Interactions between nerve growth factor binding and estradiol in early development of the zebra finch telencephalon.
The zebra finch telencephalon exhibits rapid and substantial development in the first few weeks after hatching. In parallel, the rate of estradiol synthesis is very high in the zebra finch forebrain, and estradiol can have potent neurotrophic effects in specific telencephalic regions, including those that control the learning and production of song. In an attempt to elucidate mechanisms regulating telencephalic development, potentially including a role for the large capacity for estrogen production, (125)I-nerve growth factor (NGF) binding was measured in homogenates of telencephalon from zebra finches age 3, 15, 30, 60, and 120 days. The highest density of low- and high-affinity (125)I-NGF binding sites was observed in 3-day-old finches. Using an aromatase inhibitor, Fadrozole, to reduce estradiol levels in 1 to 4-day-old zebra finches significantly decreased both high- and low-affinity (125)I-NGF binding sites. Conversely, treating adult or 8 to 14-day-old hatchlings with estradiol increased high-affinity (125)I-NGF binding sites. These results are consistent with the hypothesis that estradiol influences the level of NGF receptors, and suggest one mechanism through which the steroid could affect brain development. The data also indicate that estradiol and NGF activity may be important for very early development of the telencephalon.
Department of Pharmacology and Toxicology, Life Science Bldg., Program in Neuroscience, Michigan State University, East Lansing, Michigan 48824, USA.
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Contreras
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J
Wade
D000367:Age Factors; D000818:Animals; D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D017316:Fadrozole / Q000494:pharmacology; D005260:Female; D008297:Male; D020932:Nerve Growth Factor / Q000378:metabolism*; D011485:Protein Binding; D020800:Receptor, Nerve Growth Factor / Q000378:metabolism; D017475:Receptors, Nerve Growth Factor / Q000502:physiology*; D012741:Sexual Maturation; D020308:Songbirds / Q000254:growth & development*; D013687:Telencephalon / Q000254:growth & development* / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism
D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D013739:Testosterone; D004958:Estradiol; D020932:Nerve Growth Factor; D017316:Fadrozole