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. 2018 Dec 1:394:60-71.
doi: 10.1016/j.neuroscience.2018.10.015. Epub 2018 Oct 17.

Mu-opioid Receptor (MOR) Biased Agonists Induce Biphasic Dose-dependent Hyperalgesia and Analgesia, and Hyperalgesic Priming in the Rat

Dionéia Araldi  1 , Luiz F Ferrari  2 , Jon D Levine  3
Affiliations

Mu-opioid Receptor (MOR) Biased Agonists Induce Biphasic Dose-dependent Hyperalgesia and Analgesia, and Hyperalgesic Priming in the Rat

Dionéia Araldi et al. Neuroscience. .

Abstract

Stimulation of the mu-opioid receptor (MOR) on nociceptors with fentanyl can produce hyperalgesia (opioid-induced hyperalgesia, OIH) and hyperalgesic priming, a model of transition to chronic pain. We investigated if local and systemic administration of biased MOR agonists (PZM21 and TRV130 [oliceridine]), which preferentially activate G-protein over β-arrestin translocation, and have been reported to minimize some opioid side effects, also produces OIH and priming. Injected intradermally (100 ng), both biased agonists induced mechanical hyperalgesia and, when injected at the same site, 5 days later, prostaglandin E2 (PGE2) produced prolonged hyperalgesia (priming). OIH and priming were both prevented by intrathecal treatment with an oligodeoxynucleotide (ODN) antisense (AS) for MOR mRNA. Agents that reverse Type I (the protein translation inhibitor cordycepin) and Type II (combination of Src and mitogen-activated protein kinase [MAPK] inhibitors) priming, or their combination, did not reverse priming induced by local administration of PZM21 or TRV130. While systemic PZM21 at higher doses (1 and 10 mg/kg) induced analgesia, lower doses (0.001, 0.01, 0.1, and 0.3 mg/kg) induced hyperalgesia; all doses induced priming. Hyperalgesia, analgesia and priming induced by systemic administration of PZM21 were also prevented by MOR AS-ODN. And, priming induced by systemic PZM21 was also not reversed by intradermal cordycepin or the combination of Src and MAPK inhibitors. Thus, maintenance of priming induced by biased MOR agonists, in the peripheral terminal of nociceptors, has a novel mechanism.

Keywords: biased agonist; hyperalgesia; hyperalgesic priming; mu-opioid receptor (MOR); opioid-induced hyperalgesia (OIH).

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Conflict of interest statement

Conflict of Interest: The authors declare no competing financial interests.

