Thyrotropes in the pituitary are target cells for 1,25 dihydroxy vitamin D3.

In the anterior pituitary of the rat, target cells of 1,25 (OH)2 vitamin D3 are identified as those that secrete thyroid stimulating hormone by means of a combined technique of thaw-mount autoradiography and immunohistochemistry. The results for the first time provide evidence that suggests a central effect of 1,25 (OH)2 vitamin D3 on the modulation of thyrotropin secretion in a manner similar to that of other steroid hormones at the level of the pituitary.