PGE2/EP4 receptor and TRPV1 channel are involved in repeated restraint stress-induced prolongation of sensitization pain evoked by subsequent PGE2 challenge.

In this study, we examined role of PGE2/EP4 signaling and TRPV1 signaling in repeated restraint stress-induced prolongation of sensitization pain, a model for transition from acute to chronic pain, in both in vivo and in vitro models. We found that pre-exposure to single restraint stress induced analgesia that masked sensitization pain evoked by subsequent PGE2 challenge. However, pre-exposure to 3d consecutive restraint stress not only prolonged sensitization pain, but also increased stress hormone corticosterone (CORT) in serum, COX2 levels in paw skin, EP4 and TRPV1 levels in dorsal root ganglion (DRG) and paw skin. Pre-exposure to CORT for 3d, not 1d, also prolonged sensitization pain evoked by PGE2. Co-injection of glucocorticoid receptor (GR) antagonist RU486, COX2 inhibitor NS-398, EP4 receptor antagonist L161,982 or TRPV1 antagonist capsazepine prevented 3d restraint stress prolonged sensitization pain evoked by PGE2. In DRG cultures, CORT increased EP4 and TRPV1 protein levels through GR activation. These data suggest that PGE2/EP4 signaling and TRPV1 signaling in peripheral pain pathway contributes to repeated stress-predisposed transition from acute to chronic pain.
PMID: 31302096 [PubMed - as supplied by publisher]

Source: Brain Research - July 10, 2019 Category: Neurology Authors: Ma W, Li L, Xing S Tags: Brain Res Source Type: research