Enteric nerve fibres in the intestinal mucosa of an elasmobranch

Abstract

The presence and distribution of some neuropeptides and serotonin was investigated in the enteric nervous system of the dogfish Scyliorhinus canicula by immunohistochemical and ultrastructural methods. At the light microscope, whole mount preparations showed numerous VIP-and PHI-immunopositive nerve fibres in the lamina propria and muscolaris mucosae, while the few bombesin-and serotonin-immunopositive nerve fibres were particularly located in the blood vessel wall near smooth muscular fibres. At the electron microscope, numerous unmyelinated nerve fibres were seen in the same localization as neuropeptide-and serotoninimmunoreactivities. The terminal axons showed vesicle-containing varicosities which were alternated with narrow tracts characterized by neurofilaments and neurotubules. Six different kinds of vesicles were identified according to their size and electron-density. These different vesicles often occurred in the same varicosity, suggesting the presence of more than one peptide, together with classic neurotransmitters, in the same nerve terminal.

Dietary Lipid Modulation of Intestinal Serotonin in Ballan Wrasse (Labrus bergylta)—In Vitro Analyses

“…At the same time, a similar organization of the development of 5-HT cells within the spinal cord and brain (23,24) and a similar organization of the enteric nervous system (25,26) have been reported in teleost and cartilaginous fish. Besides, the organization of the brain serotonergic system in many fish species is considered similar to that in other vertebrates at different levels; for instance, the mRNA expression of enzymes and transporters involved in the serotonergic system is similarly regulated within vertebrates, as well as the strong implication of 5-HT in controlling GI motility (16).…”