Transient expression of a functional serotonin transporter in Merkel cells during late gestation and early postnatal rat development

• Published in: Experimental brain research 2000-02, Vol.130 (3), p.401-409
• Main Authors: HANSSON, S. R, HOFFMAN, B. J
• Format: Article
• Language: English
• Subjects: Aging; Animals; Biological and medical sciences; Carrier Proteins - drug effects; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cells, Cultured; Embryonic and Fetal Development; Fluoxetine - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Membrane Glycoproteins - drug effects; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membrane Transport Proteins; Merkel Cells - cytology; Merkel Cells - metabolism; Nerve Tissue Proteins; Quinacrine; Rats; RNA, Messenger - genetics; Serotonin - metabolism; Serotonin Plasma Membrane Transport Proteins; Skin - embryology; Skin - growth & development; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Transcription, Genetic; Vertebrates: nervous system and sense organs
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s002219900242

We and others have previously identified serotonin transporter mRNA throughout the trigeminal system in the whisker region, trigeminal ganglion, trigeminal nucleus and thalamic relay stations. In order to further implicate a role for the serotonin transporter in this sensory system, we have now characterized serotonin transporter gene expression and function in primary cultures from the rat snout, at several stages of gestation. In this study, we have demonstrated a transient expression of serotonin transporter mRNA in quinacrine-positive Merkel cells between embryonic day 16 and postnatal day 5. Peak levels of mRNA occurred at embryonic day 20 and postnatal day 1. Merkel cells in culture exhibited a transient, antidepressant-sensitive [3H]-serotonin uptake, which was maximal at a time in culture corresponding to embryonic day 22 (day of birth). This transient uptake of serotonin suggests a role for this monoamine during a critical time period of the developing trigeminal sensory system. Regulation of extracellular serotonin levels by transporter activity may reflect the specific formation of the merkel cell-sensory neuron complex in an analogous mechanism by which serotonin modulates synaptogenesis in the central nervous system.