Figure 2.
Light touch circuitry in the skin and gut. A) Skin light touch circuit is a two-receptor system, composed of the Merkel cell at the interface between epidermis and dermis, that relies on Piezo2 for mechanosensation and it uses synaptic 5-HT signaling to communicated with a mechanosensitive DRG neuron that also relies of Piezo2 for mechanosensation. (B) “GI touch” circuitry is composed of a mechanosensitive epithelial EC cell that may also rely on Piezo2 for mechanosensation and it is proposed to form a 5-HT synapse with a potentially mechanosensitive sensory neuron (either intrinsic IPAN or extrinsic that leads to the DRG or vagal nuclei).