Maternal hypothyroidism is associated with M-opsin developmental delay.

Thyroid hormones are critical for the development of opsins involved in color vision. Hypothyroid mice show delayed M-opsin development and expanded distribution of S-opsin on the retina. However, the effects of maternal hypothyroidism on opsin development remain unknown.

The Hypothalamic Paraventricular Nucleus Is the Center of the Hypothalamic-Pituitary-Thyroid Axis for Regulating Thyroid Hormone Levels.

Thyrotropin-releasing hormone (TRH) was the first hypothalamic hormone isolated that stimulates pituitary thyrotropin (TSH) secretion. TRH was also later found to be a stimulator of pituitary prolactin and distributed throughout the brain, gastrointestinal tract, and pancreatic β cells. We previously reported the development of TRH null mice (conventional TRHKO), which exhibit characteristic tertiary hypothyroidism and impaired glucose tolerance due to insufficient insulin secretion.