Effect of estrogen on rabbit gallbladder prostaglandin biosynthesis

Male and female gallbladder prostaglandin biosynthesis was compared by radiochromatographic analysis of microsomal membrane fractions. Normal female rabbit gallbladder total prostaglandin activity was 10-fold higher than the normal male rabbit gallbladder total prostaglandin activity. The normal male rabbit extracts produced PGF2 alpha and PGE2 as the major arachidonic acid metabolites. The normal female rabbit extracts synthesized PGI2 and PGE2 (20-fold higher activity than the normal male) as the major arachidonic acid metabolites present. The effect of estrogen was studied by comparing prostaglandin activity in ovariectomized female rabbits given high-dose estrogen, low-dose estrogen, and no estrogen. The zero estrogen group prostaglandin activity was 5-fold lower than the normal female group. Treatment with low- or high-dose estrogen restored the gallbladder prostaglandin activity to the level of the normal rabbit gallbladder prostaglandin activity.