Rho/ROCK acts downstream of lysophosphatidic acid receptor 1 in modulating P2X₃ receptor-mediated bone cancer pain in rats

Abstract

BackgroundLysophosphatidic acid receptor 1 and Rho/ROCK signaling is implicated in bone cancer pain development. However, it remains unknown whether the two signaling pathways function together in P2X3 receptor-mediated bone cancer pain.ResultsIn this study, using a rat model of bone cancer, we examined the expression of P2X3 and lysophosphatidic acid receptor 1 in rat dorsal root ganglion neurons and further dissected whether lysophosphatidic acid receptor 1 and Rho/ROCK-mediated pathways interacted in modulating rat pain behavior. Bone cancer was established by inoculating Walker 256 cells into the left tibia of female Wistar rats. We observed a gradual and yet significant decline in mean paw withdrawal threshold in rats with bone cancer, but not in control rats. Our immunohistochemical staining revealed that the number of P2X3- and lysophosphatidic acid receptor 1-positive dorsal root ganglion neurons was significantly greater in rats with bone cancer than control rats. Lysophosphatidic acid receptor 1 blockade with VPC32183 significantly attenuated decline in mean paw withdrawal threshold. Flinching behavior test further showed that lysophosphatidic acid receptor 1 inhibition with VPC32183 transiently but significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Rho inhibition by intrathecal BoTXC3 caused a rapid reversal in decline in mean paw withdrawal threshold of rats with bone cancer. Flinching behavior test showed that BoTXC3 transiently and significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Similar findings were observed with ROCK inhibition by intrathecal Y27632. Furthermore, VPC32183 and BoTXC3 effectively aborted the appearance of lysophosphatidic acid-induced calcium influx peak.ConclusionsLysophosphatidic acid and its receptor LPAR1, acting through the Rho-ROCK pathway, regulate P2X3 receptor in the development of both mechanical and spontaneous pain in bone cancer.

Lysophosphatidic Acid and Ion Channels as Molecular Mediators of Pain

“…For example, there is scarce information as to how this phospholipid regulates P2X3 receptors that have been shown to participate in pain (Burnstock, 2016). Only one study shows that LPA can regulate the activity of P2X3 receptors through an LPA1-mediated signaling pathway in bonce cancer pain in rats (Wu et al, 2016).…”

P2X receptor channels in chronic pain pathways

“…A recent study also uncovered a potential interaction between P2X3 receptors and the lysophosphatidic acid receptor (LPA 1 ). In a rat model of bone cancer pain‐induced mechanical pain, activation of LPA 1 , co‐expressed with P2X3 receptors in DRG neurons, potentiated ATP‐mediated currents (Wu et al ., ). Activation of the Rho/ROCK signalling pathway downstream from LPA 1 receptors is suggested as the functional link, as either LPA 1 receptor or Rho/ROCK antagonists inhibited αβ‐meATP‐evoked pain responses.…”

microRNA-329 reduces bone cancer pain through the LPAR1-dependent LPAR1/ERK signal transduction pathway in mice

“…10,11 LPAR1 is a bioactive lipid involved in the development of BCP through its regulation of the P2X3 receptor. 12 Furthermore, upregulation in LPA has been linked with an elevated risk of metastasis and pain development in bone cancer. 13 LPA-dependent cell migration has been achieved previously through the LPAR3-Gi-extracellular signal-regulated kinase (ERK)-pathway, independently of LPAR1.…”