Indirect triple-labeling immunohistochemical techniques were used to identify the presence of neuropeptide serine (NPS), neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP), and neuropeptide Y (NPY) in the ganglionated plexuses of the human gallbladder.
The ganglionated plexuses examined in this report are composed of irregularly shaped neurons that inhabit the lamina propria and the muscularis propria. Most of the neurons of the lamina propria and muscularis were triple-labeled NPS, nNOS, and NPY. Moderate numbers of neurons in the lamina propria were immunopositive for NPS and nNOS (NPY negative). This same combination of immunopositivity was also seen in the muscularis. Inversely, only a few nerve cells were found to be NPS- and NPY-IR (nNOS negative) in both layers. A small population of the neurons in both layers was observed to possess singular positivity for nNOS-, NPS-, or NPY-IR.
Triple-labeled NPS-, nNOS- and VIP-IR neurons were often observed in all layers of the gallbladder but comparatively less frequently seen when compared to the previous combination. In the lamina propria, a modest number of nerve cells were NPS- and VIP-IR. A similar observation was made of the nerve cells in the muscularis. Of all the sections examined, coexisting NPS- and NOS-, or NOS- and VIP-IR neurons were not observed. Single-labeled VIP- or NPS-IR neurons were detected. However, no single labeled nNOS-IR neurons were ever seen. Our present research has demonstrated that NPS, along with many other neuropeptides and neurotransmitters, may play an essential role in the intrinsic regulation of the human gallbladder.