Curcacycline A and B modulate apoptosis induced by heat stress in sheep oocytes during in vitro maturation

• Effect of Curcacycline A and B against heat stress induced apoptosis in oocytes was evaluated.
• Expression of apoptotic related-genes and the generation of ROS increased at 42 °C.
• Curcacycline A and B inhibited the negative effect of heat stress on meiotic maturation, expression of apoptotic genes and ROS generation in oocytes.

The main objective of the current study was to investigate the effect of Curcacycline A and B against heat stress induced apoptosis. Cumulus-oocyte complexes (COCs) were allocated in several groups were cultured at 39 °C and 42 °C in TCM-199 supplemented either with hormones alone, or with two cyclic peptides isolated from the latex of Jatropha curcas, namely Curcacycline A and B. In general, the results revealed a concrete reduction in the maturation rate of sheep oocytes cultured in TCM-199 medium at 42 °C. At the same temperature, higher percentages of sheep oocytes cultured with Curcacycline A or A + B were matured compared with TCM-199 medium alone. Both the expression of apoptotic related-genes (Bax, Bcl-2, Caspase 3, P53 and C-myc) and the generation of reactive oxygen species (ROS) increased significantly in oocytes cultured in TCM-199 medium at 42 °C. The addition of Curcacycline A and B supplements to the culture media at 42 °C suppressed the effect of heat stress on the expression of apoptotic genes and on the generation of ROS. In conclusion, results indicated that the two cyclic peptides inhibited the negative effect of heat stress on meiotic maturation, expression of apoptotic genes and ROS generation in oocytes.