Prostaglandin production by the pregnant and non-pregnant rabbit uterus

We have studied the prostaglandin synthesis of the pregnant and non-pregnant rabbit uterus in a microsomal membrane preparation, and in an ex vivo perfused uterus preparation which retains agonist stimulated prostaglandin production. In both the microsomal and isolated perfused system, prostacyclin was the major arachidonic acid metabolite produced; PGE2 was also produced in substantial quantities while TxB2 and PGF2 alpha were not detectable. Moreover, oxytocin was a specific stimulus of PGE2 release. The steroid hormone milieu influenced the level of agonist stimulated prostaglandin release; in general, ovariectomized, estrogen treated animals were more responsive to agonist stimulation than those treated with estrogen followed by progesterone. The microsomal studies indicated that the pregnant animal had a greatly enhanced capacity to metabolize arachidonic acid when compared with the non-pregnant animal. However, this was not reflected in the ability of agonists to stimulate prostaglandin release in the ex vivo perfused preparation.