PnPP‐19, a spider toxin peptide, induces peripheral antinociception through opioid and cannabinoid receptors and inhibition of neutral endopeptidase

Abstract

Background and Purpose The synthetic peptide PnPP‐19 has been studied as a new drug candidate to treat erectile dysfunction. However, PnTx2–6, the spider toxin from which the peptide was designed, induces hyperalgesia. Therefore, we intended to investigate the role of PnPP‐19 in the nociceptive pathway. Experimental Approach Nociceptive thresholds were measured by paw pressure test. PnPP‐19 was administered intraplantarly alone or with selective cannabinoid or opioid receptor antagonists. The hydrolysis of PnPP‐19 by neutral endopeptidase (NEP) (EC 3.4.24.11), an enzyme that cleaves enkephalin, was monitored by HPLC and the cleavage sites were deduced by LC–MS. Inhibition by PnPP‐19 and Leu‐enkephalin of NEP enzyme activity was determined spectrofluorimetrically. Key Results PnPP‐19 (5, 10 and 20 μg per paw) induced peripheral antinociception in rats. Specific antagonists of μ opioid receptors (clocinnamox), δ opioid receptors (naltrindole) and CB1 receptors (AM251) partly inhibited the antinociceptive effect of PnPP‐19. Inhibition of fatty acid amide hydrolase by MAFP or of anandamide uptake by VDM11 enhanced PnPP‐19‐induced antinociception. NEP cleaved PnPP‐19 only after a long incubation, and Ki values of 35.6 ± 1.4 and 14.6 ± 0.44 μmol·L−1 were determined for PnPP‐19 and Leu‐enkephalin respectively as inhibitors of NEP activity. Conclusions and Implications Antinociception induced by PnPP‐19 appears to involve the inhibition of NEP and activation of CB1, μ and δ opioid receptors. Our data provide a greater understanding of the antinociceptive effects of PnPP‐19. This peptide could be useful as a new antinociceptive drug candidate.

A spider derived peptide, PnPP-19, induces central antinociception mediated by opioid and cannabinoid systems

“…Since the peptide PnPP-19 is known to induce peripheral antinociception, we decided to investigate whether it could also interact with the central nervous system and induce antinociception mediated by activation of central signaling related to the nociceptive pathway [17]. Firstly, PnPP-19 was injected intracerebroventricularly.…”

“…For instance, PnTx3-3 (ω ctenitoxin Pn2a) and Phα1β induce an antinociceptive effect in neuropathic pain models [4, 5]. More recently, we have shown that the synthetic peptide, PnPP-19, firstly characterized as a potentiator of erectile function, also produces antinociception in rats when peripherally injected [1, 17]. We also showed that this peripheral effect involves inhibition of neutral endopeptidase (NEP) (EC 3.4.24.11), and activation of CB 1 , μ- and δ-opioid receptors [17].…”

“…More recently, we have shown that the synthetic peptide, PnPP-19, firstly characterized as a potentiator of erectile function, also produces antinociception in rats when peripherally injected [1, 17]. We also showed that this peripheral effect involves inhibition of neutral endopeptidase (NEP) (EC 3.4.24.11), and activation of CB 1 , μ- and δ-opioid receptors [17]. Therefore, the next issue to be investigated was whether PnPP-19 presents a possible central activity on nociception.…”

“…Recently we have shown that PnPP-19 induces antinociception in the peripheral nervous system [17]. We suggested that this effect is attributable to an inhibition of the neutral endopeptidase (neprilysin), which may lead to an increase of enkephalin levels and may cause activation of both μ- and δ-opioid receptors.…”

Animal Venom Components: New Approaches for Pain Treatment

“…For example, some antinociceptive spider toxins induce antinociception by affecting glutamatergic neurotransmission, blocking ASIC channels, activating opioid and cannabinoid pathways, inhibiting P2X3 receptors, among others [5,[21][22][23]. Recently, many toxins from the spider Phoneutria nigriventer have been studied by the group of Gomez [20,[24][25][26][27][28] and by our group [15,[21][22][23][24], which have highlighted the great potential of these molecules as analgesic models.…”