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Doctoral Thesis
DOI
https://doi.org/10.11606/T.10.2015.tde-16092015-141536
Document
Author
Full name
Saara Carollina Scolari
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Pirassununga, 2015
Supervisor
Committee
Binelli, Mario (President)
Lopes, Flavia Lombardi
Perecin, Felipe
Silva, Luciano Andrade
Silva, Luis Felipe Prada e
Title in Portuguese
Remodelamento dinâmico da matriz extracelular endometrial modula a receptividade em bovinos
Keywords in Portuguese
Endométrio
Matriz extracelular
Remodelamento
Abstract in Portuguese
A matriz extracelular do endométrio (ECM) é constituída por moléculas secretadas que compõem o microambiente celular e são ativadas ou suprimidas principalmente pelos hormônios esteróides ovarianos, estradiol (E2) e progesterona (P4) durante o ciclo estral. A identificação de genes envolvidos no remodelamento e receptividade pode levar à descoberta de importantes processos biológicos ligados ao sucesso gestacional. Os objetivos foram: 1. identificar a relação de diferentes tamanhos de folículos pré-ovulatórios (FPO) e corpo lúteo (CL) e de seus respectivos hormônios E2 e P4 com a expressão endometrial de genes associados com o remodelamento da ECM durante o período de pré-implantação; e 2. analisar a relação entre a expressão gênica de determinados componentes da ECM avaliada no dia 6 após inseminação artificial (IA) com sucesso gestacional. Para tal, dois experimentos foram realizados. No experimento 1, estudo 1 e estudo 2, 42 e 74 vacas Nelore (Bos indicus) adultas, respectivamente foram sincronizadas obtendo-se ao final dois grupos com distintos tamanhos FPO e CL consequentemente, distintas concentrações de E2 no proestro e P4 no diestro. Os grupos foram: Folículo Grande-CL Grande (FG-CLG; estudo 1, n=20; estudo 2, n=35) e Folículo Pequeno-CL Pequeno (FP-CLP; estudo 1, n=22; estudo 2, n=39). Amostras de tecido endometrial foram coletadas por biópsia no D0 (estro) e pós-mortem no D4 (estudo 1) e D7 (estudo 2). Concentrações de E2 e P4 foram mensuradas por radioimunoensaio (RIA) obtendo- se menores concentrações no grupo FP-CLP. No experimento 2, vacas adultas, Nelore (Bos indicus; n=33) foram sincronizadas utilizando um protocolo a base de prostaglandina F 2α (PGF2α) e observação de estro. As vacas foram inseminadas artificialmente (IA) e seis dias após, uma biópsia endometrial coletada. O diagnóstico de gestação foi realizado após 30 dias por meio de ultrasonografia (US) e então as vacas foram divididas em grupo Prenhe e Não- Prenhe (P e NP) para análise retrospectiva. Abundância de transcritos foi avaliada por sequenciamento (RNAseq) assim como qPCR em amostras de ambos experimentos. Realizaram-se também exames histológicos em amostras do D4 e D7 (estudo 2) para avaliação de colágeno total assim como espessura de fibras colágenas. Resultados determinaram uma maior abundância de transcritos relacionados ao remodelamento de MEC, em destaque TGFβ, MMPs, TIMPs e colágenos em vacas pertencentes aos grupos NP e FP-CLP. O mesmo foi observado para abundância de colágeno. No entanto, não observou-se diferença na relação entre fibras grossas e finas entre os tratamentos. Análises de correlação e regressão indicaram que folículos pré-ovulatórios de maior tamanho geram CL maiores e assim maiores concentrações de P4, a qual está negativamente associada à abundância de colágenos. Assim, de acordo com resultados aqui descritos, assume-se que a alteração da homeostase da MEC devido ao incremento na abundância de colágeno pode ser prejudicial à gestação em bovinos.
Title in English
Dynamic remodeling of endometrial extracellular matrix modulates embryo receptivity in cattle
Keywords in English
Endometrium
Extracellular matrix
Remodelling
Abstract in English
The endometrial extracellular matrix (ECM) é build up of secretory molecules that make up the cellular microenvironment and suffer activation or suppression mainly by the ovarian steroid hormones, estradiol (E2) and progesterone (P4) during the estrous cycle. The identification of genes involved in endometrial remodeling and receptivity may reveal important biological processes linked to gestational success. The objectives were: 1. identify the relationship among preovulatory follicle (POF) size and corpus luteum (CL) and its respective hormones, E2 and P4 on the endometrial expression of genes related to extracellular matrix remodeling during the pre-implantation period; and 2. analyze the relationship between endometrial ECM gene expression evaluated on day 6 post artificial insemination (AI) with pregnancy outcome. For such, two experiments were carried on. On experiment 1, study 1 and study 2, 42 and 74, respectively, adult Nelore (Bos indicus) cows were synchronized aiming to manipulate the peri-ovulatory endocrine environment, obtaining at the end of the protocol, two groups with distinct pre-ovulatory follicle (POF) and corpus luteum (CL) sizes, leading to groups with distinct E2 and P4 concentrations. The groups were: Large Follicle/CL (LF/CL; study 1, n=20, study 2, n=35) and Small Follicle/Cl (SF/CL; study 1, n=22; study 2, n=39). Endometrial samples were collected by biopsy on D0 (Estrus) and post-mortem on D4 and on study 2 post-mortem on D7. P4 and E2 concentrations were measured by RIA with a significative difference between the groups, being lower hormonal concentrations in the SF- SCL group and higher concentrations in the LF-LCL group . In experiment 2, adult Nelore (Bos indicus) cows (n=33) were synchronized using a prostaglandin 2α (PGF2α) and heat detection based protocol. The cows were AI and six days after an endometrial biopsy was collected. Pregnancy diagnosis was performed on day 30 by ultrasound (US) examination and cows were divided into pregnant and non-pregnant (P vs. NP) groups for a retrospective analysis. Histology was performed on D4 and D7 samples for total collagen abundance as well as fiber thickness. Correlation and regression analysis indicate that larger preovulatory follicles as well as higher P4 concentrations have a negative effect on collagen content. RNA- Seq analysis and confirmation by qPRC was performed on selected samples from experiment 1, study 2 and experiment 2. Comparison of mRNA levels of ECM components samples revealed higher levels of transcripts envolved in ECM remodeling, highlighting TGFβ MMPs, TIMPs and collagens in NP cows when compared with P cows as well as in the SF- SCL compared to the LF-LCL group. The same was observed for collagen abundance. However, there was no difference between thin and thick collagen fibers between treatments. Correlation and regression analysis indicate that larger POF lead to larger CL and hence, higher P4 concentrations, which has a negative effects on collagen abundance. Therefore, according to the results presented here, we can imply that an alteration in ECM homeostasis due to increased collagen abundance may be harmful to pregnancy in cows.
 
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Publishing Date
2015-10-05
 
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