Abstract
Protein kinase B (PKB/Akt) is a member of the second-messenger regulated subfamily of protein kinases. It is implicated in signaling downstream of growth factors, insulin receptor tyrosine kinases and phosphoinositide 3-kinase (PI3K). Current studies indicate that nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and PI3K help mediate inflammatory hyperalgesia. However, little is known about the role of PKB/Akt in the nociceptive system. In this study, we investigated whether PKB/Akt in primary sensory neurons is activated after noxious stimulation and contributes to pain behavior induced in rats by capsaicin. We demonstrated that phospho-PKB/Akt (p-PKB/Akt) is increased in dorsal root ganglia (DRG) at 5 min after intradermal injection of capsaicin. p-PKB/Akt is distributed predominantly in small- and medium-sized DRG cells. After capsaicin injection, p-PKB/Akt (473) is colocalized with isotectin-B4 (IB4), tyrosine kinase A (TrkA), and calcitonin gene-related peptide (CGRP). Furthermore, most transient receptor potential vanilloid type 1 (TRPV1) positive DRG neurons double label for p-PKB/Akt. Behavioral experiments show that intradermal injection of a PI3K (upstream of PKB/Akt) inhibitor, wortmannin, dose-dependently inhibits the changes in exploratory behavior evoked by capsaicin injection. The PKB/Akt inhibitor, Akt inhibitor IV, has the same effect. The results suggest that the PKB/Akt signaling pathway in the periphery is activated by noxious stimulation and contributes to pain behavior.
Original language | English (US) |
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Pages (from-to) | 286-294 |
Number of pages | 9 |
Journal | Neuroscience |
Volume | 144 |
Issue number | 1 |
DOIs | |
State | Published - Jan 5 2007 |
Keywords
- TRPV1
- dorsal root ganglion
- pain
- phosphoinositide 3-kinase
- phosphorylation
ASJC Scopus subject areas
- General Neuroscience