Inhibition of cytochrome P450c17 reduces spinal astrocyte activation in a mouse model of neuropathic pain via regulation of p38 MAPK phosphorylation.

Abstract

We have recently demonstrated that the neurosteroid-metabolizing enzyme, cytochrome P450c17 is increased in spinal astrocytes contributing to the development of mechanical allodynia in chronic constriction injury (CCI)-induced neuropathic mice. However, the mechanisms by which spinal P450c17 modulates pathological changes in astrocytes remain unclear. In this study we investigated whether P450c17 modulates astrocyte activation and whether this process is mediated by spinal p38 mitogen-activated protein kinase phosphorylation ultimately leading to the development of mechanical allodynia in CCI mice. Sciatic nerve injury induced a significant increase in glial fibrillary acidic protein (GFAP) expression in the superficial dorsal horn (SDH, laminae I-II) and nucleus proprius (NP, laminae III-IV) regions of the spinal cord dorsal horn. Repeated daily (from days 0-3 post-surgery) intrathecal administration of the P450c17 inhibitor, ketoconazole (10 nmol) significantly inhibited the CCI-induced increase in GFAP-immunoreactivity, but had no effect on the CCI-induced increase in Iba-1-immunoreactivity. In addition, intrathecal administration of ketoconazole significantly inhibited the CCI-induced increase in p38 phosphorylation, while the levels of ERK and JNK phosphorylation remained unchanged. The CCI-induced development of mechanical allodynia was attenuated by administration of either ketoconazole (10 nmol) or the p38 MAPK inhibitor, SB203580 (5 nmol). Administration of a sub-effective dose of SB203580 (0.5 nmol) potentiated the pharmacological effect of ketoconazole (1 nmol) on spinal GFAP-immunostaining, as well as, the development of mechanical allodynia following CCI. Collectively these data suggest that spinal P450c17 activates astrocytes via p38 phosphorylation, ultimately leading to the development of mechanical allodynia in a model of peripheral neuropathy.

• Authors: Sheu-Ran Choi, Alvin J Beitz, Jang-Hern Lee
• Journal: Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie (Biomed Pharmacother) Vol. 118 Pg. 109299 (Oct 2019) ISSN: 1950-6007 [Electronic] France
• PMID: 31387001 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 The Authors. Published by Elsevier Masson SAS.. All rights reserved.

Chemical References

• Imidazoles
• Pyridines
• Steroid 17-alpha-Hydroxylase
• p38 Mitogen-Activated Protein Kinases
• SB 203580
• Ketoconazole

Topics

• Animals
• Astrocytes (drug effects, enzymology, pathology)
• Constriction, Pathologic
• Disease Models, Animal
• Hyperalgesia (complications, pathology)
• Imidazoles (pharmacology)
• Ketoconazole (administration & dosage, pharmacology)
• Lumbar Vertebrae (enzymology, pathology)
• Male
• Mice
• Microglia (drug effects, pathology)
• Neuralgia (enzymology, pathology)
• Phosphorylation (drug effects)
• Pyridines (pharmacology)
• Spinal Cord (pathology)
• Spinal Cord Dorsal Horn (enzymology, pathology)
• Steroid 17-alpha-Hydroxylase (antagonists & inhibitors, metabolism)
• p38 Mitogen-Activated Protein Kinases (metabolism)