Fos induction in the brain of mice exhibiting behavioral abnormalities following administration of allylnitrile or crotononitrile

Allylnitrile and crotononitrile induce behavioral abnormalities in mice. To explore the possible involvement of the vestibular system in these behavio ral abnormalities, the expression of Fos protein, used as an indicator of n euronal activity, was examined within various brain structures in allylnitr ile-, crotononitrile- and vehicle-treated mice. In each nitrile-treated mou se, Fos expression was observed in brain structures, which were divided int o two groups. The structures in group 1 showed Fos expression between 1.5 h and 2 days postdosings, and in those in group 2 expression remained for up to 30 days postdosing. As most of these structures, especially in group 2, were identical to some Fos-positive structures observed after unilabyrinth ectomy, the present results indicate that each nitrile induces Fos expressi on by causing a change in the peripheral vestibular system, resulting in be havioral abnormalities. (C) 2000 Elsevier Science BSI. All rights reserved.