Hazardous Apoptotic Effects of 2-Bromopropane on Maturation of Mouse Oocytes, Fertilization, and Fetal Development

Abstract

2-Bromopropane (2-BP) is used as an alternative to ozone-depleting cleaning solvents. Previously, we reported that 2-BP has cytotoxic effects on mouse blastocysts and is associated with defects in subsequent development. Here, we further investigate the effects of 2-BP on oocyte maturation and subsequent pre- and post-implantation development, both in vitro and in vivo. Notably, 2-BP induced a significant reduction in the rates of oocyte maturation, fertilization, and in vitro embryonic development. Treatment of oocytes with 2-BP during in vitro maturation (IVM) resulted in increased resorption of postimplantation embryos and decreased fetal weights. Experiments with a mouse model disclosed that consumption of drinking water containing 20 μM 2-BP led to decreased oocyte maturation in vivo and fertilization in vitro, as well as impairment of early embryonic development. Interestingly, pretreatment with a caspase-3-specific inhibitor effectively prevented 2-BP-triggered hazardous effects, suggesting that embryonic impairment by 2-BP occurs via a caspase-dependent apoptotic process. A study using embryonic stem cells as the assay model conclusively demonstrated that 2-BP induces cell death processes through apoptosis and not necrosis, and inhibits early embryo development in mouse embryonic stem cells. These results collectively confirm the hazardous effects of 2-BP on embryos derived from pretreated oocytes.

Resveratrol protects against methylglyoxal‐induced apoptosis and disruption of embryonic development in mouse blastocysts

“…Our previous HPLC results showed that mice drinking water containing 20 μM MG for 4 days had serum MG levels of about 5.63 μM (Chang and Chan,). The experiments of the present study clearly confirm that 5–10 μM MG has an injurious effect on embryonic development (Figs.…”

“…In the general population, blood MG concentration is ∼ 1–2 μM, whereas diabetics have levels threefold to sixfold higher (McLellan et al,), and such elevated concentrations can be noted over several months, even years. Earlier, we reported that MG exhibited toxic effects on oocyte maturation, fertilization, blastocyst development, and sequential embryo development, both in vitro and in vivo (Chang and Chan,). In the general population, plasma MG concentrations are typically ∼ 1–2 μM.…”

“…Embryonic development is a complex process during which chemical injury can lead to developmental problems or embryonic malformation. MG has been shown to induce apoptosis, to impair oocyte maturation and fertilization, to affect blastocyst development from the morula, and to promote early‐stage death of mouse blastocysts (Hsuuw et al,; Chang and Chan,). The TE arises from the trophoblast at the blastocyst stage and develops into a sphere of epithelial cells surrounding the ICM and blastocoel.…”

“…Cells of the ICM have the potential to develop into the fetus. Our previous work showed that the ICM and TE differed in terms of apoptotic sensitivity when several chemical inducers of apoptosis were tested (Hsieh et al,; Chan,; Chang and Chan,; Tu et al,). In the present work, we found that only the ICM (thus not the TE) could trigger apoptotic processes in mouse blastocysts exposed to 5–10 μM MG and show, for the first time, that resveratrol significantly inhibits MG‐induced cell apoptosis and reduction of cell proliferation in mouse blastocysts (Figs.…”

“…Earlier studies by Hsuuw et al showed that MG elicits apoptotic biochemical changes, including all of DNA fragmentation, caspase‐3 activation, cleavage of PARP, mitochondrial cytochrome c release, and JNK activation in mouse embryonic stem cells (of the ESC‐B5 line) (Hsuuw et al,). Moreover, the compound promotes apoptosis in mouse blastocysts as well as impairment of oocyte maturation and subsequent embryonic development (Hsuuw et al,; Chang and Chan,). MG‐induced embryonic stem cell apoptosis and developmental injury are effectively prevented by curcumin, a scavenger of ROS, implying a critical role for ROS in MG‐induced damage (Hsuuw et al,).…”