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Enteric neuromodulators and mucus discharge in a fish infected with the intestinal helminth Pomphorhynchus laevis.

Bosi G, Shinn AP, Giari L, Sayyaf Dezfuli B - Parasit Vectors (2015)

Bottom Line: When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish.The presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera.The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Sciences and Technologies for Food Safety, Università degli Studi di Milano, St. Trentacoste 2, 20134, Milan, Italy. giampaolo.bosi@unimi.it.

ABSTRACT

Background: In vertebrates, the presence of enteric worms can induce structural changes to the alimentary canal impacting on the neuroendocrine system, altering the proper functioning of the gastrointestinal tract and affecting the occurrence and relative density of endocrine cells (ECs). This account represents the first immunohistochemistry and ultrastructure-based study which documents the intimate relationship between the intestinal mucous cells and ECs in a fish-helminth system, investigating the potential effects of enteric neuromodulators on gut mucus secretion/discharge.

Methods: A modified dual immunohisto- and histochemical staining technique was applied on intestinal sections from both infected and uninfected fish. Sections were incubated in antisera to a range of neuromodulators (i.e. leu-enkephalin, met-enkephalin, galanin and serotonin) and the glycoconjugate histochemistry of the mucous cells was determined using a subsequent alcian blue - periodic acid Schiff staining step. Dual fluorescent staining on sections prepared for confocal laser scanning microscopy and transmission electron microscopy were also used to document the relationship between ECs and mucous cells.

Results: From a total of 26 specimens of Squalius cephalus sampled from the River Paglia, 16 (i.e. 62 %) specimens were found to harbour an infection of the acanthocephalan Pomphorhynchus laevis (average intensity of infection 9.2 ± 0.8 parasites host(-1), mean ± standard error). When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish. The relationship between met-enkephalin-like or serotonin-like ECs and lectin DBA positive mucous cells was demonstrated through a dual fluorescent staining. The presence of tight connections and desmosomes between mucous and ECs in transmission electron micrographs provides further evidence of this intimate relationship.

Conclusions: The presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera. The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances.

No MeSH data available.


Related in: MedlinePlus

Histological sections from the intestines of Squalius cephalus infected with the acanthocephalan Pomphorhynchus laevis and treated with either the galanin (a-c) or the serotonin (d-e) antisera and a subsequent AB/PAS stain for mucous cells. There are numerous endocrine cells that are immunoreactive to the two antisera; many of these are close to the goblets of the mucous cells. The immunoreactive endocrine cells also display a range of differing morphologies including: the closed type (a, d, thick arrows), the open type with a mid-epithelial body (d-e, thin arrows), and, the open type with a “reservoir-like” appearance to them (a-c, e, arrowheads). Scale bars 20 μm
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Fig6: Histological sections from the intestines of Squalius cephalus infected with the acanthocephalan Pomphorhynchus laevis and treated with either the galanin (a-c) or the serotonin (d-e) antisera and a subsequent AB/PAS stain for mucous cells. There are numerous endocrine cells that are immunoreactive to the two antisera; many of these are close to the goblets of the mucous cells. The immunoreactive endocrine cells also display a range of differing morphologies including: the closed type (a, d, thick arrows), the open type with a mid-epithelial body (d-e, thin arrows), and, the open type with a “reservoir-like” appearance to them (a-c, e, arrowheads). Scale bars 20 μm

Mentions: Endocrine cells that were immunoreactive (IR) to each of the four anti-sera were seen in the intestinal sections of S. cephalus infected with P. laevis (Figs. 3 and 4). The number of IR cells for each anti-sera in the sections taken from acanthocephalan-infected hosts were significantly higher than those seen on sections from uninfected hosts (Figs. 3 and 4). Most of the IR ECs that were seen were of the open type, while the closed types were only encountered occasionally (Fig. 3c, f). Among the open type of IR ECs, there were a group of cells that were characteristically sub-triangular (Fig. 3c, f), and a second group that typically possessed a thin base, a large medial portion which contains the nucleus (Fig. 3f, i) or very few protuberances along its apical process that runs towards the epithelial surface (Fig. 3n). This second group of ECs will in this account be subsequently referred to as “reservoir-like cells” because of their general resemblance to select waterbodies and to help distinguish these cells from the first group of sub-triangular shaped ECs. The dual staining protocol combining a immunohistochemistry step with AB/PAS staining helps demonstrate that there is a close relationship between the ECs that immunoreactive to anti-leu-, -met-enkephalin, -galanin and -serotonin sera and the apical, large mucin granules of the mucous cells (Figs. 5 and 6).Fig. 3


Enteric neuromodulators and mucus discharge in a fish infected with the intestinal helminth Pomphorhynchus laevis.

