Effect of chronic toluene exposure on tyrosine hydroxylase-positive nerve elements in the rat forebrain : an immunohistochemical study combined with semiquantitative morphometric analysis

THE effects of chronic toluene exposure [3000 p.p.m. for 4h (09 :00-11 :00, 13 :00-15 :00)] every day for 3 weeks on immunoreactivity for tyrosine hydroxylase (TH), the rate limiting enzyme of catecholamine synthesis, in the rat forebrain were studied. In toluene-exposed rats, increases in both number and intensity of TH-immuno-reactive fibres and terminals were observed in most parts of the forebrain including the cerebral cortex, hippocampus, lateral septal nucleus and hypothalamus, compared with control rats. These findings suggest that chronic toluene exposure might influence catecholaminergic neural systems.