Adverse Effect of Superovulation Treatment on Maturation, Function and Ultrastructural Integrity of Murine Oocytes

Abstract

Regular monitoring on experimental animal management found the fluctuation of ART outcome, which showed a necessity to explore whether superovulation treatment is responsible for such unexpected outcome. This study was subsequently conducted to examine whether superovulation treatment can preserve ultrastructural integrity and developmental competence of oocytes following oocyte activation and embryo culture. A randomized study using mouse model was designed and in vitro development (experiment 1), ultrastructural morphology (experiment 2) and functional integrity of the oocytes (experiment 3) retrieved after PMSG/hCG injection (superovulation group) or not (natural ovulation; control group) were evaluated. In experiment 1, more oocytes were retrieved following superovulation than following natural ovulation, but natural ovulation yielded higher (p < 0.0563) maturation rate than superovulation. The capacity of mature oocytes to form pronucleus and to develop into blastocysts in vitro was similar. In experiment 2, a notable (p < 0.0186) increase in mitochondrial deformity, characterized by the formation of vacuolated mitochondria, was detected in the superovulation group. Multivesicular body formation was also increased, whereas early endosome formation was significantly decreased. No obvious changes in other microorganelles, however, were detected, which included the formation and distribution of mitochondria, cortical granules, microvilli, and smooth and rough endoplasmic reticulum. In experiment 3, significant decreases in mitochondrial activity, ATP production and dextran uptake were detected in the superovulation group. In conclusion, superovulation treatment may change both maturational status and functional and ultrastuctural integrity of oocytes. Superovulation effect on preimplantation development can be discussed.

Embryo responses to stress induced by assisted reproductive technologies

“…Superovulation provides a large number of oocytes, although their maturation rate can be compromised. Despite this, it has been shown that the capacity of mature oocytes to be fertilized and to develop into blastocysts is irrespective of their origin (Lee et al, ). In the mouse model, alterations in the expression of maternal poly(A)‐binding protein ( Epab ) and poly(A)‐binding protein cytoplasmic 1 ( Pabpc1 ) genes in the oocyte may explain the lower quality of oocytes and embryos obtained by superovulation (Ozturk, Yaba‐Ucar, Sozen, Mutlu, & Demir, ).…”

“…In the mouse model, alterations in the expression of maternal poly(A)‐binding protein ( Epab ) and poly(A)‐binding protein cytoplasmic 1 ( Pabpc1 ) genes in the oocyte may explain the lower quality of oocytes and embryos obtained by superovulation (Ozturk, Yaba‐Ucar, Sozen, Mutlu, & Demir, ). At the ultrastructural level, abnormalities in mitochondrial structure caused by vacuole and multivesicular body formation have been found in oocytes derived from superovulation, leading to significantly reduced mitochondrial activity (Lee et al, ). Later in development, the consequences of superovulation have been observed in lineage differentiation.…”

Harvesting of Mouse Embryos at 0.5 Dpc as a Tool to Reduce Animal Use: Data from C57BL/6J, B6*129 and FVB/NJ Strains

“…Although superovulation can improve the efficiency of embryo collection by synchronizing females and reducing the number of animals for a given purpose, it can affect oocyte and embryo's quality. Superovulation has been associated with a negative impact on oocytes and embryos by provoking changes in maternal and paternal imprinted methylation [12] [13] [14] and delaying embryonic and fetal development [14] [18]. It has also been associated with alterations in essential proteins involved in regulation and translation of maternally stored mRNA with short poly A tail, such as poly(A)-binding protein (Epab) and poly(A)-binding protein cytoplasmic 1 (Pabpc1) [16] [19].…”

“…Allowing the embryos to grow in utero after a superovulation protocol can attenuate the effect of superovulation by decreasing the number of implantation sites [23], reducing the number of living fetuses [16] [18] as well as increasing pre-implantation mortality [14]. PMSG and hCG stimulation causes changes in the uterine environment that negatively affect embryo and fetal development [18] [24], resulting in reduced litter size and foetal organ's weight [25] [26].…”

Effect of exogenous human chorionic gonadotropin on ovulation in mice

“…В работе (Wang et al, 2006) было установлено, что преимплантационные эмбрионы, полученные из незрелых ооцитов после последовательной инъекции ГСЖК и ХГЧ, с последующим дозреванием in vitro (in vitro maturation, IVM) и после искусственного оплодотворения (in vitro fertilization, IVF), хуже развиваются при культивировании in vitro (in vitro culture IVC), чем полученные из дозревших in vivo ооцитов. Суперовуляция мышей с использованием инъекций ГСЖК и ХГЧ дает меньшее число зрелых ооци тов, но при этом повышает число ооцитов с деформациями митохондрий, сниженной митохондриальной активностью и продукцией АТФ, по сравнению с ооцитами, получен ными при естественной овуляции (Lee et al, 2017). Лишь в единичных работах изучали эффекты гормональной стимуляции препаратом ХГЧ (без комбинации с ГСЖК) на развитие эмбрионов мышей (Ertzeid, Storeng, 1992;Dinopoulou et al, 2016).…”