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Distribution of serotonergic and dopaminergic nerve fibers in the salivary gland complex of the cockroach Periplaneta americana.

Baumann O, Dames P, Kühnel D, Walz B - BMC Physiol. (2002)

Bottom Line: Salivary duct segments close to the acini are locally associated with dopaminergic and serotonergic fibers, whereas duct segments further downstream have only dopaminergic fibers on their surface and within the epithelium.Our results suggest that dopamine is released on the acinar surface, close to peripheral cells, and along the entire duct system.Moreover, the presence of serotonergic and dopaminergic fiber terminals on the reservoir indicates that the functions of this structure are also regulated by dopamine and serotonin.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut für Biochemie und Biologie, Zoophysiologie, Universität Potsdam, Lennéstr, 7a, 14471 Potsdam, Germany. obaumann@rz.uni-potsdam.de

ABSTRACT

Background: The cockroach salivary gland consists of secretory acini with peripheral ion-transporting cells and central protein-producing cells, an extensive duct system, and a pair of reservoirs. Salivation is controlled by serotonergic and dopaminergic innervation. Serotonin stimulates the secretion of a protein-rich saliva, dopamine causes the production of a saliva without proteins. These findings suggest a model in which serotonin acts on the central cells and possibly other cell types, and dopamine acts selectively on the ion-transporting cells. To examine this model, we have analyzed the spatial relationship of dopaminergic and serotonergic nerve fibers to the various cell types.

Results: The acinar tissue is entangled in a meshwork of serotonergic and dopaminergic varicose fibers. Dopaminergic fibers reside only at the surface of the acini next to the peripheral cells. Serotonergic fibers invade the acini and form a dense network between central cells. Salivary duct segments close to the acini are locally associated with dopaminergic and serotonergic fibers, whereas duct segments further downstream have only dopaminergic fibers on their surface and within the epithelium. In addition, the reservoirs have both a dopaminergic and a serotonergic innervation.

Conclusion: Our results suggest that dopamine is released on the acinar surface, close to peripheral cells, and along the entire duct system. Serotonin is probably released close to peripheral and central cells, and at initial segments of the duct system. Moreover, the presence of serotonergic and dopaminergic fiber terminals on the reservoir indicates that the functions of this structure are also regulated by dopamine and serotonin.

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Distribution of serotonergic nerve fibers on the salivary gland acini Whole-mounts of salivary glands were double-labeled with anti-serotonin (red) and BODIPY FL phallacidin (blue), and imaged by confocal microscopy. Each image shows the sum of 8 consecutive optical sections (inter-section distance 0.35 μm), representing a total thickness of 2.8 μm. Serotonergic fibers and fiber endings (white arrowhead) form a network on the acinar surface (a) over the peripheral cells (asterisks). The fibers extend deep into the acini (yellow arrowheads) between the central cells that are identified by short, phallotoxin-labeled microvilli (arrows) on their luminal surface. Scale bar = 50 μm
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Figure 4: Distribution of serotonergic nerve fibers on the salivary gland acini Whole-mounts of salivary glands were double-labeled with anti-serotonin (red) and BODIPY FL phallacidin (blue), and imaged by confocal microscopy. Each image shows the sum of 8 consecutive optical sections (inter-section distance 0.35 μm), representing a total thickness of 2.8 μm. Serotonergic fibers and fiber endings (white arrowhead) form a network on the acinar surface (a) over the peripheral cells (asterisks). The fibers extend deep into the acini (yellow arrowheads) between the central cells that are identified by short, phallotoxin-labeled microvilli (arrows) on their luminal surface. Scale bar = 50 μm

Mentions: The distribution of serotonergic and dopaminergic fibers within the salivary gland complex was probed by confocal fluorescence microscopy of whole-mount preparations stained with anti-serotonin or anti-dopamine. In order to locate the various acinar cells and to provide a spatial reference for the position of the immunoreactive fibers within the tissue, specimens were co-labeled with fluorochrome-tagged phallacidin, a probe for actin filaments [2]. Peripheral cells with their densely packed, long microvilli are arranged in pairs that are visualized as brightly fluorescent "bow ties" in phallotoxin-stained preparations (Figs. 3c, 4, 7, 8). The acinar lumen surrounded by central cells with their short microvilli is delimited by weak labeling with phallotoxin (Figs. 4d,4e,4f, 7d,7e,7f, 8a,8d).


