Aims: 

Lesion of vestibular nerve evokes serious deficits in the posture of animal. After a period of time the vestibular function is restored during the vestibular compensation. Since the lesioned vestibular axons do not regenerate in mammalian species, vestibular compensation is attributed to the plasticity of CNS. On the other hand, successful regeneration is demonstrated in lower vertebrates following the injury of vestibular nerve. Experimental studies revealed that the ECM is important during the regeneration and plasticity of CNS. It is supposed that the differences in the regeneration capacity of different species may be explained by the differences in the composition of ECM.

Methods: 

In anesthetized frogs and rats the vestibulocochlear nerve was injured and at different survival times the expression of chondroitin sulfate proteoglycan (CSPG), hyaluronan (HA) and tenascin-R (TN-R) were studied in the vestibular nuclei.

Results: 

The perineuronal net (PNN) of the vestibular neurons, the condensation of ECM around the neurons, is rich in HA in both species, whereas the CSPG and TN-R show a very intensive reaction in the rat and almost negative in the frog. Following the vestibular lesion, the PNN disintegrates very early both in frog and rat, but the subsequent restoration is significantly faster in the rat.

Conclusions: 

In the rat, the more complex molecular composition of the PNN and its non-permissive CSPG content may explain the lack of the vestibular regeneration. The different time course in the restoration of PNN in the frog and rat correlates with a much slower vestibular compensation in lower vertebrates.

Support: 

OTKA K 67641 and MTA-TKI 242