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Serotonin synthesis in adrenochromaffin cells
C Delarue1, D Becquet, S Idres
1European Institute for Peptide Research, Laboratory of Molecular Endocrinology, CNRS URA 650, UA INSERM, University of Rouen, Mont-Saint-Aignan, France.
Neuroscience
|January 1, 1992
Summary
Frog adrenal glands synthesize serotonin within chromaffin cells. This amine stimulates hormone release, indicating adrenal chromaffin cells function as serotonergic paraneurons, a novel finding in adrenal gland research.
Area of Science:
- Endocrinology
- Neuroscience
- Amphibian Biology
Background:
- Amphibian inter-renal glands feature chromaffin and steroidogenic cells with paracrine communication.
- Serotonin is found in frog adrenochromaffin cells and stimulates corticosterone/aldosterone secretion.
Purpose of the Study:
- To investigate the origin of serotonin within frog chromaffin cells.
- To confirm the presence and activity of serotonin synthesis pathways in the amphibian adrenal gland.
Main Methods:
- Incubation of frog inter-renal slices with 3H-labelled tryptophan.
- Measurement of serotonin and 5-hydroxyindoleacetic acid synthesis.
- Assessment of serotonin release influenced by KCl and fluoxetine.
- Incubation with non-labelled tryptophan and 5-hydroxytryptophan.
Main Results:
- Frog inter-renal slices synthesized serotonin and 5-hydroxyindoleacetic acid from tryptophan.
- Serotonin release was enhanced by KCl and inhibited by fluoxetine, indicating uptake.
- 5-hydroxytryptophan yielded higher synthesis rates than tryptophan.
- Tryptophan-5-hydroxylase activity was detected in the adrenal gland.
Conclusions:
- Frog chromaffin cells synthesize and release serotonin, functioning as serotonergic paraneurons.
- This study provides the first evidence of tryptophan-5-hydroxylase activity in the adrenal gland.
- The findings elucidate a novel paracrine signaling pathway in amphibian adrenal function.