ACIDIC PEPTIDES AND EXCITATORY NEUROTRANSMISSION

目的是更好地了解酸性 肽在中枢神经系统中的毫秒兴奋信号中起作用 系统 我们建议进行详细的构效关系 脑内源性二肽N-乙酰基谷氨酸和 乙酰谷氨酸盐。 的柔性和构象受限的类似物 这两种肽将被合成，以帮助定义所需的空间 三个碳基部分的处置。 还将尝试 开发Ac-Asp-Glu和Asp-Glu的特异性拮抗剂。 这些尝试 将包括用其它同官能的取代羧基 部分（例如四唑、磺酸盐和膦酸盐）和显影 其中乙酰基部分被取代的亲和标记剂 具有反应性基团的酰基部分或氯甲基酮 官能团被羧基部分中的一个取代。 一个潜在 Ac-Asp-Glu的代谢稳定类似物，其中有Asp-Glu酰胺键 也将合成被烯属官能团取代的。 的 将评价所提出的化合物的电生理活性 使用两种来自大鼠脑的体外切片制备物，即嗅觉 皮质切片和海马切片。 细胞外和 将采用细胞内方法。 放射性配体结合研究将 使用突触体和突触浆的制备物进行 膜，并将测量的酸性类似物的效力 取代[3 H]-谷氨酸的特异性结合的肽， [3 H]-Ac-Asp-Glu和[3 H]-2-氨基-4-膦酰基丁酸。 我们还将 尝试开发Ac-Asp-Glu受体的有效放射性配体， 将被合成的代谢稳定的Ac-Asp-Glu类似物。 希望通过这项研究，开发出新的药理学探针 可以用来更详细地描述 以及各种受体和神经递质， 中枢神经系统中的毫秒兴奋性神经传递以及这种作用 受体和神经递质在正常和异常的神经系统中发挥作用， 功能

The objective is to gain a better understanding of the role that acidic peptides play in millisecond excitatory signaling in the central nervous system. We propose to carry out a detailed structure-activity relationship study on the endogenous brain dipeptides N-acetylaspartylglutamate and aspartylglutamate. Flexible and conformationally restricted analogues of these two peptides will be synthesized to help define the required spatial disposition of the three carbosyl moieties. Attempts will also be made to develop specific antagonists of Ac-Asp-Glu and Asp-Glu. These attempts will include replacing the carboxyl groups with other isofunctional moieties (e.g. tetrazole, sulfonate, and phosphonate) and developing affinity labeling agents in which either the acetyl moiety is replaced with acyl moieties possessing reactive groups or the chloromethyl ketone function is substituted for one of the carboxyl moieties. A potential metabolically stable analogue of Ac-Asp-Glu in which the Asp-Glu amide bond is replaced with the olefinic function will also be synthesized. The proposed compounds will be evaluated for electrophysiological activity using two in vitro slice preparations from rat brain, namely olfactory cortical slices and hippocampal slices. Both extracellular and intracellular methods will be employed. Radioligand binding studies will be conducted using preparations of synaptosomes and synaptic plasma membranes, and will measure the potency of the analogues of the acidic peptides to displace the specific binding of [3H]-glutamate, [3H]-Ac-Asp-Glu, and [3H]-2-amino-4-phosphonobutanoic acid. We will also attempt to develop an effective radioligand for Ac-Asp-Glu receptors using the metabolically stable analogue of Ac-Asp-Glu that will be synthesized. IT is hoped that through this study, new and novel pharmacological probes can be developed that can be used to delineate in more detail the number and kinds of receptors and neurotransmitters that are involved in millisecond excitatory neurotransmission in the CNS and the roles that such receptors and neurotransmitters play in normal and abnormal neurologic function.