Nocistatin and nociceptin exert opposite effects on the excitability of central amygdala nucleus-periaqueductal gray projection neurons

Mol Cell Neurosci. 2009 Jan;40(1):76-88. doi: 10.1016/j.mcn.2008.09.003. Epub 2008 Oct 1.

Abstract

Central amygdala nucleus (CeA)-periaqueductal gray (PAG) pathway is the component of descending antinociceptive circuitry. Nociceptin/orphanin FQ (N/OFQ) and nocistatin (NST) produce supraspinal pronociceptive and antinociceptive effects, respectively. We hypothesized that opposite effects of N/OFQ and NST on supraspinal pain modulation result from their opposing effects on the excitability of CeA-PAG projection neurons. This hypothesis was tested by investigating electrophysiological effects of N/OFQ and NST on medial CeA neurons that project to PAG (CeA(M)-PAG). N/OFQ hyperpolarized CeA(M)-PAG projection neurons by enhancing inwardly rectifying potassium conductance. In contrast, NST depolarized CeA(M)-PAG neurons by causing the opening of TRPC cation channels via G(alphaq/11)-PLC-PKC pathway. CeA(M)-PAG neurons hyperpolarized by N/OFQ express CRF or neurotensin mRNA. NST-responsive CeA(M)-PAG neurons contain CRF or substance P mRNA. Our study provides the evidence that the molecular and cellular basis for opposite effects of N/OFQ and NST on supraspinal pain regulation is their opposing effects on the excitability of peptidergic CeA(M)-PAG neurons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amygdala / anatomy & histology
  • Amygdala / metabolism*
  • Animals
  • Efferent Pathways / anatomy & histology
  • Efferent Pathways / physiology*
  • Membrane Potentials / physiology
  • Neurons / cytology
  • Neurons / physiology*
  • Opioid Peptides / metabolism*
  • Pain / metabolism
  • Patch-Clamp Techniques
  • Periaqueductal Gray / anatomy & histology
  • Periaqueductal Gray / metabolism*
  • Potassium Channels, Inwardly Rectifying / metabolism
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Opioid Peptides
  • Potassium Channels, Inwardly Rectifying
  • nocistatin
  • nociceptin