Neuronal expression of peripherin, a type III intermediate filament protein, in the mouse hindbrain.

Peripherin is a 57 kDa Type III intermediate filament protein associated with neurite extension, neuropathies such as amyotrophic lateral sclerosis, and cranial nerve and dorsal root projections. However, knowledge of peripherin expression in the CNS is limited. We have used immunoperoxidase histochemistry to characterise peripherin expression in the mouse hindbrain, including the inferior colliculus, pons, medulla and cerebellum. Peripherin immunolabelling was observed in the nerve fibres and nuclei that are associated with all cranial nerves [(CN) V-XII] in the hindbrain. Peripherin expression was prominent in the cell bodies and axons of the mesenchephalic trigeminal nucleus and the pars compacta region of nucleus ambiguus, and in the fibres that comprise the solitary tract, the descending spinal trigeminal tract and the trigeminal and facial nerves. A small proportion of peripherin positive fibres in CN VIII likely arise from cochlear type II spiral ganglion neurons. Peripherin positive fibres were also observed in the inferior cerebellar peduncle and folia in the intermediate zone of the cerebellum. Antibody specificity was confirmed by absence of labelling in hindbrain tissue from peripherin knockout mice. This study shows that in the adult mouse hindbrain, peripherin is expressed in discrete neuronal subpopulations that have sensory, motor and autonomic functions.