NOSH-aspirin (NBS-1120), a dual nitric oxide and hydrogen sulfide-releasing hybrid, reduces inflammatory pain

Abstract

The development of nitric oxide (NO)- and hydrogen sulfide (H2S)-releasing nonsteroidal anti-inflammatory drugs (NSAIDs) has generated more potent anti-inflammatory drugs with increased safety profiles. A new hybrid molecule incorporating both NO and H2S donors into aspirin (NOSH-aspirin) was recently developed. In the present study, the antinociceptive activity of this novel molecule was compared with aspirin in different models of inflammatory pain. It was found that NOSH-aspirin inhibits acetic acid-induced writhing response and carrageenan (Cg)-induced inflammatory hyperalgesia in a dose-dependent (5-150 μmol/kg, v.o.) manner, which was superior to the effect of the same doses of aspirin. NOSH-aspirin's antinociceptive effect was also greater and longer compared to aspirin upon complete Freund's adjuvant (CFA)-induced inflammatory hyperalgesia. Mechanistically, NOSH-aspirin, but not aspirin, was able to reduce the production/release of interleukin-1 beta (IL-1β) during Cg-induced paw inflammation. Furthermore, NOSH-aspirin, but not aspirin, reduced prostaglandin E2-induced hyperalgesia, which was prevented by treatment with a ATP-sensitive potassium channel (KATP) blocker (glibenclamide; glib.). Noteworthy, the antinociceptive effect of NOSH-aspirin was not associated with motor impairment. The present results indicate that NOSH-aspirin seems to present greater potency than aspirin to reduce inflammatory pain in several models. The enhanced effects of NOSH-aspirin seems to be due to its ability to reduce the production of pronociceptive cytokines such as IL-1 β and directly block hyperalgesia caused by a directly acting hyperalgesic mediator in a mechanism dependent on modulation of KATP channels. In conclusion, we would like to suggest that NOSH-aspirin represents a prototype of a new class of analgesic drugs with more potent effects than the traditional NSAID, aspirin.

Keywords: Aspirin and NOSH-aspirin; hyperalgesia; inflammatory pain; prostaglandins.

Figure 1

Structural components of NOSH-aspirin. The parent compound aspirin is shown in the shaded box. The parts of the molecule that releases NO and H₂S are shown in the dotted ellipses. NO, nitric oxide; H₂S, hydrogen sulfide.

Figure 2

Effect of NOSH-aspirin (NOSH-ASA) and aspirin on acetic acid-induced writhing responses in mice. Animals were pretreated orally (p.o.) with aspirin (5, 15, 150 μmol/kg), NOSH-ASA (5, 15, 150, and 450 μmol/kg) or vehicle (v), 50 min before the intraperitoneal administration of acetic acid (0.8%, i.p.). Writhing responses was assessed during 20 min after acetic acid injection. The graphic represents the percentage of inhibition relative to vehicle. Data are the means ± SEM (n = 7). *P < 0.05, **P < 0.01, and ***P < 0.001 versus vehicle group.

Figure 3

Effect of NOSH-aspirin (NOSH-ASA) on motor coordinance. Mice were treated orally with NOSH-ASA (150 μmol/kg, v.o.), diazepam (5 mg/kg, i.p.) (positive control) or vehicle and were subjected to Rota-rod test. Sections were performed before and 1, 3, and 5 h after treatments. Data are the means ± SEM (n = 6). *P < 0.05, **P < 0.01, and ***P < 0.001 versus vehicle group.

Figure 4

Effect of NOSH-aspirin (NOSH-ASA) and aspirin on carrageenan- and CFA-induced inflammatory hyperalgesia. Mice were pretreated with (A) aspirin (5, 50 and 150 μmol/kg), (B) NOSH-ASA (5, 50, and 150 μmol/kg) or vehicle (v) orally (p.o.) 30 min before the intraplantar injection of carrageenan (Cg; 100 μg/paw). The hypernociceptive responses were evaluated 3 h after carrageenan injection. (C) Percentage of inhibition caused by aspirin and NOSH-ASA (150 μmol/kg) upon carrageenan-induced hyperalgesia. (D) Animals received an injection of 10 μL of CFA in the hind paw. At 24 h after, mechanical nociceptive threshold was evaluated followed by the treated with NOSH-ASA (150 μmol/kg), aspirin (150 μmol/kg) or vehicle (p.o.). Mechanical hyperalgesia was evaluated 1, 3, 5, 7, and 24 h after treatment. Data are the means ± SEM (n = 6). *P < 0.05, **P < 0.01, and ***P < 0.001 versus vehicle-treated group. CFA, complete Freund’s adjuvant.

Figure 5

Effect of NOSH-aspirin (NOSH-ASA) and aspirin on carrageenan-induced neutrophil migration and local production of pronociceptive cytokines. Mice were pretreated with aspirin (150 μmol/kg), NOSH-ASA (150 μmol/kg) or vehicle orally 30 min before the intraplantar injection of carrageenan (Cg; 100 μg/paw) or saline. At 3 h after Cg injection plantar tissue were collected for measurement of (A) neutrophil migration (MPO activity assay) and the levels of (B) TNF-α, (C) KC/CXCL1, and (D) IL1-β by ELISA. Data are the means ± SEM (n = 6). ***P < 0.001 versus saline group. ^#P < 0.05 versus vehicle-treated group. MPO, myeloperoxidase; TNF-α, tumor necrosis factor-α; KC/CXCL1, keratinocyte-derived chemokine.

Figure 6

Effect of NOSH-aspirin (NOSH-ASA) and aspirin on PGE₂-induced hyperalgesia: involvement of K_ATP. (A) Mice were pretreated 50 min before with aspirin (150 μmol/kg), NOSH-ASA (150 μmol/kg) or vehicle (v) orally followed by intraplantar (i.p.) injection of PGE₂. Mechanical hyperalgesia was evaluated 60 min after PGE₂ injection. (B) Mice were pretreated with K_ATP blocker (glibenclamide; 10 mg/kg, i.p.) and after 30 min, they received vehicle or NOSH-ASA (150 μmol/kg), and after 50 min all groups received i.p. injection of PGE₂. Mechanical hyperalgesia was evaluated 60 min after PGE₂ injection. Data are the means ± SEM (n = 6). **P < 0.01 and ***P < 0.001 versus vehicle group, ^#P < 0.001 versus NOSH-ASA-treated group. K_ATP, ATP-sensitive potassium channel; PGE₂, prostaglandin E₂.