Distribution of TRPC1, TRPC3, and TRPC6 in the human thyroid

BACKGROUND: Little is known about the protein expression of the transient receptor potential canonical (TRPC) channels 1, 3, and 6 in the thyroid. Research in human tissue is insufficient. Our aim was to investigate the distribution of TRPC1, 3, and 6 in the healthy human thyroid. METHODS: Healthy samples were collected from seven nitrite pickling salt-ethanol-polyethylene glycol-fixed cadavers and from one patient who had undergone neck surgery (5 males, 3 females; median = 81.0, interquartile range = 6.5 years). The protein expression profiles of TRPC1, 3, and 6 were assessed using immunohistochemistry with knockout-validated antibodies. A monoclonal calcitonin antibody was used to detect calcitonin-producing C-cells. RESULTS: All samples were labeled as healthy, displaying age-appropriate signs of degeneration. TRPC1, 3, and 6 immunolabeling in thyrocytes showed irregular staining patterns leaving selected cells with intense staining, some without. The comparison of calcitonin- and TRPC1-, 3-, and 6-immunolabeled slides strongly suggested TRPC1, 3, and 6 expression in C-cells. Connective tissue showed no immunoreactivity. CONCLUSIONS: This is, to the authors' knowledge, the first detailed description of the distribution of these channels in the human thyroid. We conclude that TRPC1, 3, and 6 are expressed in thyrocytes and C-cells of the human thyroid. Further studies are necessary to confirm these small-case-number results and to explore the relevance of these versatile channels in thyroidal health and disease.