Department of Anatomy and Cell Biology, UIC, Chicago, Illinois 60612, USA.
Synapse. 2011 Dec;65(12):1282-8. doi: 10.1002/syn.20948.
Dopamine (DA) and noradrenaline (NA) modulate responses to nociceptive stimuli, within the dorsal horn of the spinal cord. Both neurotransmitters may play a role in supraspinal regulation in response to proprioceptive afferences to the dorsal horn. However, direct evidence of changes in neurotransmitter release within the dorsal horn due to non-noxious stimuli is lacking. The present study was designed to determine, whether non-nociceptive exercise produces changes in release of DA and NA within the dorsal horn, and whether these changes are associated with long-lasting inhibition after the exercise stops. Microdialysis probes, implanted in layers 2-5 of Rexed, in combination with high-performance liquid chromatography coupled to electrochemical detection (HPLC-EC) were used to measure concentrations of DA and NA metabolite (MHPG) in lumbar spinal cords of rats. Microdialysate was sampled before, during, and after a treadmill exercise of one hour. Results indicate that DA and NA releases are inhibited during non-nociceptive motor activity. At rest, DA concentration was 204 ± 10.5 pg/10 μl and was significantly decreased during exercise to -11.4% (P ≤ 0.05). Greater decrease occurred after 30 min of exercise and was of -31.4% (P ≤ 0.05). Similarly, MHPG was significantly decreased of -18% during exercise (P ≤ 0.05). When exercise stopped, both systems showed long-lasting inhibition. Exercise post-release lasted 30 min for DA and 90 min for MHPG. MHPG greatest decrease of -47.8% occurred 30 min after stopping the exercise (P ≤ 0.001). Thus, DA and NA systems seem to respond to exercise-induced proprioceptive afferent stimuli to the dorsal horn.
多巴胺（DA）和去甲肾上腺素（NA）调节脊髓背角的伤害性刺激反应。这两种神经递质可能在对背角本体感觉传入的超脊髓调节中发挥作用。然而，缺乏背角内由于非伤害性刺激引起的神经递质释放变化的直接证据。本研究旨在确定非伤害性运动是否会导致背角内 DA 和 NA 的释放发生变化，以及这些变化是否与运动停止后持久的抑制有关。微透析探针植入 Rexed 的 2-5 层，与高效液相色谱-电化学检测（HPLC-EC）相结合，用于测量大鼠腰脊髓中 DA 和 NA 代谢物（MHPG）的浓度。微透析液在跑步机运动前、运动中和运动后进行采样，运动时间为 1 小时。结果表明，DA 和 NA 的释放在非伤害性运动活动期间受到抑制。在休息时，DA 浓度为 204±10.5pg/10μl，在运动期间显著降低至-11.4%（P≤0.05）。在运动 30 分钟后发生更大的降低，为-31.4%（P≤0.05）。同样，MHPG 在运动期间显著降低了-18%（P≤0.05）。当运动停止时，两个系统都显示出持久的抑制。运动后释放持续 30 分钟用于 DA，持续 90 分钟用于 MHPG。MHPG 的最大降低-47.8%发生在运动停止后 30 分钟（P≤0.001）。因此，DA 和 NA 系统似乎对背角的运动性本体感觉传入刺激做出反应。
