Department of Integrative Medical Biology, Physiology, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden.
Department of Integrative Medical Biology, Physiology, Umeå University, Umeå, Sweden; Umeå Center for Functional Brain Imaging, Umeå University, Umeå, Sweden; Department of Radiation Sciences, Umeå University, Umeå, Sweden.
Neuroimage. 2019 Nov 15;202:116044. doi: 10.1016/j.neuroimage.2019.116044. Epub 2019 Jul 26.
There is much evidence that dopamine is vital for cognitive functioning in aging. Here we tested the hypothesis that aerobic exercise and fitness influence dopaminergic neurotransmission in the striatum, and in turn performance on offline working-memory updating tasks. Dopaminergic neurotransmission was measured by positron emission tomography (PET) and the non-displacable binding potential (BP) of [C]raclopride, i.e. dopamine (DA) D2-receptor (D2R) availability. Fifty-four sedentary older adults underwent a six-months exercise intervention, performing either aerobic exercise or stretching, toning, and resistance active control training. At baseline, higher aerobic fitness levels (VO) were associated with higher BP in the striatum, providing evidence of a link between an objective measure of aerobic fitness and D2R in older adults. BP decreased substantially over the intervention in both groups but the intervention effects were non-selective with respect to exercise group. The decrease was several times larger than any previously estimated annual decline in D2R, potentially due to increased endogenous DA. Working-memory was unrelated to D2R both at baseline and following the intervention. To conclude, we provide partial evidence for a link between physical exercise and DA. Utilizing a PET protocol able to disentangle both D2R and DA levels could shed further light on whether, and how, aerobic exercise impacts the dopaminergic system in older adults.
有大量证据表明，多巴胺对于衰老过程中的认知功能至关重要。在这里，我们检验了这样一个假设，即有氧运动和健康水平会影响纹状体中的多巴胺能神经传递，进而影响离线工作记忆更新任务的表现。通过正电子发射断层扫描（PET）和[C]raclopride 的不可置换结合潜力（BP）来测量多巴胺能神经传递，即多巴胺（DA）D2 受体（D2R）的可用性。54 名久坐不动的老年人接受了为期六个月的运动干预，分别进行有氧运动或伸展、强化和阻力主动控制训练。在基线时，较高的有氧运动能力（VO）与纹状体中的 BP 较高相关，这为有氧运动能力的客观测量与老年人的 D2R 之间存在联系提供了证据。两组的 BP 在干预过程中均显著下降，但干预效果与运动组无关。下降幅度比以前估计的 D2R 每年的下降幅度大几倍，可能是由于内源性 DA 的增加。工作记忆与 D2R 无关，无论是在基线还是在干预后。总之，我们提供了部分证据表明，体育锻炼与 DA 之间存在联系。利用能够区分 D2R 和 DA 水平的 PET 方案，可以进一步阐明有氧运动是否以及如何影响老年人的多巴胺能系统。
