Efeitos da superestimulação ovariana sobre a competência oocitária e embrionária em bovinos: possível participação dos exossomos presentes no fluido folicular
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Data
2016-03-04
Autores
Franchi, Fernanda Fagali [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A superestimulação ovariana é uma das biotecnologias utilizadas com objetivo de aumentar o potencial reprodutivo de fêmeas com alto valor econômico através da obtenção de múltiplas ovulações e tem sido amplamente empregada na espécie bovina. O conhecimento da dinâmica folicular permitiu o desenvolvimento de diversos protocolos hormonais capazes de regular o desenvolvimento folicular, o momento e o número de ovulações produzidas. As duas gonadotrofinas mais utilizadas para induzir o crescimento de múltiplos folículos durante esses protocolos são o hormônio folículo-estimulante (FSH) e a gonadotrofina coriônica equina (eCG); e ambos têm se mostrado eficazes. Sabe-se que a utilização da superestimulação ovariana utilizando FSH provoca mudanças positivas nos complexos cumulus-oócito (CCOs) e que a utilização do eCG no final do tratamento superestimulatório aumenta a resposta ovulatória, a ocorrência de estro, as concentrações de progesterona e as taxas de prenhes em programas de inseminação artificial (IA). Deste modo, o uso desses protocolos parece alterar o microambiente folicular e consequentemente a competência dos CCOs que se desenvolvem nele. Dentre os vários fatores presentes nesse microambiente estão as vesículas extracelulares (VEs; incluindo os exossomos), que carregam diversas moléculas como mRNA e microRNAs (miRNAs). Diante disso, o presente estudo visou avaliar o efeito da superestimulação ovariana com FSH ou FSH combinado a eCG, sobre a expressão gênica de embriões produzidos a partir de CCOs recuperados de vacas superestimuladas. Adicionalmente, verificou-se se os exossomos presentes no fluido folicular dessas vacas, quando adicionadas durante a maturação in vitro (MIV) de CCOs, provenientes de folículos antrais (3-8mm), são capazes de alterar aspectos celulares e moleculares dos CCOs, bem como a produção de blastocistos in vitro. Em suma, os resultados demonstraram que a superestimulação ovariana altera a abundância de mRNAs, relacionados à competência embrionária, em blastocistos produzidos à partir dos CCOs recuperados das vacas superestimuladas. Adicionalmente, também parece modular o conteúdo das exossomos, uma vez que genes relacionados à competência oocitária foram positivamente regulados nos CCOs cultivados na presença dos exossomos, no entanto, sem alterar a competência do CCOs em produzir blastocistos.
Ovarian superestimulation is a biotecnology used to increase the reproductive potential of females with high economic value by obtaining multiple ovulations and has been widely used in cattle. The follicular dynamics knowledge allows the development of numerous hormonal protocols able to regulate follicular development, the moment and the number of ovulations produced. Two most used gonadotrophins to induce the growth of multiple follicles during these protocols are follicle stimulating hormone (FSH) and chorionic gonadotropin equine (eCG) and both have proven effective. It is known that the ovarian superstimulation using FSH causes positives changes in cumulus-oocyte complexes (COCs) and the use of eCG at the end of superstimulatory treatment increases the ovulatory response, the oestrus occurrence, progesterone concentrations and pregnancy rates in artificial insemination (AI). Thus, these protocols seems to alter the follicular microenvironment and therefore the competence of COCs that development it. Among the several factors presents in this microenvironment are the extracellular vesicles (EVs; including the exosomes), that carry different molecules such mRNA and microRNA (miRNAs). Therefore, this study aimed to assess the effects of ovarian superstimulation with FSH or FSH combined with eCG on embryo gene expression produced from COCs recovered from superstimulated cows. Additionally, it was checked if the exosomes presents in follicular fluid from these cows, when added during in vitro maturation (IVM) of COCs from antral follicles (3-8mm), are able to altering COCs cellular and molecular aspects and the in vitro blastocyst production. Briefly, the results showed the ovarian superstimulation change the mRNA abundance related to the embryo competence in blastocyst produced from COCs recovered from superstimulated cows. Furthermore, it also seems to modulate the exosome content, since the genes related to the oocyte competence are upregulated in COCs cultured in exosomes presence, however, without changing the COCs competence to produce blastocysts.
Ovarian superestimulation is a biotecnology used to increase the reproductive potential of females with high economic value by obtaining multiple ovulations and has been widely used in cattle. The follicular dynamics knowledge allows the development of numerous hormonal protocols able to regulate follicular development, the moment and the number of ovulations produced. Two most used gonadotrophins to induce the growth of multiple follicles during these protocols are follicle stimulating hormone (FSH) and chorionic gonadotropin equine (eCG) and both have proven effective. It is known that the ovarian superstimulation using FSH causes positives changes in cumulus-oocyte complexes (COCs) and the use of eCG at the end of superstimulatory treatment increases the ovulatory response, the oestrus occurrence, progesterone concentrations and pregnancy rates in artificial insemination (AI). Thus, these protocols seems to alter the follicular microenvironment and therefore the competence of COCs that development it. Among the several factors presents in this microenvironment are the extracellular vesicles (EVs; including the exosomes), that carry different molecules such mRNA and microRNA (miRNAs). Therefore, this study aimed to assess the effects of ovarian superstimulation with FSH or FSH combined with eCG on embryo gene expression produced from COCs recovered from superstimulated cows. Additionally, it was checked if the exosomes presents in follicular fluid from these cows, when added during in vitro maturation (IVM) of COCs from antral follicles (3-8mm), are able to altering COCs cellular and molecular aspects and the in vitro blastocyst production. Briefly, the results showed the ovarian superstimulation change the mRNA abundance related to the embryo competence in blastocyst produced from COCs recovered from superstimulated cows. Furthermore, it also seems to modulate the exosome content, since the genes related to the oocyte competence are upregulated in COCs cultured in exosomes presence, however, without changing the COCs competence to produce blastocysts.
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Palavras-chave
Superestimulação ovariana, Exossomos, Maturação in vitro, FSH, eCG