Uptake of (3)H labeled synthetic progestin by rat brain and pituitary. A radioautography study

The distribution of cells concentrating R 5020, a potent synthetic progestin, in the brain and pituitary of estrogen-primed ovariectomized rat was investigated by radioautography. In the brain, radioactivity was found concentrated in nuclei of neurons in the preoptic region (nucleus (n.) preopticus pars suprachiasmatica, n. preopticus periventricularis, n. preopticus medialis) and in the medio basal hypothalamus (n. ventromedialis and n. arcuatus). In the anterior pituitary, a significant number of labeled cells was observed.