Collateral projections from the lateral parabrachial nucleus to the paraventricular thalamic nucleus and the central amygdaloid nucleus in the rat

Neurosci Lett. 2016 Aug 26:629:245-250. doi: 10.1016/j.neulet.2016.07.017. Epub 2016 Jul 14.

Abstract

Combined the retrograde double tracing with immunofluorescence histochemical staining, we examined the neurons in the lateral parabrachial nucleus (LPB) sent collateral projections to the paraventricular thalamic nucleus (PVT) and central amygdaloid nucleus (CeA) and their roles in the nociceptive transmission in the rat. After the injection of Fluoro-gold (FG) into the PVT and tetramethylrhodamine-dextran (TMR) into the CeA, respectively, FG/TMR double-labeled neurons were observed in the LPB. The percentages of FG/TMR double-labeled neurons to the total number of FG- or TMR-labeled neurons were 6.18% and 9.09%, respectively. Almost all of the FG/TMR double-labeled neurons (95%) exhibited calcitonin gene-related peptide (CGRP) immunoreactivity. In the condition of neuropathic pain, 94% of these neurons showed FOS immunoreactivity. The present data indicates that some of CGRP-expressing neurons in the LPB may transmit nociceptive information toward the PVT and CeA by way of axon collaterals.

Keywords: Calcitonin gene-related peptide; Central amygdaloid nucleus; Collateral projection; FOS; Lateral parabrachial nucleus; Paraventricular thalamic nucleus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons
  • Central Amygdaloid Nucleus / cytology*
  • Male
  • Midline Thalamic Nuclei / cytology*
  • Neural Pathways / cytology
  • Neuroanatomical Tract-Tracing Techniques
  • Neurons / cytology*
  • Parabrachial Nucleus / cytology*
  • Rats
  • Rats, Sprague-Dawley