C-fiber numbers increase in the epidermis and papillary dermis of dry skin-derived itch-prone model rats

Abstract

　It is difficult for nurses to know when patients experience the sensation of itching. This is especially true when it comes to older patients with advanced cognitive impairment, since they may not be able to communicate with the nursing staff. An objective identification and evaluation method in regards to itching would therefore help nurses provide appropriate care. As a first step, we have created an itch-prone rat model exhibiting an increased number of C fibers, thus mimicking the dry-skin model. To accomplish this, acetone/diethyl ether mixture/distilled water treatment was applied to the skin. We observed for the first time an increase in the number of C fibers in the papillary dermis using this treatment. A similar increase was also found in the epidermis, consistent with previous studies. The results of current study suggest that the increase in the number of C fibers in the epidermis reflects nerve elongation, while the increase of these fibers in the papillary dermis is due to a promotion of nerve branching. As there are no reports of branching at the ends of C fibers in relation to itching, further research is required in this area.