Expression of vitamin D receptors in the superior cervical ganglia of rats

Aiming to evaluate the possible presence and role of vitamin D in the sympathetic nervous system, the distribution and occurrence of VDRs, 1α-hydroxylase and CYP24 in rat superior cervical ganglia (SCGs) of rats in different neuronal subpopulations and satellite glia was investigated by using immunohistochemistry. VDR immunoreactivity was observed in cytoplasm as well as in nuclei of almost all neurons in the SCG. Intensity of VDR fluorescence was significantly higher in the cytoplasm of NPY negative somata, in comparison to NPY positive neurons (p<0.05). Immunoreactivity for 1α- hydroxylase was also observed in the cytoplasm of all neurons of the SCG, but the intensity of fluorescence was less strong in nuclei. To the contrary, the immunoreactivity for CYP24 was much stonger in the nuclei, although it was present in a lower grade also in the cytoplasm of neurons. VDR and 1α-hydroxylase immunofluorescence was observed in many non- neuron cells, except in satellite glial cells, which presented with weak CYP24 immunofluorescence. Expression of the VDRs and the key metabolizing enzymes indicates the important role of active vitamin D in the autonomic nervous system and the ability of sympathetic neurons to activate and deactivate vitamin D for its autocrine and paracrine roles.