Mechanisms Of Synaptic Plasticity In The Adult And Devel

对于神经科学家和整个社会来说，一个关键问题是遗传和环境在人类大脑出生后发育中的相对作用。环境刺激范围很广，从有害的（例如化学毒物）到有益的（母亲的指示），但所有这些都有可能影响儿童基因组指导的发育程序。突触和发育可塑性小组的研究重点是确定1）大脑中的连接（突触）如何响应神经元活动而长期变化，2）出生后早期发育期间的突触可塑性如何不同于成人的可塑性，以及3）经验如何通过发育期间的突触消除来塑造脑回路。在我们运作的第二年，我们在制定将用于实现上述第一个项目的一些方法方面取得了重大进展。我们相信突触功效的长期变化需要新RNA的表达，为此，我们专注于神经元动作电位对基因表达的调节。为了测量由动作电位调节的酶活性，我们开发了一种从少量脑组织中分离细胞核的方法，该脑组织首先在体外进行电刺激。使用这种方法，我们已经确定了一个高分子量的细胞外信号调节激酶（ERK）的神经元细胞核内的神经元刺激后磷酸化的复合物。我们已经进一步确定了这种复合物的推定成分，现在正在用质谱法确认我们的结果。在进一步的努力，以确定基因是如何转录响应神经元的活动，我们已经利用了一种方法，使用蛋白质/DNA阵列来测量多达150个转录因子的激活状态。我们正在用电泳迁移率变动试验（EMSA）验证这些研究的结果。这些研究检查神经元活动的转录调控将导致了解突触可塑性所需的基因是如何调节的。连同上面列出的研究目标，这些研究应该使我们更好地了解环境因素如何在大脑发育中发挥作用，以便我们可以开始解决有毒物质暴露引起的脑部疾病的相关问题。

A critical issue for both neuroscientists and society at large concerns the relative roles of genetics and environment in the postnatal development of the human brain. Environmental stimuli are wide ranging, from the detrimental (chemical toxicants, for example) to the beneficial (a mother's instructions), but all have the potential to influence the developmental program of a child as directed by its genome. The research done in the Synaptic and Developmental Plasticity Group focuses on determining 1) how the connections in the brain (synapses) change on a long-term basis in response to neuronal activity, 2) how synaptic plasticity during early postnatal development is different from plasticity in the adult, and 3) how experience shapes brain circuitry through synapse elimination during development. During our second year of operation, we have made significant progress in developing some of the methodologies that will be used in achieving the first of the aforementioned projects. We believe that long-term changes in synaptic efficacy require expression of new RNA and toward that end, we have focused on the regulation of gene expression by neuronal action potentials. To measure enzyme activity modulated by action potentials, we have developed a method for isolating nuclei from small amounts of brain tissue, which had first been electrically stimulated in vitro. Using this method, we have identified a high molecular weight complex of Extracellular signal Regulated Kinase (ERK) within neuronal nuclei that is phosphorylated after neuronal stimulation. We have further identified putative components of this complex and are now in the process of confirming our results with mass spectrometry. In a further effort to determine how genes are transcribed in response to neuronal activity, we have taken advantage of a method using a protein/DNA array to measure the activation states of up to 150 transcription factors. We are in the process of validating the results of these studies with electrophoretic mobility shift assays (EMSAs). These studies examining transcriptional regulation by neuronal activity will lead to an understanding of how genes required for synaptic plasticity are regulated. Together with the research goals listed above, these studies should bring us a better appreciation of how environmental factors play a role in brain development so that we may begin to address the associated problems of brain disease caused by toxicant exposure.