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This study aimed to assess the effect of the insulin-like grow factor 1 (IGF-1) treatment during in vitro maturation on the gene expression and developmental ability of ovine oocytes. Ovine cumulus-oocyte complexes (COC) were matured in vitro without (control) or with the supplementation of IGF-1 (100 ng/ml) and then subjected to in vitro fertilization and culture. The rate of oocyte maturation and embryo development was recorded and expression of the selected genes (involved in the PI3K/Akt and apoptosis signaling) was assessed in the matured oocytes. The IGF-1 treatment significantly (p <.05) improved the oocyte maturation rate (%) as compared to the control (81.5 ± 2.40 vs. 73.6 ± 0.94). Similarly, as compared to the control, the IGF-1 treatment significantly (p <.05) improved the rate (%) of cleavage (54.7 ± 1.58 vs. 67.2 ± 3.65) and the formation of 4–8 cell embryos (30.7 ± 2.89 vs. 44.1 ± 4.01) and morula (20.7 ± 2.08 vs. 32.8 ± 2.78). The IGF-1 treatment significantly (p <.05) upregulated the expression of IGF1R, PI3KR1, AKT1 and BCL2 and downregulated the expression of GSK3β, FOXO3 and CASP9 in the matured oocytes. In conclusion, the IGF-1 treatment significantly improved the developmental competence of ovine oocytes through the regulation of the PI3K/Akt and apoptosis signaling. [ABSTRACT FROM AUTHOR]

The effect of interleukin-6 (IL-6) supplementation during the different phases of in vitro embryo culturing (IVC) on embryo development and embryonic gene expression was studied in ovine. IL-6 was added to IVC medium during the late phases (72–192 h; 5, 10, and 25 ng/ml IL-6) or entire period (0–192 h; 10 ng/ml IL-6) of IVC to determine its effect on embryo development. Further, the effect of IL-6 (10 ng/ml) supplementation at the 72 h of IVC on gene expressions associated with JAK/STAT signalling and pluripotency in 8–16 cell embryos (1 h post-supplementation) and compact morulae (48 h post-supplementation), and apoptosis and primitive endoderm (PrE) development in compact morulae was investigated. The supplementation of 10 ng/ml IL-6 during the late phases of IVC significantly (P < 0.05) increased blastocyst formation (35.2 ± 1.52%) compared to the control (21.1 ± 1.11%), and 5 ng/ml (25.9 ± 2.98%) or 25 ng/ml (16.5 ± 0.73%) IL-6 groups. Conversely, IL-6 (10 ng/ml) treatment throughout the IVC period significantly (P < 0.05) decreased the rate of cleavage (55.4 ± 1.57%) and blastocyst formation (14.5 ± 1.28%) compared to the control group (65.8 ± 1.35% and 21.5 ± 0.97%, respectively). In 8–16 cell embryos and compact morulae, the IL-6 treatment significantly (P < 0.05) affected the expression of genes associated with JAK/STAT signalling and pluripotency. Further, the treatment significantly (P < 0.05) downregulated BAX and CASP3, and upregulated GATA6 expression in compact morulae. In conclusion, IL-6 supplementation affected the in vitro development of ovine embryos in a dose- and time-dependent manner. The beneficial effect of IL-6 on the development of late-stage embryos was mediated through the changes in gene expressions associated with JAK/STAT signalling, pluripotency, apoptosis and PrE development. • Effect of IL-6 on development and gene expression of ovine embryos was assessed. • IL-6 had a dose- and stage-dependent influence on embryo development in vitro. • IL-6 promoted development of the late-stage embryos. • Beneficial effect of IL-6 was mediated through JAK/STAT and pluripotency signalling. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Exogenous IL-7 affected in vitro maturation of ovine oocytes. • Oocyte maturation was improved with low concentration (1 ng/ml) of exogenous IL-7. • Higher concentrations of exogenous IL-7 were detrimental for oocyte maturation. • Higher exogenous IL-7 likely caused ROS-mediated oxidative stress. • Higher exogenous IL-7 also stimulated apoptotic signalling. Abstract Interleukin-7 (IL-7) mediated signals are linked to development, proliferation, survival and differentiation of cells. Recent evidences indicate its role in oocyte maturation process as well. Nevertheless, the underlying mechanisms of IL-7 involvement in oocyte maturation are not well characterized. In addition, currently no information is available on the effect of exogenous IL-7 on oocyte maturation in ovine or any other species. In this study, the effect of IL-7 supplementation during in vitro maturation (IVM) on the maturation rate, production of reactive oxygen species (ROS) and gene expression of ovine cumulus-oocyte complexes (COC) was assessed. IL-7 (0.5, 1, 2, 5 and 10 ng/ml) was supplemented in IVM medium at the beginning (0 h) and maturation rate of COC was assessed at the completion of IVM (24 h). The maturation rate (%) was found significantly (P = 0.000) greater with the 1 ng/ml of IL-7 supplementation (69.5) than control (60.0). In contrast, the maturation rate was reduced significantly (P = 0.000) with the 2 (47.1), 5 (39.2) and 10 ng/ml (39.1) of IL-7 as compared to the control. The level of intracellular ROS in the matured COC was found considerably higher with the 5 ng/ml of IL-7 followed by 1 ng/ml of IL-7 and control. It was evident that in the presence of superoxide dismutase-inhibitor, 1 ng/ml of IL-7 did not stimulate oocyte maturation. In contrast, oocyte maturation was improved with 5 ng/ml of IL-7 supplementation in the presence of NADPH-oxidase-inhibitor. IL-7 supplementation influenced gene expression in COC in a dose and time dependant manner. The expression of genes related to ROS production and apoptosis were upregulated and the genes associated with antioxidant mechanisms were downregulated noticeably with the supplementation of 5 ng/ml of IL-7. In conclusion, IL-7 at low concentration was beneficial for oocyte maturation, which was likely mediated through the favourable level of intracellular ROS and antioxidant mechanisms. In contrast, the detrimental effects of greater IL-7 concentrations on oocyte maturation were possibly arbitrated through the ROS-mediated oxidative stress, compromised antioxidant mechanism and stimulated apoptotic signalling. [ABSTRACT FROM AUTHOR]