ABSTRACT
BACKGROUND: It has recently been reported that the peripheral nervous system has an important role in the hair growth and hair cycle change, which is mediated by neuropeptides. Furthermore, the expression of various growth factors and apoptosis-related molecules are important in the hair growth and hair cycle change. Therefore, it is important that the relationship between the influence of neuropeptides and expression of various factors that regulate hair growth is analysed. OBJECTIVE: The purpose of this study was to investigate the relationship between influence of neuropeptides and expression of various hair growth-related factors in the hair follicle, after pre- treatment of cultured hair follicles and dermal papilla cells with a calcitonin gene-related peptide (CGRP). METHOD: Normal human scalp samples were obtained, and anagen hair follicles and dermal papilla cells were isolated and cultured in Dulbeco?s Modified Eagle's Medium (DMEM) with several combinations of supplements, in an air incubator with an atmosphere of 5% CO2/95%. The culture plates were divided into two groups: a control group (DMEM only) and a CGRP group(10-7M CGRP dissolved in DMEM). The results were then evaluated by measuring the linear hair growth and hair follicle morphology under a light microscope. In addition, after pre-treatment of cultured hair follicles and dermal papilla cells with CGRP, we examined changes of expression of hair growth factors (FGF-7, IGF-1, VEGF), hair growth-inhibitory factors (IL-1alpha, IL-1beta) and apoptosis-related molecules (p53, caspase-3). RESULTS: The following results were obtained: 1. The CGRP did not have statistically significant effect on the rate of linear hair growth in cultured hair follicles. However, it shortened the anagen stage of the hair cycle. 2. In hair follicles, the expression of IL-1beta, a hair growth inhibitory factor, was increased in the CGRP group, compared to the control. The expression of caspase-3, an apoptosis-related molecule, was also found to be higher than the control. In dermal papilla cells, no change in morphology, expression of hair growth factors or apoptosis-related molecules were found. However the expression of IL-1beta was increased, compared to the control. CONCLUSION: From these results, we can conclude that CGRP has a growth-inhibitory effect, especially in shortening the duration of the anagen phase without affecting the linear hair growth rate. CGRP also shows a hair growth-inhibitory effect at the molecular level in hair follicles and dermal papilla cells.