Toluene alters brainstem enkephalinergic system in rats.

Acute exposure to high doses of toluene can generate respiratory depression. However, neurotoxic mechanism of its action in the brainstem is not completely clear. In this work, acute, but not subchronic, exposure of rats to toluene increased leu-enkephalin immunostaining in several myelencephalic nuclei implicated in cardiorespiratory control. Due to the physiological role of enkephalins in the central regulation of breathing, it is suggested that the enkephalinergic system could play a role in neurotoxic respiratory depression induced by high dose acute toluene exposure.