The mycotoxins alternariol and alternariol methyl ether negatively affect progesterone synthesis in porcine granulosa cells in vitro

Mycotoxins as contaminants of animal food can impair fertility in farm animals. In the regulation of female fertility the ovarian steroid hormone progesterone (P4) plays an important role. In the present study we have investigated the influence of the mycotoxins alternariol (AOH), alternariol mono-methyl ether (AME), and tenuazonic acid (TeA) on cell viability, P4 synthesis, abundance of the key enzymes of P4 synthesis, P450 cholesterol side-chain cleavage enzyme (P450SCC) and 3-β-hydroxysteroid dehydrogenase (3-β-HSD), and of the corresponding Cyp11a1 and Hsd3b transcripts in cultured pig granulosa cells. Already 0.8 μM, AOH and AME inhibited P4 secretion and 1.6 μM also significantly reduced cell viability. The abundance of P450scc protein but not of Cyp11a1 or Hsd3b transcripts was already significantly reduced by 0.8 μM AOH and AME. 1.6 μM AOH but not AME significantly reduced the abundance of α-tubulin and also clearly affected actin protein concentrations. TeA neither impaired viability nor P4 secretion. Also mycotoxin extracts isolated from naturally occurring Alternaria strains by HPLC purification inhibited cell viability and P4 synthesis, however at higher concentrations compared to AOH and AME. In conclusion, AOH and AME, but not TeA specifically inhibited P4 secretion in cultured porcine granulosa cells. Alternaria toxin contaminated food may therefore affect reproductive performance in pig and other mammalian species.