Distribution of serotonergic and dopaminergic nerve fibers in the salivary gland complex of the cockroach Periplaneta americana.

Baumann O, Dames P, Kühnel D, Walz B - BMC Physiol. (2002)

Distribution of serotonergic nerve fibers on the salivary gland acini Whole-mounts of salivary glands were double-labeled with anti-serotonin (red) and BODIPY FL phallacidin (blue), and imaged by confocal microscopy. Each image shows the sum of 8 consecutive optical sections (inter-section distance 0.35 μm), representing a total thickness of 2.8 μm. Serotonergic fibers and fiber endings (white arrowhead) form a network on the acinar surface (a) over the peripheral cells (asterisks). The fibers extend deep into the acini (yellow arrowheads) between the central cells that are identified by short, phallotoxin-labeled microvilli (arrows) on their luminal surface. Scale bar = 50 μm
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC117224&req=5

Figure 4: Distribution of serotonergic nerve fibers on the salivary gland acini Whole-mounts of salivary glands were double-labeled with anti-serotonin (red) and BODIPY FL phallacidin (blue), and imaged by confocal microscopy. Each image shows the sum of 8 consecutive optical sections (inter-section distance 0.35 μm), representing a total thickness of 2.8 μm. Serotonergic fibers and fiber endings (white arrowhead) form a network on the acinar surface (a) over the peripheral cells (asterisks). The fibers extend deep into the acini (yellow arrowheads) between the central cells that are identified by short, phallotoxin-labeled microvilli (arrows) on their luminal surface. Scale bar = 50 μm
Mentions: The distribution of serotonergic and dopaminergic fibers within the salivary gland complex was probed by confocal fluorescence microscopy of whole-mount preparations stained with anti-serotonin or anti-dopamine. In order to locate the various acinar cells and to provide a spatial reference for the position of the immunoreactive fibers within the tissue, specimens were co-labeled with fluorochrome-tagged phallacidin, a probe for actin filaments [2]. Peripheral cells with their densely packed, long microvilli are arranged in pairs that are visualized as brightly fluorescent "bow ties" in phallotoxin-stained preparations (Figs. 3c, 4, 7, 8). The acinar lumen surrounded by central cells with their short microvilli is delimited by weak labeling with phallotoxin (Figs. 4d,4e,4f, 7d,7e,7f, 8a,8d).

Bottom Line: Salivary duct segments close to the acini are locally associated with dopaminergic and serotonergic fibers, whereas duct segments further downstream have only dopaminergic fibers on their surface and within the epithelium.Our results suggest that dopamine is released on the acinar surface, close to peripheral cells, and along the entire duct system.Moreover, the presence of serotonergic and dopaminergic fiber terminals on the reservoir indicates that the functions of this structure are also regulated by dopamine and serotonin.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut für Biochemie und Biologie, Zoophysiologie, Universität Potsdam, Lennéstr, 7a, 14471 Potsdam, Germany. obaumann@rz.uni-potsdam.de

ABSTRACT

Background: The cockroach salivary gland consists of secretory acini with peripheral ion-transporting cells and central protein-producing cells, an extensive duct system, and a pair of reservoirs. Salivation is controlled by serotonergic and dopaminergic innervation. Serotonin stimulates the secretion of a protein-rich saliva, dopamine causes the production of a saliva without proteins. These findings suggest a model in which serotonin acts on the central cells and possibly other cell types, and dopamine acts selectively on the ion-transporting cells. To examine this model, we have analyzed the spatial relationship of dopaminergic and serotonergic nerve fibers to the various cell types.

Results: The acinar tissue is entangled in a meshwork of serotonergic and dopaminergic varicose fibers. Dopaminergic fibers reside only at the surface of the acini next to the peripheral cells. Serotonergic fibers invade the acini and form a dense network between central cells. Salivary duct segments close to the acini are locally associated with dopaminergic and serotonergic fibers, whereas duct segments further downstream have only dopaminergic fibers on their surface and within the epithelium. In addition, the reservoirs have both a dopaminergic and a serotonergic innervation.

Conclusion: Our results suggest that dopamine is released on the acinar surface, close to peripheral cells, and along the entire duct system. Serotonin is probably released close to peripheral and central cells, and at initial segments of the duct system. Moreover, the presence of serotonergic and dopaminergic fiber terminals on the reservoir indicates that the functions of this structure are also regulated by dopamine and serotonin.

Show MeSH
Related in: MedlinePlus