The regulatory role of steroid hormones on the PGF/PGE ratio in target tissues.

Estrogen has been found to regulate cyclic nucleotide and prostaglandin levels in the rat uterus. This action of estrogen is associated with a simultaneous rise in cyclic GMP and PFG levels. Alterations in PG levels are either independent of or secondary to the formation of cyclic GMP. The mechanism by which estrogen induces the rise in uterine PGFs, although not precisely defined, is associated with alterations of the enzymes rather than of the substrates involved with prostglandin synthesis.