Nocistatin inhibits 5-hydroxytryptamine release in the mouse neocortex via presynaptic Gi/o protein linked pathways

Br J Pharmacol. 2007 Oct;152(4):549-55. doi: 10.1038/sj.bjp.0707377. Epub 2007 Jul 9.


Background and purpose: Nocistatin (NST) is a neuropeptide generated from cleavage of the nociceptin/orphanin FQ (N/OFQ) precursor. Evidence has been presented that NST acts as a functional antagonist of N/OFQ, although NST receptor and transduction pathways have not yet been identified. We previously showed that N/OFQ inhibited [(3)H]5-hydroxytryptamine ([(3)H]5-HT) release from mouse cortical synaptosomes via activation of NOP receptors. We now investigate whether NST regulates [(3)H]5-HT release in the same preparation.

Experimental approach: Mouse and rat cerebrocortical synaptosomes in superfusion, preloaded with [(3)H]5-HT and stimulated with 1 min pulses of 10 mM KCl, were used.

Key results: Bovine NST (b-NST) inhibited the K(+)-induced [(3)H]5-HT release, displaying similar efficacy but lower potency than N/OFQ. b-NST action underwent concentration-dependent and time-dependent desensitization, and was not prevented either by the NOP receptor antagonist [Nphe(1) Arg(14),Lys(15)]N/OFQ(1-13)-NH(2) (UFP-101) or by the non-selective opioid receptor antagonist, naloxone. Contrary to N/OFQ, b-NST reduced [(3)H]5-HT release from synaptosomes obtained from NOP receptor knockout mice. However, both N/OFQ and NST were ineffective in synaptosomes pre-treated with the G(i/o) protein inhibitor, Pertussis toxin. NST-N/OFQ interactions were also investigated. Co-application of maximal concentrations of both peptides did not result in additive effects, whereas pre-application of maximal b-NST concentrations partially attenuated N/OFQ inhibition.

Conclusions and implications: We conclude that b-NST inhibits [(3)H]5-HT release via activation of G(i/o) protein linked pathways, not involving classical opioid receptors and the NOP receptor. The present data strengthen the view that b-NST is, per se, a biologically active peptide endowed with agonist activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics, Opioid / pharmacology
  • Animals
  • Cattle
  • Dose-Response Relationship, Drug
  • Electric Stimulation
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism*
  • Mice
  • Naloxone / pharmacology
  • Narcotic Antagonists / pharmacology
  • Neocortex / drug effects*
  • Neocortex / metabolism
  • Opioid Peptides / pharmacology*
  • Potassium Chloride / pharmacology
  • Serotonin / metabolism*
  • Serotonin Antagonists / pharmacology
  • Synaptosomes / drug effects
  • Synaptosomes / metabolism
  • Time Factors
  • Tritium


  • (Nphe(1),Arg(14),Lys(15))N-OFQ NH(2)
  • Analgesics, Opioid
  • Narcotic Antagonists
  • Opioid Peptides
  • Serotonin Antagonists
  • nocistatin
  • Tritium
  • Serotonin
  • Naloxone
  • Potassium Chloride
  • GTP-Binding Protein alpha Subunits, Gi-Go