A novel α-conopeptide Eu1.6 inhibits N-type (CaV2.2) calcium channels and exhibits potent analgesic activity

Sci Rep. 2018 Jan 17;8(1):1004. doi: 10.1038/s41598-017-18479-4.

Abstract

We here describe a novel α-conopeptide, Eu1.6 from Conus eburneus, which exhibits strong anti-nociceptive activity by an unexpected mechanism of action. Unlike other α-conopeptides that largely target nicotinic acetylcholine receptors (nAChRs), Eu1.6 displayed only weak inhibitory activity at the α3β4 and α7 nAChR subtypes and TTX-resistant sodium channels, and no activity at TTX-sensitive sodium channels in rat dorsal root ganglion (DRG) neurons, or opiate receptors, VR1, KCNQ1, L- and T-type calcium channels expressed in HEK293 cells. However, Eu1.6 inhibited high voltage-activated N-type calcium channel currents in isolated mouse DRG neurons which was independent of GABAB receptor activation. In HEK293 cells expressing CaV2.2 channels alone, Eu1.6 reversibly inhibited depolarization-activated Ba2+ currents in a voltage- and state-dependent manner. Inhibition of CaV2.2 by Eu1.6 was concentration-dependent (IC50 ~1 nM). Significantly, systemic administration of Eu1.6 at doses of 2.5-5.0 μg/kg exhibited potent analgesic activities in rat partial sciatic nerve injury and chronic constriction injury pain models. Furthermore, Eu1.6 had no significant side-effect on spontaneous locomotor activity, cardiac and respiratory function, and drug dependence in mice. These findings suggest α-conopeptide Eu1.6 is a potent analgesic for the treatment of neuropathic and chronic pain and opens a novel option for future analgesic drug design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Analgesics / chemical synthesis
  • Analgesics / isolation & purification
  • Analgesics / pharmacology*
  • Animals
  • Calcium / metabolism
  • Calcium Channels, N-Type / metabolism*
  • Chronic Pain / drug therapy*
  • Chronic Pain / metabolism
  • Chronic Pain / physiopathology
  • Conotoxins / chemical synthesis
  • Conotoxins / isolation & purification
  • Conotoxins / pharmacology*
  • Conus Snail / chemistry
  • Ganglia, Spinal / cytology
  • Ganglia, Spinal / drug effects
  • Ganglia, Spinal / metabolism
  • HEK293 Cells
  • Humans
  • Injections, Intramuscular
  • Injections, Intravenous
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Neurons / cytology
  • Neurons / drug effects
  • Neurons / metabolism
  • Oocytes / drug effects
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Peptides / chemical synthesis
  • Peptides / isolation & purification
  • Peptides / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Sciatic Neuropathy / drug therapy*
  • Sciatic Neuropathy / metabolism
  • Sciatic Neuropathy / physiopathology
  • Solid-Phase Synthesis Techniques
  • Xenopus laevis

Substances

  • Analgesics
  • CACNA1B protein, human
  • Calcium Channels, N-Type
  • Conotoxins
  • Peptides
  • Calcium