Co-localization of vasoactive intestinal polypeptide, gamma-aminobutyric acid and choline acetyltransferase in neocortical interneurons of the adult rat

Brain Res. 1997 May 23;757(2):209-17. doi: 10.1016/s0006-8993(97)00218-7.


Interneurons immunoreactive for vasoactive intestinal polypeptide (VIP) are integral elements of columnar organization patterns in the rat cerebral cortex. By application of the sensitive mirror technique, the co-localization of VIP with the classical inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and the acetylcholine-synthesizing enzyme, choline acetyltransferase (ChAT), was investigated in neocortical neurons. Furthermore, the frequency of co-localization of ChAT with GABA was determined. In a sample of 118 VIP-immunoreactive neurons, mostly from the primary somatosensory cortex, it was demonstrated that virtually all of them reveal immunoreactivity for GABA and, therefore, are to be GABAergic. Moreover, 34% of mostly bipolar, VIP-positive neurons contained ChAT and are, thus, supposedly cholinergic as well. Co-localization of VIP and ChAT varied according to cortical laminae. Finally, 88% of a total of 60 ChAT-immunoreactive neurons were also immunostained for GABA. It is concluded that almost all VIP-immunoreactive neurons and most of the cholinergic neurons in rat neocortex represent partly overlapping subpopulations of inhibitory interneurons utilizing GABA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cerebral Cortex / cytology
  • Cerebral Cortex / metabolism*
  • Choline O-Acetyltransferase / metabolism*
  • Immunohistochemistry
  • Interneurons / metabolism*
  • Male
  • Rats
  • Rats, Wistar
  • Tissue Distribution
  • Vasoactive Intestinal Peptide / metabolism*
  • gamma-Aminobutyric Acid / metabolism*


  • Vasoactive Intestinal Peptide
  • gamma-Aminobutyric Acid
  • Choline O-Acetyltransferase