Role of insulin-like growth factor 1 on cross-bred Bos indicus cattle germinal vesicle oocytes exposed to heat shock

Abstract

Germinal vesicle (GV) oocytes are susceptible to heat stress. However, neither the cellular mechanisms triggered by elevated temperature nor the thermoprotective effects of insulin-like growth factor (IGF) on GV oocytes are completely understood. Therefore, a series of experiments was conducted to determine the direct effects of IGF1 (0, 12.5, 25, 50 and 100ng mL) on heat-treated GV oocytes. Butyrolactone-arrested GV oocytes were cultured at 38.5°C (control) or 41°C (heat shock; HS) for 14h in the presence of different concentrations of IGF1. Exposure of GV oocytes to 41°C increased (P<0.05) the number of terminal deoxyribonucleotidyl transferase-mediated fluorescein-dUTP nick end-labelling (TUNEL)-positive oocytes. At concentrations of 12.5 and 25ng mL, IGF1 tended to minimise these negative effect of HS (P=0.07). However, neither HS nor IGF1 had any effect on caspase activity. HS also decreased (P<0.05) GV oocyte mitochondrial activity and developmental competence to the blastocyst stage. These deleterious effects of HS were alleviated (P<0.05) by 12.5ng mL IGF1. This concentration of IGF1 did not affect cleavage rate, the percentage of TUNEL-positive blastomeres and total blastocyst cell number regardless of temperature. In conclusion, exposure of GV oocytes to HS triggered the apoptotic cascade and compromised oocyte developmental competence. Physiological concentrations of IGF1 had a beneficial effect on heat-shocked GV oocytes.

Shading effect on physiological parameters and in vitro embryo production of tropical adapted Nellore heifers in integrated crop-livestock-forest systems

“…Alterations in cortisol serum concentrations were very clear after acute stressful situations, like Nellore management on corral (Lima et al 2017 ) and after weaning (Chaves et al 2015 ). Black Angus heifers assigned to pen with four different shade treatments for 8 weeks during summer showed different serum cortisol concentration in accord with shade treatment (Brown-Brandl 2018 ).…”

Role of Growth Differentiation Factor 9 and Bone Morphogenetic Protein 15 in Ovarian Function and Their Importance in Mammalian Female Fertility — A Review

“…Given the above, we can see that the type II receptor (BMPRII) has great importance for the adequate follicular development and acquisition of oocyte competence, besides being a common receptor for GDF9 and BMP15, it is still responsible for initiating a signaling cascade that comprises several events, starting from the phosphorylation and activation of the type I receptors. BMPRII, or receptor of bone morphogenetic protein type II, is expressed in the granulosa cells in the early stages of folliculogenesis in both ruminant primordial follicles as in preantral follicles in rodents, and continues to be expressed in all subsequent stages of follicular development ( Juengel and McNatty, 2005 ; Lima, 2012 ).…”

Influence of long-term thermal stress on the in vitro maturation on embryo development and Heat Shock Protein abundance in zebu cattle

“…It is known that zebu breeds are more tolerant to heat ( Hansen, 2004 ). However, there is a limit to this, as heat stress at different temperatures and durations during the IVM of zebu COCs impairs in vitro embryo development ( Lima et al., 2017 ; reviewed by Paula-Lopes et al., 2013 ). However, to the best of our knowledge, no study has demonstrated the effects of low-temperature stress during the IVM of bovine oocytes.…”