Co-localization of Trk neurotrophin receptors and regulatory peptides in the endocrine cells of the teleostean stomach.
Recently it has been observed that a subpopulation of gut endocrine cells in vertebrates express Trk-like proteins, suggesting that neurotrophins could regulate the synthesis and storage of amines and peptides of these cells. Nevertheless, the peptides and amines present in the endocrine cells that express Trks have not been characterized. In this study we used immunohistochemistry to investigate the occurrence of Trk-like proteins (TrkA-like, TrkB-like and TrkC-like) and the possible co-localization of these with peptides and/or biogenic amines in the endocrine cells of the stomach of three teleost (bass, gilt-head and scorpionfish). No TrkA-like immunoreactivity (IR) was detected in the stomach of these species, whereas TrkB-like IR and TrkC-like IR were observed in numerous cells of the gastric epithelium. TrkB-like immunoreactive cells were present in all three species examined, and were particularly abundant in the blind sac. Conversely, TrkC-like immunoreactive cells were found only in the bass stomach, apparently co-localized with TrkB-like IR. TrkB-like IR was found co-localized with somatostatin IR in scorpionfish, and with somatostatin and CGRP IR in gilt-head and bass. Gastric endocrine cells expressing 5-HT, glucagon, insulin, met-, leu-enkephalin, substance P, PYY, VIP, CCK, NPY, bombesin and motilin were unreactive for Trk-like proteins. The present results provide direct evidence for the occurrence of Trk-like neurotrophin receptor proteins in a subpopulation of the teleostean gastric endocrine cells and suggest that neurotrophins could regulate, as in neurons, the expression of some neuropeptides such as somatostatin and CGRP.
De Girolamo
P
P
Dipartimento di Strutture, Funzioni, e Tecnologie Biologiche, Università di Napoli "Federico II," 80137 Naples, Italy. degirola@unina.it
Lucini
C
C
Vega
J A
JA
Andreozzi
G
G
Coppola
L
L
Castaldo
L
L
D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D019858:Enteroendocrine Cells / Q000166:cytology / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D010473:Perciformes / Q000378:metabolism*; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism*; D013045:Species Specificity
D015415:Biomarkers; D009479:Neuropeptides; D017475:Receptors, Nerve Growth Factor