Effects of the mycotoxins alpha- and beta-zearalenol on regulation of progesterone synthesis in cultured granulosa cells from porcine ovaries.

Mycotoxins as contaminants of animal food can impair fertility and can cause abnormal fetal development in farm animals. Therefore, the present study has investigated whether derivatives of the mycotoxin zearalenone, alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL), influence progesterone synthesis via cytochrome p450 side chain cleavage enzyme (p450scc) and 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) in cultured porcine granulosa cells. Both enzymes are essential for the conversion of cholesterol to progesterone. No differences in basal progesterone levels and numbers of viable cell were observed between untreated granulosa cells and those treated with alpha- or beta-ZOL (15 and 30 microM). FSH (0.01 microg/ml) or forskolin (10 microM) enhanced the basal progesterone secretion in the absence of mycotoxins. The addition of alpha- or beta-ZOL (7.5, 15 and 30 microM) to cultures stimulated with FSH (0.01 microg) or forskolin (10 microM) reduced progesterone synthesis and the levels of p450scc and 3beta-HSD transcripts in a dose-dependent manner (P<0.05). The enzymatic activity of 3beta-HSD and the abundance of p450scc protein were also reduced by these mycotoxins. In conclusion, effects of mycotoxins on FSH receptor-dependent and receptor-independent pathways indicate that adenylate cyclase activity and/or regulatory pathways further downstream are targets of mycotoxin actions. The apparent dose-dependent reduction of p450scc and 3beta-HSD transcripts implies an effect of alpha- and beta-ZOL on transcriptional regulation of these enzymes.