Journal of Nippon Medical School: Vol.69 No.5 page.428

Journal of Nippon Medical School

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ArticleTitle A Histochemical Study of Substance P in the Rat Spinal Cord: Effect of Transcutaneous Electrical Nerve Stimulation

AuthorList Tomoyuki Rokugo, Toshitsugu Takeuchi and Hiromoto Ito

Affiliation Department of Orthopaedic Surgery, Nippon Medical School

Language EN

Volume 69

Issue 5

Year 2002

Page 428-433

Received April 10, 2002

Accepted May 10, 2002

Keywords transcutaneous electrical nerve stimulation, substance P, rat spinal cord

Abstract The effects of pain stimulant and transcutaneous electrical nerve stimulation (TENS) on changes in substance P (SP) levels were investigated in the dorsal root ganglion (DRG) and dorsal horn of the spinal cord of Sprague-Dawley rats. The rats were divided into three groups: control, formalin stimulation and formalin+TENS. In all rats, the right sciatic nerve was attached to a hook electrode for recording, and the right lower leg was connected to a ring electrode. As a pain stimulant for the formalin stimulation group and formalin+TENS group, 50μl of a 5%formalin was injected into the right paw. At the same time, TENS (50Hz, 50V) for 5 minutes was applied via the ring electrode to the formalin+TENS group. After completing the stimulation, the components of the sciatic nerve, i. e. the DRG of the fourth to sixth lumbar spinal roots and a part of spinal cord, were removed. SP-like immunoreactivity (SP-LI) in the DRGs was quantified by the ELISA method. For the spinal cord, immunohistochemical staining for SP was carried out using an avidin-biotin immunoperoxidase method. Using an NIH image, the SP grains in the nerve ends, which were seen as dark brown stains on the Rexed laminae I and II in the dorsal horn of the spinal cord, were counted within a 450μm² area. The results showed that SP-LI levels of both the DRG and the dorsal horn of the spinal cord in the formalin+TENS group were significantly reduced as compared with formalin stimulation group. Based on the fact that SP is a nociceptive neurotransmitter, the present study suggests that TENS reduces production of SP in the DRG, and shows analgesic effects by suppressing nociception via C-fiber in the peripheral nerves.

Correspondence to Tomoyuki Rokugo, Department of Orthopaedic Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
rokugo@aioros.ocn.ac.jp

ArticleTitle	A Histochemical Study of Substance P in the Rat Spinal Cord: Effect of Transcutaneous Electrical Nerve Stimulation
AuthorList	Tomoyuki Rokugo, Toshitsugu Takeuchi and Hiromoto Ito
Affiliation	Department of Orthopaedic Surgery, Nippon Medical School
Language	EN
Volume	69
Issue	5
Year	2002
Page	428-433
Received	April 10, 2002
Accepted	May 10, 2002
Keywords	transcutaneous electrical nerve stimulation, substance P, rat spinal cord
Abstract	The effects of pain stimulant and transcutaneous electrical nerve stimulation (TENS) on changes in substance P (SP) levels were investigated in the dorsal root ganglion (DRG) and dorsal horn of the spinal cord of Sprague-Dawley rats. The rats were divided into three groups: control, formalin stimulation and formalin+TENS. In all rats, the right sciatic nerve was attached to a hook electrode for recording, and the right lower leg was connected to a ring electrode. As a pain stimulant for the formalin stimulation group and formalin+TENS group, 50μl of a 5%formalin was injected into the right paw. At the same time, TENS (50Hz, 50V) for 5 minutes was applied via the ring electrode to the formalin+TENS group. After completing the stimulation, the components of the sciatic nerve, i. e. the DRG of the fourth to sixth lumbar spinal roots and a part of spinal cord, were removed. SP-like immunoreactivity (SP-LI) in the DRGs was quantified by the ELISA method. For the spinal cord, immunohistochemical staining for SP was carried out using an avidin-biotin immunoperoxidase method. Using an NIH image, the SP grains in the nerve ends, which were seen as dark brown stains on the Rexed laminae I and II in the dorsal horn of the spinal cord, were counted within a 450μm² area. The results showed that SP-LI levels of both the DRG and the dorsal horn of the spinal cord in the formalin+TENS group were significantly reduced as compared with formalin stimulation group. Based on the fact that SP is a nociceptive neurotransmitter, the present study suggests that TENS reduces production of SP in the DRG, and shows analgesic effects by suppressing nociception via C-fiber in the peripheral nerves.
Correspondence to	Tomoyuki Rokugo, Department of Orthopaedic Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan rokugo@aioros.ocn.ac.jp