Impact of Therapeutic Ultrasound on Metabolic Hormone Release From Thyroid Gland

This study focused on determining if ultrasound therapy could stimulate and control the function of the thyroid gland, specifically the synthesis and release of metabolic hormones thyroxine (T4) and triiodothyronine (T3) in a physiologically relevant ex vivo model.

Excised thyroid glands obtained from healthy adult Sprague-Dawley rats were diced into sections and placed in wells containing 1 mL of Krebs Ringer Buffer with 5 mmol glucose. Continuous, unfocused ultrasound was applied at 1 W/cm² for 5 minutes at frequencies of 600 kHz, 800 kHz, and 1 MHz using a circular planar transducer positioned at the near field-far field transition distance. Samples were collected at time points 0, 5, and 35 minutes after ultrasound sonication. T3 and T4 concentrations were analyzed using competitive enzyme-linked immunosorbent assays, and histological examination was performed using hematoxylin and eosin staining.

There was no statistically significant difference in T4 or T3 release between the ultrasound treated and sham treated samples at any combination of frequency and time point tested (p > .05 for all comparisons). Histological analysis revealed no structural abnormalities or gross microscopic changes in ultrasound-treated samples.

Unlike previous studies demonstrating ultrasound-stimulated insulin release from pancreatic beta cells, therapeutic ultrasound at the tested parameters did not stimulate T3 or T4 release from ex vivo thyroid tissue.