Journal of Neuroscience, Vol 6, 1628-1634, Copyright © 1986 by Society for Neuroscience
Immunohistochemical demonstration of GABAergic neurons in the enteric nervous system
KR Jessen, JM Hills and MJ Saffrey
Application of a highly specific antiserum against GABA to whole-mount
preparations of the guinea pig and rat myenteric plexus resulted in
discrete and unambiguous immunolabeling of a subpopulation of myenteric
neuronal cell bodies and fibers. The anti-GABA antiserum, which was raised
against GABA conjugated by glutaraldehyde to BSA, was applied to
glutaraldehyde-fixed whole mounts and subsequently visualized using the
peroxidase-antiperoxidase method. In the guinea pig ileum and colon,
immunoreactive varicose nerve fibers and scattered nerve cell bodies were
found within the myenteric plexus. Immunostained fibers were also seen in
the tertiary plexus and in the circular muscle, running parallel to the
muscle bundles. GABA immunoreactivity in these intramuscular nerves was
most pronounced in the colon. In the rat, immunoreactive fibers were
prominent throughout the myenteric plexus. They formed dense networks
within the myenteric ganglia, which also contained immunopositive nerve
cell bodies, and ran between them in the interconnecting nerves. Some
immunoreactive nerve fibers were seen in the circular muscle. Control
experiments using non-immune sera or adsorbed anti-GABA antiserum showed no
staining. These results add a definitive support to our previous suggestion
that GABA serves as an autonomic neurotransmitter in vertebrates. In
addition to the present immunohistochemical evidence, this hypothesis is
supported by biochemical, autoradiographic, transmitter release,
electrophysiological, and pharmacological studies on the enteric nervous
system of several species. It is now important to determine the functional
role of GABAergic neurons within the complex neuronal circuitry that
controls gut functions.