Loganin prevents CXCL12/CXCR4-regulated neuropathic pain via the NLRP3 inflammasome axis in nerve-injured rats.

Abstract

BACKGROUND:

Neuropathic pain has been shown to be modulated by the activation of the chemokine C-X-C motif ligand 12 (CXCL12)/chemokine CXC receptor 4 (CXCR4) dependent nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome. Loganin, an iridoid glycoside, was proven to prevent neuropathic pain, but its underlying mechanisms related to NLRP3 activation are still unknown.

PURPOSE:

This study investigated the underlying mechanisms of loganin's effect on chronic constriction injury (CCI)-induced NLRP3 inflammasome activation in the spinal cord.

METHODS:

Sprague-Dawley rats were randomly divided into four groups: sham, CCI, sham + loganin, and CCI + loganin. Loganin (5 mg/kg/day) was administered intraperitoneally starting the day after surgery. Paw withdrawal threshold (PWT) and latency (PWL) were assessed before CCI and on days 1, 3, 7 and 14 after CCI. Spinal cords were collected for western blots and immunofluorescence studies.

RESULTS:

Loganin prevented CCI-attenuated PWT and PWL, suggesting improved mechanical allodynia and thermal hyperalgesia. The expression of CXCL12, CXCR4, thioredoxin-interacting protein (TXNIP), NLRP3 inflammasome (NLRP3, ASC, and caspase-1), IL-1β, and IL-18 were enhanced on day 7 after CCI, and all were reduced after loganin treatment. Dual immunofluorescence also showed that increased CXCL12, CXCR4, and NLRP3 were colocalized with NeuN (neuronal marker), GFAP (astrocyte marker), and Iba1 (microglial marker) on day 7 in the ipsilateral spinal dorsal horn (SDH). These immunoreactivities were attenuated in loganin-treated rats. Moreover, loganin decreased the assembly of NLRP3/ASC inflammasome after CCI in the ipsilateral SDH. Loganin appears to attenuate CCI-induced neuropathic pain by suppressing CXCL12/CXCR4-mediated NLRP3 inflammasome.

CONCLUSION:

Our findings suggest that loganin might be a suitable candidate for managing CCI-provoked neuropathic pain.

• Authors: Kuang-I Cheng, Sin-Lan Chen, Jong-Hau Hsu, Yu-Chi Cheng, Yu-Chin Chang, Chien-Hsing Lee, Jwu-Lai Yeh, Zen-Kong Dai, Bin-Nan Wu
• Journal: Phytomedicine : international journal of phytotherapy and phytopharmacology (Phytomedicine) Vol. 92 Pg. 153734 (Nov 2021) ISSN: 1618-095X [Electronic] Germany
• PMID: 34536822 (Publication Type: Journal Article)
• Copyright: Copyright © 2021 Elsevier GmbH. All rights reserved.

Chemical References

• Cell Cycle Proteins
• Cxcr4 protein, rat
• Inflammasomes
• Iridoids
• NLR Family, Pyrin Domain-Containing 3 Protein
• Nlrp3 protein, rat
• Receptors, CXCR4
• Receptors, Chemokine
• TXNIP protein, rat
• loganin

Topics

• Animals
• Cell Cycle Proteins
• Hyperalgesia (drug therapy)
• Inflammasomes
• Iridoids
• NLR Family, Pyrin Domain-Containing 3 Protein
• Neuralgia (drug therapy)
• Rats
• Rats, Sprague-Dawley
• Receptors, CXCR4
• Receptors, Chemokine
• Spinal Cord