Nuclear retention characteristics of [3H]estrogen by cells in four estrogen target regions of the rat brain.

Nuclear retention of radioactivity was studied in neural estrogen target cells 15 min-7 h after i.v. injection of [3H]estradiol. Maximal uptake occurred by 15 min. Cells of the medial preoptic nucleus retained the label longer than did those of the medial amygdaloid nucleus. Cells of the ventromedial nucleus and arcuate nucleus exhibited similar retention profiles which were intermediate between the medial preoptic and medial amygdaloid cells. These data are discussed in relation to observations that the duration of nuclear occupancy by estrogens is proportional to the magnitude of the cellular response.