Journal of Neuroscience, Vol 7, 3117-3130, Copyright © 1987 by Society for Neuroscience
Neuronal colocalization of peptides, catecholamines, and catecholamine- synthesizing enzymes in guinea pig paracervical ganglia
JL Morris and IL Gibbins
Department of Anatomy and Histology, Flinders University of South Australia, Bedford Park.
The patterns of colocalization of neuropeptides, catecholamines, and
catecholamine-synthesizing enzymes were examined in principal neurons and
nerve terminals in guinea pig paracervical ganglia using a double- labeling
immunohistochemical procedure. A small proportion of nerve cell bodies
(less than 10%) had the characteristics of catecholamine- synthesizing
neurons and presumably were noradrenergic. Another 50% of the nerve cell
bodies contained immunoreactivity (IR) to dopamine-beta- hydroxylase (DBH),
but did not have any other characteristics of noradrenergic neurons; they
did not contain detectable catecholamines, or IR to dopa decarboxylase
(DDC) or tyrosine (TH) hydroxylase, nor did they take up exogenous
catecholamines. Half of the catecholamine neurons had neuropeptide Y
(NPY)-IR, and a small number (0.5% total neurons) had somatostatin
(Som)-IR. Most of the non-noradrenergic neurons with DBH-IR (40-50% total
neurons) contained IR for dynorphin (Dyn), NPY, and vasoactive intestinal
peptide (VIP), and about half of them (20-25% total) also contained Som-IR.
Ten to twenty percent of neurons contained IR to Som, but not to any other
antigen examined here. Nerve terminals with substance P (SP)-IR or
enkephalin (Enk)-IR were prominent in all ganglia. SP-IR fibers formed
dense baskets only around those neurons with DBH/Dyn/NPY/VIP (+/- Som)-IR,
while fibers with very bright Enk-IR were associated selectively with those
neurons with Som-IR alone. In addition, most TH-IR nerve cell bodies were
surrounded by NPY-IR varicose nerve fibers. In conclusion, this analysis of
combinations of peptides and enzymes contained in principal neurons of the
paracervical ganglia allows us to identify as many as 11 different neuron
populations. The functional significance of the presence of the same
neuropeptide (e.g., NPY) in different neuron populations is as yet unknown.
Some of these classes of neurons are associated specifically with
immunohistochemically distinct types of presynaptic nerve fibers, which
suggests that different immunohistochemically defined classes of neurons
represent different functional pathways.