Abstract
ABSTRACTBackground: The venom of Phoneutria nigriventer spider is a source of numerous bioactive substances, including some toxins active in insects. An example is PnTx4(5-5) that shows a high insecticidal activity and no apparent toxicity to mice, although it inhibited NMDA-evoked currents in rat hippocampal neurons. In this work the analgesic activity of PnTx4(5-5) (renamed Γ-ctenitoxin-Pn1a) was investigated. Methods: The antinociceptive activity was evaluated using the paw pressure test in rats, after hyperalgesia induction with intraplantar injection of carrageenan or prostaglandin E2 (PGE2). Results: PnTx4(5-5), subcutaneously injected, was able to reduce the hyperalgesia induced by PGE2 in rat paw, demonstrating a systemic effect. PnTx4(5-5) administered in the plantar surface of the paw caused a peripheral and dose-dependent antinociceptive effect on hyperalgesia induced by carrageenan or PGE2. The hyperalgesic effect observed in these two pain models was completely reversed with 5 µg of PnTx4(5-5). Intraplantar administration of L-glutamate induced hyperalgesic effect that was significantly reverted by 5 μg of PnTx4(5-5) injection in rat paw. Conclusion: The antinociceptive effect for PnTx4(5-5) was demonstrated against different rat pain models, i.e. induced by PGE2, carrageenan or glutamate. We suggest that the antinociceptive effect of PnTx4(5-5) may be related to an inhibitory activity on the glutamatergic system.
Highlights
The venom of Phoneutria nigriventer spider is a source of numerousΓ-ctenitoxin-Pn1a bioactive substances, including some toxins active in insects
PnTx4(5-5) administered in the plantar surface of the paw caused a peripheral and dose-dependent antinociceptive effect on hyperalgesia induced by carrageenan or prostaglandin E2 (PGE2)
We suggest that the antinociceptive effect of PnTx4(5-5) may be related to an inhibitory activity on the glutamatergic system
Summary
The venom of Phoneutria nigriventer spider is a source of numerousΓ-ctenitoxin-Pn1a bioactive substances, including some toxins active in insects. In the last four decades, animal venoms have been recognized as potential sources of pharmacological agents and physiological tools The interest in these venoms has extended into the isolation and the development of new proteins and peptides or their derivatives with therapeutic importance. A good example is Captopril®, an antihypertensive drug, which development was based on the pathophysiological studies of Bothrops jararaca envenoming, more than a half century ago [1,2] Another example is ziconotide, a peptide derived from Conus magus snail venom, known under the trade name Prialt®, approved by the US Food and Drug Administration in 2004 for the treatment of chronic pains [3,4]
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