Dexamethasone attenuates neuropathic pain through spinal microglial expression of dynorphin A via the cAMP/PKA/p38 MAPK/CREB signaling pathway.
Brain Behav Immun
; 119: 36-50, 2024 Jul.
Article
in En
| MEDLINE
| ID: mdl-38555991
ABSTRACT
This study aimed to elucidate the opioid mechanisms underlying dexamethasone-induced pain antihypersensitive effects in neuropathic rats. Dexamethasone (subcutaneous and intrathecal) and membrane-impermeable Dex-BSA (intrathecal) administration dose-dependently inhibited mechanical allodynia and thermal hyperalgesia in neuropathic rats. Dexamethasone and Dex-BSA treatments increased expression of dynorphin A in the spinal cords and primary cultured microglia. Dexamethasone specifically enhanced dynorphin A expression in microglia but not astrocytes or neurons. Intrathecal injection of the microglial metabolic inhibitor minocycline blocked dexamethasone-stimulated spinal dynorphin A expression; intrathecal minocycline, the glucocorticoid receptor antagonist Dex-21-mesylate, dynorphin A antiserum, and κ-opioid receptor antagonist GNTI completely blocked dexamethasone-induced mechanical antiallodynia and thermal antihyperalgesia. Additionally, dexamethasone elevated spinal intracellular cAMP levels, leading to enhanced phosphorylation of PKA, p38 MAPK and CREB. The specific adenylate cyclase inhibitor DDA, PKA inhibitor H89, p38 MAPK inhibitor SB203580 and CREB inhibitor KG-501 completely blocked dexamethasone-induced anti-neuropathic pain and increased microglial dynorphin A exprression. In conclusion, this study reveal that dexamethasone mitigateds neuropathic pain through upregulation of dynorphin A in spinal microglia, likely involving the membrane glucocorticoid receptor/cAMP/PKA/p38 MAPK/CREB signaling pathway.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Spinal Cord
/
Dexamethasone
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Dynorphins
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Signal Transduction
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Rats, Sprague-Dawley
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Cyclic AMP Response Element-Binding Protein
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Microglia
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Cyclic AMP-Dependent Protein Kinases
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Cyclic AMP
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P38 Mitogen-Activated Protein Kinases
Limits:
Animals
Language:
En
Journal:
Brain Behav Immun
Journal subject:
ALERGIA E IMUNOLOGIA
/
CEREBRO
/
PSICOFISIOLOGIA
Year:
2024
Type:
Article
Affiliation country:
China