The rat vomeronasal organ is a vitamin D target

- Sensory cells of the rat VNO contain DBP in apical dendrites and in axons.
- VNO Sensory neurons have in part nuclear immunoreactivity for VDR.
- Some of the ciliated cells in the non-sensory part of the VNO show VDR and DBP.
- A fraction of the subepithelial glands contain DBP.
- RT-PCR of the VNO reveals both DBP and VDR encoding transcripts.

We studied the expression of vitamin D receptor and of vitamin D binding protein in the rat vomeronasal organ. With immunofluorescence, in situ hybridization and with reverse transcriptase PCR we found both proteins in sensory as well as in non-sensory cells. Sensory neurons contained immunoreactivity for vitamin D3 receptor in nuclei, in portions of the cytoplasm, and in apical dendrites and their microvilli. Vitamin D binding protein was observed in sensory neuron axons and cytoplasm, mostly confined to dendrites. Colocalization appeared in the contact zone of supporting cells and sensory dendrites. Both proteins were also found in single ciliated cells within the non-sensory epithelium. Vitamin D binding protein was also localized in secretory vesicles in a portion of the vomeronasal glands. Our findings suggest that the rat vomeronasal organ is a vitamin D target.