The Mechanism of Contralateral Hyperalgesia in the Persistent Muscle Pain Rat Model.

, Sohn, Min Kyun; , Kang, Sang Kuk; , Lee, Sheng Huo; , Han, Sang Min

Original Article

Journal of the Korean Academy of Rehabilitation Medicine 2004;28(5):477-482.

Sohn, Min Kyun , Kang, Sang Kuk , Lee, Sheng Huo , Han, Sang Min

Department of Rehabilitation Medicine, Chungnam National University College of Medicine, Korea. actksk@medimail.co.kr

지속적 근육통 모델 쥐에서 반대측 다리에 발생하는 통각과민의 기전

손민균, 강상국, 이승활, 한상민

충남대학교 의과대학 재활의학교실

Abstract

Objective
This study was designed to investigate the mechanism of the primary afferent input to spread of contralateral hyperalgesia in the persistent muscle pain model in the rat.
Method
Muscle pain was induced by twice repeated intramuscular injections of pH 6.0 buffered saline into the unilateral gastrocnemius muscle of the rats. Change of mechanical withdrawal threshold to von-Frey filament was measured after ipsilateral laser irradiation, anesthetic blockade with lidocaine and dorsal rhizotomy (L2∼L6) to reduce primary afferent input from the tissue injury.
Results
Bilateral persistent mechanical hyperalgesia in the hind paw was evoked after second injection. Ipsilateral laser irradiation, lidocaine injection and dorsal rhizotomy had no effect on the contralateral spread of mechanical hyperalgesia.
Conclusion
These results suggest that contralateral hyperalgesia was produced by, but didn't need to be maintained by inputs from an injury. Therefore, central nervous systems are responsible for the contralateral spread of hyperalgesia. (J Korean Acad Rehab Med 2004; 28: 477-482)

Key Words: Persistent muscle pain, Contralateral hyperalgesia, Laser irradiation, Lidocaine block, Rhizotomy