Burden and dose-related neurochemical effects of intermittent cyclohexane vapour inhalation in rats.

Intermittent daily inhalation exposure to 300, 1000 or 2000 ppm of cyclohexane vapour resulted in a dose-dependent solvent concentration in the perirenal fat in rats. The linear relationship changed between the first and second week of exposure as the body solvent burden decreased, despite the continued exposure: this was especially clear in the brain cyclohexane analyses. The salient feature in the brain was the reduction in the activity of azoreductase, while no change could be found in the RNA or glutathione content or in glutathione peroxidase activity. The azoreductase activity was somewhat below the control range after a 2-week withdrawal period, while no solvent could be found and other biochemical variables were within the control ranges.