Toluene alters appetite, NPY, and galanin immunostaining in the rat hypothalamus

Toluene is a neurotoxic organic solvent widely used in industry and extensively inhaled by solvent abusers. Toluene, diluted 1:1 in olive oil, was administered intraperitoneally at a dose of 1.3 ml/kg/day for 4 days. Controls received the vehicle in the same dose and duration. Food intake and body weight were measured daily. A regional hypothalamic NPY and galanin immunocytochemical study was also performed. Acute toluene administration in rats generated a reduction in food intake and body weight gain. A significant decrease in NPY immunostaining in the paraventricular nucleus and an increase in arcuate nucleus without changes in other hypothalamic regions were observed. Also, acute toluene administration increased galanin immunostaining in paraventricular and arcuate nuclei. These results suggest that the hypothalamic NPY arcuate-paraventricular projection is involved in the anorectic effect of acute high-dose toluene administration. Changes in regional hypothalamic galanin expression could represent a compensatory mechanism against toluene-induced anorexia. (C) 2003 Elsevier Inc. All rights reserved.