Cooper Stephanie E, Venton B Jill
Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, VA 22904-4319, USA.
Anal Bioanal Chem. 2009 May;394(1):329-36. doi: 10.1007/s00216-009-2616-0. Epub 2009 Feb 3.
Tyramine and octopamine are biogenic amine neurotransmitters in invertebrates that have functions analogous to those of the adrenergic system in vertebrates. Trace amounts of these neurotransmitters have also been identified in mammals. The purpose of this study was to develop an electrochemical method using fast-scan cyclic voltammetry at carbon-fiber microelectrodes to detect fast changes in tyramine and octopamine. Because tyramine is known to polymerize and passivate electrode surfaces, waveform parameters were optimized to prevent passivation. No fouling was observed for octopamine when the electrode was scanned from 0.1 to 1.3 V and back at 600 V/s, while a small decrease of less than 10% of the signal was seen for 15 repeated exposures to tyramine. The technique has limits of detection of 18 nM for tyramine and 30 nM for octopamine, much lower than expected levels in insects and lower than basal levels in some brain regions of mammals. Current was linear with concentration up to 5 microM. This voltammetry technique should be useful for measuring tyramine and octopamine changes in insects, such as the fruit fly, Drosophila melanogaster.
酪胺和章鱼胺是无脊椎动物中的生物胺神经递质，其功能与脊椎动物中的肾上腺素能系统类似。在哺乳动物中也已鉴定出痕量的这些神经递质。本研究的目的是开发一种电化学方法，利用碳纤维微电极上的快速扫描循环伏安法来检测酪胺和章鱼胺的快速变化。由于已知酪胺会聚合并使电极表面钝化，因此对波形参数进行了优化以防止钝化。当电极以600 V/s的速度从0.1 V扫描到1.3 V并返回时，未观察到章鱼胺有污染现象，而在对酪胺进行15次重复检测时，信号出现了小于10%的小幅下降。该技术对酪胺的检测限为18 nM，对章鱼胺的检测限为30 nM，远低于昆虫体内的预期水平，且低于哺乳动物某些脑区的基础水平。电流与浓度在高达5 microM时呈线性关系。这种伏安法技术对于测量昆虫（如黑腹果蝇）体内酪胺和章鱼胺的变化应该是有用的。
