Serum Lipoprotein Changes in Female Rats Treated with Progesterone or Synthetic Gestagens Alone or in Combination with Estradiol. I. Total and Fractionated Cholesterol and Lipoprotein Pattern

Abstract

In adult female rats, the effects of progesterone (P), norethisterone acetate (NEA), levonorgestrel (LNG), dienogest (DEG) and chlormadinone acetate (CMA) given alone at doses of 2.5 or 10 mg/kg p.o. or in combination with s.c. implanted estradiol (E2) on total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-C), low-density-lipoprotein cholesterol (LDL-C) and very-low-density-lipoprotein cholesterol (VLDL-C) were investigated. Additionally, the lipoprotein pattern was determined using agarose gel electrophoresis. Synthetic gestagens derived from nortestosterone (NEA, LNG, DEG) lowered TC by reduction of HDL-C and LDL-C, whereas E2 induced an increase of these lipids. The decrease of HDL-C and LDL-C caused by the gestagens was also found in E2 pretreated rats. In contrast, the pregnane related CMA and P given alone did not diminish TC, HDL-C or LDL-C. But they partly reversed the enhancing effect of E2 on the HDL-C fraction following their simultaneous administration. The results suggest that the cholesterol lowering effects of gestagens are mediated rather via androgen than via progesterone receptors.

Serum Lipoprotein Changes in Female Rats Treated with Progesterone or Synthetic Gestagens Alone or in Combination with Estradiol. II. Serum Triglycerides and Hepatic Triglyceride Release

“…In a previous study in rats was shown that pregnane derived gestagens such as chiormadinone acetate or progesterone differ from 19-norgestagens by the lack of both the serum cholesterol lowering and its corresponding estradiol antagonizing activities (Tkocz et al, 1985;Tkocz et al, 1988). In this paper the modulating influence of these two types of gestagens on the triglyceride (TG) metabolism of female rats is discussed.…”

“…E2 was given as implant or in an aqueous vehicle (2% ethanol: tylose). Further details see (Tkocz et al, 1988).…”

“…The cholesterol content of the HDL -and LDL-fractions in rat serum was shown to be increased after acute treatment of the animals with 19-norgestagens such as NEA, LNG and DEG but not with gestagens derived from pregnane like CMA or progesterone (Tkocz et al, 1985;Tkocz et al, 1988). The pre-ß-fraction which contains the bulk of lipoprotein triglycerides was only increased in part by these gestagens.…”