THE EFFECTS OF DIFFERENT ESTRADIOL DELIVERY METHODS ON PLASMA ESTRADIOL LEVELS IN MICE

Abstract

Evidence suggests that estrogen plays a role in decreasing the risk of developing colon cancer. Numerous animal studies demonstrate possible mechanisms to explain how estradiol (E2) prevents this disease. Many of these studies involve removing the ovaries of mice and replacing E2 at a controlled dose for the length of the study. One method of E2 delivery involves compacting E2 and cholesterol into a pellet and implanting it subcutaneously on the back of the animal. While the release patters of silastic implants have been studied previously, the compressed powder pellets release patterns has not. It is unclear if the results of studies using this hormone delivery method come from a steady release of the E2 over the entirety of the study or if it is the result of a giant influx of E2 levels just at the beginning. This ten-week experiment compared the amounts of E2 released from an E2 compressed powder pellet, a silastic E2 implant and a control cholesterol implant. To observe the amount of estradiol released, female mice were first ovariectomized and received either a treatment of: E2, control, or a silastic implant of E2. Each week following the surgery, a group of mice were sacrificed from each of the three treatment groups. The blood was tested using an ELISA test to determine the levels of estradiol. The results showed that there was peak of E2 directly following the implantation of the pellet and a week after implanting the silastic E2, but the levels then remained constant.