[Synaptic plasticity in the sex steroid-sensitive neuroendocrine brain].

Sex steroids are known to modulate neural development and neural circuit formation in both developing and adult sex steroid-sensitive neuroendocrine brain of mammals. During perinatal period, estrogen or aromatizable androgen can act as a neurotropic factor on neural tissues, stimulating axonal and dendritic growth and synapse formation. The development of sexual dimorphic synaptic organization may reflect sex steroid-modulating synaptogenesis in the hypothalamus and limbic system during perinatal period. The onset of puberty may also be due, at least in part, to stimulation of synapse formation by estrogen in the hypothalamus. In adulthood, estrogen has a facilitatory effect on synapse formation in neural structures such as septum, hypothalamus and midbrain with or without brain lesion, and androgen plays a significant role in regulating synaptic remodeling in the androgen-sensitive spinal motoneuron pools. Thus, sex steroids seems to be critical from developmental period to adulthood for organizing and reorganizing neuronal circuitry driving neuroendocrine and behavioral functions.