Effects of acute benzene exposure on brain enkephalin immunostaining and degradation

Benzene is a widely used industrial neurotoxin. Its action in the brain is not completely clear. Acute exposure to benzene in vivo reduces aminopeptidase activity in the hypothalamus and in the brain stem, and in vitro treatment with this toxicant generates a dose-related inhibition of this enzyme, notably in the brain stem. Enkephalin immunostaining shows a significant increase in substantia nigra, central gray (dorsal, lateral and pontine), and tegmental nuclei in acute in vivo benzene-treated rats with respect to controls. In summary, this work shows an effect of benzene on the enkephalinergic system, which could be related to the naloxone-reversible analgesia induced by the aromatic hydrocarbon.