Ak. Vanvliet et al., VASTATINS HAVE A DISTINCT EFFECT ON STEROL SYNTHESIS AND PROGESTERONESECRETION IN HUMAN GRANULOSA-CELLS IN-VITRO, Biochimica et biophysica acta, L. Lipids and lipid metabolism, 1301(3), 1996, pp. 237-241
Lovastatin and simvastatin are strong inhibitors of cholesterol synthe
sis in cultured human granulosa cells, as measured within 6 days after
isolation, with IC50-values of respectively 27.0 and 18.2 nM obtained
after 3.5 hours of incubation with the drugs. Pravastatin is a much w
eaker inhibitor of cholesterol synthesis (IC50-value of 977.8 nM) in t
hese cells. Under these conditions inhibition of cholesterol synthesis
had no influence on progesterone secretion into the medium which was
probably due to the presence of large cholesterol pools in the cells.
To deplete these pools, granulosa cells were cultured for 7 days after
which the culture medium was changed into medium supplemented with 20
% lipoprotein-depleted serum to deprive the cells of exogenous cholest
erol. Additionally, 30 mIU of follicle-stimulating hormone and luteini
zing hormone per ml were added to stimulate the progesterone productio
n and secretion, thereby decreasing the cholesteryl ester pools. After
48 h of incubation, culture was continued without hormones for anothe
r two days. Thereafter, the cells were preincubated for 24 h without o
r with 1 mu M of lovastatin, simvastatin or pravastatin in medium cont
aining lipoprotein-deficient serum and the above-mentioned hormones. T
his period is followed by incubation for another 24 h in the presence
of [C-14]acetate after which cells and media were collected for determ
ination of C-14-labelled sterols synthesized and progesterone secreted
into the media. Now, lovastatin and simvastatin, which strongly inhib
ited sterol synthesis, significantly attenuated the secretion of proge
sterone. One mu M of pravastatin had no significant effect on sterol s
ynthesis nor on progesterone secretion. When the latter experiment was
performed under conditions in which exogenous cholesterol was provide
d in the form of human low density lipoproteins, no influence of the v
astatins on progesterone secretion was observed, So under conditions i
n which the cholesterol pools were decreased, lovastatin and simvastat
in attenuated the progesterone secretion, whereas pravastatin did not.
When pools were filled by exogenous cholesterol, no effect on progest
erone secretion by either of the drugs was observed.