Döhler K D
Pharma Bissendorf Peptide, Hannover, Germany.
Int Rev Cytol. 1991;131:1-57. doi: 10.1016/s0074-7696(08)62016-1.
A number of brain structures and a great number of brain functions have been shown to be sexually dimorphic. It has also been shown that development and differentiation of these structures and functions proceeds during a critical pre- and postnatal period of increased susceptibility, and is controlled by gonadal steroids and neurotransmitter substances. The brain of male and female mammals seems to be still undifferentiated before the period of increased susceptibility to gonadal steroids and neurotransmitters starts. Feminization of brain structure and functions, e.g., establishment of the cyclic LH-surge mechanism and the expression of lordosis behavior, seems to depend on the moderate interaction of estrogens with the developing nervous system. Defeminization and masculinization of brain functions seem to be established during interaction of the developing nervous system with androgens, which have to be converted, at least in part, into estrogens. Structural differentiation of the male brain, e.g., the sexually dimorphic nucleus of the preoptic area (SDN-POA), seems to be exclusively estrogen-dependent, during differentiation of male brain functions, however, estrogens may be supportive, rather than directive, to the primary action of androgens. The molecular mechanisms of sexual differentiation of the brain are not yet fully understood. It seems, however, that the priming action of gonadal steroids during the period of increased susceptibility is either mediated by neurotransmitters, or neurotransmitters modulate the priming action of gonadal steroids. In particular, the adrenergic, the serotoninergic, the cholinergic, and possibly the dopaminergic system were shown to have strong influences on sexual differentiation of brain structure and functions. In contrast to the great number of available studies on the influence of gonadal steroids on sexual differentiation of the brain, there are rather few studies available concerning the influence of neurotransmitter systems. The available results are partly contradictory, so that an interpretation must be done with caution and will leave plenty of room for speculation. Postnatal application of compounds which stimulate or inhibit adrenergic activity mainly affected the neural control of gonadotropin secretion, and had only minor influences on differentiation of behavior patterns. It seems, however, that adrenergic participation in the differentiation of the center for cyclic gonadotropin release is very complex and stimulatory and inhibitory components may operate simultaneously. Activation or inhibition of beta-adrenergic receptors during postnatal development was shown to impair the responsiveness of the center for cyclic gonadotropin release to gonadal steroids, and impairs the expression of ejaculatory behavior in male rats.(ABSTRACT TRUNCATED AT 400 WORDS)
大量脑结构和众多脑功能已被证明具有性别二态性。研究还表明，这些结构和功能的发育与分化在出生前和出生后的关键易感性增强期进行，并受性腺类固醇和神经递质物质控制。在对性腺类固醇和神经递质的易感性增强期开始之前，雄性和雌性哺乳动物的大脑似乎仍未分化。脑结构和功能的雌性化，例如促黄体生成素周期性激增机制的建立和脊柱前凸行为的表达，似乎取决于雌激素与发育中的神经系统的适度相互作用。脑功能的去雌性化和雄性化似乎是在发育中的神经系统与雄激素相互作用期间建立的，雄激素至少部分必须转化为雌激素。雄性大脑的结构分化，例如视前区的性别二态核（SDN-POA），似乎完全依赖雌激素，然而在雄性脑功能分化过程中，雌激素可能对雄激素的主要作用起支持作用，而非指导作用。大脑性别分化的分子机制尚未完全了解。然而，似乎在易感性增强期性腺类固醇的启动作用要么由神经递质介导，要么神经递质调节性腺类固醇的启动作用。特别是，已表明肾上腺素能、5-羟色胺能、胆碱能以及可能的多巴胺能系统对脑结构和功能的性别分化有强烈影响。与大量关于性腺类固醇对大脑性别分化影响的现有研究相比，关于神经递质系统影响的研究相当少。现有结果部分相互矛盾，因此必须谨慎解读，且仍有大量推测空间。出生后应用刺激或抑制肾上腺素能活性的化合物主要影响促性腺激素分泌的神经控制，对行为模式分化的影响较小。然而，肾上腺素能参与周期性促性腺激素释放中枢的分化似乎非常复杂，刺激和抑制成分可能同时起作用。出生后发育期间β-肾上腺素能受体的激活或抑制已被证明会损害周期性促性腺激素释放中枢对性腺类固醇的反应性，并损害雄性大鼠射精行为的表达。（摘要截选至400词）
