Confocal imaging of HuC/D RNA-binding proteins in adult rat primary sensory neurons.

HuC/D RNA-binding proteins are antigens that are specifically expressed in nerve cells. In the present study, immunocytochemistry and laser confocal microscopy were used to study the cellular distribution of HuC/D RNA-binding proteins in adult rat primary sensory neurons. Colocalization with the protein gene product 9.5 (PGP 9.5) was used to identify sensory neurons. Confocal laser imaging showed that HuC/D antigens are expressed in the cytoplasm of all rat primary sensory neurons. Most neurons also showed anti-HuC/D immuno-positivity in the nucleus. The demonstration of the ubiquitous expression of HuC/D antigens in primary sensory neurons gives us a possible explanation for the severe pathological lesions observed in dorsal root ganglia in association with the paraneoplastic Hu Syndrome.