BIOCHEMICAL CORRELATES OF 5-HT NEURONAL ACTIVITY

色氨酸羟化酶（TrpH）是合成色氨酸的限速酶， 5-CNS中的羟色胺（5-HT），将色氨酸转化为 5-羟色氨酸（5-HTP）的反应，也需要分子 氧和还原的蝶呤辅因子。 该项目侧重于以下因素， 可能调节这种酶的活性，从而调节脑中5-HT的合成 在体内，特别强调在其 动力学行为可能造成的。 5-HT神经元冲动流增加， 色氨酸在体内的羟基化和皮质醇的体外活性 TrpH和分析神经元放电对动力学的影响 因此，酶的特性是该项目的主要焦点。 这些 研究将扩展到其他5-HT投影区域，特别是 脊髓，有证据表明TrpH的调节特性可能是 不同. 阻断5-HT冲动流对酶活性的影响 也将被审查。 将比较的性质， 体内活化的酶与体外活化的酶在 磷酸化条件。 还将探讨以下可能性： 向5-HT神经元核中施用其它物质（主要是 肽），其可能在那里起到传递器/调节器的作用， 5-HT神经元末端投射中的酶活性，例如通过 对5-HT神经元活性的影响。 最后调节酶的活性 在末端区域与细胞体之间以及在不同末端之间， 场将进行比较。 这项研究是由各种证据， 肽可以改变切片或突触体中的酶活性， 直接受体介导的相互作用的结果，而不是通过效应 对5-HT神经元放电率的影响 将在体外测量酶活性 在人工还原的蝶呤辅因子的亚饱和浓度下， 6-甲基-5，6，7，8-四氢蝶呤（6 MPH 4）或天然辅因子 四氢生物蝶呤，也在体内，通过5-HTP的积累， 脱羧酶抑制剂的存在，以确定是否 体外检测到的活性增加在体内也得到表达。 该5-HTP 在每种情况下形成的将被高性能液体隔离 通过高效液相色谱法（HPLC）分析样品，并通过电化学检测（EC）定量。 本研究有助于加深我们对5-HT调控的认识 合成，中枢单胺递质，这是已知的参与 在调节或调节多种功能，包括情绪或 影响。

Tryptophan hydroxylase (TrpH), the rate limiting enzyme in the synthesis of 5-hydroxytryptamine (5-HT) in CNS, converts tryptophan to 5-hydroxytryptophan (5-HTP) in a reaction that also requires molecular oxygen and reduced pterin cofactor. The project focusses on factors that may regulate the activity of this enzyme and hence 5-HT synthesis in brain in vivo with particular emphasis on the contribution that changes in its kinetic behaviour may make. 5-HT neuronal impulse flow increases both the hydroxylation of tryptophan in vivo, and the in vitro activity of cortical TrpH and an analysis of the effects of neuronal firing on the kinetic properties of the enzyme is thus a major focus of the project. These studies will be extended to other 5-HT projection areas, particularly spinal cord where evidence exists that regulatory properties of TrpH may be different. The effects on enzyme activity of blockade of 5-HT impulse flow will also be examined. Comparisons will be made of the properties of enzyme activated in vivo with those of enzyme activated in vitro under phosphorylating conditions. The possibility will also be explored that administration into the 5-HT neuronal nuclei of other substances (largely peptides) that may serve a transmitter/modulator role there can influence enzyme activity in the terminal projections of 5-HT neurons e.g. through effects on 5-HT neuronal activity. Finally regulation of enzyme activity in terminal regions versus the cell body and between different terminal fields will be compared. This study is prompted by evidence that various peptides can alter enzyme activity in slices or synaptosomes presumably as a result of direct receptor mediated interactions rather than via effects on 5-HT neuronal firing rate. Enzyme activity will be measured in vitro under subsaturating concentrations of artificial reduced pterin cofactor, 6-methyl-5,6,7,8-tetrahydropterin (6MPH4) or the natural cofactor tetrahydrobiopterin and also in vivo, by the accumulation of 5-HTP in the presence of a decarboxylase inhibitor in order to determine whether increases in activity detected in vitro are expressed in vivo. The 5-HTP formed in each case will be isolated by high performance liquid chromatography (HPLC) and quantitated by electrochemical detection (EC). This study should enhance our understanding of the regulation of 5-HT synthesis, a central monoamine transmitter, which is known to be involved in modulating or regulating a wide variety of functions including mood or affect.