Decrease in the descending inhibitory 5-HT system in rats with spinal nerve ligation

作者：Liu, Feng-Yu; Qu, Xiao-Xiu; Ding, Xu; Cai, Jie; Jiang, Hong; Wan, You; Han, Ji-Sheng; Xing, Guo-Gang^*

来源：Brain Research, 2010, 1330: 45-60.

DOI：10.1016/j.brainres.2010.03.010

• 5-Hydroxytryptamine
• 5-Hydroxytryptamine receptor
• WDR neurons
• Spinal cord
• Neuropathic pain
• Electrophysiology

The descending serotonergic (5-HT) system is shown to be plastically altered under pathological conditions such as inflammation or peripheral nerve lesion. Although much evidence indicates that the potentiation of descending facilitatory 5-HT pathways may contribute to the development of chronic pain, the inhibition of descending inhibitory 5-HT system may be functionally more important to the development of central sensitization and neuropathic pain. In the present study, we observed that the inhibitory effects of 5-HT and its receptor agonists including 1A, 1B, 3, 4, and probably 2C receptor agonists, on the C-fiber responses of dorsal horn wide dynamic range (WDR) neurons in the spinal cord decreased significantly following spinal nerve ligation (SNL). Furthermore, we found that the antagonistic effects of 5-HT 1B, 2C, 3, and 4 receptor antagonists on the 5-HT-induced inhibition of C-fiber responses of WDR neurons were also attenuated after SNL. In consistent with these observations, we also found an obvious decrease in the content of 5-HT and 5-HIAA, and a marked increase in the turnover rate of 5-HT (5-HIAA/5-HT) in the ipsilateral dorsal half of the lumbar spinal cord after SNL. These data indicate that a loss or decrease in the descending inhibitory 5-HT system upon the spinal processing of nociceptive information appears to occur following spinal nerve injury, and this kind of decrease in the descending inhibitory 5-HT system is proposed to be involved in the development of central sensitization and ultimately to the nerve injury-induced neuropathic pain.

• 出版日期2010-5-12
• 单位北京大学