An early effect of estradiol at hepatic level, previous to its protein synthesis activation.

Liver glycogen phosphorylase activity is increased before protein synthesis activation by estradiol. This effect is not blocked by antibiotics (actinomycin D and cycloheximide) inhibitor of protein synthesis. At times very similar to those of phosphorylase activation, cAMP levels are not enhanced, as would be expected, but slightly depleted. At similar times, cGMP levels are dramatically increased.