Effects of mancozeb, metalaxyl and tebuconazole on steroid production by bovine luteal cells in vitro.

Mancozeb, metalaxyl and tebucanazole are widely used pesticides in agriculture and industry to treat plant pathogenic fungi. Livestock may be exposed to such substances by consuming contaminated plants. The present study was designed to evaluate the effects of these three fungicides on bovine luteal cell steroidogenesis. Luteal slices from mid-cycle corpus luteum were dissociated into single cell suspension in aerated (O2) culture media (DMEM/F12) by enzymatic digestion. The cells were incubated in newborn calf serum (10%) for 18 h and then with serum-free media containing mancozeb (0.01 µM, 0.1 µM, 1 µM), tebuconazole (1 µM, 10 µM, 100 µM) or metalaxyl (100 µM, 500 µM, 2500 µM) for additional 96 h. The medium was replaced on day 1 and 3; and the retrieved medium was stored at -20 °C until progesterone assay. Treatment of cells with three different fungicides induced dose dependent variable decrease in steroid synthesis during incubation periods. Incubation of cells with 1 µM mancozeb exhibited a 33% decline in steroid synthesis on day 3 and 48% decline on day 5 compared with controls. Treatment of cells with 100 µM tebuconazole and 500 µM metalaxyl resulted in a 65% and 31% decrease, respectively, in progesterone accumulation on day 5 of incubation. Fungicide induced suppressive effects on luteal steroidogenesis were as metalaxyl < tebuconazole < mancozeb. Results of the present study suggest that designated concentrations of all three fungicides studied might have varying degrees of adverse effects on luteal steroidogenesis.