Bosi G, Shinn AP, Giari L, Sayyaf Dezfuli B - Parasit Vectors (2015)

Histological sections from the intestines of Squalius cephalus infected with the acanthocephalan Pomphorhynchus laevis and treated with either the galanin (a-c) or the serotonin (d-e) antisera and a subsequent AB/PAS stain for mucous cells. There are numerous endocrine cells that are immunoreactive to the two antisera; many of these are close to the goblets of the mucous cells. The immunoreactive endocrine cells also display a range of differing morphologies including: the closed type (a, d, thick arrows), the open type with a mid-epithelial body (d-e, thin arrows), and, the open type with a “reservoir-like” appearance to them (a-c, e, arrowheads). Scale bars 20 μm
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4495775&req=5

Fig6: Histological sections from the intestines of Squalius cephalus infected with the acanthocephalan Pomphorhynchus laevis and treated with either the galanin (a-c) or the serotonin (d-e) antisera and a subsequent AB/PAS stain for mucous cells. There are numerous endocrine cells that are immunoreactive to the two antisera; many of these are close to the goblets of the mucous cells. The immunoreactive endocrine cells also display a range of differing morphologies including: the closed type (a, d, thick arrows), the open type with a mid-epithelial body (d-e, thin arrows), and, the open type with a “reservoir-like” appearance to them (a-c, e, arrowheads). Scale bars 20 μm
Mentions: Endocrine cells that were immunoreactive (IR) to each of the four anti-sera were seen in the intestinal sections of S. cephalus infected with P. laevis (Figs. 3 and 4). The number of IR cells for each anti-sera in the sections taken from acanthocephalan-infected hosts were significantly higher than those seen on sections from uninfected hosts (Figs. 3 and 4). Most of the IR ECs that were seen were of the open type, while the closed types were only encountered occasionally (Fig. 3c, f). Among the open type of IR ECs, there were a group of cells that were characteristically sub-triangular (Fig. 3c, f), and a second group that typically possessed a thin base, a large medial portion which contains the nucleus (Fig. 3f, i) or very few protuberances along its apical process that runs towards the epithelial surface (Fig. 3n). This second group of ECs will in this account be subsequently referred to as “reservoir-like cells” because of their general resemblance to select waterbodies and to help distinguish these cells from the first group of sub-triangular shaped ECs. The dual staining protocol combining a immunohistochemistry step with AB/PAS staining helps demonstrate that there is a close relationship between the ECs that immunoreactive to anti-leu-, -met-enkephalin, -galanin and -serotonin sera and the apical, large mucin granules of the mucous cells (Figs. 5 and 6).Fig. 3

Bottom Line: When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish.The presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera.The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Sciences and Technologies for Food Safety, Università degli Studi di Milano, St. Trentacoste 2, 20134, Milan, Italy. giampaolo.bosi@unimi.it.

ABSTRACT

Background: In vertebrates, the presence of enteric worms can induce structural changes to the alimentary canal impacting on the neuroendocrine system, altering the proper functioning of the gastrointestinal tract and affecting the occurrence and relative density of endocrine cells (ECs). This account represents the first immunohistochemistry and ultrastructure-based study which documents the intimate relationship between the intestinal mucous cells and ECs in a fish-helminth system, investigating the potential effects of enteric neuromodulators on gut mucus secretion/discharge.

Methods: A modified dual immunohisto- and histochemical staining technique was applied on intestinal sections from both infected and uninfected fish. Sections were incubated in antisera to a range of neuromodulators (i.e. leu-enkephalin, met-enkephalin, galanin and serotonin) and the glycoconjugate histochemistry of the mucous cells was determined using a subsequent alcian blue - periodic acid Schiff staining step. Dual fluorescent staining on sections prepared for confocal laser scanning microscopy and transmission electron microscopy were also used to document the relationship between ECs and mucous cells.

Results: From a total of 26 specimens of Squalius cephalus sampled from the River Paglia, 16 (i.e. 62 %) specimens were found to harbour an infection of the acanthocephalan Pomphorhynchus laevis (average intensity of infection 9.2 ± 0.8 parasites host(-1), mean ± standard error). When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish. The relationship between met-enkephalin-like or serotonin-like ECs and lectin DBA positive mucous cells was demonstrated through a dual fluorescent staining. The presence of tight connections and desmosomes between mucous and ECs in transmission electron micrographs provides further evidence of this intimate relationship.

Conclusions: The presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera. The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances.

No MeSH data available.


Related in: MedlinePlus