Figure 4.

Estradiol promotes synaptogenesis; estradiol prevents synaptogenesis. An important component of estradiol-induced masculinization of the developing brain is establishment of synaptic patterns that will endure into adulthood and subserve the neural networks of hormonally regulated behavior and physiology. A, In the preoptic area and ventromedial hypothalamus, 2 brain regions critical to the control of sexual behavior, estradiol organizes the synaptic pattern by promoting the development and stabilization of dendritic spine synapses. The mechanism by which this is achieved is fundamentally different in the 2 regions, but involves glutamate and ionotropic glutamate receptors in both cases. B, The arcuate nucleus exerts regulatory control over the anterior pituitary gland and in this region estradiol acts to suppress the formation of dendritic spine synapses. Astrocytes in this region are also differentiated by estradiol, exhibiting a more complex and stellate morphology than those not exposed to estradiol during this sensitive period of development.