Unexpected detrimental effect of Insulin like growth factor-1 on bovine oocyte developmental competence under heat stress

Abstract

Purpose To investigate the effects of Insulin like growth factor-1 (IGF-1) on bovine oocyte developmental competence under heat stress. Methods In Experiment 1, bovine cumulus-oocyte complexes (COCs) were cultured at 38.5 or 41°C for the first 12 h of maturation in the presence of either 100 ng/ml human recombinant (hr)-IGF-1 or acetic acid. In Experiment 2, COCs were cultured in 38.5 or 41°C for the first 12 h of maturation in the presence either of 100 ng/ml hr-IGF-1 or acetic acid. After fertilization, putative zygotes were cultured for 8 days.Results In experiment 1, addition of rh-IGF-1 to maturation medium at 38.5°C significantly increased the proportion of M II oocytes and decreased the percentage of TUNEL-positive oocytes compared to the other groups. However, addition of rh-IGF-1 to maturation medium under heat stress increased the percentage of TUNEL-positive oocytes. In experiment 2, addition of rh-IGF-1 under heat sress did not affect cleavage rate, whereas, blastocyst formation rate decreased in heatstressed and heat-stressed plus rh-IGF-1 groups. Similarly, The number of trophectoderm cells and total cell number were decreased in heat-stressed and heat-stressed plus rh-IGF-1 groups and the percentage of TUNEL-positive nuclei were increased in heat-stressed and heat-stressed plus rh-IGF-1 groups compared to the other groups. Conclusion The results of the present study demonstrate that IGF-1 decreases oocyte developmental competence and total cell number and increases TUNEL-positive nuclei at heat stress condition. These unexpected results of IGF-1 during maturation period under heat stress condition warrant further optimizations and investigations.

Synergistic Effect of Insulin on <i>in vitro</i> Development of Immature Bovine Oocytes

“…This could be due to differences in glucose utilization of the early embryo (morula), compared to the late embryos (blastocyst) (Harvey and Kaye, 1990). The post-compacted embryos are more sensitive to insulin (Zhandi et al, 2009). Scientists demonstrated a stage-specific binding by insulin which could be related to embryonic metabolism and switch from lactate to glucose uptake.…”

Factors affecting the in vitro embryo production in cattle associated to ovum pick up sistem

“…On the other hand, some findings provided evidence for bovine HSO to mature faster than non-heat-stressed counterparts (Edwards et al, 2005;Schrock et al, 2007; Andreu- Vazquez et al, 2010). In agreement with our results, oocytes heat-stressed during the germinal vesicle stage (bovine: Payton et al, 2004;mouse: LaRosa and Downs, 2007) or during maturation (bovine: Ju et al, 2005;Schrock et al, 2007;Edwards et al, 2009;Zhandi et al, 2009;Rispoli et al, 2011;Payton et al, 2011) have shown competence in overcoming the first cellular division similar to that found in non-HSO. In addition, we observed that HS treatment improved the ability of the oocytes to form blastocysts.…”

“…In this regard, Pribenszky et al (2010) highlighted a number of studies in which sub-lethal stress treatments (such as high hydrostatic pressure, osmotic stress, HS or OS) might increase the morphological survival, fertilization ability, and in vitro development, both in gametes and embryos. However, in contrast to these results, it has also been shown that HS treatment during IVM had no effect (bovine: Ju et al 1999;Roth and Hansen, 2004b;Schrock et al, 2007;Roth and Hansen, 2009), or may even decrease the blastocyst rate (bovine: Lawrence et al, 2004;Roth and Hansen, 2004a, b;Edwards et al, 2005;Ju et al, 2005;pig: Tseng et al, 2006;Sugiyama et al, 2007;Soto and Smith., 2009;Zhandi et al, 2009;Rispoli et al, 2011). This seeming controversy on the effects of HS could probably be explained by the different temperatures and timing schedule of the HS treatments and the methodology used in the cited reports.…”

Developmental competence of mammalian oocytes-insights into molecular research and the promise of microfluidic technology: a review

“…It has been also established that IGF-1 plays a role in nuclear maturation of the oocyte (Xia et al 1994). However, Zhandi et al (2009) stated that during heat stress, supplementation of IGF-1 led to activation of some unknown pathway, which resulted in an increase in apoptosis. Supplementation of IGF-1 into IVM medium failed to increase the number of oocytes that reached the blastocyst stage.…”

“…It is well established that heat stress alters the zona pelucida surface and cytoplasm, which leads to impaired sperm penetration (Edwards and Hansen 1996). Moreover, increased production of reactive oxygen species due to the high glucose consumption leads to apoptosis even in the presence of IGF-1 (Zhandi et al 2009). …”