National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2011

11. Neuropathological changes in auditory brainstem nuclei in cattle with experimentally induced bovine spongiform encephalopathy

Japanese

Bovine spongiform encephalopathy (BSE) is characterized by the appearance of spongy lesions in the brain, particularly in brainstem nuclei. This study evaluated the degenerative changes observed in the central auditory brainstem of BSE-challenged cattle. The changes were assessed by determining the severity of vacuolation and the presence of disease-associated prion protein (PrPSc). Sixteen 2- to 4-month old female Holstein-Friesian calves were inoculated intracerebrally with a BSE agent. BSE-challenged animals developed the characteristic clinical signs of BSE approximately 18 months post-inoculation (mpi) and advanced neurological signs after 22 mpi. Before the appearance of clinical signs (i.e. at 3, 10, 12, and 16 mpi), vacuolar change was absent or mild, and PrPSc deposition in auditory brainstem nuclei was minimal. Two cattle killed at 18 and 19 mpi had no clinical signs and showed mild vacuolar degeneration and moderate amounts of PrPSc accumulation in the auditory brainstem pathway. BSE-challenged animals that developed clinical sings (i.e. after 20 mpi) displayed more prominent changes in the nucleus of the inferior colliculus compared with those in the other nuclei of the auditory brainstem and medial geniculate body. Neuropathological changes characterized by spongy lesions accompanied by PrPSc accumulation in the auditory brainstem nuclei of BSE-infected cattle may be associated with hyperacusis.
(Prion Disease Research Center)

References:

Fukada S. et al (2011) J. Comp. Pathol. 145(2-3):302-307

Centers・Institutes