Individual and combined effects of fumonisin B1 and deoxynivalenol or zearalenone on porcine granulosa cell steroid production

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium species, frequently occurring in corn in combination with trichothecenes and zearalenone (ZEA). There is a lack of information on the potential effects of FB1 on reproduction in swine. Thus, the goal of this study was to determine if FB1, alone and combined with deoxynivalenol (DON) or ZEA, can impair pig reproductive functions via affecting granulosa cell steroidogenesis. Granulosa cells from small porcine follicles (1-5 mm) were cultured for 2 days in 5% foetal bovine serum and 5% porcine serum-containing medium followed by 2 days in serum-free medium containing 500 ng/ml of testosterone (as an estradiol precursor), 30 ng/ml of FSH and 30 ng/ml of IGF-I with or without FB1 (10 M), DON (3.4 M) and ZEA (9.4 M). At the end of the experiments medium was collected from individual wells and concentrations of progesterone and estradiol were determined by radioimmunoassay. Numbers of granulosa cells in the same wells that medium was collected were determined by a Coulter counter and used to calculate steroid production on a ng or pg per 105 cell basis. FB1 and ZEA, alone and combined, had no effect (P > 0.10) on FSH plus IGF-I induced estradiol production, whereas DON strongly inhibited (by 67%; P < 0.0001) estradiol production and no difference was detected in combination with FB1. Alone, FB1 or ZEA increased (P < 0.0001) FSH plus IGF-I-induced progesterone production by 59% and 51%, respectively. Combination of FB1 with ZEA resulted in an increase of progesterone production (91%; P < 0.0001) that was significantly higher than those induced by the two fusariotoxins alone. DON drastically inhibited (by 74%; P < 0.0001) progesterone production, and FB1 had little effect on this response. In conclusion, the present study indicates that FB1 may alter steroid production in swine, and provides information on the interactions between FB1 and DON or ZEA in granulosa cells. These interactions and direct ovarian effects should be considered in swine reproductive failures.