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Merkel Cells in Somatosensation

  • Published:
Chemosensory Perception

Abstract

Merkel cells are rare epidermal cells whose function in the skin is still debated. These cells localize to highly touch-sensitive areas of vertebrate epithelia, including palatine ridges, touch domes, and finger tips. In most cases, Merkel cells complex with somatosensory afferents to form slowly adapting touch receptors; it is unclear, however, whether mechanosensory transduction occurs in the Merkel cell, the somatosensory afferent, or both. Classic anatomical results suggest that Merkel cells are sensory cells that transduce mechanical stimuli and then communicate with sensory afferents via neurotransmission. This model is supported by recent molecular, immunohistochemical and physiological studies of Merkel cells in vitro and in intact tissues. For example, Merkel cells express essential components of presynaptic machinery, including molecules required for release of the excitatory neurotransmitter glutamate. Moreover, Merkel cells in vitro and in vivo are activated by mechanical stimuli, including hypotonic-induced cell swelling. Although these findings support the hypothesis that Merkel cells are sensory receptor cells, a definitive demonstration that Merkel cells are necessary and sufficient to transduce touch awaits future studies.

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Abbreviations

PC:

Pacinian corpuscle

RA:

rapidly adapting

SAI:

slowly adapting type I

SAII:

slowly adapting type II

5-HT:

5-hydroxytryptamine/serotonin

SNARE:

soluble N ethylmaleimide sensitive factor attachment receptor

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Acknowledgment

We thank Ms. Jennifer LaRey for providing valuable comments on the manuscript. Electrophysiological recordings were performed by E.A.L. in the laboratory of Dr. Jonathon Howard at the University of Washington. The authors were supported by grants from the Gillson Longenbaugh Foundation (to E.A.L.), the National Institutes of Health (NIAMS grant AR051219 to E.A.L.), and the National Science Foundation (graduate fellowship to H.H.).

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  1. Neuroscience Graduate Program, University of California, San Francisco, CA, 94158-2324, USA

    Henry Haeberle

  2. Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA

    Henry Haeberle

  3. Departments of Neuroscience, Molecular Physiology and Biophysics, and Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Smith Building, room S636A, Mail stop BCM295, Houston, TX, 77030, USA

    Ellen A. Lumpkin

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Haeberle, H., Lumpkin, E.A. Merkel Cells in Somatosensation. Chem. Percept. 1, 110–118 (2008). https://doi.org/10.1007/s12078-008-9012-6

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