ROLE OF NEURAL PLASTICITY IN PUBERTY

这个项目的长期目标是了解负责触发我们自己物种青春期开始的机制。 在人类和其他高等灵长类动物中，下丘脑GnRH脉冲产生系统在成年时为垂体-性腺轴提供主要驱动力，在婴儿期起作用。 然而，在青春期前发育期间，控制灵长类性腺功能的神经内分泌轴的活动被下丘脑GnRH脉冲发生器的非性腺抑制所阻止，并保持在长期的静止状态。 因此，灵长类动物的青春期是由GnRH脉冲发生器活动的重新唤醒触发的。这种青春期控制系统似乎是人类、猿和猴子所独有的。 虽然青春期是人类发展的一个重要里程碑，与行为、认知功能、前景的巨大变化有关，在某些情况下，还与情感障碍的发生有关，但对这一发展阶段发生的基本神经生物学知之甚少。这个问题将在本提案中使用的agonadal雄性恒河猴，一个代表性的高等灵长类动物，作为一个实验范例来解决。 具体目标1 -检验假设，即下丘脑内侧基底核（MBH）中NPY张力的增加是青春期前发育期间对GnRH脉冲释放施加限制的关键组成部分;具体目标2 -确定从幼年到青春期状态过渡期间丢失的GnRH胞体突触输入的表型;具体目标3 -确定除了细胞体和树突外，正中隆起水平GnRH网络的结构重塑是否与青春期脉冲性GnRH释放再增强的开始相关;具体目标4 -为了确定在发育的青春期前阶段结束时抑制GnRH神经元网络内的结构重塑是否阻止了青春期的开始 RNA酶保护试验和原位杂交将用于跟踪NPY基因表达的发育变化。 蛋白质水平将通过蛋白质印迹法测定。 NPY在MBH中的作用将使用脑室内施用的NPY受体拮抗剂或抗体来阻断。 反义寡核苷酸可阻断NPY的合成。 将使用光学和电子显微镜研究下丘脑的结构重塑。 将应用标准的包埋前和包埋后免疫细胞化学程序来定量GnRH胞体、树突和轴突终末的突触输入和神经胶质鞘的变化。 通过在青春期下丘脑的这一区域注射或过度表达神经内氨酸酶，尝试阻断该区域GnRH网络的可塑性。

The long term goal of this project is to understand the mechanisms that are responsible for triggering the onset of puberty in our own species. In man and other higher primates, the hypothalamic GnRH pulse generating system, which, in the adult, provides the principal drive to the pituitary-gonadal axis, is functional during infancy. During prepubertal development, however, activity of the neuroendocrine axis governing primate gonadal function is arrested and held in a protracted state of quiescence by non-gonadal restraint of the hypothalamic GnRH pulse generator. Puberty in primates is thus triggered by a reawakening of GnRH pulse generator activity. Such a pubertal control system appears unique to man, apes and monkeys. Although puberty represents a major landmark in human development that is associated with dramatic changes in behavior, cognitive function, outlook, and, in some cases, with the onset of affective disorders, little is known about the fundamental neurobiology underlying the onset of this developmental stage. This problem will be addressed in the present proposal using the agonadal male rhesus monkey, a representative higher primate, as an experimental paradigm. The following Specific Aims Will be addressed: Specific Aim 1 - To test the hypothesis that an increase in NPY tone in the mediobasal hypothalamus (MBH) is a critical component of the restraint that is imposed upon pulsatile GnRH release during prepubertal development; Specific Aim 2 - To determine the phenotype of the synaptic input to GnRH perikarya that is lost during the transition from the juvenile to the pubertal state; Specific Aim 3 - To determine whether structural remodeling of the GnRH network at the level of the median eminence, in addition to that at the cell body and dendrites, occurs in association with the onset of the pubertal reaugmentation of pulsatile GnRH release; Specific Aim 4 - To determine whether inhibition of structural remodeling within the GnRH neuronal network at the end of the prepubertal phase of development prevents the onset of puberty. RNAse protection assays and in situ hybridization will be used to track developmental changes in NPY gene expression. Protein levels will be determined by Western blotting. The action of NPY in the MBH will be blocked using NPY receptor antagonists or antibodies administered intracerebroventricularly. Synthesis of NPY will be blocked with antisense oligodeoxynucleotides. Structural remodeling in the hypothalamus will be studied using both the light and electron microscope. Standard pre-embedding and post-embedding immunocytochemical procedures will be applied to quantitate changes in synaptic input and glial ensheathment of GnRH perikarya, dendrites and axonal terminals. Attempts will be made to block plasticity in the GnRH network of the pubertal hypothalamus by injecting or overexpressing endoneuraminidase in this region of the brain.