Role of GPCR (mu-opioid)–receptor tyrosine kinase (epidermal growth factor) crosstalk in opioid-induced hyperalgesic priming (type II)

Abstract

Repeated stimulation of mu-opioid receptors (MORs), by an MOR-selective agonist DAMGO induces type II priming, a form of nociceptor neuroplasticity, which has 2 components: opioid-induced hyperalgesia (OIH) and prolongation of prostaglandin-E2 (PGE2)-induced hyperalgesia. We report that intrathecal antisense knockdown of the MOR in nociceptors, prevented the induction of both components of type II priming. Type II priming was also eliminated by SSP-saporin, which destroys the peptidergic class of nociceptors. Because the epidermal growth factor receptor (EGFR) participates in MOR signaling, we tested its role in type II priming. The EGFR inhibitor, tyrphostin AG 1478, prevented the induction of prolonged PGE2-induced hyperalgesia, but not OIH, when tested out to 30 days after DAMGO. However, even when repeatedly injected, an EGFR agonist did not induce hyperalgesia or priming. A phosphopeptide, which blocks the interaction of Src, focal adhesion kinase (FAK), and EGFR, also prevented DAMGO-induced prolongation of PGE2 hyperalgesia, but only partially attenuated the induction of OIH. Inhibitors of Src and mitogen-activated protein kinase (MAPK) also only attenuated OIH. Inhibitors of matrix metalloproteinase, which cleaves EGF from membrane protein, markedly attenuated the expression, but did not prevent the induction, of prolongation of PGE2 hyperalgesia. Thus, although the induction of prolongation of PGE2-induced hyperalgesia at the peripheral terminal of peptidergic nociceptor is dependent on Src, FAK, EGFR, and MAPK signaling, Src, FAK, and MAPK signaling is only partially involved in the induction of OIH.

In Vitro Nociceptor Neuroplasticity Associated with In Vivo Opioid-Induced Hyperalgesia

“…We have previously demonstrated that several inflammatory mediators, which act as agonists at cell surface receptors on nociceptor (Aley et al, 2000;Reichling and Levine, 2009;Bogen et al, 2012;Ferrari et al, 2013a,b) and MOR agonists (e.g., DAMGO, fentanyl, and morphine) (Araldi et al, 2015(Araldi et al, , 2017(Araldi et al, , 2018aFerrari et al, 2019), produce hyperalgesic priming, a form of nociceptor neuroplasticity thought to contribute to the transition from acute to chronic pain. A key feature of the primed nociceptor is that it responds to pronociceptive mediators, prototypically prostaglandin E 2 (PGE 2 ), with markedly enhanced and prolonged mechanical hyperalgesia (Aley et al, 2000;Parada et al, 2003bParada et al, , 2005Reichling and Levine, 2009;Ferrari et al, 2014Ferrari et al, , 2016Ferrari et al, , 2019Araldi et al, 2015Araldi et al, , 2017Araldi et al, , 2018aAraldi et al, ,c, 2019Khomula et al, 2017). Intradermal MOR agonists, in a dose that does not affect mechanical nociceptive threshold in opioid-naive rats, induces robust hyperalgesia in rats previously treated systemically with a MOR agonist (Araldi et al, 2018a).…”

“…A key feature of the primed nociceptor is that it responds to pronociceptive mediators, prototypically prostaglandin E 2 (PGE 2 ), with markedly enhanced and prolonged mechanical hyperalgesia (Aley et al, 2000;Parada et al, 2003bParada et al, , 2005Reichling and Levine, 2009;Ferrari et al, 2014Ferrari et al, , 2016Ferrari et al, , 2019Araldi et al, 2015Araldi et al, , 2017Araldi et al, , 2018aAraldi et al, ,c, 2019Khomula et al, 2017). Intradermal MOR agonists, in a dose that does not affect mechanical nociceptive threshold in opioid-naive rats, induces robust hyperalgesia in rats previously treated systemically with a MOR agonist (Araldi et al, 2018a).…”

“…It is not known whether the priming, which is characteristically observed along with OIH (Araldi et al, 2015(Araldi et al, , 2017(Araldi et al, , 2018aFerrari et al, 2019), have shared mechanisms or if they are just a parallel process. Recently, we distinguished two types of hyperalgesic priming, with distinct cellular mechanisms (Araldi et al, 2015).…”

“…Relative change in rheobase (as the percentage decrease) was used as a measure of the magnitude of sensitization (Ferrari et al, 2018). We previously demonstrated a contribution of peptidergic (predominantly IB4 Ϫ ) and IB4binding (predominantly nonpeptidergic) nociceptors, leading us to infer an important role of weakly IB4 ϩ DRG neurons, which are peptidergic (Fang et al, 2006), to opioid-induced priming (Araldi et al, 2015(Araldi et al, , 2018a. We used in vitro IB4-labeling of live neurons undergoing electrophysiological recordings to separate small-diameter DRG neurons into three classes: strongly IB4 ϩ (nonpeptidergic), weakly IB4 ϩ (peptidergic), and IB4 Ϫ (peptidergic) (Petruska et al, 2000;Fang et al, 2006;Woolf and Ma, 2007;Khomula et al, 2013Khomula et al, , 2017.…”

“…We have recently shown that depending on the opioid used, and its dose and route of administration, opioids are capable of inducing acute hyperalgesia, even after a single administration (Araldi et al, 2015(Araldi et al, , 2018b(Araldi et al, ,c, 2019Ferrari et al, 2019). In particular, clinically used -opioid receptor (MOR) agonists, fentanyl (Araldi et al, 2018c) and morphine (Araldi et al, 2019;Ferrari et al, 2019), as well as the highly selective MOR agonist, DAMGO (Araldi et al, 2015(Araldi et al, , 2017(Araldi et al, , 2018a, produce OIH and hyperalgesic priming, a form of nociceptor neuroplasticity characterized by a persistent increase in responsivity of nociceptors to proalgesic mediators (Ferrari et al, 2010;Joseph and Levine, 2010b;Alvarez et al, 2014;Araldi et al, 2015;Khomula et al, 2017). Recent evidence has implicated a role of the action of MOR agonists on primary afferent nociceptors in OIH (Corder et al, 2017).…”