Expression and development of a functional plasmalemmal 5-hydroxytryptamine transporter by thyroid follicular cells.

Tamir H, Hsiung SC, Liu KP, Blakely RD, Russo AF, Clark MS, Nunez EA, Gershon MD
Endocrinology. 1996 137 (10): 4475-86

PMID: 8828510 · DOI:10.1210/endo.137.10.8828510

5-Hydroxytryptamine (5-HT) is synthesized and secreted by thyroid parafollicular (PF) cells. As all PF granules contain 5-HT, it is released whenever PF cells secrete. Because 5-HT stimulates follicular (F) cells and can modulate their response to TSH, 5-HT has been proposed to be a paracrine PF to F cell transmitter. This role would require a thyroid mechanism to rapidly inactivate 5-HT. A 5-HT transporter (SERT) in the plasma membrane of serotonergic neurons inactivates neuronal 5-HT. We thus tested the hypothesis that this molecule is expressed in the thyroid. Messenger RNA encoding SERT was demonstrated in both the human thyroid and a rat F cell line (FRTL-5). SERT immunoreactivity was detected in rat F, but not PF, cells. Transporter-mediated uptake of [3H]5-HT by F cells arose early in development (E13 in mice) and was maintained in adult life in mice, guinea pigs, bats, and rats (FRTL-5 cells). These observations indicate that a functional SERT is expressed in the thyroid, not by the 5-HT-secreting PF cells, but by their putative F cell targets.

MeSH Terms (20)

Aging Animals Autoradiography Carrier Proteins Cell Line Cell Membrane Chiroptera Fetus Guinea Pigs Humans Immunohistochemistry Male Membrane Glycoproteins Membrane Transport Proteins Mice Nerve Tissue Proteins Rats Serotonin Serotonin Plasma Membrane Transport Proteins Thyroid Gland

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