Estrogen receptor development in the absence of growth hormone and prolactin: studies in dwarf mice

The concentration of high-affinity estradiol binding sites in the uteri and pituitaries of normal and two dwarf strains of mice was studied. The two dwarf strains are characterized by their total absence of growth hormone or prolactin synthesis and low or absent TSH production. The uteri of the dwarf mice are small but the receptor concentration per unit of DNA was similar to the normals. Nuclear and cytoplasmic distribution studies and saturation analysis detected no differences in receptor characteristics between dwarf and normal mice. These results demonstrate that prolactin, growth hormone and TSH do not control the developmental increase in uterine estrogen receptor that normally occurs in the young mouse. The concentration of estrogen receptor per unit of DNA in the pituitaries of the dwarfs was only 20-30% of normal animals of the same strain. This suggests that estrogen receptor in the mouse pituitary is associated to a great extent with lactotrophs and/or somatotrophs which are absent in the dwarfs.