| Summary: | Thyroid hormones regulate essential physiological processes, including metabolism, reproduction, and growth. A key constituent of all thyroid hormones is iodine. To obtain and concentrate iodine, vertebrates utilize a protein called the sodium iodide symporter (NIS). While most commonly associated with the thyroid and digestive tract, I have confirmed preliminary evidence from a single fish species, red drum (Sciaenops ocellatus), for a novel location of NIS expression: the brain. The objective of this study was to examine whether this expression exists in other teleost fish species and to more precisely identify the anatomical locations of neural NIS expression. Brains from several species of marine and freshwater fish, (tilapia; Oreochromis niloticus, channel catfish; Ictalurus punctatus, zebrafish; Danio rerio, and hybrid striped bass; Morone saxatilis) spanning three taxonomic orders (Cypriniformes, Perciformes, and Siluriformes), were collected and subjected to RT-PCR to identify NIS expression. This study found NIS to be present in the brains of all 5 experimental species, but only present in the previously confirmed sub-pharyngeal areas of red drum and zebrafish. Its uniform distribution across these species suggests that NIS may perform a novel, as yet undescribed role in iodine transport in the central nervous system. Localization of NIS expression within the brain is, therefore, a critical next step in elucidating its function.
|
|---|