Exocytotic release of vasoative intestinal polypeptide and serotonin from mucosal nerve fibres and endocrine cells of the intestine of the goldfish (Carassius auratus) and the tilapia (Oreochromis mossambicus): an ultrastructural study.
In earlier studies were determined the effect, presence and ultrastructure of vasoactive intestinal polypeptide (VIP) and 5-hydroxytryptamine (5-HT)-containing nerve fibres in the tilapia and goldfish intestinal mucosa. 5-HT-labelled varicosities were found close to the epithelial cells; however, synaptic membrane specializations have never been observed. VIP-like immunoreactive nerve fibres appear to be located less frequently close to the goldfish epithelium, as in the tilapia intestine, in which the distance between the VIP- or 5-HT-labelled varicosities and the epithelial cells was also rather large (more than 2 micros). To establish a possible role of VIP and 5-HT as neurotransmitters involved in the regulation of fish intestinal epithelium both electron microscopical and immunoelectron microscopical methods were used to visualize the release of 5-HT and VIP from nerve fibres. We found exocytoses from VIP-ergic and serotonergic varicosities in the muscle layers of both fish. Directly underneath the intestinal epithelium of the goldfish, it was demonstrated that 5-HT could be released from scarce varicosities. The release of 5-HT in the tilapia intestinal mucosa could only be observed from endocrine cells.
Kiliaan
A J
AJ
Institute of Neurobiology, University of Amsterdam, The Netherlands.
Scholten
G
G
Groot
J A
JA
D001078:APUD Cells / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D017615:Enteric Nervous System / Q000378:metabolism / Q000648:ultrastructure*; D005089:Exocytosis; D006054:Goldfish; D007413:Intestinal Mucosa / Q000294:innervation / Q000378:metabolism / Q000648:ultrastructure*; D016253:Microscopy, Immunoelectron; D012701:Serotonin / Q000378:metabolism*; D017210:Tilapia; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
D012701:Serotonin; D014660:Vasoactive Intestinal Peptide