Effects of ultraviolet radiation on human cutaneous nerve fibres

Abstract

Quantification of cell damage induced by UV radiation provides useful information for identification of new skin care compounds with neuroprotective properties.

Neuroprotective effects of a new skin care formulation following ultraviolet exposure

“…In accordance with previous studies, we confirm here that exposure to UV irradiation significantly decreases density of nerve fibres in human skin (2,8). These UV‐induced effects are desirable in attenuating pruritus observed in certain skin diseases (for example, psoriasis) where phototherapy is a therapeutic option.…”

“…Samples were counterstained with DAPI and analysis was performed using a fluorescence microscope (Zeiss Axioskop 40; Carl Zeiss do Brasil Ltda., São Paulo, Brazil). Further details of this technique can be found elsewhere (2).…”

“…Briefly, five fields (100×) per treatment were analysed and positive cells/axons were identified using excitation in blue (488‐nm) light; images were acquired with an Image Pro Plus Capture Kit digital camera (Media Cybernetics, Silver Spring, MD, USA). Further details of the image analysis have previously been described (2). Tissue densities of cells were quantified by automatic pixel selection (Adobe Photoshop CS3); all images had a spatial resolution of 4 pixels per μm 2 .…”

“…The fibres link to mechanoreceptors (free nerve endings), thermoreceptors and nociceptors of the skin. We have recently observed reduced numbers of skin free nerve endings following ex vivo UV exposure (2). Peripheral neuropathy or damage to nerves of the peripheral nervous system is also associated with reduced nerve endings in several diseases, including sensorimotor neuropathy, neuritis and diabetic neuropathy (3).…”

Is there still a role for UV therapy in itch treatment?

“…Wallengren and Sundler showed that either UVB/A, PUVA or NB‐UVB decreased the number of intraepidermal (PGP 9.5 positive) nerve fibres (IENF) and dermal CGRP‐positive nerve fibres in non‐inflamed gluteal skin in ten patients with different skin diseases . Rodriguez et al also showed that IENF was lower in human skin samples after single ex vivo UVB or UVA irradiations.…”