Olanzapine Attenuates Mechanical Allodynia in a Rat Model of Partial Sciatic Nerve Ligation.
10.3344/kjp.2015.28.3.185
- Author:
Taeko FUKUDA
1
;
Soichiro YAMASHITA
;
Setsuji HISANO
;
Makoto TANAKA
Author Information
1. Department of Anesthesiology, University of Tsukuba, Tsukuba, Japan. taekof@md.tsukuba.ac.jp
- Publication Type:Original Article
- Keywords:
Mechanical allodynia;
Microglia;
Neuropathic pain;
Olanzapine;
Rat model;
Spinal dorsal horn
- MeSH:
Anesthesia;
Animals;
Horns;
Humans;
Hyperalgesia*;
Isoflurane;
Ligation*;
Male;
Microglia;
Models, Animal*;
Neuralgia;
Rats, Sprague-Dawley;
Sciatic Nerve*;
Spinal Cord
- From:The Korean Journal of Pain
2015;28(3):185-192
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: Neuropathic pain is a global clinical problem; nevertheless, nerve injury treatment methods remain limited. Olanzapine has antinociceptive and anti-nueropathic properties; however, its preventive effects have not been assessed in nerve injury models. METHODS: We prepared a partial sciatic nerve ligation (Seltzer model) or sham-operated model in male Sprague-Dawley rats under isoflurane anesthesia. In a pre-treatment study, we administered olanzapine (10 mg/kg) intraperitoneally 1 h before nerve ligation. In post-treatment and dose-dependent studies, we injected 3 different doses of olanzapine intraperitoneally 1 h after nerve ligation. Mechanical allodynia was measured before and 7 days after surgery. Immunohistochemical analysis using anti-Iba-1 antibody was used to assess the effect of olanzapine at the spinal level. RESULTS: In the pre-treatment study, median withdrawal thresholds of the normal saline groups were significantly lower than those of the sham-operated groups; however, those of the olanzapine (10 mg/kg) and sham-operated groups were not different. In the post-treatment and dose-dependent studies, the median withdrawal thresholds of the olanzapine (2.5 mg/kg) and normal saline groups were not different; however, those of the olanzapine (10 and 50 mg/kg) groups were significantly higher than those of the normal saline groups. Olanzapine did not have a significant effect on the density of Iba-1 staining. CONCLUSIONS: Olanzapine attenuated mechanical allodynia dose-dependently in the Seltzer model. This anti-allodynic effect of olanzapine was observed even when injected 1 h after nerve ligation. This effect of olanzapine appeared to be unrelated to microglia activation in the ipsilateral dorsal horn of the lumbar spinal cord.
