Afrah Abdullahi Warsame, Fiskå Atle, Gjerstad Johannes, Gustafsson Henrik, Tjølsen Arne, Olgart Leif, Stiller Carl Olav, Hole Kjell, Brodin Ernst
Department of Physiology and Pharmacology, Division of Pharmacological Pain Research, Karolinska Hospital, Karolinska Institutet, Stockholm, Sweden.
Pain. 2002 Mar;96(1-2):49-55. doi: 10.1016/s0304-3959(01)00414-6.
Long-term potentiation (LTP) in wide dynamic range (WDR) neurons in the dorsal horn has been suggested to contribute to central sensitization and the development of chronic pain. Indirect experimental evidence indicates an involvement of substance P (SP), in this respect. The aim of the present study was to monitor the extracellular level of substance P-like immunoreactivity (SP-LI) in the dorsal horn of the rat during and after induction of LTP in WDR neurons in vivo. Electrophysiological recordings of single (WDR) neurons were performed in parallel with microdialysis in the dorsal horn under urethane-anaesthesia. The amount of SP-LI in the microdialysate was determined by radioimmunoassay. As previously shown, high frequency conditioning stimulation of the sciatic nerve induced an increased firing response of WDR neurons. An increased response to C-fibre stimulation, but not A-fibre stimulation, could be determined. A significant increase of the extracellular level of SP-LI in the dorsal horn was detected during, but not after, induction of LTP. These data suggest that SP may be involved in the induction of LTP by high frequency stimulation. However, the maintenance of spinal LTP following high frequency peripheral nerve stimulation does not seem to depend on an increased release of SP.
背角广动力范围（WDR）神经元中的长时程增强（LTP）被认为与中枢敏化及慢性疼痛的发展有关。间接实验证据表明，在这方面P物质（SP）参与其中。本研究的目的是在体内诱导WDR神经元产生LTP的过程中及之后，监测大鼠背角中P物质样免疫反应性（SP-LI）的细胞外水平。在乌拉坦麻醉下，对背角中的单个WDR神经元进行电生理记录，并同时进行微透析。通过放射免疫分析法测定微透析液中SP-LI的含量。如先前所示，高频刺激坐骨神经可诱导WDR神经元的放电反应增加。可以确定对C纤维刺激的反应增加，但对A纤维刺激的反应未增加。在诱导LTP的过程中，但不是在诱导LTP之后，检测到背角中SP-LI的细胞外水平显著增加。这些数据表明，SP可能参与高频刺激诱导的LTP。然而，高频外周神经刺激后脊髓LTP的维持似乎并不依赖于SP释放的增加。
