Nickel-induced structural and functional alterations in porcine granulosa cells in vitro.

The present study was aimed at investigating the effect of nickel chloride (NiCl2) on secretion of progesterone (P), ultrastructure and apoptosis in porcine granulosa cells. NiCl2 was added to the cells to achieve a Ni(2+) concentration of 62.5, 125, 250, 500 and 1,000 μmol/L. A control group contained no NiCl2 addition. Quantification of P was performed directly from aliquots of the media from control and treated porcine granulosa cells after 48 h of culture using radioimmunoassay. Quantification of apoptotic cells was performed using terminal deoxynucleotidyl transferase dUTP nick end labelling assay, and ultrastructural changes were analyzed using transmission electron microscopy. A concentration-dependent depletion of P production was observed significantly for 1,000 μmol/L NiCl2. The percentage of apoptotic cells was increased in all experimental groups significantly only after addition of 1,000 μmol/L NiCl2. After addition of ≥250 μmol/L NiCl2, a higher incidence of euchromatin was observed. Also, lipid droplets and vacuoles in the cytoplasm increased after addition of ≥250 μmol/L NiCl2. NiCl2 induced the decrease in numbers of mitochondria and smooth endoplasmic reticulum after treatment with ≥500 μmol/L NiCl2. Our findings suggest a negative effect of NiCl2 on steroidogenesis and apoptosis as well as ultrastructure of porcine granulosa cells.