Nonylphenol kills special reproductive cells in male rats by changing the cell's outside membrane.

Sep 27, 2008

Gong, Y, XP Pan, Y Huang, ZS Gao, HX Yu and X Han. 2008. NP-induced biophysical and biochemical alterations of rat testicular Sertoli cell membranes related to disturbed intracellular Ca2+ homeostasis. Toxicology Letters online September 2, 2008.

In this new study, researchers have learned that the environmental pollutant nonylphenol causes its toxic effects in male testis cells by penetrating the protective cell membrane, altering the membrane's characteristics and disrupting the cell's delicate internal environment.

Low levels of nonylphenol (NP) damage and eventually kill cells essential for making sperm by changing their protective membranes in ways that alter the important balance of calcium ions inside. NP is a surfactant widely used in the manufacture of detergents, herbicides, insecticides, plastics and emulsifiers. NP is commonly found in the water environment and can bioaccumulate in aquatic species, such as fish, shrimp and shell fish. Humans are at risk of exposure to NP primarily via the food chain. Exposure to NP can cause harm to the reproductive system in wildlife and laboratory animals. but the actual way that NP causes this damage has been unknown.

All cells in the body are enclosed in a semi-permeable membrane that helps  maintain the right environment inside the cell (much like the walls of your house), allowing specific molecules to enter and leave and preventing others. Certain molecules must be kept out; others are allowed in – and all in the right sequence and at the right amount. One critical molecule in this balance is calcium. In this study, Dr. Gong and colleagues discovered that at low concentrations, NP physically alters the membranes of male gonad cells, called Sertoli cells, in laboratory rats, allowing more calcium to enter. This causes a disruption in the balance of calcium inside the cell, leading to a succession of adverse responses inside that ultimately result in cell death.