Toxicity of 7-ketocholesterol on lethality, growth, reproduction, and germline apoptosis in the nematode Caenorhabditis elegans.

7-Ketocholesterol is one of the most abundant cholesterol oxides, and is known to be cytotoxic to various types of cultured mammalian cells; however, little is known regarding its effects in vivo. With the use of the nematode Caenorhabditis elegans as model organism, in vivo toxicity of 7-ketocholesterol was investigated. The aim of the study was to examine the effects on life span, as well as short-term effects on reproduction, thermotolerance, germline apoptosis, and reactive oxygen species (ROS) generation resulting from C. elegans exposure to 7-ketocholesterol at concentrations ranging from 0 to 200 µg/ml. Results indicated that 7-ketocholesterol reduced reproductive capacity, shortened the life span in a concentration-dependent manner, and impaired thermotolerance of the adult nematode. 7-Ketocholesterol also induced germline apoptotic cell death and increased ROS generation in adult worms. Thus, the model organism C. elegans is recommended for assessment of the safety and bioactivity of cholesterol oxides.