Properties of mouse cutaneous rapidly adapting afferents: relationship to skin viscoelasticity
Grigg, Peter ; Robichaud, Daniel R. ; Del Prete, Zaccaria
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UMass Chan Affiliations
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Keywords
*Adaptation, Physiological
Animals
Elasticity
Electric Stimulation
Electrophysiology
Logistic Models
Mechanoreceptors
Mice
Mice, Inbred C57BL
Mice, Mutant Strains
Models, Biological
Nonlinear Dynamics
Normal Distribution
Skin
*Skin Physiology
Stress, Mechanical
Tensile Strength
Time Factors
Viscosity
Life Sciences
Medicine and Health Sciences
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Abstract
When skin is stretched, stimuli experienced by a cutaneous mechanoreceptor neuron are transmitted to the nerve ending through the skin. In these experiments, we tested the hypothesis that the viscoelastic response of the skin influences the dynamic response of cutaneous rapidly adapting (RA) neurons. Cutaneous RA afferent neurons were recorded in 3 species of mice (Tsk, Pallid, and C57BL6) whose skin has different viscoelastic properties. Isolated samples of skin and nerve were stimulated mechanically with a dynamic stretch stimulus, which followed a pseudo Gaussian waveform with a bandwidth of 0-60 Hz. The mechanical response of the skin was measured as were responses of single RA cutaneous mechanoreceptor neurons. For each neuron, the strength of association between spike responses and the dynamic and static components of stimuli were determined with multiple logistic regression analysis. The viscoelastic material properties of each skin sample were determined indirectly, by creating a nonlinear (Wiener-Volterra) model of the stress-strain relationship, and using the model to predict the complex compliance (i.e., the viscoelastic material properties). The dynamic sensitivity of RA mechanoreceptor neurons in mouse hairy skin was weakly related to the viscoelastic properties of the skin. Loss modulus and phase angle were lower (indicating a decreased viscous component of response) in Tsk and Pallid than in C57BL6 mice. However, RA mechanoreceptor neurons in Tsk and Pallid skin did not differ from those in C57 skin with regard to their sensitivity to the rate of change of stress or to the rate of change of incremental strain energy. They did have a decreased sensitivity to the rate of change of tensile strain. Thus the skin samples with lower dynamic mechanical response contained neurons with a somewhat lower sensitivity to dynamic stimuli.
Source
J Neurophysiol. 2004 Aug;92(2):1236-40. Epub 2004 Mar 17. Link to article on publisher's site