Figures

Figure 1.
Figure 1.. Mechanical hyperalgesia induced by intradermal administration of biased MOR agonists.
Rats received an intradermal injection of vehicle (5 μL of saline containing 2% DMSO; A and B, black bars), PZM21 (100 ng/5 μL; A, gray bars) or TRV130 (100 ng/5 μL; B, dotted bars), and mechanical nociceptive threshold was evaluated 30 min and 24 hours later. In both PZM21- and TRV130-treated groups a decrease in the mechanical nociceptive threshold was observed 30 min after their intradermal injection (F(1,10) = 148.1, *** p < 0.0001 [A]; F (1,10) = 84.56, **** p < 0.0001 [B], when vehicle-treated groups are compared with the PZM21- or TRV130-treated groups at 30 min after injection; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). By 24 hours after intradermal vehicle, PZM21 and TRV130 mechanical nociceptive threshold had returned to pre-treatment baseline. (n = 6 paws per group).
Figure 2.
Figure 2.. Hyperalgesic priming induced by biased MOR agonists.
Rats were treated intradermally with vehicle (5 μL; A and B, black bars), PZM21 (100 ng/5 μL; A, gray bars) or TRV130 (100 ng/5 μL; B, dotted bars). Five days later, when the mechanical nociceptive threshold was not different from the pre-vehicle/agonist baselines (A: t(5) = 0.6984; p = 0.5160, for the vehicle-treated group and, t(5) = 0.2104; p = 0.8417, for the PZM21-treated group; B: t(5)= 0.4385; p = 0.6793, for the vehicle-treated group, and t(5) = 0.9068; p = 0.4061, for the TRV130-treated group, when the mechanical nociceptive threshold is compared before and after treatments; paired Student’s t test), PGE2 (100 ng/5 μL) was injected intradermally and the mechanical nociceptive threshold evaluated 30 min and 4 hours later. Measured 30 min after its injection, PGE2-induced hyperalgesia was present in all biased MOR agonist-treated groups. However, in the groups treated with PZM21 (A) and TRV130 (B), but not in the vehicle-treated group, PGE2 induced prolonged hyperalgesia, observed at the fourth hour after its injection (A: F(1,10) = 107.4, **** p < 0.0001; B: F(1,10) = 58.15, **** p < 0.0001; when vehicle-treated groups are compared with the PZM21- or TRV130-treated groups at the fourth hour after the injection of PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). These findings support the suggestion that local/intradermal injection of biased MOR agonists induce hyperalgesic priming in the peripheral terminal of the nociceptor. (n = 6 paws per group)
Figure 3.
Figure 3.. MOR dependence of OIH and priming induced by biased agonists.
Rats were treated intrathecally with oligodeoxynucleotides (ODN) mismatch (MM-ODN; 120 μg/20 μL/day; black bars; A and B) or antisense (AS-ODN; 120 μg/20 μL/day, gray bars; A and B) against MOR mRNA, once a day, for 3 consecutive days. On the fourth day, approximately 17 hours after the last intrathecal administration of ODNs, PZM21 (100 ng/5 μL; A) or TRV130 (100 ng/5 μL; B) was injected intradermally, on the dorsum of the hind paw, and mechanical nociceptive threshold evaluated 30 min after injection. In MOR AS-ODN-treated groups, intradermal injection of PZM21 and TRV130 did not induce hyperalgesia, as observed in the MOR MM-ODN-treated groups (A: t(10) = 8.18, **** p < 0.0001; B: t(10) = 12.02, **** p = 0.0003; when the hyperalgesia in the MOR MM-ODN-treated group is compared to MOR AS-ODNtreated group 30 min after intradermal PZM21 or TRV130; unpaired Student’s t test). At the end of the 4th day, rats again received MOR MM- or AS-ODN. On the 5th day, approximately 24 hours after intradermal administration of PZM21 and TRV130, when the mechanical nociceptive threshold was not different from pre-MOR agonist baselines (A: t(5) = 0.3953; p = 0.7089, for the MOR MM-ODN-treated group and, t(5) = 1.472; p = 0.2009, for the MOR AS-ODN-treated group; B: t(5)= 0.237; p = 0.8220, for the MOR MM-ODN-treated group, and t(5) = 1.328; p = 0.2414, for the MOR AS-ODN-treated group, when the mechanical nociceptive threshold is compared before and after biased MOR agonists; paired Student’s t test), PGE2 (100 ng/5 μL) was injected intradermally, and the mechanical nociceptive threshold evaluated 30 min and 4 hours later. In the group treated with MOR AS-ODN, which received intradermal PZM21, the prolongation of PGE2-induced hyperalgesia was markedly attenuated (A; F(1,10) = 47.62, **** p < 0.0001; when the hyperalgesia in the MM-ODN- and the AS-ODN-treated groups is compared at the fourth hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test); however, the prolongation of PGE2-induced hyperalgesia was prevented in the MOR ASODN-treated group, which received intradermal TRV130 (B; F(1,10) = 64.88, **** p < 0.0001; when the hyperalgesia in the MM-ODN- and the AS-ODN-treated groups is compared at the fourth hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). These findings indicate that both OIH and priming, induced by intradermal injection of biased agonists, are MOR dependent. (n = 6 paws per group)
