Immunohistochemical reactions of receptors to met-enkephalin, VIP, substance P, and CGRP located on Merkel cells in the rat sinus hair follicle.

The role of Merkel cells in type I cutaneous mechanoreceptors remains enigmatic though mechanical transduction or neuromodulation function has been proposed. It has been shown that mammalian Merkel cells express immunohistochemical reactions of met-enkephalin, VIP, substance P, and CGRP, though the reactivity differs between species. If any one of these peptides acts as a transmitter or modulator for Merkel nerve terminals, these structures must have a specific receptor for the substance.

Receptors and transporter for serotonin in Merkel cell-nerve endings in the rat sinus hair follicle. An immunohistochemical study.

Serotonin (5-HT) has been a candidate for neurotransmitters in cutaneous type I mechanoreceptors (i.e., Merkel cell-nerve endings).

Immunohistochemical expressions of mGluR5, P2Y2 receptor, PLC-beta1, and IP3R-I and -II in Merkel cells in rat sinus hair follicles.

We previously found that Merkel cells (MCs) of the rat and monkey show a strong immunoreaction of the alpha-subunit of Gq protein. The Galphaq-subunit isoform activates isozymes of phospholipase C-beta (PLC-beta), which produces inositol-(1,4,5)-triphosphate (IP3) which mobilizes intracellular Ca(++) from calcium stores via IP3 receptors. Glutamate and adenosine triphosphate (ATP), which are candidates for neurotransmitters in Merkel endings, are known to couple to Galphaq.

Recent progress in studies on Merkel cell biology.

Merkel cells ubiquitously distribute in the skin of vertebrates, from cyclostomes to mammals. It is well known that mammalian Merkel cells coupled with axon terminals of type I sensory nerve fibers form slowly adapting mechanoreceptors, Merkel endings, within the epidermis. However, there are still many unresolved problems in the biology of Merkel cells.