Yaksh T L, Hammond D L, Tyce G M
Fed Proc. 1981 Nov;40(13):2786-94.
Descending monoamine pathways have been shown to modulate the processing of nociceptive information. Several lines of evidence support this hypothesis: 1) stimulation of brain-stem sites by intracerebral electrodes or the local application of opiates inhibits spinal reflex activity, this effect being antagonized by intrathecal monoamine antagonists; 2) the iontophoretic administration of monoamines in the spinal cord will antagonize the discharge of dorsal horn nociceptors; and 3) the intrathecal administration of monoamines will elevate the pain threshold in the unanesthetized animal. One natural mode of activating this intrinsic circuit appears to be through the activation of small-diameter afferents. Recent evidence has shown that such somatic stimulation causes the release of 5-hydroxytryptamine and norepinephrine. The role of this system appears to be in modulating the properties of sensory processing at the spinal cord level.
下行单胺能通路已被证明可调节伤害性信息的处理。多条证据支持这一假说：1）通过脑内电极刺激脑干部位或局部应用阿片类药物可抑制脊髓反射活动，鞘内注射单胺拮抗剂可拮抗这种作用；2）在脊髓中离子导入单胺会拮抗背角伤害感受器的放电；3）鞘内注射单胺会提高未麻醉动物的痛阈。激活这一内在回路的一种自然方式似乎是通过激活小直径传入神经。最近的证据表明，这种躯体刺激会导致5-羟色胺和去甲肾上腺素的释放。该系统的作用似乎是在脊髓水平调节感觉处理的特性。
