Middlemiss D N, Hutson P H
Merck, Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, U.K.
J Neurosci Methods. 1990 Sep;34(1-3):23-8. doi: 10.1016/0165-0270(90)90038-h.
In contrast to in vivo release methods, in vitro release techniques utilising brain slices or synaptosomes affords a simple and reproducible means of measuring both receptor affinity and efficacy of drugs acting at prejunctional receptors in the CNS. Most studies have used brain tissue loaded with radiolabelled neurotransmitter or its precursor via the high affinity uptake system for these substances which are present on nerve terminals. Depolarisation evoked release induced by either high K+ or electrical field stimulation increases the release of radioactivity and this overflow can be readily measured by liquid scintillation counting. Recent studies have started to emphasise the measurement of the release of endogenous neurotransmitters from brain tissue using similar depolarisation stimuli. Examples include the release of dopamine, noradrenaline, adrenaline and 5-HT and their control by presynaptic receptors. Most of these studies have used HPLC with ECD detection as a means of separating and analysing for the transmitter of interest. The relative strengths and weaknesses of the measurement of radiolabelled or endogenous neurotransmitter release in vitro as a means of identifying presynaptic receptors is discussed.
与体内释放方法不同，利用脑切片或突触体的体外释放技术提供了一种简单且可重复的方法，用于测量药物作用于中枢神经系统突触前受体的受体亲和力和效力。大多数研究通过存在于神经末梢上的这些物质的高亲和力摄取系统，使用装载有放射性标记神经递质或其前体的脑组织。由高钾离子或电场刺激诱发的去极化释放会增加放射性的释放，这种溢出可以通过液体闪烁计数很容易地测量出来。最近的研究开始强调使用类似的去极化刺激来测量脑组织中内源性神经递质的释放。例子包括多巴胺、去甲肾上腺素、肾上腺素和5-羟色胺的释放及其由突触前受体的控制。这些研究大多使用带电化学检测的高效液相色谱法作为分离和分析感兴趣递质的手段。本文讨论了体外测量放射性标记或内源性神经递质释放作为识别突触前受体方法的相对优缺点。
