Chowen J A, Azcoitia I, Cardona-Gomez G P, Garcia-Segura L M
Unit of Investigation, Hospital Niño Jesús, Madrid, Spain.
J Pediatr Endocrinol Metab. 2000 Sep-Oct;13(8):1045-66. doi: 10.1515/jpem.2000.13.8.1045.
Gonadal steroid hormones have multiple effects throughout development on steroid responsive tissues in the brain. The belief that the cellular morphology of the adult brain cannot be modulated or that the synaptic connectivity is "hard-wired" is being rapidly refuted by abundant and growing evidence. Indeed, the brain is capable of undergoing many morphological changes throughout life and gonadal steroids play an important role in many of these processes. Gonadal steroids are implicated in the development of sexually dimorphic structures in the brain, in the control of physiological behaviors and functions and the brain's response to physiological or harmful substances. The effect of sex steroids on neuroprotection and neuroregeneration is an important and expanding area of investigation. Astroglia are targets for estrogen and testosterone and are apparently involved in the actions of sex steroids on the central nervous system. Sex hormones induce changes in the expression of glial fibrillary acidic protein, the growth of astrocytic processes and the extent to which neuronal membranes are covered by astroglial processes. These changes are linked to modifications in the number of synaptic inputs to neurons and suggest that astrocytes may participate in the genesis of gonadal steroid-induced sex differences in synaptic connectivity and synaptic plasticity in the adult brain. Astrocytes and tanycytes may also participate in the cellular effects of sex steroids by releasing neuroactive substances and by regulating the local accumulation of specific growth factors, such as insulin-like growth factor-I, that are involved in estrogen-induced synaptic plasticity and estrogen-mediated neuroendocrine control. Astroglia may also be involved in the regenerative and neuroprotective effects of sex steroids since astroglial activation after brain injury or after peripheral nerve axotomy is regulated by sex hormones.
性腺甾体激素在整个发育过程中对大脑中甾体反应性组织具有多种作用。认为成人大脑的细胞形态无法调节或突触连接是“硬连线”的观点正被大量且不断增加的证据迅速反驳。事实上，大脑在一生中能够经历许多形态变化，性腺甾体在其中许多过程中发挥着重要作用。性腺甾体与大脑中性别二态性结构的发育、生理行为和功能的控制以及大脑对生理或有害物质的反应有关。性甾体对神经保护和神经再生的影响是一个重要且不断扩展的研究领域。星形胶质细胞是雌激素和睾酮的作用靶点，显然参与性甾体对中枢神经系统的作用。性激素会诱导胶质纤维酸性蛋白表达的变化、星形细胞突起的生长以及神经元膜被星形胶质细胞突起覆盖的程度。这些变化与神经元突触输入数量的改变有关，表明星形胶质细胞可能参与成年大脑中性腺甾体诱导的突触连接和突触可塑性性别差异的形成。星形胶质细胞和伸长细胞也可能通过释放神经活性物质以及调节特定生长因子（如胰岛素样生长因子-I）的局部积累来参与性甾体的细胞效应，胰岛素样生长因子-I参与雌激素诱导的突触可塑性和雌激素介导的神经内分泌控制。星形胶质细胞也可能参与性甾体的再生和神经保护作用，因为脑损伤或外周神经轴突切断后星形胶质细胞的激活受性激素调节。
