The protein tyrosine kinase inhibitor, genistein, decreases excitability of nociceptive neurons.

Published

Journal Article

One mechanism by which neurons regulate their excitability is through ion channel phosphorylation. Compounds that increase nociceptive neuron excitability can cause hyperalgesia or allodynia whereas compounds that decrease nociceptive neuron excitability can be used as analgesics to relieve pain arising from inflammation or trauma. To identify targets that may cause a decrease in nociceptive neuron excitability, we have investigated the effects of genistein, a specific inhibitor of protein tyrosine kinases (PTKs), on capsaicin-sensitive neurons from cultured rat trigeminal ganglion neurons. It was found that genistein decreased the number of evoked action potentials, and hence their excitability. To determine whether genistein's effects occur through the inhibition of PTKs, we also tested the effects of two of its inactive analogues, daidzein and genistin. Whereas daidzein decreased excitability, albeit to a lower extent than genistein, excitability was unaffected by genistin. To determine which currents are involved in genistein's reduction in nociceptive neuron excitability, whole-cell voltage-clamp measurements were performed on voltage-gated sodium and potassium currents. One hundred micromolar genistein, daidzein and genistin inhibited tetrodotoxin-resistant voltage-gated sodium currents 74, 42, and 3%, respectively. Genistein markedly inhibited delayed rectifier (IK) and IA potassium currents, whereas daidzein and genistin were comparatively ineffective. In summary, we found that genistein's ability to inhibit nociceptive neuron excitability arises primarily from its non-specific inhibition of voltage-dependent sodium channels.

Full Text

Duke Authors

Cited Authors

  • Liu, L; Yang, T; Simon, SA

Published Date

  • November 2004

Published In

Volume / Issue

  • 112 / 1-2

Start / End Page

  • 131 - 141

PubMed ID

  • 15494193

Pubmed Central ID

  • 15494193

International Standard Serial Number (ISSN)

  • 0304-3959

Digital Object Identifier (DOI)

  • 10.1016/j.pain.2004.08.005

Language

  • eng

Conference Location

  • United States