Interactions between progestins and estradiol on serum lipids in the rat.

In female rats the influence of progestins of the estrane type [norethisterone acetate (NEA), norgestrel (NG) and dienogest (DEG)] and of the pregnane type [chlormadinone acetate (CMA), progesterone (P)] on total cholesterol (TC) and high-density-lipoprotein cholesterol (HDL-C) in serum has been investigated in combination with estradiol (E). E increased TC (45%) and HDL-C (12%). NEA, NG and DEG alone decreased TC maximally by 58% and HDL-C maximally by 67%, CMA and P were without influence. In combination with E, the gestagens NEA, NG and DEG suppressed the E-induced increase of TC and HDL-C, whereas CMA and P did not counteract the TC increase. The effects of estrogen/gestagen combinations on HDL-C in the serum of rats are similar to those in men, but species differences in the lipoprotein metabolism must be taken into consideration.