Journal of Neuroscience, Vol 7, 1717-1727, Copyright © 1987 by Society for Neuroscience
Neuropeptide Y-like immunoreactivity in bullfrog sympathetic ganglia is restricted to C cells
JP Horn, WD Stofer and S Fatherazi
Staining the entire chain of paravertebral sympathetic ganglia in the
bullfrog with an antiserum against porcine neuropeptide Y (NPY) revealed
that, in each ganglion, a subpopulation of neurons expresses NPY-like
immunoreactivity. Chromaffin cells in the sympathetic ganglia and in the
adrenal gland were not stained by the anti-NPY serum. Since neurons in
ganglia 9 and 10 of the sympathetic chain can be classified into 3 distinct
groups on the basis of established electrophysiological criteria, we sought
to identify the neurons in these ganglia that contain the NPY-like
immunoreactivity. Accordingly, a series of cells was impaled with
intracellular recording electrodes, identified as either fast B-, slow B-,
or C-type neurons, filled with Lucifer yellow, and then processed with the
anti-NPY serum for indirect immunofluorescence. These double-label
experiments revealed that NPY- like immunoreactivity is expressed
selectively by C-type sympathetic neurons. Counts of immunoreactive cells
indicate that 55% of the neurons in ganglia 9 and 10 are C cells. A major
target of the C cells appears to be the vasculature. In 3 different tissues
innervated by sympathetic neurons, namely, the adrenal gland, the sartorius
muscle, and the skin of the hindlimb, axons containing NPY-like
immunoreactivity were found primarily within or near blood vessels. Within
14-60 d after extirpation of sympathetic ganglia 9 and 10, most
immunoreactive axons in the sartorius muscle and nearby skin disappeared.
In conjunction with other evidence, the possibility arises that sympathetic
C cells function as vasomotor neurons that use an NPY- like substance and
epinephrine as cotransmitters.