Immunohistochemical identification of serotonin and noradrenalin containing structures within the nerve plexuses of rat ileum.
The distribution of 5-hydroxytryptamine (= serotonin = 5-HT) and noradrenalin (NA) in the enteric plexuses of the rat ileum was studied using immunocytochemical techniques. 5-HT-like immunoreactive fibers were observed only in the myenteric plexus, surrounding the ganglionic cells, which are all unreactive. NA-like immunoreactive fibers were present in all layers of the ileum: in the myenteric plexus, they were localized in the nodes, forming a network all round the neuronal perikarya; in the Meissner plexus, positive axons were arranged in a delicate network; submucosal blood vessels were often provided by NA-immunopositive nerve plexus. In the inner circular muscle layer the immunoreactive NA-positive fibers run within nerve bundles mainly parallel with the smooth muscle cells. The 5-HT immunoreactive material was depleted by treatment with reserpine; depletion of NA by 6-hydroxy-dopamine was also observed; on the contrary, no depletion of 5-HT by 5,7-dihydroxytryptamine was obtained. To confirm the validity of these results, specific antibodies to tyrosine hydroxylase (TH) and aromatic 1-aminoacid-decarboxylase (AADC), two enzymes involved in the synthesis of catecholamines, were used. In conclusion these experiments indicate that 5-HT is present, probably as a transmitter, in certain fibres of the rat myenteric plexus, distributed in a way similar to that of NA-containing fibers. However, at variance with NA fibers, 5-HT fibers are not present in other regions of the intestine wall.
Elbal
M T
MT
Departamento de Biologia Celular, Universidad de Murcia, Espana.
Taxi
J
J
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D005260:Female; D006892:Hydroxydopamines / Q000494:pharmacology; D007082:Ileum / Q000737:chemistry* / Q000187:drug effects / Q000294:innervation; D008297:Male; D009197:Myenteric Plexus / Q000737:chemistry* / Q000187:drug effects; D009638:Norepinephrine / Q000032:analysis*; D016627:Oxidopamine; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology; D012701:Serotonin / Q000032:analysis*; D014364:Tryptophan / Q000494:pharmacology
D006892:Hydroxydopamines; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D012110:Reserpine; D014364:Tryptophan; D016627:Oxidopamine; D010293:Pargyline; D009638:Norepinephrine