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Papers of the Week

Papers: 23 Feb 2019 - 1 Mar 2019

Animal Studies, Pharmacology/Drug Development

2019 May 01



Spinal cytochrome P450c17 plays a key role in the development of neuropathic mechanical allodynia: Involvement of astrocyte sigma-1 receptors.


Choi S-R, Roh D-H, Yoon S-Y, Choi H-S, Kang S-Y, Han H-J, Beitz AJ, Lee J-H
Neuropharmacology. 2019 May 01; 149:169-180.
PMID: 30797030.


While evidence indicates that sigma-1 receptors (Sig-1Rs) play an important role in the induction of peripheral neuropathic pain, there is limited understanding of the role that the neurosteroidogenic enzymes, which produce Sig-1R endogenous ligands, play during the development of neuropathic pain. We examined whether sciatic nerve injury upregulates the neurosteroidogenic enzymes, cytochrome P450c17 and 3β-hydroxysteroid dehydrogenase (3β-HSD), which modulate the expression and/or activation of Sig-1Rs leading to the development of peripheral neuropathic pain. Chronic constriction injury (CCI) of the sciatic nerve induced a significant increase in the expression of P450c17, but not 3β-HSD, in the ipsilateral lumbar spinal cord dorsal horn at postoperative day 3. Intrathecal administration of the P450c17 inhibitor, ketoconazole during the induction phase of neuropathic pain (day 0 to day 3 post-surgery) significantly reduced the development of mechanical allodynia and thermal hyperalgesia in the ipsilateral hind paw. However, administration of the 3β-HSD inhibitor, trilostane had no effect on the development of neuropathic pain. Sciatic nerve injury increased astrocyte Sig-1R expression as well as dissociation of Sig-1Rs from BiP in the spinal cord. These increases were suppressed by administration of ketoconazole, but not by administration of trilostane. Co-administration of the Sig-1R agonist, PRE084 restored the development of mechanical allodynia originally suppressed by the ketoconazole administration. However, ketoconazole-induced inhibition of thermal hyperalgesia was not affected by co-administration of PRE084. Collectively these results demonstrate that early activation of P450c17 modulates the expression and activation of astrocyte Sig-1Rs, ultimately contributing to the development of mechanical allodynia induced by peripheral nerve injury.