Extremely Low Frequency Magnetic Field Exposure Attenuates Pain By Inactivation Of Descending Facilitatory System In Complete Spinal Cord Injured Rats

Abstract

Background: To investigate the effect of chronic exposure to extremely low frequency magnetic field (ELF-MF) on pain modulation status of completely spinal cord injured (SCI) in rats. Methods: Male Wistar rats were divided into Sham (Laminectomy), SCI (complete transection of T13 spinal cord) and SCI+MF (ELF-MF: 17.96 µT, 50 Hz, 2h/day exposure to SCI rats) groups. Pain was studied by utilizing threshold of tail flick (TTF), forepaw lick latency (FPL) and its modulation by temporal summation (TS) and diffuse noxious inhibitory control (DNIC). These tests were performed before surgery (week 0), and after surgery (weeks 4 and 8). Locomotor function was assessed by BBB score at post-SCI weeks 1,3,5,7 and 8. At the end of week 8, spinal cords were collected for histological analysis. Results: Data revealed post-SCI significant decrease in TTF and FPL. The amplitude of TS response was increased, while TTF response was not disappeared after pressure pain application in DNIC paradigm. SCI rats also revealed a significant lower BBB score. However, MF exposure to SCI rats significantly restored the above parameters. Conclusion: Our observations suggested reduction in post-SCI hyperalgesia by inactivation of descending facilitatory system after MF exposure to SCI rats.