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.

The influence of progesterone (P) and synthetic gestagens given alone or in combination with estradiol (E2) on triglyceride (TG) concentration in serum of adult female rats was studied. Norethisterone acetate (NEA), levonorgestrel (LNG), dienogest (DEG), chlormadinone acetate (CMA) and P were administered orally at a dose of 10 mg/kg for three times. E2 was given chronically by s.c. implants. Synthetic gestagens and P were without any effect on the TG serum concentrations but E2 elevated the TG level by 168%. This E2-induced TG increase was not reversed by synthetic gestagens or P given orally but only by P s.c. after combined treatment with E2 plus gestagens. In a second experiment the hepatic TG release into the blood was studied using the model of Triton WR-1339 induced hypertriglyceridemia. E2 as well as the synthetic gestagens stimulated the TG release while the natural P failed to produce this effect. Following treatment with E2 plus gestagens, the E2 stimulated TG release was not significantly influenced by the gestagens. It is concluded that both the hepatic TG release into and the TG removal from the circulation may be stimulated by gestagens.