Transneuronal induction of the highly sialylated isoform of the neural cell adhesion molecule following nerve injury

Polysialylated Neural Cell Adhesion Molecule Supports Regeneration of Neurons in the Nucleus Ambiguus After Unilateral Recurrent Laryngeal Nerve Avulsion in Adult Rats

OBJECTIVES

A correlation appears to exist between the expression of the polysialic acid neural cell adhesion molecule (PSA-NCAM) and repair in central nervous system (CNS) diseases. However, the expression of PSA-NCAM in the CNS after peripheral nerve injury remains unclear. This study aimed to evaluate the expression of PSA-NCAM in the ipsilateral nucleus ambiguus (NA) after unilateral recurrent laryngeal nerve (RLN) avulsion.

MATERIALS AND METHODS

The left RLN of adult Sprague Dawley rats were avulsed. The expression of PSA-NCAM, PSA-NCAM/NeuN, and PSA-NCAM/Tuj1 in the brain stem was investigated using immunohistochemistry. The results were subjected to one-way analysis of variance followed by the Tukey post hoc test for statistical analyses.

RESULTS

PSA-NCAM-positive and PSA-NCAM/NeuN and PSA-NCAM/Tuj1 double-labeled positive cells were observed 7 days post injury in the ipsilateral NA. PSA-NCAM/NeuN and PSA-NCAM/Tuj1 double-labeled cells were observed at 21 and 7 days post injury, respectively. PSA-NCAM/NeuN double-labeled cells were also found in the contralateral NA.

CONCLUSIONS

After unilateral avulsion of the RLN, the expression of PSA-NCAM in the ipsilateral NA was correlated with the proliferation and the differentiation of neural cells. PSA-NCAM expression may be used as a predictor of the initiation of repair in neural cells.

Sacral nerve stimulation increases activation of the primary somatosensory cortex by anal canal stimulation in an experimental model

BACKGROUND

Sacral and posterior tibial nerve stimulation may be used to treat faecal incontinence; however, the mechanism of action is unknown. The aim of this study was to establish whether sensory activation of the cerebral cortex by anal canal stimulation was increased by peripheral neuromodulation.

METHODS

A multielectrode array was positioned over the right primary somatosensory cortex of anaesthetized rats. A brief burst of electrical stimulation was applied to either the left sacral root or the left posterior tibial nerve, and evoked potentials from anal canal stimulation were signal-averaged at intervals over 1 h. At the end of the experiment, the cerebral cortex was removed and probed for polysialylated neural cell adhesion molecule (PSA-NCAM).

RESULTS

Sacral nerve root and posterior tibial nerve stimulation significantly increased the peak amplitude of primary cortical evoked potentials by 54.0 and 45.1 per cent respectively. This change persisted throughout the period of observation. The density of PSA-NCAM-positive cells in the somatosensory cortex underlying the electrode array was increased by approximately 50 per cent in the sacral nerve-stimulated group.

CONCLUSION

Brief sacral neuromodulation induces profound changes in anal canal representation on the primary somatosensory cortex, providing a plausible hypothesis concerning the mechanism of action of neuromodulation in the treatment of faecal incontinence.