The effects of high body energy reserve on ovarian and oviductal responses in bovine females

• Autor(a) principal: Bastos, Natália Marins
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/74/74135/tde-06032023-152130/
• topic: Consumo de matéria seca; Dry matter intake; Extracellular vesicles; Insulin; Insulina; miRNA; miRNAs; Vesículas extracelulares

The metabolic status controls the reproductive function, and the elevated body energy reserve (BER) can affect oocyte and early embryo quality. However, the molecular and physiological mechanisms by which this occurs are still unclear. The main aim of this thesis is to evaluate the elevated BER in ovarian and oviductal responses in bovine females. In chapter 1, is presented a review about the oviductal ability based on its dynamic and systemic changes during reproductive events, as well as the extracellular vesicles (EVs) contribution in this process. In chapters 2 and 3, the same animal model was used to evaluate ovarian and oviductal responses respectively. Thus, Nellore cows from the same herd were randomly submitted to a feedlot period with two nutritional plans with different dry matter intake (DMI) in order to obtain cows with different BER: cows with high body energy reserve (HBER: Ad libitum diet) and moderate body energy reserve (MBER: cows fed 70% of HBER group ingestion). At the end of the feeding period, animals were submitted to estrous synchronization and artificial insemination. Animals were slaughtered approximately 120 h after ovulation induction. In chapter 2, cows were weekly weighted and evaluated for subcutaneous fat thickness and insulin serum concentration along the experimental period. The ovulation was analyzed by ultrasound and after slaughter the reproductive tracts were collected for embryo recovery and samples collection. Cumulus-oocyte-complexes (COC) and follicular fluid were collected from 3-6 mm in diameter ovarian follicles to perform miRNA analysis of cumulus cells (CC) and extracellular vesicles from follicular fluid (EV FF). As expected, differences were observed among MBER and HBER groups for body weight, fat thickness, and insulin serum concentration. HBER animals showed lower ovulation and embryo recovery rates compared to MBER animals. Different miRNAs were found among CC and EV FF within groups, suggesting that the BER may influence follicular communication. In chapter 3, analyzes were performed only from animals which had an 8-cell embryo in isthmus. It was evaluated the molecular profile of extracellular vesicles from oviductal flushing (OF-EVs) and luminal epithelial cells (OV-Cell), and histomorphological analysis in oviductal tissue for ampullary and isthmic oviductal regions. The HBER group presented higher concentration in ampullary extracellular vesicles (AMP-EVs) and larger sizer in isthmic extracellular vesicles (IST-EVs). In AMP-EVs the miRNA profile showed that the differently expressed miRNAs were predicted to regulate pathways associated with cell growth, migration, differentiation and metabolism, being the HBER group may be more susceptible to insulin modulation. The MBER animals showed higher ampullary vascularization than HBER. Additionally, the miRNA profile and differential gene expression (DEG) performed in ampullary (AMP-Cell) and isthmic (IST-Cell) luminal epithelial cells mainly revealed pathways related with insulin metabolism. The results showed here indicates that the ovarian and oviductal responses are influenced by elevated BER once the ovulation rate and communication within the follicle is altered, as the embryo recovery rate and environment/composition at the ampulla and isthmus.