LeBlanc J, Ducharme M B
Department of Physiology, School of Medicine, Laval University, Quebec City, Canada.
Physiol Behav. 2007 Jun 8;91(2-3):208-11. doi: 10.1016/j.physbeh.2007.02.011. Epub 2007 Mar 2.
Dopamine (DA) the precursor of noradrenaline (NA) has been shown to have many functions such as its influence on endorphins activity and its association with hedonic impact, anxiety and depression. However with regard to the sympathetic nervous system activity, the role of DA has merely been considered as being the precursor of NA. We have shown in a previous study a positive correlation between the resting plasma level of NA and those found during exposure to a physical stress. No explanation was proposed to explain this finding. Enhanced sympathetic nervous system activity has been shown to increase the secretion of NA as well as DA. It is not known however if the secretion of DA during exposure to stress parallels that of NA. What are the interactions between the two amines and also between values at rest and during exposure to stress? For that reason a test was used which consisted of blowing cold wind (4 degrees C at 60 km/h) on the face of a group of subjects and measuring plasma concentration of the two amines before, during and after the test. For a given individual, the increase of either plasma NA or DA in response to the cold wind stress parallels the resting plasma concentrations of these two amines respectively. Low level of one amine at rest coincides with low increase during the stress. Furthermore the results have shown that when the plasma level of either one of these two amines is high in response to stress, the values of the other amine are small; both amines are not high or low at the same time. The literature suggests that dopamine beta hydroxylase (DBH), the enzyme which catalyzes the synthesis of NA from DA, may provide an explanation to our findings. Lower DBH activity of this enzyme would result in a lower NA and a greater DA storage and secretion. Further investigation is needed to verify this possibility.
多巴胺（DA）是去甲肾上腺素（NA）的前体，已被证明具有多种功能，如对内啡肽活性的影响以及与享乐影响、焦虑和抑郁的关联。然而，关于交感神经系统活动，DA的作用仅仅被视为NA的前体。我们在先前的研究中表明，静息血浆中NA的水平与身体应激时测得的水平呈正相关。但未对这一发现给出解释。已表明交感神经系统活动增强会增加NA以及DA的分泌。然而，尚不清楚应激期间DA的分泌是否与NA平行。这两种胺之间以及静息值与应激期间的值之间有什么相互作用？因此，采用了一种测试方法，即对一组受试者面部吹冷风（4摄氏度，风速60公里/小时），并在测试前、测试期间和测试后测量这两种胺的血浆浓度。对于给定个体，对冷风应激反应时血浆NA或DA的增加分别与这两种胺的静息血浆浓度平行。静息时一种胺水平低与应激期间增加量低相吻合。此外，结果表明，当这两种胺中的任何一种在应激时血浆水平较高时，另一种胺的值较小；两种胺不会同时高或低。文献表明，多巴胺β羟化酶（DBH），即催化从DA合成NA的酶，可能为我们的发现提供解释。该酶较低的DBH活性会导致较低的NA以及较高的DA储存和分泌。需要进一步研究来验证这种可能性。
