S9 liver fraction is cytotoxic to neurons in dissociated culture.
Methods to evaluate the neurotoxicity of chemicals in vitro must take into account that many xenobiotics exert their toxic effects through metabolites. S9 fraction of liver homogenate has been used in cultures of bacterial and mammalian cells as a system for metabolic activation. The suitability of the S9 activation system for long-term neurotoxicity studies in vitro was investigated in dissociated cultures of murine spinal cord-dorsal root ganglia. Exposure to amounts of S9 greater than 0.07 mg S9 protein/ml of culture medium for 4 days or longer was cytotoxic to all types of neurons in the cultures. Non-neuronal cells tolerated higher exposures, but contained numerous cytoplasmic inclusions when 0.35 mg S9 protein was included in the medium. It was demonstrated that cytotoxicity was caused by the particulate, microsomal fraction of S9. It is concluded that direct incorporation of S9 fraction in the growth medium (0.07 mg S9 protein/ml or greater) is not a suitable method of generating metabolites in dissociated cultures of central nervous system when several days are required to elicit a biological response. Cytotoxicity can be prevented by using tissue culture inserts to separate cultured cells from S9 particulate fraction by a microporous membrane.
Kohn
J
J
Montreal Neurological Institute, McGill University, Quebec, Canada.
Durham
H D
HD
D000818:Animals; D001711:Biotransformation / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000378:metabolism*
D003577:Cytochrome P-450 Enzyme System