Specific uptake of tritiated serotonin in the adult rat pancreas

Evidence for the presence of serotonergic fibers

S. B. Koevary, R. C. McEvoy, Efrain Azmitia

Research output: Contribution to journalArticle

Abstract

Fragments of adult rat pancreas were incubated in vitro with tritiated serotonin at concentrations from 10-8 to 10-7 M. The pancreas exhibited an uptake of serotonin which was saturable, with an uptake constant (Km) of 8.75 x 10-7 M, and a Vmax of 873 pmoles per gram. Specificity was determined by the addition of fluoxetine or norepinephrine to the reaction mixture, both at 10-5 M. Fluoxetine significantly reduced the 3H-5HT uptake, whereas norepinephrine was without effect. Metergoline (10-6 M), a specific 5-HT postsynaptic receptor blocker, similarly had no effect on the serotonin uptake in the pancreas. Radioautography of the fragments following uptake of tritiated serotonin (5 x 10-8 M) revealed silver-grain aggregates dispersed along blood vessels in the interstitial spaces of the exocrine and endocrine pancreas, areas known to be traversed by nerve fibers. There were no silver-grain aggregates over the exocrine or islet parenchymal cells. These data support the hypothesis that the pancreas is innervated by serotonergic fibers. Further evidence for this hypothesis was provided by a preliminary study demonstrating the presence of tryptophan hydroxylase in pancreatic homogenates. These serotonergic fibers may be involved in the regulation of pancreatic secretion.

Original languageEnglish (US)
Pages (from-to)361-368
Number of pages8
JournalAmerican Journal of Anatomy
Volume159
Issue number3
StatePublished - 1980

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Pancreas
Serotonin
Fluoxetine
Islets of Langerhans
Silver
Norepinephrine
Metergoline
Tryptophan Hydroxylase
Exocrine Pancreas
Serotonin Receptors
Autoradiography
Nerve Fibers
Blood Vessels

ASJC Scopus subject areas

  • Anatomy

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Specific uptake of tritiated serotonin in the adult rat pancreas : Evidence for the presence of serotonergic fibers. / Koevary, S. B.; McEvoy, R. C.; Azmitia, Efrain.

In: American Journal of Anatomy, Vol. 159, No. 3, 1980, p. 361-368.

Research output: Contribution to journalArticle

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