Topography of NPY-, somatostatin-, and VIP-immunoreactive, neuronal subpopulations in the guinea pig celiac-superior mesenteric ganglion and their projection to the pylorus

Abstract

The topography of the peptidergic neuronal subpopulations in the guinea pig celiac-superior mesenteric ganglion was studied analyzing the distribution of immunoreactivity to neuropeptide Y (NPY), somatostatin (SOM), and vasoactive intestinal polypeptide (VIP)/polypeptide HI (PHI). For comparison, the ganglion was also studied using antisera against the 2 catecholamine-synthesizing enzymes tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH). Approximately 65% of the neuronal cell bodies contained NPY-like immunoreactivity (NPY-LI), whereas 25% of the principal ganglion cells contained SOM-like immunoreactivity (SOM-LI). Though occasional cells were found to contain both NPY-LI and SOM-LI, these peptides had a complementary distribution in the ganglion, with NPY cells in the celiac poles and SOM cells in the superior mesenteric pole. The vast majority of both the NPY- and SOM-positive cells also contained TH-like immunoreactivity (TH-LI), confirming their catecholaminergic, presumably noradrenergic, nature. Some noradrenergic neurons seemed to lack NPY- and SOM-LI. Small numbers of VIP/PHI-containing cell bodies were found in areas where the NPY-immunoreactive neurons predominated. Many of the VIP/PHI-positive cells contained NPY-LI and occasionally also TH-LI. The immunohistochemical markers were also observed in fibers. Thus, a comparatively weak NPY-LI was seen in smooth fibers, probably representing axons and axon bundles. SOM-LI was seen in a similar type of fiber but also in more strongly fluorescent fibers with a varicose appearance. The latter fibers were observed only in the SOM-dominated part of the ganglion, often surrounding the ganglion cells. Varicose fibers with a similar distribution containing DBH-like immunoreactivity (DBH-LI) were also seen. In addition, DBH- and TH-LI were seen in smooth axonlike processes. VIP-positive fibers exhibited a very dense fiber network, almost exclusively related to the SOM cell-dominated part of the ganglion. The projection of the postganglionic sympathetic neurons was studied with special reference to the pylorus using a combination of retrograde axonal tracing and indirect immunofluorescence techniques. Seventy-two hours after injection of the fluorescent tracer Fast Blue into the pyloric sphincter, labeled neurons were found in the ganglion. By comparing the Fast Blue-labeled cells with the immunoreactive cell bodies, neurons containing both dye and NPY- or SOM-LI were observed. In elution-restaining experiments, it was established that the majority of these cells were also immunoreactive to TH, indicating that they produce noradrenaline.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical demonstration of choline acetyltransferase-immunoreactive preganglionic nerve fibers in guinea pig autonomic ganglia.

“…A large proportion of the noradrenergic ganglion cells in the sympathetic ganglia contain NPY (31,32), a 36 amino acid peptide (11). These cell bodies also exhibit a somewhat patchy distribution within the ganglion as shown in this study.…”

Neurochemical differentiation of functionally distinct populations of autonomic neurons

“…No chromaffin cells expressed detectable Som-IR. The morphology and neurochemical profile of these tightly packed cells was similar to the extraadrenal and adrenal chromaffin cells described in sympathetic ganglia of adult guinea pigs (Lindh et al, 1986;Macrae et al, 1986).…”

“…First, the three major functionally distinct subpopulations of catecholamine-synthesizing neurons in the coeliac ganglion can be distinguished by their neurochemical code: Vasoconstrictor neurons contain immunoreactivity (-IR) for neuropeptide Y (NPY) in addition to tyrosine hydroxylase (TH); neurons inhibiting gut secretion contain somatostatin-IR (Som-IR) as well as TH-IR; neurons inhibiting gut motility contain TH-IR but neither NPY-IR nor Som-IR (Hökfelt et al, 1977;Lundberg et al, 1982;Costa and Furness, 1984;Lindh et al, 1986;Macrae et al, 1986). Second, there is a clear topographical organisation of these neuronal subpopulations within the bilobed ganglion: Vasoconstrictor neurons are located predominantly in the lateral regions of each lobe; whereas neurons inhibiting secretion or motility are largely restricted to the medial region of the ganglion (Lindh et al, 1986;Macrae et al, 1986;Keast et al, 1993). Therefore, in this study, we used a range of immunohistochemical markers for cells of the sympathoadrenal lineage, general neuronal markers, transmitter-related markers, and Schwann cell markers, to determine the precise sequence of formation and differentiation of the coeliac ganglion and associated chromaffin tissue at embryonic and fetal stages of guinea pig development.…”

Sympathetic innervation of the ileocecal junction in horses

“…The greater numbers of dendrites is associated with the motility and secretion-controlling neurons receiving synaptic inputs directly from the gut, via IFANs, in addition to preganglionic neuron innervation, whereas the only substantial innervation received by vasoconstrictor neurons is from sympathetic preganglionic neurons (Gibbins et al, 2003). In other species that have been examined, neurons of different functions in PVG are clustered, and thus the endings of IFANs are also in patches in the ganglia (Lindh et al, 1986;Macrae et al, 1986). These endings have distinct chemical codes in other species, including CGRP-and nNOS-IR (Lindh et al, 1986;Macrae et al, 1986;Mann et al, 1995).…”