Effects of catechol estrogen methyl ethers on lipid metabolism in prepubertal rats

Thirty-five day old ovariectomised rats were given daily subcutaneous injections (0.05-5.0 micrograms/100 gm body weight) of estradiol (E2) 2-methoxyestradiol (2-ME2) or 4-methoxyestradiol (4-ME2) for six days. At the end of the last injection, the animals were sacrificed and serum lipoproteins were analysed. It was observed that cholesterol decreased significantly in normal fed animals who received E2 and 4-ME2, while no effect was seen in cholesterol fed animals. In the E2 treated group there was a decrease in esterified and free cholesterol, while in the 4-ME2 group only esterified cholesterol decreased. High density lipoproteins were significantly elevated in the E2 treated group. However, there was an increase in very low density lipoproteins and a decrease in low density lipoproteins in 2-ME2 and 4-ME2 treated groups. These results suggest that catechol estrogens may play an important role in the lipoprotein metabolism and atherosclerotic diseases, and the mechanism of action may differ from that of estradiol.