O efeito do fator de crescimento semelhante à insulina-I em oócitos de vacas Bos indicus e Bos taurus expostas ao estresse térmico un vitro

• Autor(a) principal: Risolia, Pedro Henrique Bugallo [UNESP]
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/108541
• topic: Bovino - Reprodução; Oócitos; Fertilização in vitro; Zebu; Cattle Reproduction

Microenvironmental alterations on reproductive tract compromise oocyte competence and pre-implicational embryo development in bovine. This fact is well characterized in animals exposed to heat stress. Bos indicus have fenotypic and genotypic adaptations which confers a higher tolerance to high temperatures compared with Bos taurus, suffering a reduction in the pregnancy rates during the hot months. This infertility caused by heat stress is a multifactorial problem, however it has been shown that oocyte and embryo are very susceptible to deleterious effects of high temperature. The cellular damage induced by high temperature could be manipulated by insulin-like growth factor I (IGF-I), which besides minimizing the spontaneous cell death, IGF-I rescue cells which have already initiated the apoptosis induced by different agents or stresses. The first step of this project aimed to evaluate dose-response effect of IGF-I during the maturation in vitro (MIV) in a non-defined medium (pre-experiment 1: MIV - 10% of bovine fetal serum) and semi-defined (preexperiment 2: MIV - 6 mg/mL of bovine albumin serum) in competence of bovine oocytes. Therefore, cumulus-oocyte complexes (CCOs) obtained of cows (Bos indicus crossbreed) from a slaughterhouse were matured in vitro in non-defined and semidefined MIV medium supplemented with 0 (vehicle control), 6,25; 12,5; 25; 50; 100 or 200 ng/mL of IGF-I for 22-24 h. After, oocytes were fertilized (FIV) and cultured in vitro (CIV). The adition of 25 ng/ml of IGF-I on non-defined and semi-defined MIV medium increased porcentage of cleavage on day 3 and blastocysts rate in day 8 after fertilization. In this way, 25 ng/ml IGF-I was used on second step of this experiment, which objective was to evaluate the role of IGF-I on oocyte competence of oocytes collected from Bos indicus – Nelore (NEL; n= 6) and Bos taurus-Holstein (HPB; n= 6) exposed to heat stress. Therefore, cows adapted ...