Ethanol decreases progesterone synthesis in human placental cells: Mechanism of ethanol effect

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Fetal alcohol syndrome (FAS) is a set of signs and symptoms in offsprings born to mothers who abuse alcohol during pregnancy. We postulated that impairment in the placental endocrine function contribute to FAS. In this study, we examined in vitro effects of ethanol on the placental cells' (cytotrophoblast cells) capacity to synthesize progesterone. Cytotrophoblast cells were isolated from normal term placenta and were incubated (2 × 10 6) with 20-, 30-, and 40-mM doses of ethanol for 6 h. Progesterone was measured in the incubate by RIA. The results showed that, at the 20mM dose of ethanol, progesterone synthesis was significantly decreased ( p < 0.01), at the 30-mM dose level there was a further decrease of 20%. The differences between 30- and 40-mM ethanol dose levels were not significant. To determine the mechanism of ethanol effects on progesterone synthesis, cytotrophoblast cells were preincubated with 30 mM ethanol followed by 10 μl of LDL (10 μl LDL = 80 μg cholesterol) and vice versa. The results showed that ethanol effects on progesterone synthesis was dependent on whether ethanol was added prior to or following the addition of LDL in the medium. If ethanol was added in the medium prior to LDL, progesterone synthesis was decreased significantly ( p > 0.01); however, when ethanol was added after the LDL, ethanol had no effect on progesterone synthesis. In the experiment where ethanol and LDL were added simultaneously in the medium, ethanol blunted the stimulatory effect of LDL on progesterone synthesis. To determine whether ethanol affects steroid-producing enzymes localized in the cell organelles mitochondria and microsome were isolated and incubated together with LDL (5 μl LDL = 40 μg cholesterol) in the presence of 30 or 40 mM ethanol. Progesterone was isolated, quantitated, and the results showed that ethanol had no affect on progesterone synthesis suggesting that capacity of steroid-producing enzymes was not affected in the presence of ethanol. From these data, we conclude that ethanol decreased progesterone synthesis in the cytotrophoblast cells, and decrease is caused by blocking of substrate (cholesterol) entry into cell organelles.