Incorporation of [³H]inositol into phosphoinositides and inositol phosphates by rabbit blastocysts

Abstract

Preimplantation rabbit embryos collected at the early morula stage were cultured to blastocysts in the presence of [3H]inositol. The blastocysts were lysed, and both the aqueous and lipid portions were analysed for incorporated radioactivity. Thin-layer chromatographic separation of the lipid portion indicated that [3H]inositol was incorporated into phosphatidylinositol, phosphatidylinositol 4-phosphate, and phosphatidylinositol 4,5-bisphosphate. HPLC anion-exchange chromatography indicated that [3H]inositol was incorporated into inositol phosphates, including the two second messengers, inositol 1,4,5-triphosphate and inositol 1,3,4,5-tetrakisphosphate, and also inositol monophosphate and inositol 1,4-bisphosphate. These results provide evidence that rabbit blastocysts may have an active phosphatidylinositol second messenger system, which may be responsive to intrauterine factors or intraembryonic paracrine factors.

Inositol transport in preimplantation rabbit embryos: effects of embryo stage, sodium, osmolality and metabolic inhibitors

“…As blastocyst protein content is highly correlated (r = 0.934) with surface area (Morgan and Kane, 1993), it is probable that inositol uptake is also highly correlated with blastocyst protein content.…”

“…1). The protein content and number of cells increase from about 0.16 g protein at the one-cell stage immediately after fertilization (Morgan and Kane, 1993) to about 7 g protein and about 80 000 cells in the day 6 blastocyst just before implantation (Daniel, 1964;Morgan and Kane, 1993). In contrast, the mouse blastocyst at implantation has <100 cells and 20-40 ng of protein (Schiffner and Spielmann, 1976).…”

“…One of the vitamins essential for rabbit blastocyst expansion and growth is myo-inositol (Kane, 1988;Fahy and Kane, 1992) and inositol also stimulates zona pellucida shedding or 'hatching' by hamster blastocysts (Kane and Bavister, 1988). It has been demonstrated that [ 3 H]inositol is incorporated into the phosphoinositides and inositol phosphates of the PtdIns cycle by rabbit and cattle blastocysts (Fahy and Kane, 1993;Hynes et al, 2000), and into PtdIns and PtdIns4P by mouse blastocysts Higgins and Kane, 2003).…”

Uptake and incorporation ofmyo-inositol by bovine preimplantation embryos from two-cell to early blastocyst stages

“…Inositol is essential for expansion and DNA synthesis in rabbit blastocysts at the stage when the blastocysts are starting to rapidly increase cell number and protein content (Kane, 1989;Fahy and Kane, 1992) and inositol also stimulates hatching of hamster blastocysts (Kane and Bavister, 1988). Inositol is incorporated into the phosphoinositides and inositol phosphates of preimplantation mouse and rabbit embryos Fahy and Kane, 1993). There is also strong evidence that the phosphatidylinositol system is essential for blastocyst formation in the mouse, both from inhibitor studies (Stachecki and Armant, 1996a,b) and gene knockout studies (Wang et al, 1998).…”

Pre-treatment effect of myo-inositol and l-5, methyltetrahydrofolate in ovulation induction oocyte quality and pregnancy outcome in clomiphene resistance polycystic ovarian disease

“…13,14 It is clear that myo-inositol is a precursor of the synthesis of phosphoinosides, in particular it constitutes the phosphatidylinositol signal transduction system, known to be involved in the regulation of several cellular function, including cell proliferation. 15 The presence of Myo-inositol in human body fluid, its role as precursor of the inositol phospholipids responsible for the generation of important intracellular signals essential for mammalian oocyte development and its higher concentration in FF containing oocytes of good quality suggests that the supplementation with myo-inositol in IVF techniques, could positively influence the final result of the reproduction technique. [16][17][18] …”