Touch Induces Local Mechanical Strain in C. elegans Sensory Neurons

Abstract Cutaneous mechanosensory neurons are activated by mechanical loads applied to the skin likely to result in local mechanical strain within sensory neurons. Using a microfluidics device to deliver controlled stimuli to intact animals and large, immobile and fluorescent protein-tagged mitochondria as fiducial markers in the touch receptor neurons (TRNs), we visualized and measured touch-induced mechanical strain in C. elegans worms. At steady-state, touch stimuli sufficient to activate TRNs induce an average strain of 3.1% at the center of the actuator and that this strain decays to near zero at the edges of the actuator. We also measured strain in animals carrying mutations affecting links between the extracellular matrix (ECM) and the TRNs, but could not detect any differences in touch-induced mechanical strain between wild-type and mutant animals. Collectively, these results demonstrate that touching the skin induces local mechanical strain in intact animals and suggest that a fully intact ECM is not essential for transmitting mechanical strain from the skin to cutaneous mechanosensory neurons.