Change in perineuronal net of rat vestibular nuclear neurons in development and in injury

Abstract

Perineuronal net (PN) is a lattice-like extracellular matrix surrounding neurons. With the use of the lectin Wisteria floribunda agglutinin as a cytochemical marker, we studied the expression patterns of PN within the vestibular nuclei in normal postnatal rats (P1 to adult) as well as in adult rats at 5 to 11 days after unilateral labyrinthectomy (UL). In uninjured rats, PN was detectable by P3 in the vestibular nucleus as fuzziness about neuronal cell bodies. From P9 onwards, the fuzzy PN was progressively consolidated into a network organization. The fuzziness was no longer observable after P12. During postnatal development, the number of cell bodies indicating PN was found to increase, reaching adult level by P21. In unilateral labyrinthectometomized rats, the PN on the labyrinth-intact side remained similar to uninjured age-matched rats. On the lesioned side at 5 days after UL, the PN recapitulated the fuzziness of early postnatal stages of uninjured rats. By 11 days after UL, the PN resumed the network pattern. Taken together, our findings suggest that the PN plays a crucial role in modulating the pericellular environment of vestibular nuclear neurons both during postnatal development of normal rats as well as in adult rats following destruction of the ipsilateral inner ear.