Rösser Nina, Berger Klaus, Vomhof Peter, Knecht Stefan, Breitenstein Caterina, Flöel Agnes
Department of Neurology, University of Muenster, Münster, Germany.
Physiol Behav. 2008 Mar 18;93(4-5):1024-9. doi: 10.1016/j.physbeh.2008.01.011. Epub 2008 Jan 16.
Several animal studies demonstrated that olfaction is modulated by dopamine (DA). We examined if such results could be replicated in humans. Thus, we tested olfaction in elderly healthy humans before and after external administration of levodopa in a double-blind, placebo-controlled, randomized cross-over study. Main outcome measure was the sum of correctly identified odors in an odor identification paradigm. In contrast to what had been demonstrated in rats, levodopa did not improve olfaction. We even noted a trend for the reverse. Blood pressure, mood ratings, as well as performance in a simple motor task were comparable between conditions, indicating that levodopa did not induce differences in general arousal, mood, attention, or reaction time. Our findings may be explained by differences in the distribution of dopaminergic receptor subtypes in the olfactory system in animals and humans, by relative differences in dosing regimes, or by subtle differences in the respective paradigms. These hypotheses have to be tested in future experiments, but our study demonstrates that results from animal studies cannot be directly transferred to the human situation.
多项动物研究表明，嗅觉受多巴胺（DA）调节。我们研究了此类结果是否能在人类身上得到重现。因此，我们在一项双盲、安慰剂对照、随机交叉研究中，对老年健康人群在外部给予左旋多巴前后的嗅觉进行了测试。主要结局指标是气味识别范式中正确识别气味的总数。与在大鼠身上所证明的情况相反，左旋多巴并未改善嗅觉。我们甚至注意到一种相反的趋势。不同条件下的血压、情绪评分以及简单运动任务的表现相当，这表明左旋多巴并未在总体唤醒、情绪、注意力或反应时间上引起差异。我们的发现可能是由于动物和人类嗅觉系统中多巴胺能受体亚型分布的差异、给药方案的相对差异，或者各自范式中的细微差异所致。这些假设必须在未来的实验中进行检验，但我们的研究表明，动物研究的结果不能直接应用于人类情况。
