1,3,5-TRINITROBENZENE-INDUCED ENCEPHALOPATHY IN MALE FISCHER-344 RATS

Administration of 1,3,5-trinitrobenzene (TNB) to male Fischer-344 rats produced ataxia after 6 or 7 oral doses (71 mg/kg). Light microscopic examination after 10 days revealed petechial hemorrhages in the brain stem and cerebellum and bilaterally symmetric degeneration and necros is (malacia) with reactive gliosis in the cerebellar peduncles. The ma lacia was dorsal and lateral to the fourth ventricle involving the cer ebellar nuclei, medial and lateral vestibular nuclei, and inferior col liculi. Blood vessels associated with the lesion had widened Virchow-R obin spaces, occasionally with extravasated erythrocytes. Rats adminis tered daily oral doses of 35.5 mg/kg of TNB for 10 days and 35.5 and 7 1 mg/kg of TNB for 1 or 4 days did not have brain lesions.