REGIONAL BRAIN DOSIMETRY OF TRICHLOROETHANE IN MICE AND RATS FOLLOWING INHALATION EXPOSURES

While certain neuroactive volatile organic compounds (VOCs) have been reported to have an uneven distribution in various anatomically distin ctive brain regions, this has not yet been reported for the short-chai n aliphatic halogenated hydrocarbons. Therefore, the uptake and region al brain distribution of 1,1,1-trichloroethane (TRI) in mice and rats following inhalation exposure were examined. Male Sprague-Dawley rats and CD-1 mice were exposed to TRI at either 3500 or 5000 ppm for 10, 3 0, 60, or 120 min. Seven brain regions from rats and three from mice w ere sampled, and TRI concentrations in the blood and brain tissues wer e determined by headspace gas chromatography. In both species, the med ulla oblongata was found to have the highest TRI concentrations, while cortex (in both species) and hippocampus (only sampled in rats) conta ined the lowest TRI concentrations. Substantial differences were also observed between the two species, as the mice exhibited higher capacit y to accumulate TRI in the blood as well as in the brain regions. It a ppears that lipid content is a main factor influencing the differentia l disposition of TRI among the brains regions. Physiological differenc es in the respiratory systems of the two species and the physiochemica l properties of the chemical favoring diffusion toward lipid-rich comp artments could also have been expected to account for the patterns of regional distribution and species differences.