Energy substrates, mitochondrial membrane potential and human preimplantation embryo division

Abstract

Carbohydrate additives to modern embryo culture media are based on three basic energy sources, glucose, pyruvate and lactate. Although the use of these substrates is almost universal, debate continues as to the roles of the individual components in the human. This is mainly due to the lack of human embryos for research and the reliance on animal model systems. In the present work, the human embryo was used to study the role of the above simple substrates in the maintenance of the mitochondrial membrane potential and cell division. The mitochondrial membrane potential was measured with fluorescence techniques. Cell division was scored as the number of blastomeres on day 3. Both the mitochondrial membrane potential and cell division were dramatically lost in the absence of energy sources. The mitochondrial membrane potential and cell division were normal in media containing all three energy sources, or in pyruvate-containing media. Both glucose and lactate individually proved poor energy sources for the maintenance of the mitochondrial membrane potential. However, cell division continued in the presence of glucose, suggesting that some energy production can continue. These data suggest that pyruvate is an absolute requirement for mitochondrial respiration and cell cleavage during human preimplantation development. The role of lactate is as yet unclear.

Astaxanthin ameliorates heat stress-induced impairment of blastocyst development In Vitro: –astaxanthin colocalization with and action on mitochondria–

“…As in the present study, physiological, environmental, or clinical factors can decrease ΔΨm in human oocytes and early embryos, which is one of proposed causes of their compromised quality and IVF outcome. These factors include advanced age of women [34,52], clinical hyperstimulation protocol [8], cryopreservation [20], and the condition of in vitro culture [53]. Therefore, Δ<m-promoting effects of Ax in challenged conditions shown in the present study may be applicable for ameliorating the effects of deleterious factors involved in human IVF.…”

Effect of vitrification on mitochondrial membrane potential in human metaphase II oocytes

“…The MII oocytes contain several hundreds of thousand mitochondria, which provide energy for fertilization and embryo development [15]. Many studies showed that there was a closely association between mitochondria activity and early embryonic development [12,[16][17][18]. Wilding M et al reported that the efficiency of mitochondrial respiration in oocytes and preimplantation embryos were correlated with the programmed rate of embryo development [12].…”

Mitochondria and human preimplantation embryo development

“…These data suggest that both aerobic and anaerobic respiration pathways are active during both oocyte maturation and embryo preimplantation development, but aerobic respiration is upregulated during blastocyst development and implantation. Elimination of pyruvate drastically reduces the rate of development in human embryos, whereas elimination of glucose and lactate had little effect (Wilding et al 2002). Evidence from mice also suggests that embryos can develop and even implant adequately in the absence of mitochondrial respiration, although development does not continue until birth (Piko & Chase 1973, Larsson et al 1998, Li et al 2000.…”