ACIDIC PEPTIDES AND EXCITATORY NEUROTRANSMISSION

我们的目标是更好地理解酸性物质的作用 多肽在中枢神经毫秒兴奋信号中的作用 系统。我们建议进行详细的结构-活动关系 内源性脑二肽N-乙酰天冬氨酸和谷氨酸的研究 天冬氨酸谷氨酸。灵活的和构象受限的类似物 这两个多肽将被合成以帮助定义所需的空间 三个羧基的处置。还将尝试 开发Ac-Asp-Glu和Asp-Glu的特异性拮抗剂。这些尝试 将包括用其他等官能团取代羧基 基团(如四氮唑、磺酸盐和磷酸盐)和显影 亲和标记剂，其中乙酰基被取代 含有活性基团或氯甲基酮的酰基部分 官能团被其中一个羧基取代。一种潜力 Ac-Asp-Glu代谢稳定的类似物，其中Asp-Glu酰胺键 被取代的烯烃功能也将被合成。这个 建议的化合物将进行电生理活性评估。 使用两种大鼠脑组织的体外切片制备物，即嗅觉 大脑皮层切片和海马片。胞外和 将采用细胞内方法。放射性配基结合研究将 使用突触小体和突触血浆的准备进行 膜，并将测量酸性类似物的效力 取代[~3H]-谷氨酸的特异性结合的多肽， [3 H]-Ac-Asp-Glu和[3 H]-2-氨基-4-膦酸丁酸。我们还将 尝试开发一种有效的Ac-Asp-Glu受体的放射性配体 将合成的代谢稳定的Ac-Asp-Glu类似物。 希望通过这项研究，为新的、新的药理探索 可以开发出可以用来更详细地描绘数字的 以及多种受体和神经递质参与 中枢神经的毫秒兴奋性神经传递及其作用 受体和神经递质在正常和异常神经系统中的作用 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.