Developmental Changes in Estrogen Receptors in Mouse Cerebral Cortex between Birth and Postweaning: Studied by Autoradiography with llβ-Methoxy-16α- [125I]Iodoestradiol*

The presence of estrogen receptor cells in postnatal cerebral cortex and their topographical and numerical changes between birth and postweaning were examined. On postnatal days 0, 2, 8, 12, 18, and 25, six mice (three males and three females) were injected sc with 0.25 μ/100 g BW 11β methoxy-16α-[125I]iodoestradiol ([125I]MIE2). Two additional males on postnatal day 2 were each sc injected with 250 μg/100 g BW 17β-estradiol 1 h before radiolabeled ligand to establish the specificity of nuclear label. Two hours after the injection of [125I]MIE2 brains were frozen, and 4-μm sections were thawmounted and processed for autoradiography. Autoradiograms were exposed for 1–45 days, and cortical cells with nuclear uptake and retention of [125I]MIE2 were evaluated at the levels of the frontal pole, preoptic area, and central and posterior hypothalamus. At birth, cells with nuclear label were found predominantly in deep cortical layers. Between birth and postnatal day 2, the number of labeled cells increased in dee...