Effect of ganglioside GT1b on the <i>in vitro</i> maturation of porcine oocytes and embryonic development

Abstract

Ganglioside is an acidic glycosphingolipid with sialic acids residues. This study was performed to investigate the effect and mechanism of ganglioside GT1b in porcine oocytes in the process of in vitro maturation (IVM) and preimplantation development. Metaphase II (MII) rates were significantly (P < 0.05) different between the control group and the 5 nM GT1b treatment group. Intracellular glutathione (GSH) levels in oocytes matured with 5 nM and 20 nM and GT1b decreased significantly (P < 0.05). The 10 nM group showed a significant (P < 0.05) decrease in intracellular reactive oxygen species (ROS) levels compared with the control group. Subsequently, the level of intracellular Ca2+ in oocytes treated with different concentrations of GT1b was measured. Intracellular Ca2+ was significantly (P < 0.05) increased with a higher concentration of GT1b in a dose-dependent manner. Real-time PCR was performed and showed that the expression of bradykinin 2 receptor (B2R) and calcium/calmodulin-dependent protein kinase II delta (CaMKIIδ) in cumulus cells was significantly (P < 0.05) decreased in the 20 nM GT1b treatment group. Treatment with 5 nM GT1b significantly (P < 0.05) decreased the expression of CaMKIIδ. In oocytes, treatment with 5 nM GT1b significantly (P < 0.05) decreased CaMKIIγ and POU5F1 (POU domain, class 5, transcription factor 1). However, treatment with 20 nM GT1b significantly (P < 0.05) increased the expression of POU5F1. Finally, embryonic developmental data showed no significant differences in the two experiments (parthenogenesis and in vitro fertilization). In conclusion, the results of the present study indicated that GT1b plays an important role in increasing the nuclear maturation rate and decreasing the intracellular ROS levels during IVM. However, GT1b inhibited maturation of the cytoplasm by maintaining intracellular Ca2+ in the process of oocyte maturation regardless of the cell cycle stage. Therefore, GT1b is thought to act on another mechanism that controls intracellular Ca2+.

Effects of Gangliosides on Spermatozoa, Oocytes, and Preimplantation Embryos

“…To be sure, CaMKII γ and CaMKII δ are expressed in porcine cumulus cells and oocytes [62]. Incidentally, it is noted that intracellular Ca 2+ levels are increased with a higher concentration of GT1b in a dose-dependent manner during oocyte IVM [62]. The results show that the addition of GT1b to the culture medium temporarily activates CaMKII in neuroblastoma-glioma hybridoma (NG108-15) cells or rat hippocampal cells [101].…”

“…Exogenously added GD1b and GT1b reduced the level of superoxide anions produced by phorbol,12-myristate acetate (PMA)-stimulated human sperm [18]. Gavella et al [62] reported that ganglioside micelles attached to the ejaculated sperm membrane to provide a diffusion barrier and delayed ROS production ( Figure 2). Moreover, exogenous GT1b increases the oocyte nuclear maturation rate by reducing ROS during porcine IVM [62].…”

“…Gavella et al [62] reported that ganglioside micelles attached to the ejaculated sperm membrane to provide a diffusion barrier and delayed ROS production ( Figure 2). Moreover, exogenous GT1b increases the oocyte nuclear maturation rate by reducing ROS during porcine IVM [62].…”

“…Moreover, in mouse oocytes, CaMKII also interacts with molecules that control cell cycle and Ca 2+ signaling in mouse oocytes [100]. To be sure, CaMKII γ and CaMKII δ are expressed in porcine cumulus cells and oocytes [62]. Incidentally, it is noted that intracellular Ca 2+ levels are increased with a higher concentration of GT1b in a dose-dependent manner during oocyte IVM [62].…”

Production of transgenic pigs using a pGFAP-CreERT2/EGFPLoxP inducible system for central nervous system disease models

“…Oocyte collection and in vitro maturation was performed according to Hwang et al [ 18 ]. Briefly, porcine ovaries were collected from a slaughterhouse.…”