Activity of foot skin mechanoreceptors and afferent nerve fibres in the adult rat sciatic nerve are altered after central axotomy of sensory neurons

The functional properties of skin mechanoreceptors were examined in the hin d foot of normal rats in comparison with animals subjected to dorsal rhizot omy. Evoked nerve impulses were recorded from afferent nerve fibres of the tibial nerve. The decentralized mechanoreceptors displayed evidence of auto nomous functioning, but with several abnormalities as compared to normal an imals. There was a decreased sensitivity to mechanical stimulation and a lo wer adaptive capacity as a consequence of rhizotomy. The underlying mechani sm is suggested to be a loss of central trophic support because of the inte rrupted link between the central nervous system and the sensory ganglion ce ll periphery. The findings indicate that mechanical receptors continue functioning under conditions when sensory impulses flow cannot reach postsynaptic target neur ons in the central nervous system, but stop at the level of the primary sen sory neuron. (C) 2000 IBRO. Published by Elsevier Science Ltd.