Effects of oestradiol and progesterone on the metabolism of [U-14C]glucose by mouse morulae and early blastocysts in vitro.

The addition of progesterone (10(-7) to 10(-5) M) and/or oestradiol (10(-10) M) during 24-h chase culture of pulse-labelled morulae-early blastocysts did not affect the degradation of radiolabelled glycogen or other biochemical fractions. The presence of a high concentration of progesterone (10(-5) M) during 5-h pulse culture significantly inhibited incorporation of substrate carbon from [U-14C]glucose into both the acid-soluble and acid-insoluble glycogen fractions, but had no effect on non-glycogen fractions. Catabolic utilization of glucose as estimated by the rate of carbon dioxide and lactate production was not affected by the presence of progesterone (10(-7) to 10(-5) M), oestradiol (10(-10) to 10(-8) M) or a combination of both. The results indicate that ovarian steroids at expected physiological concentrations do not directly influence embryonic energy metabolism.