No abstract

No abstract

gas anesthesia. Isotopic tracers of 13C, D3-Met, 13C3-Ser and D2-Cys were administered as a 4 hour prime-constant rate infusion. Blood samples were obtained at 3, 3.5, 3.75 and 4 hours. After sacrifice, germinal vesicle stage oocytes were isolated and denuded. The rate of appearance of each amino acid being traced was calculated using the tracer dilution method.RESULTS: Dietary protein restriction caused differential responses in the kinetics and concentrations of plasma serine and glycine, and folate supplementation did not ameliorate the observed responses. The total flux of serine, a methyl group donor, was higher in the LP and LPF groups (P<0.005), and was associated with higher plasma serine concentrations in the LP and LPF groups (P<0.01; 442 and 433 vs. 281 mmol/L) compared to controls. The plasma concentration of glycine was also higher in the LP and LPF groups vs. controls (P<0.001; 367 and 357 vs. 244 mmol/L). Methionine transsulfuration to cysteine was faster in the LP and LPF groups (P<0.05 and P<0.01), and this was associated with a higher plasma concentration of cysteine in the LPF group vs. controls (P<0.05; 218 and 167 mmol/L). The rate of methionine transmethylation was also faster in the LP and LPF groups vs. controls (P<0.01 for both comparisons). There was a trend toward significance for increased oocyte concentrations of serine and glycine in the LP and LPF groups. Analyses regarding intraoocyte kinetics are ongoing.CONCLUSIONS: Dietary isocaloric protein restriction results in profound changes in plasma single carbon metabolism. Protein restriction elicited a disregard for methionine conservation in favor of cysteine production via transsulfuration. Transsulfuration is the pathway through which cysteine is produced for synthesis of the antioxidant glutathione, suggesting that glutathione production was prioritized over methionine conservation in a protein restricted model. Supplementation with folate did not further increase the rate of production of cysteine in plasma or oocytes. These metabolic responses may affect the growth, development and programming of preovulatory oocytes.

No abstract

No abstract

No abstract

No abstract

No abstract