L-05   NEUROPEPTIDES AND NEUROTRANSMITTERS IN HAIR GROWTH CONTROL

E MJ Peters*, A. Peter*, E. Hagen*, R. Paus+, PC Arck*. * Psychoneuroimmunology, Biomedical Research Center, Charité, Humboldt University, Berlin, Germany. + Department of Dermatology, University Hospital Eppendorf, University of Hamburg, Hamburg, Germany.

Cutaneous innervation transports a multitude of neurogenic factors into skin, many of which exert a plethora of biologic actions long transcending the framework of neuronal signaling. Neurogenic factors such as noradrenaline (NA) or substance P (SP) are now known as potent keratinocyte-growth factors and immune-modulators in skin are also produced by skin cells. Exploitation of the murine hair cycle as a model system for neuro-cutaneous interaction has revealed, that the hair follicle and adjacent structures are densely innervated by noradrenergic and peptidergic nerve fibres, and that this innervation fluctuates in a hair cycle dependent manner. Most intriguingly, during anagen-development in murine back skin, nerve fibre numbers in dermis and subcutis as well as in perifollicular networks increase profoundly and transiently as do NA and SP content and nerve fibre densities. These fluctuations are accompanied by fluctuations in mast cell nerve fiber contracts. In organ cultured early anagen back skin anagen can be promoted by adrenomimetic drugs or SP. In contrast, during late anagen and catagen development NA and SP decrease. Increased SP+ innervation as well as exogenous SP in late anagen mice perceiving stress induce premature termination of the hair growth cycle in mice. These findings open a corridor to better understanding of murine hair growth regulation and allow discussion of new therapeutic strategies in the therapy of hair growth disorders especially when associated with stress.