INCREASING OR DECREASING NERVOUS ACTIVITY MODULATES THE SEVERITY OF THE GLIOVASCULAR LESIONS OF 1,3-DINITROBENZENE IN THE RAT - EFFECTS OF THE TREMORGENIC PYRETHROID, BIFENTHRIN, AND OF ANESTHESIA

To test the hypothesis that altered neuronal activity may influence th e extent and severity of the gliovascular lesions produced by 1,3-dini trobenzene (DNB) rats were either given the tremorgenic pyrethroid, Bi fenthrin, or anaesthetised during various dosing schedules of DNB. Whe n compared with controls dosed only with DNB, Bifenthrin tremor made b oth the ataxia and other functional effects caused by DNB more pronoun ced. Lesions in the brain stem were made significantly more severe and widespread across three dose levels of DNB. Centres such as facial nu clei, motor nuclei of fifth nerve, subthalamic nuclei and mamillary bo dies, not damaged by DNB alone, were also affected in some animals. Ln contrast, general anaesthesia by either isoflurane ur urethane decrea sed the severity of the lesions, this being more pronounced with ureth ane. The character of the tissue changes, however, was not altered by these additional procedures. These findings support the suggestion tha t neuronal activity is one important determinant of the selective vuln erability of sensitive brain stem nuclei to glio-vascular damage from DNB intoxication.