Figure 4.
Figure 4.. Type of priming induced by biased MOR agonists.
Rats received an intradermal injection of PZM21 (100 ng/5 μL; A) or TRV130 (100 ng/5 μL; B). Five days later, vehicle (5 μL; black bars), cordycepin (1 μg/5 μL; dotted bars), the combination (dark gray bars) of SU6656 (1 μg/2 μL) + U0126 (1 μg/2 μL), or the combination (light gray bars) of cordycepin (1 μg/2 μL) + SU6656 (1 μg/2 μL) + U0126 (1 μg/2 μL) were injected intradermally, followed 10 min later, by PGE2 (100 ng/5 μL), injected at the same site, on the dorsum of the hind paw. PGE2 induced hyperalgesia at 30 min after injection, was attenuated in groups treated with SU6656 + U0126 and cordycepin + SU6656 + U0126 (A: F(1,10) = 4.635, * p = 0.0128; B: F(1,10) = 3.132, * p = 0.0485; when the hyperalgesia in vehicle-, SU6656 + U0126-, and cordycepin + SU6656 + U0126-treated groups is compared 30 min after intradermal PGE2; two-way repeatedmeasures ANOVA followed by Bonferroni post hoc test). However, in all groups, PGE2 induced prolonged hyperalgesia, detected at the 4th hour after its injection (A: F(1,10) = 0.025, p = 0.9944; B: F(1,10) = 1.535, p = 0.1224; when the hyperalgesia in all treated-groups is compared at the 4th hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). These data indicate that PZM21 and TRV130 induce a Type of priming that is not maintained by signaling pathways that maintain Type I or II priming. (n = 6 paws per group)
Figure 5.
Figure 5.. Effect of systemically administered biased MOR agonist.
Groups of rats were treated subcutaneously with vehicle (veh; saline containing 2% DMSO; black circle) or PZM21 (0.001, 0.01, 0.1, 0.3, 1 or 10 mg/kg; 100 μL/100 g body weight; white circles) and mechanical nociceptive threshold evaluated 30 min later. A. Thirty min after subcutaneous injection of PZM21, all groups treated with low doses of PZM21 (0.001, 0.01, 0.1, and 0.3 mg/kg) were hyperalgesic (F(6,47) = 119.7, **** p < 0.0001; when the groups treated with low doses of PZM21 were compared to the vehicle-treated group at 30 min after s.c. injection; one-way repeated-measures ANOVA followed by Bonferroni post hoc test), while in the groups treated with the high doses (1 and 10 mg/kg) analgesia was observed (F(6,47) = 119.7, **** p < 0.0001, when the groups treated with high doses of PZM21 were compared to the vehicle-treated group at 30 min after s.c. injection; one-way repeated-measures ANOVA followed by Bonferroni post hoc test). In all groups that received s.c. PZM21, at 120 min after injection, the mechanical nociceptive threshold was not different when compared to the vehicle-treated group (data not shown; F(6,47) = 1.062, ns, p > 0.9999 for 0.001-, 0.01-, and 0.1 mg/kg-treated groups; ns, p = 0.5634 for 0.3 mg/kg-treated group; ns, p = 0.4589 for 1 mg/kg-treated group; and ns, p = 0.9256 for 10 mg/kg-treated group, when all subcutaneous PZM21-treated groups are compared to the vehicle-treated group at 120 min after injection; one-way repeated-measures ANOVA followed by Bonferroni post hoc test). B. Five days after subcutaneous administration of vehicle and PZM21, a time at which the mechanical nociceptive threshold was not different from the pre-MOR agonist baseline (t(5) = 0.9337; p = 0.3933, for the vehicle-treated group, t(5) = 0.6956; p = 0.5177, for the 0.001 mg/kg-treated group, t(5) =1.225; p = 0.2752, for the 0.01 mg/kg-treated group, t(5) = 0.2832; p = 0.7884, for the 0.1 mg/kg-treated group, t(5) = 2.15; p = 0.0842, for the 0.3 mg/kg-treated group, t(5) = 0.2225; p = 0.8327, for the 1 mg/kg-treated group, and t(5) = 0.6143; p = 0.5659, for the 10 mg/kg-treated group, when the mechanical nociceptive threshold is compared before and after subcutaneous vehicle or PZM21; paired Student’s t test), PGE2 (100 ng/5 μL) was injected intradermally, on the dorsum of the hindpaw, and mechanical nociceptive threshold evaluated 30 min and 4 h after injection. In all groups treated with subcutaneous PZM21, PGE2 induced prolonged hyperalgesia (F(2,70) = 1024.0, **** p < 0.0001, when the hyperalgesia in the systemic PZM21-treated groups is compared with the vehicle-treated group at the 4th hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). (n = 6 paws per group)
Figure 6.
Figure 6.. MOR dependence of hyperalgesia and priming induced by systemically administered low dose PZM21.
