Morales Dalanezi Felipe, Mogollon Garcia Henry David, de Andrade Ferrazza Rodrigo, Fagali Franchi Fernanda, Kubo Fontes Patricia, de Souza Castilho Anthony Cesar, Gouveia Nogueira Marcelo Fábio, Dos Santos Schmidt Elizabeth Moreira, Sartori Roberto, Pinheiro Ferreira João Carlos
School of Veterinary Medicine and Animal Science, São Paulo State University, Rua Prof Dr Walter Mauricio Correa, sn, 18.618-681, Botucatu, Brazil.
Institute of Biosciences, São Paulo State University, Botucatu, São Paulo, Brazil.
Anim Reprod Sci. 2019 Jun;205:94-104. doi: 10.1016/j.anireprosci.2019.04.008. Epub 2019 Apr 24.
The effect of heat stress (HS) on cattle reproduction is deleterious with respect to ovarian follicular development and oocyte quality. The objective of this study was to investigate the effect of follicular fluid extracellular vesicles (EVs) obtained from cows maintained in thermoneutral (TN) or HS conditions on in vitro oocyte maturation. Nonlactating cows were estrous synchronized. Immediately after ovulation day (D1), the cows were randomly assigned to TN or HS environments. Follicular fluid from all follicles from each treatment was pooled, and EVs were obtained. Pools of 20 cumulus oocyte-complexes (COCs), were allocated to the following treatments: Control (n = 4 COC pools): matured in base medium; TN (n = 4 COC pools): matured in base medium supplemented with TN EV suspension; and HS (n = 4 COC pools): matured in base medium that was supplemented with the HS EV suspension. All treatments were conducted at 38.5 °C for 24 h in a humid atmosphere with 5% CO2. After maturation, the COCs were evaluated for meiotic progression, DNA integrity and oocyte quality-related gene expression. When the experimental groups were compared with the control group, a treatment effect was not observed for meiotic progression and DNA integrity. In the cumulus cells of TN group, there was relatively lesser expression of the IGFBP4 gene. In the oocytes of the TN as compared with the HS group, the IGFBP2, BMP15, GDF9, CDCA8, HAS2, RPL15, STAT3 and PFKP genes were expressed to a lesser extent. The findings indicated that oocytes matured in the presence of EVs from the follicular fluid of cows collected when there were TN conditions, however, there was a lesser expression of genes related to oocyte quality.
热应激（HS）对牛的繁殖在卵泡发育和卵母细胞质量方面具有有害影响。本研究的目的是调查从处于热中性（TN）或热应激条件下的奶牛获得的卵泡液细胞外囊泡（EVs）对体外卵母细胞成熟的影响。对非泌乳奶牛进行发情同步处理。在排卵日（D1）后立即将奶牛随机分配到TN或热应激环境中。将每种处理的所有卵泡的卵泡液汇集在一起，获得细胞外囊泡。将20个卵丘卵母细胞复合体（COCs）分组，进行以下处理：对照组（n = 4个COC组）：在基础培养基中成熟；TN组（n = 4个COC组）：在补充了TN细胞外囊泡悬浮液的基础培养基中成熟；热应激组（n = 4个COC组）：在补充了热应激细胞外囊泡悬浮液的基础培养基中成熟。所有处理均在38.5°C、5%二氧化碳的潮湿大气中进行24小时。成熟后，评估COCs的减数分裂进程、DNA完整性和与卵母细胞质量相关的基因表达。当将实验组与对照组进行比较时，未观察到减数分裂进程和DNA完整性方面的处理效应。在TN组的卵丘细胞中，IGFBP4基因的表达相对较少。与热应激组相比，TN组卵母细胞中IGFBP2、BMP15、GDF9、CDCA8、HAS2、RPL15、STAT3和PFKP基因的表达程度较低。研究结果表明，在存在来自处于热中性条件下收集的奶牛卵泡液细胞外囊泡的情况下成熟的卵母细胞，然而，与卵母细胞质量相关的基因表达较少。
