Influência do estresse térmico na secreção de interferon tau por embriões bovinos produzidos in vitro: alteração na expressão gênica em células luteais

Abstract

Among the main factors that directly affect the efficiency and profitability of the ruminant production chain is the influence of the environment, genetics and animal health. The reduction in conception rates during hot months can be 20 to 30% compared to months of thermal comfort. The influence of heat stress on fertility reduction is a multifactorial problem, compromising the functioning of different tissues and cell types. Thermal stress has a direct impact on the period of early embryonic development, on the formation and development of the competent corpus luteum and on maternal recognition of pregnancy. This is the period that occurs in the first days after fertilization, when the conceptus signals its presence to the mother, seeking to increase the useful life of the corpus luteum, avoiding luteolysis by blocking the synthesis of prostaglandin F2 alpha. It is known that bovine embryos synthesize and secrete IFNT as early as day 07 of development, and that embryos subjected to heat stress, In Vitro, reduce IFNT production on day 7 of embryonic development. Our hypothesis is that the IFNT signaling pathway in luteal cells is altered as a result of lower IFNT production by bovine embryos subjected to heat stress. Our aim was to evaluate the response of a primary culture of bovine luteal cells cultured with conditioned medium from embryos produced in vitro under heat stress. After thermal stress of embryos produced in vitro, as described by Amaral et al, (2020). The first experiment was carried out with the objective of evaluating the response of bovine luteal cells treated with different doses of roIFNT, namely 0ng, 0.1ng and 1ng of roIFNT, where the medium was composed of 60% DMEM and 40% SOF + roIFNT . The second experiment, on the other hand, sought to evaluate the effect of the conditioned medium of the stressed embryos under the primary culture of bovine luteal cells, being the groups: without influence of the embryos (NE), group kept under normal temperature of In Vitro culture of embryos (EC), group stressed during the In Vitro maturation phase (IVM), group stressed during In Vitro fertilization (IVF), group stressed during In Vitro cultivation (IVC) and the group that was submitted to temperature increase in all stages of production In Vitro Embryos (MFC). We conclude that the conditioned medium of embryos subjected to thermal stress during embryonic development was able to change the expression of genes stimulated by IFNT in primary culture of bovine corpus luteum cells, at 6 hours. In addition to altering the expression of genes related to angiogenesis, within 18 hours.