Men D S, Matsui Y
Department of Physiology, Showa University School of Dentistry, Tokyo, Japan.
Brain Res Bull. 1994;34(3):177-82. doi: 10.1016/0361-9230(94)90058-2.
Noradrenaline (NA) release in the rat lumbar spinal cord (L3-4) in response to variable intensity, selective stimulation of large (A-beta), small myelinated (A-delta), and unmyelinated (C) afferent fibers was examined by in vivo microdialysis with high performance liquid chromatography and electrochemical detection. Application of 100 mM K+ solution via the dialysis probe increased NA in the dialysate. Thoracic segment transection rostral to the probe depressed the NA level. Transcutaneous stimulation of peripheral nerves had the following effects: 1) High intensity stimulation of afferent A-delta or C fibers increased spinal NA release, which was decreased by thoracic spinal cord transection. 2) Stimulation of afferent A-beta or A-delta fibers at low intensity did not affect the NA level. 3) High intensity stimulation of afferent A-beta fibers depressed NA release in half of the trials. Results indicate that many NA-containing nerve terminals that innervate the lumbar spinal cord originate from supraspinal structures. Somatic neural inputs from afferent C fibers and high-threshold A-delta, but not A-beta nor low-threshold A-delta fibers, activate the descending NA system and release the NA in the spinal cord. The descending NA system may participate in antinociception.
采用高效液相色谱和电化学检测的体内微透析技术，研究了大鼠腰段脊髓（L3 - 4）中去甲肾上腺素（NA）的释放情况，该释放是对不同强度选择性刺激大（A - β）、小髓鞘（A - δ）和无髓鞘（C）传入纤维的反应。通过透析探针施加100 mM K⁺溶液可增加透析液中的NA含量。在探针上方进行胸段横断会降低NA水平。经皮刺激外周神经有以下作用：1）高强度刺激传入A - δ或C纤维会增加脊髓NA释放，胸段脊髓横断会使其降低。2）低强度刺激传入A - β或A - δ纤维不影响NA水平。3）在一半的试验中，高强度刺激传入A - β纤维会抑制NA释放。结果表明，支配腰段脊髓的许多含NA神经末梢起源于脊髓上结构。来自传入C纤维和高阈值A - δ纤维而非A - β纤维或低阈值A - δ纤维的躯体神经输入，激活下行NA系统并在脊髓中释放NA。下行NA系统可能参与抗伤害感受。
