Expression of vanilloid VR1 receptor in PC12 cells

Capsaicin, a pungent ingredient of chili pepper, activates vanilloid receptor subtype 1 (VR1), which is a nonselective cation channel with high Ca(2+) permeability. Although VR1 and its splice variant are highly expressed in sensory neurons, they are expressed in neuronal cells in brain and peripheral non-neuronal cells. In this study, we investigated whether VR1 is expressed in PC12 cells, rat pheochromocytoma. Capsaicin at concentrations above 100 microM induced an increase in intracellular free Ca(2+) concentrations by influx from extracellular spaces, and the effect was blocked by capsazepine, a selective antagonist of VR1. VR1 transcript and protein were detected by reverse transcription-polymerase chain reaction and Western blotting analysis, respectively. Immunocytochemical analysis revealed that VR1 protein was expressed in the cytosol and the plasma membrane of PC12 cells, and treatment with the antisense oligonucleotide for VR1 decreased the expression. VR1 in PC12 cells showed different characters from that in sensory neurons; capsaicin concentration-dependency and heat- and nerve growth factor-sensitivities. These results suggested that VR1 was functionally expressed in PC12 cells. The usefulness of PC12 cell line for studying functions and/or expression of VR1 is discussed.