Hormonal influences and body energy reserve on the modulation of the intrafolicular and periconceptional reproductive environment

Abstract

In 30 years, the global population growth associated with the high demand for animal protein will claim for a high evolution of the beef cattle production indexes. The increase in livestock efficiency is based on several factors, among which the reproductive index of the herd represents a great intercession of this segment. Reproductive biotechnologies are tools capable of optimizing the productivity and reproductive potential of males and females. However, although these biotechnologies improve reproductive rates, the success of a pregnancy depends on the adequate development of the ovarian follicle and the embryo. Acting as mediators of intercellular communication, extracellular vesicles (EVs), present in body fluids, play an important role modulating the reproductive tract environment. The profile of EVs is altered depending on the environment where these vesicles are produced, thus demonstrating how the environment modulates cell development and consequently the contents of extracellular vesicles. Therefore, based on this information, we can highlight the relevance of understanding the periovulatory and periconceptional environments in the face of endocrine variations and environmental responses, as well as their impact on gamete and embryo quality, respectively. Thus, this research aims to use two animal models to understand how the periovulatory and periconceptional environments are modulated by progesterone and the high body energy reserve. Specific Aim 1: To understand the effects modulated by the levels of progesterone (P4) and by the body energy reserve in the intra-follicular environment. This study aims to test the following hypotheses: 1) Follicles of 3-6 mm in diameter ipsilateral and contralateral to the corpus luteum and coming from ovaries in stage 3 of the estrous cycle (high level of plasma P4;> 9ng / ml) presents different follicular environments due to the different concentrations of intra-follicular progesterone. 2) 3-6 mm follicles from stage 1 ovaries presents different follicular environments due to higher body energy reserves. In this study, genes and miRNAs modulated by different follicular environments will be evaluated in follicular cells as well as in EVs. Specific Aim 2: To determine the effects of proximity to the corpus luteum and the altered body energy reserve in the periconceptional environment of the oviduct. This study aims to test the following hypotheses: 1) Oviducts ipsilateral and contralateral to the corpus luteum in stage 1 of the estrous cycle (low plasma P4 level; <4ng / ml) presents different environments due to different concentrations of estrogen and progesterone from the ovulated follicle and the newly formed corpus luteum, respectively. 2) Oviducts in stage 1 of the estrous cycle have different environments due to higher body energy reserves. In this study, genes and miRNAs modulated by the proximity of the corpus luteum and body energy reserve will be studied in oviductal cells as well as in EVs. Therefore, we believe that due to the importance of EVs as carriers of information within the follicular environment, the results obtained in these experiments will have a great impact on the understanding of the mechanisms of gene expression and the acquisition of oocyte competence. Additionally, we hope that due to the importance of the oviduct environment for the embryonic genome activation, the results obtained here will have great impact on understanding the mechanisms modulating livestock efficiency related gene expression and the possible negative effects on genes involved with epigenetic changes. Therefore, we believe that these experiments are innovative, and the results obtained here will be important to generate new directions in the research involving the in vitro embryo production for cattle as well as for humans. (AU)