Garcia-Segura L M, Dueñas M, Busiguina S, Naftolin F, Chowen J A
Instituto Cajal, C.S.I.C., Madrid, Spain.
J Steroid Biochem Mol Biol. 1995 Jun;53(1-6):293-8. doi: 10.1016/0960-0760(95)00066-9.
Recent evidence indicates that, in addition to their well known effects on neurons, gonadal steroids may exert part of their neural effects through astroglia. In adult female rats astroglia participate in the phasic remodelling of synapses that takes place during the estrous cycle in the arcuate nucleus of the hypothalamus under the influence of estradiol. Astroglia also appear to be involved in the genesis of sex differences in synaptic connectivity. Gonadal steroids influence hypothalamic astroglia differentiation in vitro and in vivo. In monolayer mixed neuronal-glial cultures from fetal rat hypothalami, estradiol induces a progressive differentiation of astrocytes from a flattened epithelioid morphology to bipolar, radial and stellate shapes. This effect of estradiol on astroglia is dependent on the expression of specific molecules on the neuronal surface, such as the polysialic acid-rich form of the neural cell adhesion molecule. In the rat arcuate nucleus in situ, perinatal androgen influences astroglia gene expression and differentiation, resulting in a sex difference in astroglia organization by postnatal day 20. By this day, the amount of neuronal surface covered by astroglial processes is higher in males than in females. This difference in the coverage of neuronal surface by astroglia may be directly related to the reduced number of synaptic contacts that is established on the soma of male neurons compared to females.
最近的证据表明，除了对神经元的众所周知的作用外，性腺类固醇可能通过星形胶质细胞发挥其部分神经作用。在成年雌性大鼠中，星形胶质细胞参与下丘脑弓状核在发情周期中在雌二醇影响下发生的突触阶段性重塑。星形胶质细胞似乎也参与突触连接性性别差异的形成。性腺类固醇在体外和体内影响下丘脑星形胶质细胞的分化。在来自胎鼠下丘脑的单层混合神经元-胶质细胞培养物中，雌二醇诱导星形胶质细胞从扁平上皮样形态逐渐分化为双极、放射状和星状形态。雌二醇对星形胶质细胞的这种作用取决于神经元表面特定分子的表达，例如富含多唾液酸形式的神经细胞粘附分子。在大鼠原位弓状核中，围产期雄激素影响星形胶质细胞基因表达和分化，导致出生后第20天星形胶质细胞组织出现性别差异。到这一天，雄性大鼠中被星形胶质细胞突起覆盖的神经元表面面积比雌性大鼠更大。星形胶质细胞对神经元表面覆盖的这种差异可能与雄性神经元胞体上建立的突触接触数量比雌性减少直接相关。
