Effect of IUDs on uterine cyclic AMP in rabbits

The mechanism(s) whereby the intrauterine device (IUD) prevents implantation are poorly understood. Sim showed that the presence of an IUD in the rat uterus was associated with an increase in cyclic AMP content and adenyl cyclase activity. Cyclic AMP has been implicated in a variety of uterine biosynthetic processes and in the control of spontaneous uterine contractions. The present study was designed to determine the effect of a plastic and copper bearing IUD on levels of cyclic AMP in the uteri of oestrous rabbits. Levels of cyclic AMP in control (no IUD in either horn) and IUD-containing uteri are shown in Table 1. Cyclic AMP was significantly (P<0.04) lower in the uteri containing plastic or plastic copper IUDs by 1 month and remained depressed for up to 3 months. Levels returned to control values in animals in which the plastic IUD was removed at 2 months, but remained depressed after removal of the plastic copper IUDs.