Effects of MK-801 and Morphine on Spinal C-Fos Expression during the Development of Neuropathic Pain.
10.3349/ymj.2002.43.3.370
- Author:
Youn Woo LEE
1
;
Kyung Ah PARK
;
Won Taek LEE
Author Information
1. Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea. ywleepain@yumc.yonsei.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Allodynia;
central sensitization;
spinal c-fos;
MK-801;
morphine
- MeSH:
Analgesics, Opioid/*pharmacology;
Animal;
Dizocilpine Maleate/*pharmacology;
Excitatory Amino Acid Antagonists/*pharmacology;
Hyperesthesia/etiology/*metabolism;
Ligation;
Male;
Morphine/*pharmacology;
Proto-Oncogene Proteins c-fos/*metabolism;
Rats;
Rats, Sprague-Dawley;
Spinal Cord/*metabolism;
Spinal Nerves/injuries;
Wounds and Injuries/complications
- From:Yonsei Medical Journal
2002;43(3):370-376
- CountryRepublic of Korea
- Language:English
-
Abstract:
The purpose of this study was to investigate the expression of c-fos in the spinal cord during the development of allodynia, induced by peripheral nerve injury. Following tight ligation of the left L5 and L6 spinal nerves of Sprague- Dawley rat, the lumbar spinal cord was postfixed following perfusion. Frontal frozen sections of 40nm were immunostained according to the peroxidase-antiperoxidase method. The allodynic threshold was checked with 8 calibrated von Frey filaments. MK-801 (0.3 mg/kg), morphine (3 mg/kg) and saline (as a placebo) were administered subcutaneously 30 min before, and 24 and 48 hrs after surgery. The tactile threshold decreased below 3 g since 2 days after surgery in the saline and morphine groups, but delayed a little in the MK-801 group. In the superficial layer the number of Fos-like immunoreactive neurones (Fos-LI) peaked at 2 hours and decreased thereafter, and reached normal levels 24 hrs following operation, for all groups. In the deep layer they were biphasic, - peaking at 2 and 24 hrs - in the saline group, but were suppressed in the morphine and MK-801 groups until 7 days following operation. The above discrepancy between the number of Fos-LI and the allodynic threshold showed that central sensitizations are not critically involved in the development of nerve injury induced tactile allodynia.
