Reduction of Spinal Cyclooxygenase-2 with Transcutaneous Electrical Nerve Stimulation and Cold Therapy in Rats of Carrageenan-induced Inflammatory Muscle Pain / 대한해부학회지

ABSTRACT

The purpose of this study was to investigate the effects of transcutaneous electrical nerve stimulation (TENS) and cold therapy on cyclooxygenase-2 (COX-2) expression in lumbar spinal cord and on secondary hyperalgesia produced by muscle pain. Muscle pain was experimentally induced by injection of 2% carrageenan into gastrocnemius muscle of Sprague-Dawley rats. For assessment of secondary hyperalgesia, the rats were tested for paw withdrawal latency (PWL) and tail flick latency (TFL) to heat stimulus. COX-2 expression in lumbar cord was examined using RT-PCR and immunohistochemistry. Secondary hyperalgesia to heat stimulus was significantly reduced in the both TENS- and cold-treatment groups, compared to the control group. The COX-2 mRNA levels were down-regulated in the lumbar spinal cord in the both TENS- and cold-treatment groups. In addition, COX-2 immunoreactivity was decreased in the dorsal horn of the lumbar spinal cord in the both TENS- and cold-treatment groups. These results suggested that decreased COX-2 expression in the lumbar spinal cord of the subjects receiving TENS treatment and cold therapy might be an important factor for reducing secondary hyperalgesia produced by muscle pain.