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Original Article

The Korean Journal of Pain 2020; 33(1): 13-22

Published online January 1, 2020 https://doi.org/10.3344/kjp.2020.33.1.13

Copyright © The Korean Pain Society.

Antinociceptive and neuroprotective effects of bromelain in chronic constriction injury-induced neuropathic pain in Wistar rats

Ahmed Olalekan Bakare and Bamidele Victor Owoyele

Neuroscience and Inflammation Unit, Department of Physiology, Faculty of Basic Medical Sciences, University of Ilorin, Ilorin, Nigeria

Correspondence to:Ahmed Olalekan Bakare
Neuroscience and Inflammation Unit, Department of Physiology, Faculty of Basic Medical Sciences, University of Ilorin, Ilorin, Kwara State 240003, Nigeria
Tel: +234-8039101606
Fax: +234-031-221593
E-mail: wlabwise@gmail.com

Received: June 7, 2019; Revised: September 21, 2019; Accepted: September 22, 2019

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

The continuous search for a novel neuropathic pain drug with few or no side effects has been a main focus of researchers for decades. This study investigated the antinociceptive and neuroprotective effects of bromelain in sciatic nerve ligation-induced neuropathic pain in Wistar rats.

Methods

Forty-eight Wistar rats randomly divided into eight groups comprised of six animals each were used for this study. Peripheral neuropathy was induced via chronic constriction of the common sciatic nerve. Thermal hyperalgesic and mechanical allodynia were assessed using a hotplate and von Frey filaments, respectively. The functional recovery and structural architecture of the ligated sciatic nerve were evaluated using the sciatic functional index test and a histological examination of the transverse section of the sciatic nerve. The neuroprotective effects of bromelain were investigated in the proximal sciatic nerve tissue after 21 days of treatment.

Results

Bromelain significantly (P < 0.05) attenuated both the thermal hyperalgesia and mechanical allodynic indices of neuropathic pain. There were improvements in sciatic function and structural integrity in rats treated with bromelain. These rats showed significant (P < 0.05) increases in sciatic nerve nuclear transcription factors (nuclear factor erythroid-derived-2-related factors-1 [NrF-1] and NrF-2), antioxidant enzymes (superoxide dismutase and glutathione), and reduced membrane-lipid peroxidation compared with the ligated control group.

Conclusions

This study suggest that bromelain mitigated neuropathic pain by enhancing the activities of nuclear transcription factors (NrF-1 and NrF-2) which increases the antioxidant defense system that abolish neuronal stress and structural disorganization.

Keywords: Antioxidants, Bromelain, Hyperalgesia, Neuralgia, Neuroprotection, NF-E2-Related Factor 2, NFI Transcription Factors, Nuclear Respiratory Factor 1, Rats, Wistar