Utilization of [U-14C] Glucose by Preimplantation Rat Embryo Cultured In Vitro.

Abstract

Abstract:The oxidation and incorportion of [U-14 C] glucose were examined in preimplantation rat embryos. An increasing capacity for incorporation and oxidation of glucose after the 1-cell stage was observed and the oxidative turnover of this substrate at the blastocyst stage was ten times more than that at the 1-cell stage. To evaluate how glucose is utilized for the synthesis of embryo lipids, 2-cell embryos and blastocysts were cultured for 5 h in medium containing [U-14 C] glucose, and total lipids extracted from the embryo were separated into various neutral lipids and phospholipids by thin layer chromatography and radioactivities of these lipid fractions were measured. Most of the radioactivity was recovered in triacylglycerols in both stages, and radioactivities were also found in other neutral lipids and phospholipids. These results indicate that [U-14 C] glucose was certainly utilized for oxidation and the synthesis of various lipids in embyros at the preimplamtation stage. Key words: Incorporation of glucose, Distribution of glucose, Oxidation of glucose, Lipid synthesis, Rat embryo.The composition characteristics of several kinds of saturated and unsaturated fatty acids in rat embryo and oviduct and uterine fluids were reported [1]. Moreover, it was demonstrated that the development of rat embryos was seriously affected in the absence of fatty acids bound to BSA in the culture medium [2]. Furthermore, in the absence of carbohydrate substrates, either the free fatty acids or those added to the culture medium had stronger effects on the development of rat embryos than carbohydrate substrates added to the culture medium [3]. Flynn and Hillman [4] reported that lipid synthesis from [U-14 C] glucose could be performed in preimplantation mouse embryos cultured in vitro.The present study was undertaken to test the oxidation and to characterize the incorporation of [U-14 C] glucose by preimplantation rat embryos. Materials and Methods Animals and embryo collectionEight week-old rats of Wistar Imamich strain were raised under controlled light conditions(12 h light:12 h darkness: light on at 06:00 A.M.). The females were mated naturally overnight with the males, and examined for the presence of vaginal plugs the next morning. One-, two-, four-, and eight cell embryos, morula and blastocysts were collected from mated females by the flushing of oviducts at 8, 32, 56 and 76 h and of the uterus at 84 and 108 h after ovulation, respectively. Experiment 1Incorporation and oxidation experiments with 18.5 KBq [U-14 C] glucose (Specific activity: 10 µM/mM) were performed according to the method of Brinster [5]. The embryos were pooled with medium and 10 embryos were transferred to 0.1 ml BMOC III containing radioactive glucose in one microtube, and 1 ml Hyamine in another microtube. The contents of the two microtubes were then transferred to a scintillation vial. The scintillation vials were airtight and incubated for 3 h at 37°C under 5% CO 2 in air. Then the reaction was stopped by the addition of cold PCA to a final ...

The beneficial effect of fructose and glucose on in vitro maturation and the fertilization of porcine oocytes

“…This also suggests that porcine oocytes have a tendency to meet their energy requirement from the exogenous hexose sources. Though there are previous reports on the utilization of radioactive methionine and glucose in Mongolian gerbil [33] and rat [34] embryos, respectively, there is little information on fructose utilization in porcine embryos. Nonetheless, Guixe et al [35] proposed that fructose plays an important role in the utilization of 14 C-glucose in frog oocytes.…”