Effect of mono-ethylhexyl phthalate on MA-10 Leydig tumor cells

We examined the effect of mono-ethylhexyl phthalate (MEHP) on MA-IO Leydig tumor cell structure and function. Cells were exposed to various concentrat ions of MEHP for 24 h and then stimulated with saturating concentrations of hCG for 2.5 h. Progesterone production, cell viability, and protein conten t were moderately inhibited by low concentrations and severely inhibited by high concentrations of MEHP. Electron microscopy showed a variety of alter ations in the MEHP-treated cells, increasing in severity with increasing co ncentrations of MEHP. Lipid droplets were profoundly affected in the cells treated with MEHP and morphologic evidence that metabolism of lipid storage droplets ceases at approximately the same time progesterone synthesis stop s was seen. Morphometric studies indicated that the number of lipid droplet s appeared to be increased 2.5-fold over control levels at MEHP concentrati ons of 10(-6) to 10(-3) M whereas mitochondrial volume fraction decreased. These results suggest that MEHP in Leydig cells may act as a mitochondrial toxicant and lipid metabolism disrupter. (C) 2001 Elsevier Science Inc. All rights reserved.