Phenanthrenequinone disrupts progesterone production in rat luteal cells

The ability of the environmental contaminant phenanthrene (PH) and its phot ooxidized product phenanthrenequinone (PHQ) to disrupt progesterone secreti on was examined in a model system of in vitro suspensions of luteal cells f rom the rat. Treatment with PHQ dramatically inhibited luteinizing hormone (LH) stimulated progesterone secretion. PHQ also generated a significant in crease in reactive oxygen species (ROS). In the absence of LH, however, PHQ stimulated a small increase in basal progesterone secretion. The parent co mpound, PH, did not alter progesterone or ROS release. Since there is evide nce that PHQ lowers the activity of nitric oxide synthase (NOS) and that ni tric oxide (NO) affects progesterone production, we examined the response t o the NOS inhibitors N-monomethyl-L-arginine, Zn protoporphyrin-9, and amin oguanidine in luteal cells. However, there was no effect of these agents on LH stimulated progesterone secretion. These results indicated that PHQ is a potent disrupter of progesterone secretion and should perhaps be consider ed in assessing the risk of PH to humans. (C) 2001 Elsevier Science Inc. Al l rights reserved.