. The results indicated that insulin added to DCM influenced levels of transcripts related to cellular stress (HSP70-1 and PRDX1) and oocyte competence (GDF9) in bovine oocytes and at higher concentrations enhanced blastocyst production.

Effects of PI3K and FSH on steroidogenesis, viability and embryo development of the cumulus–oocyte complex after in vitro culture

“…The in vitro rates of embryo development were similar to those described by Mota et al (2015), and no differences were observed between 0FSH and 0FSH 100LY groups (Fig. 6).…”

“…Polar body extrusion is strongly influenced by FSH (Mota et al, 2015) and PI3K. The F-actin in oocytes is dependent on PtdIns(3,4,5)P3, which is produced by proteins such as PI3K.…”

“…Oocyte maturation corresponds to nuclear (polar body extrusion) and cytoplasmic maturation, which includes the production of RNAs and proteins for embryo development (Ferreira et al , 2009). Polar body extrusion is strongly influenced by FSH (Mota et al , 2015) and PI3K. The F-actin in oocytes is dependent on PtdIns(3,4,5)P3, which is produced by proteins such as PI3K.…”

“…After culture, the COCs were fertilized according to the methods described by Mota et al (2015), and embryo culture was performed using SOF medium as described by Gulart (2015).…”

Mesenchymal Stem Cell-Conditioned Medium Modulates Apoptotic and Stress-Related Gene Expression, Ameliorates Maturation and Allows for the Development of Immature Human Oocytes after Artificial Activation

“…Two media were used. Medium I was α-minimum essential medium (α-MEM) and was used as a control medium [ 21 ]. Medium II was hUCM [ 22 ].…”