Rats received intrathecal injections of MM-ODN (120 μg/20 μL/day; black bar) or AS-ODN (120 μg/20 μL/day; dotted bar) against MOR mRNA, daily for 3 consecutive days. A. On the fourth day, approximately 17 hours after the last ODN injection, PZM21 (0.01 mg/kg) was injected subcutaneously and the mechanical nociceptive evaluated 30 min after its injection. Subcutaneous PZM21 did not induce hyperalgesia in the group treated with AS-ODN for MOR (t(10) = 7.284, **** p < 0.0001, when the hyperalgesia in the MM-ODN- and the AS-ODN-treated groups is compared after subcutaneous PZM21; unpaired Student’s t test). At the end of the 4th day, rats received MOR MM- or AS-ODN, intrathecally. B. On the fifth day, approximately 24 hours after systemic PZM21, when the mechanical nociceptive threshold was not different from pre-PZM21 baseline (t(5) = 0.5423; p = 0.6109, for the MM-ODN-treated group, and t(5) = 0.6705; p = 0.5323, for the AS-ODN-treated group, when the mechanical nociceptive threshold is compared before and after PZM21; paired Student’s t test), PGE2 (100 ng/5 μL) was injected intradermally and mechanical nociceptive threshold evaluated 30 min and 4 h later. Intradermal PGE2 did not induce prolonged hyperalgesia in the AS-ODN-treated group (F(1,10) = 55.86, **** p < 0.0001, when the hyperalgesia in the MM-ODN- and the AS-ODN-treated groups is compared at the fourth hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test), indicating that systemic low dose of PZM21-induced hyperalgesia and priming is MOR dependent. (n = 6 paws per group)
Figure 7.
Figure 7.. MOR dependence of analgesia and priming induced by high dose systemic PZM21.
Rats received intrathecal injections of MM-ODN (120 μg/20 μL/day; black bar) or AS-ODN (120 μg/20 μL/day; gray bar) against MOR mRNA, daily for 3 consecutive days. A. On the fourth day, approximately 17 hours after the last ODN injection, PZM21 (1 mg/kg) was injected subcutaneously and mechanical nociceptive evaluated 30 min after its injection. In the group treated with MOR AS-ODN, analgesia induced by subcutaneous injection of PZM21 was prevented (t(10) = 4.929, *** p = 0.0006, when the hyperalgesia in the MM-ODN- and the ASODN-treated groups is compared 30 min after subcutaneous PZM21; unpaired Student’s t test). At the end of the 4th day, rats received another dose of MOR MM- or AS-ODN. B. Approximately 24 hours after systemic PZM21 (1 mg/kg), when the mechanical nociceptive threshold was not different from pre-PZM21 baseline (t(5) =1.464; p = 0.2031, for the MM-ODN-treated group, and t(5) = 0.6956; p = 0.5177, for the AS-ODN-treated group, when the mechanical nociceptive threshold is compared before and after PZM21; paired Student’s t test), PGE2 (100 ng/5 μL) was injected intradermally and mechanical nociceptive threshold evaluated 30 min and 4 h after injection. In the MOR AS-ODN-treated group, the prolongation of PGE2-induced hyperalgesia was prevented (F(1,10) = 101.2, **** p < 0.0001, when the hyperalgesia in the MM-ODN- and the AS-ODN-treated groups is compared at the fourth hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). These findings support the suggestion that analgesia and priming induced by high dose PZM21 (1 mg/kg), are both MOR dependent. (n = 6 paws per group)
Figure 8.
Figure 8.. Novel mechanism for maintenance of priming induced by systemically administered low and high dose PZM21.
Groups of rats were treated systemically with PZM21 (0.01 mg/kg [A] or 1 mg/kg [B]; 100 μL/100 g body weight). Five days later, vehicle (5 μL; black bars), cordycepin (1 μg/5 μL; gray bars), the combination (dotted bars) of SU6656 (1 μg/2 μL) + U0126 (1 μg/2 μL), or the combination (white bars) of cordycepin (1 μg/2 μL) + SU6656 (1 μg/2 μL) + U0126 (1 μg/2 μL) was injected intradermally, followed 10 min later by PGE2 (100 ng/5 μL), injected at the same site on the dorsum of the hind paw. PGE2-induced hyperalgesia, at 30 min, was attenuated in the SU6656 + U0126- and cordycepin + SU6656 + U0126-treated groups (A: F(3,20) = 5.633, ** p = 0.0058; B: F(3,20) = 6.805, ** p = 0.0024, when the hyperalgesia in the vehicle- and the inhibitors-treated groups is compared at 30 min after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test). However, the prolongation of PGE2 hyperalgesia induced by a low (0.01 mg/kg, A) and a high dose (1 mg/kg, B) of PZM21 was not affected by cordycepin, the combination of SU6656 + U0126 or even by the combination of 3 inhibitors (A: ns, F(3,20) = 0.2403, p = 0.8672; B: ns, F(3,20) = 1.791, p = 0.1813, when the hyperalgesia in the vehicle- and the inhibitors-treated groups is compared at the fourth hour after intradermal PGE2; two-way repeated-measures ANOVA followed by Bonferroni post hoc test), compatible with the suggestion that systemic PZM21 induces priming that does not involve signaling pathways involved in the maintenance of Type I and II priming. (n = 6 paws per group)
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