Dopamine/glutamate and hypoxic injury in newborn brain

我们的总体假设是，大脑的中度缺氧/缺血损伤激活了许多途径， 如果不对抗，则会导致神经元凋亡或坏死死亡（损伤），而其他神经元则会导致神经元凋亡或坏死。 保护作用，部分是通过对抗前者。这些过程的相对活性决定了 结果。在目前的建议中，我们将新生小猪的大脑进行分级缺氧/缺血 损伤和定量监测的反应的关键中间体的推定的损害和保护 在存在和不存在选择性阻断剂和活化剂的情况下， 具体而言，我们将测试以下假设： 1.缺氧/缺血损伤改变新生仔猪纹状体CREB和DARPP-32的磷酸化 这是长期细胞和组织损伤的重要决定因素。这些变化的模式 （方向、幅度和持续时间）取决于侮辱的严重程度。 2.新生仔猪纹状体中CREB和DARPP-32磷酸化的改变， 缺氧缺血性损伤取决于细胞外多巴胺增加的幅度。 3.多巴胺通过D1和D2受体对CREB和DARPP-32磷酸化发挥作用。 4.在缺氧和缺血/缺氧期间，过量的多巴胺释放增强谷氨酸毒性， 通过调节谷氨酸受体的活性而导致神经元损伤。 5. CREB磷酸化水平升高有助于缺氧缺血后神经元存活 通过增加Bcl-2的表达和增加Bcl-2/Bax的比值来抑制细胞凋亡。 还将在上述模型中测定凋亡标志物半胱天冬酶的表达，并将其与细胞凋亡相关。 以上参数。这些和其他编码代谢调节因子的基因的表达与 将使用DMA微阵列筛选多巴胺以及那些有助于细胞存活和死亡的多巴胺。 我们的工作将提供一个更好的理解负责损伤/死亡的分子机制， 大脑细胞缺氧后的反应这种理解将是更有效地 治疗已经经历了一段时间的大脑供氧不足的患者。

Our overall hypothesis is that moderate hypoxic/ischemic insult to the brain activates a number of pathways which, if unopposed, lead to apoptotic or necrotic death of neurons (damaging) while others have a protective role, in part by countering the former. The relative activity of these processes determines the outcome. In the present proposal, we will subject the brain of newborn piglets to graded hypoxic/ischemic insults and quantitatively monitor the responses of key intermediates of the putative damaging and protective pathways in the presence and absence of selective blocking and activating agents. Specifically we will test following hypotheses: 1. Hypoxic/ischemic insult alters the phosphorylation of CREB and DARPP-32 in striatum of newborn piglets and this is an important determinant of long term cellular and tissue injury. The pattern of these alterations (direction, magnitude and duration) depends on the severity of insult. 2. The alterations in phosphorylation of CREB and DARPP-32 in striatum of newborn piglets that results from hypoxic-ischemic insult depends on the magnitude of the increase in extracellular dopamine. 3. Dopamine exerts its action on CREB and DARPP-32 phosphorylation through the D1 and D2 receptors. 4. During hypoxia and ischemia/hypoxia the excessive dopamine release potentiates glutamate toxicity and neuronal injury by modulating glutamate receptor activity. 5. Elevated levels of CREB phosphorylation contribute to neuronal survival following hypoxic and ischemic insults by increasing Bcl-2 expression and increasing Bcl-2/Bax ratio. Expression of caspase, a marker of apoptosis, will also be determined in the above models and correlated with the above parameters. Expression of these and other genes coding for metabolic regulators linked to dopamine as well as those contributing to cell survival and death will be screened using DMAmicroarrays. Our work will provide a better understanding the molecular mechanisms responsible for injury/death of brain cells following periods of oxygen deprivation. This understanding will be the basis for more effective treatment of patients who have been subjected to a period(s) of insufficient oxygen delivery to the brain.