Regional difference in epidermal thinning after skin denervation

Area of Science:

• Neuroscience
• Dermatology
• Tissue Biology

Background:

• Denervation of skin significantly impacts epidermal structure and function.
• Previous studies in rats showed epidermal thinning after denervation, but regional differences within the same innervation territory were unclear.
• The timeline of epidermal nerve degeneration following nerve injury in mice was not well-established.

Purpose of the Study:

• To investigate the differential effects of sciatic nerve denervation on epidermal thickness in various regions of the mouse hind foot.
• To determine the early degeneration pattern of epidermal nerves after nerve injury in mice.
• To explore the role of sensory nerves in maintaining epidermal homeostasis.

Main Methods:

• Sciatic nerve transection was performed in mice to induce denervation.
• Epidermal thickness was measured in different hind foot skin areas (interpad, heel, pad) at various time points post-transection.
• Epidermal nerve degeneration was assessed within 48 hours.
• Sciatic nerve crush injury was used to study reinnervation effects.

Main Results:

• Epidermal nerves degenerated within 48 hours after sciatic nerve transection.
• Significant and differential epidermal thinning occurred seven days post-denervation, with the interpad area showing the most pronounced reduction (34.6%).
• The heel area showed no significant thinning, while the pad area exhibited intermediate thinning.
• Reinnervation following sciatic nerve crush reversed the epidermal thinning.

Conclusions:

• Sensory nerves exert trophic influences on the epidermis, likely via diffusible factors.
• The degree of epidermal thinning after denervation is region-specific within the same innervation territory.
• These findings highlight the crucial role of neuro-cutaneous interactions in maintaining skin structure.