Thyroid Hormone Regulation of Deiodinase in Red Drum (Sciaenops ocellatus)
The thyroid gland is known to be important in the regulation of metabolism,growth, and reproduction in both mammalian and non-mammalian species. However, little information is available how thyroid hormones act on target tissues in non-mammalian species such as fish. Fish are difficult to study because we do not currently have an effective, non-invasive method for administering thyroid hormone to them or for studying the effects of altered thyroid hormone levels on their tissues. As a result, research done on fish often utilizes pharmacological dosages of stressfully-administered thyroid hormone, causing experimental artifacts. In my study, I developed a thyroid hormone immersion system to generate physiological increases of the thyroid hormone thyroxine (T4) in the red drum (Sciaenops ocellatus), a commercially important fish species. Immersion experiments were performed, where red drum were kept in 20-gallon glass tanks – with either T4-treated or control solution-treated tank water, and the system recirculating water flow turned off – for the course of the set immersion period. Immersion in T4-treated tank water for 40 hours induced an increase in circulating T4 from 8.3 ng/mL (in control fish) to 28.7 ng/mL (in T4-treated fish), within the physiological range. This physiological elevation of T4 did not induce significant changes in liver IRD gene expression, considered to be a marker of pharmacological elevation of thyroid hormones. These results showed that thyroid hormone immersion should be an effective, non-invasive method for administration of physiological levels of thyroid hormone to red drum.
Ron, Laura (2011). Thyroid Hormone Regulation of Deiodinase in Red Drum (Sciaenops ocellatus). Honors and Undergraduate Research. Available electronically from